#include <std/format.h>

fn u32 format_hexadecimal(String buffer, u64 hexadecimal)
{
    u64 value = hexadecimal;
    if (value)
    {
        u8 reverse_buffer[16];
        u8 reverse_index = 0;

        while (value)
        {
            u8 digit_value = value % 16;
            u8 ascii_ch = digit_value >= 10 ? (digit_value + 'a' - 10) : (digit_value + '0');
            value /= 16;
            reverse_buffer[reverse_index] = ascii_ch;
            reverse_index += 1;
        }

        u32 index = 0;

        while (reverse_index > 0)
        {
            reverse_index -= 1;
            buffer.pointer[index] = reverse_buffer[reverse_index];
            index += 1;
        }

        return index;
    }
    else
    {
        buffer.pointer[0] = '0';
        return 1;
    }
}

fn u32 format_decimal(String buffer, u64 decimal)
{
    u64 value = decimal;
    if (value)
    {
        u8 reverse_buffer[64];
        u8 reverse_index = 0;

        while (value)
        {
            u8 digit_value = (value % 10);
            u8 ascii_ch = digit_value + '0';
            value /= 10;
            reverse_buffer[reverse_index] = ascii_ch;
            reverse_index += 1;
        }

        u32 index = 0;
        while (reverse_index > 0)
        {
            reverse_index -= 1;
            buffer.pointer[index] = reverse_buffer[reverse_index];
            index += 1;
        }

        return index;
    }
    else
    {
        buffer.pointer[0] = '0';
        return 1;
    }
}

STRUCT(SmallIntResult)
{
    u64 mantissa;
    s32 exponent;
    u8 is_small_int;
};

#define double_mantissa_bits 52
#define double_exponent_bits 11
#define double_bias 1023

#define double_pow5_bitcount 125
#define double_pow5_inv_bitcount 125

// Returns floor(log_10(2^e)); requires 0 <= e <= 1650.
fn u32 log10_pow2(const s32 e)
{
  // The first value this approximation fails for is 2^1651 which is just greater than 10^297.
  assert(e >= 0);
  assert(e <= 1650);
  return (((u32) e) * 78913) >> 18;
}

// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
fn s32 pow5_bits(const s32 e)
{
  // This approximation works up to the point that the multiplication overflows at e = 3529.
  // If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
  // than 2^9297.
  assert(e >= 0);
  assert(e <= 3528);
  return (s32) (((((u32) e) * 1217359) >> 19) + 1);
}

#define DOUBLE_POW5_INV_BITCOUNT 125
#define DOUBLE_POW5_BITCOUNT 125

#define DOUBLE_POW5_INV_TABLE_SIZE 342
#define DOUBLE_POW5_TABLE_SIZE 326

global_variable const u8 DIGIT_TABLE[200] = {
  '0','0','0','1','0','2','0','3','0','4','0','5','0','6','0','7','0','8','0','9',
  '1','0','1','1','1','2','1','3','1','4','1','5','1','6','1','7','1','8','1','9',
  '2','0','2','1','2','2','2','3','2','4','2','5','2','6','2','7','2','8','2','9',
  '3','0','3','1','3','2','3','3','3','4','3','5','3','6','3','7','3','8','3','9',
  '4','0','4','1','4','2','4','3','4','4','4','5','4','6','4','7','4','8','4','9',
  '5','0','5','1','5','2','5','3','5','4','5','5','5','6','5','7','5','8','5','9',
  '6','0','6','1','6','2','6','3','6','4','6','5','6','6','6','7','6','8','6','9',
  '7','0','7','1','7','2','7','3','7','4','7','5','7','6','7','7','7','8','7','9',
  '8','0','8','1','8','2','8','3','8','4','8','5','8','6','8','7','8','8','8','9',
  '9','0','9','1','9','2','9','3','9','4','9','5','9','6','9','7','9','8','9','9'
};

global_variable const u64 DOUBLE_POW5_INV_SPLIT[DOUBLE_POW5_INV_TABLE_SIZE][2] =
{
    {                    1u, 2305843009213693952u }, { 11068046444225730970u, 1844674407370955161u },
    {  5165088340638674453u, 1475739525896764129u }, {  7821419487252849886u, 1180591620717411303u },
    {  8824922364862649494u, 1888946593147858085u }, {  7059937891890119595u, 1511157274518286468u },
    { 13026647942995916322u, 1208925819614629174u }, {  9774590264567735146u, 1934281311383406679u },
    { 11509021026396098440u, 1547425049106725343u }, { 16585914450600699399u, 1237940039285380274u },
    { 15469416676735388068u, 1980704062856608439u }, { 16064882156130220778u, 1584563250285286751u },
    {  9162556910162266299u, 1267650600228229401u }, {  7281393426775805432u, 2028240960365167042u },
    { 16893161185646375315u, 1622592768292133633u }, {  2446482504291369283u, 1298074214633706907u },
    {  7603720821608101175u, 2076918743413931051u }, {  2393627842544570617u, 1661534994731144841u },
    { 16672297533003297786u, 1329227995784915872u }, { 11918280793837635165u, 2126764793255865396u },
    {  5845275820328197809u, 1701411834604692317u }, { 15744267100488289217u, 1361129467683753853u },
    {  3054734472329800808u, 2177807148294006166u }, { 17201182836831481939u, 1742245718635204932u },
    {  6382248639981364905u, 1393796574908163946u }, {  2832900194486363201u, 2230074519853062314u },
    {  5955668970331000884u, 1784059615882449851u }, {  1075186361522890384u, 1427247692705959881u },
    { 12788344622662355584u, 2283596308329535809u }, { 13920024512871794791u, 1826877046663628647u },
    {  3757321980813615186u, 1461501637330902918u }, { 10384555214134712795u, 1169201309864722334u },
    {  5547241898389809503u, 1870722095783555735u }, {  4437793518711847602u, 1496577676626844588u },
    { 10928932444453298728u, 1197262141301475670u }, { 17486291911125277965u, 1915619426082361072u },
    {  6610335899416401726u, 1532495540865888858u }, { 12666966349016942027u, 1225996432692711086u },
    { 12888448528943286597u, 1961594292308337738u }, { 17689456452638449924u, 1569275433846670190u },
    { 14151565162110759939u, 1255420347077336152u }, {  7885109000409574610u, 2008672555323737844u },
    {  9997436015069570011u, 1606938044258990275u }, {  7997948812055656009u, 1285550435407192220u },
    { 12796718099289049614u, 2056880696651507552u }, {  2858676849947419045u, 1645504557321206042u },
    { 13354987924183666206u, 1316403645856964833u }, { 17678631863951955605u, 2106245833371143733u },
    {  3074859046935833515u, 1684996666696914987u }, { 13527933681774397782u, 1347997333357531989u },
    { 10576647446613305481u, 2156795733372051183u }, { 15840015586774465031u, 1725436586697640946u },
    {  8982663654677661702u, 1380349269358112757u }, { 18061610662226169046u, 2208558830972980411u },
    { 10759939715039024913u, 1766847064778384329u }, { 12297300586773130254u, 1413477651822707463u },
    { 15986332124095098083u, 2261564242916331941u }, {  9099716884534168143u, 1809251394333065553u },
    { 14658471137111155161u, 1447401115466452442u }, {  4348079280205103483u, 1157920892373161954u },
    { 14335624477811986218u, 1852673427797059126u }, {  7779150767507678651u, 1482138742237647301u },
    {  2533971799264232598u, 1185710993790117841u }, { 15122401323048503126u, 1897137590064188545u },
    { 12097921058438802501u, 1517710072051350836u }, {  5988988032009131678u, 1214168057641080669u },
    { 16961078480698431330u, 1942668892225729070u }, { 13568862784558745064u, 1554135113780583256u },
    {  7165741412905085728u, 1243308091024466605u }, { 11465186260648137165u, 1989292945639146568u },
    { 16550846638002330379u, 1591434356511317254u }, { 16930026125143774626u, 1273147485209053803u },
    {  4951948911778577463u, 2037035976334486086u }, {   272210314680951647u, 1629628781067588869u },
    {  3907117066486671641u, 1303703024854071095u }, {  6251387306378674625u, 2085924839766513752u },
    { 16069156289328670670u, 1668739871813211001u }, {  9165976216721026213u, 1334991897450568801u },
    {  7286864317269821294u, 2135987035920910082u }, { 16897537898041588005u, 1708789628736728065u },
    { 13518030318433270404u, 1367031702989382452u }, {  6871453250525591353u, 2187250724783011924u },
    {  9186511415162383406u, 1749800579826409539u }, { 11038557946871817048u, 1399840463861127631u },
    { 10282995085511086630u, 2239744742177804210u }, {  8226396068408869304u, 1791795793742243368u },
    { 13959814484210916090u, 1433436634993794694u }, { 11267656730511734774u, 2293498615990071511u },
    {  5324776569667477496u, 1834798892792057209u }, {  7949170070475892320u, 1467839114233645767u },
    { 17427382500606444826u, 1174271291386916613u }, {  5747719112518849781u, 1878834066219066582u },
    { 15666221734240810795u, 1503067252975253265u }, { 12532977387392648636u, 1202453802380202612u },
    {  5295368560860596524u, 1923926083808324180u }, {  4236294848688477220u, 1539140867046659344u },
    {  7078384693692692099u, 1231312693637327475u }, { 11325415509908307358u, 1970100309819723960u },
    {  9060332407926645887u, 1576080247855779168u }, { 14626963555825137356u, 1260864198284623334u },
    { 12335095245094488799u, 2017382717255397335u }, {  9868076196075591040u, 1613906173804317868u },
    { 15273158586344293478u, 1291124939043454294u }, { 13369007293925138595u, 2065799902469526871u },
    {  7005857020398200553u, 1652639921975621497u }, { 16672732060544291412u, 1322111937580497197u },
    { 11918976037903224966u, 2115379100128795516u }, {  5845832015580669650u, 1692303280103036413u },
    { 12055363241948356366u, 1353842624082429130u }, {   841837113407818570u, 2166148198531886609u },
    {  4362818505468165179u, 1732918558825509287u }, { 14558301248600263113u, 1386334847060407429u },
    { 12225235553534690011u, 2218135755296651887u }, {  2401490813343931363u, 1774508604237321510u },
    {  1921192650675145090u, 1419606883389857208u }, { 17831303500047873437u, 2271371013423771532u },
    {  6886345170554478103u, 1817096810739017226u }, {  1819727321701672159u, 1453677448591213781u },
    { 16213177116328979020u, 1162941958872971024u }, { 14873036941900635463u, 1860707134196753639u },
    { 15587778368262418694u, 1488565707357402911u }, {  8780873879868024632u, 1190852565885922329u },
    {  2981351763563108441u, 1905364105417475727u }, { 13453127855076217722u, 1524291284333980581u },
    {  7073153469319063855u, 1219433027467184465u }, { 11317045550910502167u, 1951092843947495144u },
    { 12742985255470312057u, 1560874275157996115u }, { 10194388204376249646u, 1248699420126396892u },
    {  1553625868034358140u, 1997919072202235028u }, {  8621598323911307159u, 1598335257761788022u },
    { 17965325103354776697u, 1278668206209430417u }, { 13987124906400001422u, 2045869129935088668u },
    {   121653480894270168u, 1636695303948070935u }, {    97322784715416134u, 1309356243158456748u },
    { 14913111714512307107u, 2094969989053530796u }, {  8241140556867935363u, 1675975991242824637u },
    { 17660958889720079260u, 1340780792994259709u }, { 17189487779326395846u, 2145249268790815535u },
    { 13751590223461116677u, 1716199415032652428u }, { 18379969808252713988u, 1372959532026121942u },
    { 14650556434236701088u, 2196735251241795108u }, {   652398703163629901u, 1757388200993436087u },
    { 11589965406756634890u, 1405910560794748869u }, {  7475898206584884855u, 2249456897271598191u },
    {  2291369750525997561u, 1799565517817278553u }, {  9211793429904618695u, 1439652414253822842u },
    { 18428218302589300235u, 2303443862806116547u }, {  7363877012587619542u, 1842755090244893238u },
    { 13269799239553916280u, 1474204072195914590u }, { 10615839391643133024u, 1179363257756731672u },
    {  2227947767661371545u, 1886981212410770676u }, { 16539753473096738529u, 1509584969928616540u },
    { 13231802778477390823u, 1207667975942893232u }, {  6413489186596184024u, 1932268761508629172u },
    { 16198837793502678189u, 1545815009206903337u }, {  5580372605318321905u, 1236652007365522670u },
    {  8928596168509315048u, 1978643211784836272u }, { 18210923379033183008u, 1582914569427869017u },
    {  7190041073742725760u, 1266331655542295214u }, {   436019273762630246u, 2026130648867672343u },
    {  7727513048493924843u, 1620904519094137874u }, {  9871359253537050198u, 1296723615275310299u },
    {  4726128361433549347u, 2074757784440496479u }, {  7470251503888749801u, 1659806227552397183u },
    { 13354898832594820487u, 1327844982041917746u }, { 13989140502667892133u, 2124551971267068394u },
    { 14880661216876224029u, 1699641577013654715u }, { 11904528973500979224u, 1359713261610923772u },
    {  4289851098633925465u, 2175541218577478036u }, { 18189276137874781665u, 1740432974861982428u },
    {  3483374466074094362u, 1392346379889585943u }, {  1884050330976640656u, 2227754207823337509u },
    {  5196589079523222848u, 1782203366258670007u }, { 15225317707844309248u, 1425762693006936005u },
    {  5913764258841343181u, 2281220308811097609u }, {  8420360221814984868u, 1824976247048878087u },
    { 17804334621677718864u, 1459980997639102469u }, { 17932816512084085415u, 1167984798111281975u },
    { 10245762345624985047u, 1868775676978051161u }, {  4507261061758077715u, 1495020541582440929u },
    {  7295157664148372495u, 1196016433265952743u }, {  7982903447895485668u, 1913626293225524389u },
    { 10075671573058298858u, 1530901034580419511u }, {  4371188443704728763u, 1224720827664335609u },
    { 14372599139411386667u, 1959553324262936974u }, { 15187428126271019657u, 1567642659410349579u },
    { 15839291315758726049u, 1254114127528279663u }, {  3206773216762499739u, 2006582604045247462u },
    { 13633465017635730761u, 1605266083236197969u }, { 14596120828850494932u, 1284212866588958375u },
    {  4907049252451240275u, 2054740586542333401u }, {   236290587219081897u, 1643792469233866721u },
    { 14946427728742906810u, 1315033975387093376u }, { 16535586736504830250u, 2104054360619349402u },
    {  5849771759720043554u, 1683243488495479522u }, { 15747863852001765813u, 1346594790796383617u },
    { 10439186904235184007u, 2154551665274213788u }, { 15730047152871967852u, 1723641332219371030u },
    { 12584037722297574282u, 1378913065775496824u }, {  9066413911450387881u, 2206260905240794919u },
    { 10942479943902220628u, 1765008724192635935u }, {  8753983955121776503u, 1412006979354108748u },
    { 10317025513452932081u, 2259211166966573997u }, {   874922781278525018u, 1807368933573259198u },
    {  8078635854506640661u, 1445895146858607358u }, { 13841606313089133175u, 1156716117486885886u },
    { 14767872471458792434u, 1850745787979017418u }, {   746251532941302978u, 1480596630383213935u },
    {   597001226353042382u, 1184477304306571148u }, { 15712597221132509104u, 1895163686890513836u },
    {  8880728962164096960u, 1516130949512411069u }, { 10793931984473187891u, 1212904759609928855u },
    { 17270291175157100626u, 1940647615375886168u }, {  2748186495899949531u, 1552518092300708935u },
    {  2198549196719959625u, 1242014473840567148u }, { 18275073973719576693u, 1987223158144907436u },
    { 10930710364233751031u, 1589778526515925949u }, { 12433917106128911148u, 1271822821212740759u },
    {  8826220925580526867u, 2034916513940385215u }, {  7060976740464421494u, 1627933211152308172u },
    { 16716827836597268165u, 1302346568921846537u }, { 11989529279587987770u, 2083754510274954460u },
    {  9591623423670390216u, 1667003608219963568u }, { 15051996368420132820u, 1333602886575970854u },
    { 13015147745246481542u, 2133764618521553367u }, {  3033420566713364587u, 1707011694817242694u },
    {  6116085268112601993u, 1365609355853794155u }, {  9785736428980163188u, 2184974969366070648u },
    { 15207286772667951197u, 1747979975492856518u }, {  1097782973908629988u, 1398383980394285215u },
    {  1756452758253807981u, 2237414368630856344u }, {  5094511021344956708u, 1789931494904685075u },
    {  4075608817075965366u, 1431945195923748060u }, {  6520974107321544586u, 2291112313477996896u },
    {  1527430471115325346u, 1832889850782397517u }, { 12289990821117991246u, 1466311880625918013u },
    { 17210690286378213644u, 1173049504500734410u }, {  9090360384495590213u, 1876879207201175057u },
    { 18340334751822203140u, 1501503365760940045u }, { 14672267801457762512u, 1201202692608752036u },
    { 16096930852848599373u, 1921924308174003258u }, {  1809498238053148529u, 1537539446539202607u },
    { 12515645034668249793u, 1230031557231362085u }, {  1578287981759648052u, 1968050491570179337u },
    { 12330676829633449412u, 1574440393256143469u }, { 13553890278448669853u, 1259552314604914775u },
    {  3239480371808320148u, 2015283703367863641u }, { 17348979556414297411u, 1612226962694290912u },
    {  6500486015647617283u, 1289781570155432730u }, { 10400777625036187652u, 2063650512248692368u },
    { 15699319729512770768u, 1650920409798953894u }, { 16248804598352126938u, 1320736327839163115u },
    {  7551343283653851484u, 2113178124542660985u }, {  6041074626923081187u, 1690542499634128788u },
    { 12211557331022285596u, 1352433999707303030u }, {  1091747655926105338u, 2163894399531684849u },
    {  4562746939482794594u, 1731115519625347879u }, {  7339546366328145998u, 1384892415700278303u },
    {  8053925371383123274u, 2215827865120445285u }, {  6443140297106498619u, 1772662292096356228u },
    { 12533209867169019542u, 1418129833677084982u }, {  5295740528502789974u, 2269007733883335972u },
    { 15304638867027962949u, 1815206187106668777u }, {  4865013464138549713u, 1452164949685335022u },
    { 14960057215536570740u, 1161731959748268017u }, {  9178696285890871890u, 1858771135597228828u },
    { 14721654658196518159u, 1487016908477783062u }, {  4398626097073393881u, 1189613526782226450u },
    {  7037801755317430209u, 1903381642851562320u }, {  5630241404253944167u, 1522705314281249856u },
    {   814844308661245011u, 1218164251424999885u }, {  1303750893857992017u, 1949062802279999816u },
    { 15800395974054034906u, 1559250241823999852u }, {  5261619149759407279u, 1247400193459199882u },
    { 12107939454356961969u, 1995840309534719811u }, {  5997002748743659252u, 1596672247627775849u },
    {  8486951013736837725u, 1277337798102220679u }, {  2511075177753209390u, 2043740476963553087u },
    { 13076906586428298482u, 1634992381570842469u }, { 14150874083884549109u, 1307993905256673975u },
    {  4194654460505726958u, 2092790248410678361u }, { 18113118827372222859u, 1674232198728542688u },
    {  3422448617672047318u, 1339385758982834151u }, { 16543964232501006678u, 2143017214372534641u },
    {  9545822571258895019u, 1714413771498027713u }, { 15015355686490936662u, 1371531017198422170u },
    {  5577825024675947042u, 2194449627517475473u }, { 11840957649224578280u, 1755559702013980378u },
    { 16851463748863483271u, 1404447761611184302u }, { 12204946739213931940u, 2247116418577894884u },
    { 13453306206113055875u, 1797693134862315907u }, {  3383947335406624054u, 1438154507889852726u },
    { 16482362180876329456u, 2301047212623764361u }, {  9496540929959153242u, 1840837770099011489u },
    { 11286581558709232917u, 1472670216079209191u }, {  5339916432225476010u, 1178136172863367353u },
    {  4854517476818851293u, 1885017876581387765u }, {  3883613981455081034u, 1508014301265110212u },
    { 14174937629389795797u, 1206411441012088169u }, { 11611853762797942306u, 1930258305619341071u },
    {  5600134195496443521u, 1544206644495472857u }, { 15548153800622885787u, 1235365315596378285u },
    {  6430302007287065643u, 1976584504954205257u }, { 16212288050055383484u, 1581267603963364205u },
    { 12969830440044306787u, 1265014083170691364u }, {  9683682259845159889u, 2024022533073106183u },
    { 15125643437359948558u, 1619218026458484946u }, {  8411165935146048523u, 1295374421166787957u },
    { 17147214310975587960u, 2072599073866860731u }, { 10028422634038560045u, 1658079259093488585u },
    {  8022738107230848036u, 1326463407274790868u }, {  9147032156827446534u, 2122341451639665389u },
    { 11006974540203867551u, 1697873161311732311u }, {  5116230817421183718u, 1358298529049385849u },
    { 15564666937357714594u, 2173277646479017358u }, {  1383687105660440706u, 1738622117183213887u },
    { 12174996128754083534u, 1390897693746571109u }, {  8411947361780802685u, 2225436309994513775u },
    {  6729557889424642148u, 1780349047995611020u }, {  5383646311539713719u, 1424279238396488816u },
    {  1235136468979721303u, 2278846781434382106u }, { 15745504434151418335u, 1823077425147505684u },
    { 16285752362063044992u, 1458461940118004547u }, {  5649904260166615347u, 1166769552094403638u },
    {  5350498001524674232u, 1866831283351045821u }, {   591049586477829062u, 1493465026680836657u },
    { 11540886113407994219u, 1194772021344669325u }, {    18673707743239135u, 1911635234151470921u },
    { 14772334225162232601u, 1529308187321176736u }, {  8128518565387875758u, 1223446549856941389u },
    {  1937583260394870242u, 1957514479771106223u }, {  8928764237799716840u, 1566011583816884978u },
    { 14521709019723594119u, 1252809267053507982u }, {  8477339172590109297u, 2004494827285612772u },
    { 17849917782297818407u, 1603595861828490217u }, {  6901236596354434079u, 1282876689462792174u },
    { 18420676183650915173u, 2052602703140467478u }, {  3668494502695001169u, 1642082162512373983u },
    { 10313493231639821582u, 1313665730009899186u }, {  9122891541139893884u, 2101865168015838698u },
    { 14677010862395735754u, 1681492134412670958u }, {   673562245690857633u, 1345193707530136767u }
};
// Best case: use 128-bit type.
fn u64 mul_shift_64(const u64 m, const u64* const mul, const s32 j)
{
    const u128 b0 = u128_u64_mul(u128_from_u64(m), mul[0]);
    const u128 b2 = u128_u64_mul(u128_from_u64(m), mul[1]);
    return u64_from_u128(u128_shift_right(u128_u64_add(b2, u128_shift_right_by_64(b0)),  j - 64));
    // return (u64) (((b0 >> 64) + b2) >> (j - 64));
}

fn u64 mul_shift_all_64(const u64 m, const u64* const mul, const s32 j, u64* const vp, u64* const vm, const u32 mmShift)
{
    *vp = mul_shift_64(4 * m + 2, mul, j);
    *vm = mul_shift_64(4 * m - 1 - mmShift, mul, j);
    return mul_shift_64(4 * m, mul, j);
}

// Returns e == 0 ? 1 : [log_2(5^e)]; requires 0 <= e <= 3528.
// fn s32 log2_pow5(const s32 e)
// {
//   // This approximation works up to the point that the multiplication overflows at e = 3529.
//   // If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
//   // than 2^9297.
//   assert(e >= 0);
//   assert(e <= 3528);
//   return (s32) ((((u32) e) * 1217359) >> 19);
// }
// Returns floor(log_10(5^e)); requires 0 <= e <= 2620.
fn u32 log10_pow5(const s32 e) {
  // The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
  assert(e >= 0);
  assert(e <= 2620);
  return (((u32) e) * 732923) >> 20;
}

global_variable const u64 DOUBLE_POW5_SPLIT[DOUBLE_POW5_TABLE_SIZE][2] =
{
    {                    0u, 1152921504606846976u }, {                    0u, 1441151880758558720u },
    {                    0u, 1801439850948198400u }, {                    0u, 2251799813685248000u },
    {                    0u, 1407374883553280000u }, {                    0u, 1759218604441600000u },
    {                    0u, 2199023255552000000u }, {                    0u, 1374389534720000000u },
    {                    0u, 1717986918400000000u }, {                    0u, 2147483648000000000u },
    {                    0u, 1342177280000000000u }, {                    0u, 1677721600000000000u },
    {                    0u, 2097152000000000000u }, {                    0u, 1310720000000000000u },
    {                    0u, 1638400000000000000u }, {                    0u, 2048000000000000000u },
    {                    0u, 1280000000000000000u }, {                    0u, 1600000000000000000u },
    {                    0u, 2000000000000000000u }, {                    0u, 1250000000000000000u },
    {                    0u, 1562500000000000000u }, {                    0u, 1953125000000000000u },
    {                    0u, 1220703125000000000u }, {                    0u, 1525878906250000000u },
    {                    0u, 1907348632812500000u }, {                    0u, 1192092895507812500u },
    {                    0u, 1490116119384765625u }, {  4611686018427387904u, 1862645149230957031u },
    {  9799832789158199296u, 1164153218269348144u }, { 12249790986447749120u, 1455191522836685180u },
    { 15312238733059686400u, 1818989403545856475u }, { 14528612397897220096u, 2273736754432320594u },
    { 13692068767113150464u, 1421085471520200371u }, { 12503399940464050176u, 1776356839400250464u },
    { 15629249925580062720u, 2220446049250313080u }, {  9768281203487539200u, 1387778780781445675u },
    {  7598665485932036096u, 1734723475976807094u }, {   274959820560269312u, 2168404344971008868u },
    {  9395221924704944128u, 1355252715606880542u }, {  2520655369026404352u, 1694065894508600678u },
    { 12374191248137781248u, 2117582368135750847u }, { 14651398557727195136u, 1323488980084844279u },
    { 13702562178731606016u, 1654361225106055349u }, {  3293144668132343808u, 2067951531382569187u },
    { 18199116482078572544u, 1292469707114105741u }, {  8913837547316051968u, 1615587133892632177u },
    { 15753982952572452864u, 2019483917365790221u }, { 12152082354571476992u, 1262177448353618888u },
    { 15190102943214346240u, 1577721810442023610u }, {  9764256642163156992u, 1972152263052529513u },
    { 17631875447420442880u, 1232595164407830945u }, {  8204786253993389888u, 1540743955509788682u },
    {  1032610780636961552u, 1925929944387235853u }, {  2951224747111794922u, 1203706215242022408u },
    {  3689030933889743652u, 1504632769052528010u }, { 13834660704216955373u, 1880790961315660012u },
    { 17870034976990372916u, 1175494350822287507u }, { 17725857702810578241u, 1469367938527859384u },
    {  3710578054803671186u, 1836709923159824231u }, {    26536550077201078u, 2295887403949780289u },
    { 11545800389866720434u, 1434929627468612680u }, { 14432250487333400542u, 1793662034335765850u },
    {  8816941072311974870u, 2242077542919707313u }, { 17039803216263454053u, 1401298464324817070u },
    { 12076381983474541759u, 1751623080406021338u }, {  5872105442488401391u, 2189528850507526673u },
    { 15199280947623720629u, 1368455531567204170u }, {  9775729147674874978u, 1710569414459005213u },
    { 16831347453020981627u, 2138211768073756516u }, {  1296220121283337709u, 1336382355046097823u },
    { 15455333206886335848u, 1670477943807622278u }, { 10095794471753144002u, 2088097429759527848u },
    {  6309871544845715001u, 1305060893599704905u }, { 12499025449484531656u, 1631326116999631131u },
    { 11012095793428276666u, 2039157646249538914u }, { 11494245889320060820u, 1274473528905961821u },
    {   532749306367912313u, 1593091911132452277u }, {  5277622651387278295u, 1991364888915565346u },
    {  7910200175544436838u, 1244603055572228341u }, { 14499436237857933952u, 1555753819465285426u },
    {  8900923260467641632u, 1944692274331606783u }, { 12480606065433357876u, 1215432671457254239u },
    { 10989071563364309441u, 1519290839321567799u }, {  9124653435777998898u, 1899113549151959749u },
    {  8008751406574943263u, 1186945968219974843u }, {  5399253239791291175u, 1483682460274968554u },
    { 15972438586593889776u, 1854603075343710692u }, {   759402079766405302u, 1159126922089819183u },
    { 14784310654990170340u, 1448908652612273978u }, {  9257016281882937117u, 1811135815765342473u },
    { 16182956370781059300u, 2263919769706678091u }, {  7808504722524468110u, 1414949856066673807u },
    {  5148944884728197234u, 1768687320083342259u }, {  1824495087482858639u, 2210859150104177824u },
    {  1140309429676786649u, 1381786968815111140u }, {  1425386787095983311u, 1727233711018888925u },
    {  6393419502297367043u, 2159042138773611156u }, { 13219259225790630210u, 1349401336733506972u },
    { 16524074032238287762u, 1686751670916883715u }, { 16043406521870471799u, 2108439588646104644u },
    {   803757039314269066u, 1317774742903815403u }, { 14839754354425000045u, 1647218428629769253u },
    {  4714634887749086344u, 2059023035787211567u }, {  9864175832484260821u, 1286889397367007229u },
    { 16941905809032713930u, 1608611746708759036u }, {  2730638187581340797u, 2010764683385948796u },
    { 10930020904093113806u, 1256727927116217997u }, { 18274212148543780162u, 1570909908895272496u },
    {  4396021111970173586u, 1963637386119090621u }, {  5053356204195052443u, 1227273366324431638u },
    { 15540067292098591362u, 1534091707905539547u }, { 14813398096695851299u, 1917614634881924434u },
    { 13870059828862294966u, 1198509146801202771u }, { 12725888767650480803u, 1498136433501503464u },
    { 15907360959563101004u, 1872670541876879330u }, { 14553786618154326031u, 1170419088673049581u },
    {  4357175217410743827u, 1463023860841311977u }, { 10058155040190817688u, 1828779826051639971u },
    {  7961007781811134206u, 2285974782564549964u }, { 14199001900486734687u, 1428734239102843727u },
    { 13137066357181030455u, 1785917798878554659u }, { 11809646928048900164u, 2232397248598193324u },
    { 16604401366885338411u, 1395248280373870827u }, { 16143815690179285109u, 1744060350467338534u },
    { 10956397575869330579u, 2180075438084173168u }, {  6847748484918331612u, 1362547148802608230u },
    { 17783057643002690323u, 1703183936003260287u }, { 17617136035325974999u, 2128979920004075359u },
    { 17928239049719816230u, 1330612450002547099u }, { 17798612793722382384u, 1663265562503183874u },
    { 13024893955298202172u, 2079081953128979843u }, {  5834715712847682405u, 1299426220705612402u },
    { 16516766677914378815u, 1624282775882015502u }, { 11422586310538197711u, 2030353469852519378u },
    { 11750802462513761473u, 1268970918657824611u }, { 10076817059714813937u, 1586213648322280764u },
    { 12596021324643517422u, 1982767060402850955u }, {  5566670318688504437u, 1239229412751781847u },
    {  2346651879933242642u, 1549036765939727309u }, {  7545000868343941206u, 1936295957424659136u },
    {  4715625542714963254u, 1210184973390411960u }, {  5894531928393704067u, 1512731216738014950u },
    { 16591536947346905892u, 1890914020922518687u }, { 17287239619732898039u, 1181821263076574179u },
    { 16997363506238734644u, 1477276578845717724u }, {  2799960309088866689u, 1846595723557147156u },
    { 10973347230035317489u, 1154122327223216972u }, { 13716684037544146861u, 1442652909029021215u },
    { 12534169028502795672u, 1803316136286276519u }, { 11056025267201106687u, 2254145170357845649u },
    { 18439230838069161439u, 1408840731473653530u }, { 13825666510731675991u, 1761050914342066913u },
    {  3447025083132431277u, 2201313642927583642u }, {  6766076695385157452u, 1375821026829739776u },
    {  8457595869231446815u, 1719776283537174720u }, { 10571994836539308519u, 2149720354421468400u },
    {  6607496772837067824u, 1343575221513417750u }, { 17482743002901110588u, 1679469026891772187u },
    { 17241742735199000331u, 2099336283614715234u }, { 15387775227926763111u, 1312085177259197021u },
    {  5399660979626290177u, 1640106471573996277u }, { 11361262242960250625u, 2050133089467495346u },
    { 11712474920277544544u, 1281333180917184591u }, { 10028907631919542777u, 1601666476146480739u },
    {  7924448521472040567u, 2002083095183100924u }, { 14176152362774801162u, 1251301934489438077u },
    {  3885132398186337741u, 1564127418111797597u }, {  9468101516160310080u, 1955159272639746996u },
    { 15140935484454969608u, 1221974545399841872u }, {   479425281859160394u, 1527468181749802341u },
    {  5210967620751338397u, 1909335227187252926u }, { 17091912818251750210u, 1193334516992033078u },
    { 12141518985959911954u, 1491668146240041348u }, { 15176898732449889943u, 1864585182800051685u },
    { 11791404716994875166u, 1165365739250032303u }, { 10127569877816206054u, 1456707174062540379u },
    {  8047776328842869663u, 1820883967578175474u }, {   836348374198811271u, 2276104959472719343u },
    {  7440246761515338900u, 1422565599670449589u }, { 13911994470321561530u, 1778206999588061986u },
    {  8166621051047176104u, 2222758749485077483u }, {  2798295147690791113u, 1389224218428173427u },
    { 17332926989895652603u, 1736530273035216783u }, { 17054472718942177850u, 2170662841294020979u },
    {  8353202440125167204u, 1356664275808763112u }, { 10441503050156459005u, 1695830344760953890u },
    {  3828506775840797949u, 2119787930951192363u }, {    86973725686804766u, 1324867456844495227u },
    { 13943775212390669669u, 1656084321055619033u }, {  3594660960206173375u, 2070105401319523792u },
    {  2246663100128858359u, 1293815875824702370u }, { 12031700912015848757u, 1617269844780877962u },
    {  5816254103165035138u, 2021587305976097453u }, {  5941001823691840913u, 1263492066235060908u },
    {  7426252279614801142u, 1579365082793826135u }, {  4671129331091113523u, 1974206353492282669u },
    {  5225298841145639904u, 1233878970932676668u }, {  6531623551432049880u, 1542348713665845835u },
    {  3552843420862674446u, 1927935892082307294u }, { 16055585193321335241u, 1204959932551442058u },
    { 10846109454796893243u, 1506199915689302573u }, { 18169322836923504458u, 1882749894611628216u },
    { 11355826773077190286u, 1176718684132267635u }, {  9583097447919099954u, 1470898355165334544u },
    { 11978871809898874942u, 1838622943956668180u }, { 14973589762373593678u, 2298278679945835225u },
    {  2440964573842414192u, 1436424174966147016u }, {  3051205717303017741u, 1795530218707683770u },
    { 13037379183483547984u, 2244412773384604712u }, {  8148361989677217490u, 1402757983365377945u },
    { 14797138505523909766u, 1753447479206722431u }, { 13884737113477499304u, 2191809349008403039u },
    { 15595489723564518921u, 1369880843130251899u }, { 14882676136028260747u, 1712351053912814874u },
    {  9379973133180550126u, 2140438817391018593u }, { 17391698254306313589u, 1337774260869386620u },
    {  3292878744173340370u, 1672217826086733276u }, {  4116098430216675462u, 2090272282608416595u },
    {   266718509671728212u, 1306420176630260372u }, {   333398137089660265u, 1633025220787825465u },
    {  5028433689789463235u, 2041281525984781831u }, { 10060300083759496378u, 1275800953740488644u },
    { 12575375104699370472u, 1594751192175610805u }, {  1884160825592049379u, 1993438990219513507u },
    { 17318501580490888525u, 1245899368887195941u }, {  7813068920331446945u, 1557374211108994927u },
    {  5154650131986920777u, 1946717763886243659u }, {   915813323278131534u, 1216698602428902287u },
    { 14979824709379828129u, 1520873253036127858u }, {  9501408849870009354u, 1901091566295159823u },
    { 12855909558809837702u, 1188182228934474889u }, {  2234828893230133415u, 1485227786168093612u },
    {  2793536116537666769u, 1856534732710117015u }, {  8663489100477123587u, 1160334207943823134u },
    {  1605989338741628675u, 1450417759929778918u }, { 11230858710281811652u, 1813022199912223647u },
    {  9426887369424876662u, 2266277749890279559u }, { 12809333633531629769u, 1416423593681424724u },
    { 16011667041914537212u, 1770529492101780905u }, {  6179525747111007803u, 2213161865127226132u },
    { 13085575628799155685u, 1383226165704516332u }, { 16356969535998944606u, 1729032707130645415u },
    { 15834525901571292854u, 2161290883913306769u }, {  2979049660840976177u, 1350806802445816731u },
    { 17558870131333383934u, 1688508503057270913u }, {  8113529608884566205u, 2110635628821588642u },
    {  9682642023980241782u, 1319147268013492901u }, { 16714988548402690132u, 1648934085016866126u },
    { 11670363648648586857u, 2061167606271082658u }, { 11905663298832754689u, 1288229753919426661u },
    {  1047021068258779650u, 1610287192399283327u }, { 15143834390605638274u, 2012858990499104158u },
    {  4853210475701136017u, 1258036869061940099u }, {  1454827076199032118u, 1572546086327425124u },
    {  1818533845248790147u, 1965682607909281405u }, {  3442426662494187794u, 1228551629943300878u },
    { 13526405364972510550u, 1535689537429126097u }, {  3072948650933474476u, 1919611921786407622u },
    { 15755650962115585259u, 1199757451116504763u }, { 15082877684217093670u, 1499696813895630954u },
    {  9630225068416591280u, 1874621017369538693u }, {  8324733676974063502u, 1171638135855961683u },
    {  5794231077790191473u, 1464547669819952104u }, {  7242788847237739342u, 1830684587274940130u },
    { 18276858095901949986u, 2288355734093675162u }, { 16034722328366106645u, 1430222333808546976u },
    {  1596658836748081690u, 1787777917260683721u }, {  6607509564362490017u, 2234722396575854651u },
    {  1823850468512862308u, 1396701497859909157u }, {  6891499104068465790u, 1745876872324886446u },
    { 17837745916940358045u, 2182346090406108057u }, {  4231062170446641922u, 1363966306503817536u },
    {  5288827713058302403u, 1704957883129771920u }, {  6611034641322878003u, 2131197353912214900u },
    { 13355268687681574560u, 1331998346195134312u }, { 16694085859601968200u, 1664997932743917890u },
    { 11644235287647684442u, 2081247415929897363u }, {  4971804045566108824u, 1300779634956185852u },
    {  6214755056957636030u, 1625974543695232315u }, {  3156757802769657134u, 2032468179619040394u },
    {  6584659645158423613u, 1270292612261900246u }, { 17454196593302805324u, 1587865765327375307u },
    { 17206059723201118751u, 1984832206659219134u }, {  6142101308573311315u, 1240520129162011959u },
    {  3065940617289251240u, 1550650161452514949u }, {  8444111790038951954u, 1938312701815643686u },
    {   665883850346957067u, 1211445438634777304u }, {   832354812933696334u, 1514306798293471630u },
    { 10263815553021896226u, 1892883497866839537u }, { 17944099766707154901u, 1183052186166774710u },
    { 13206752671529167818u, 1478815232708468388u }, { 16508440839411459773u, 1848519040885585485u },
    { 12623618533845856310u, 1155324400553490928u }, { 15779523167307320387u, 1444155500691863660u },
    {  1277659885424598868u, 1805194375864829576u }, {  1597074856780748586u, 2256492969831036970u },
    {  5609857803915355770u, 1410308106144398106u }, { 16235694291748970521u, 1762885132680497632u },
    {  1847873790976661535u, 2203606415850622041u }, { 12684136165428883219u, 1377254009906638775u },
    { 11243484188358716120u, 1721567512383298469u }, {   219297180166231438u, 2151959390479123087u },
    {  7054589765244976505u, 1344974619049451929u }, { 13429923224983608535u, 1681218273811814911u },
    { 12175718012802122765u, 2101522842264768639u }, { 14527352785642408584u, 1313451776415480399u },
    { 13547504963625622826u, 1641814720519350499u }, { 12322695186104640628u, 2052268400649188124u },
    { 16925056528170176201u, 1282667750405742577u }, {  7321262604930556539u, 1603334688007178222u },
    { 18374950293017971482u, 2004168360008972777u }, {  4566814905495150320u, 1252605225005607986u },
    { 14931890668723713708u, 1565756531257009982u }, {  9441491299049866327u, 1957195664071262478u },
    {  1289246043478778550u, 1223247290044539049u }, {  6223243572775861092u, 1529059112555673811u },
    {  3167368447542438461u, 1911323890694592264u }, {  1979605279714024038u, 1194577431684120165u },
    {  7086192618069917952u, 1493221789605150206u }, { 18081112809442173248u, 1866527237006437757u },
    { 13606538515115052232u, 1166579523129023598u }, {  7784801107039039482u, 1458224403911279498u },
    {   507629346944023544u, 1822780504889099373u }, {  5246222702107417334u, 2278475631111374216u },
    {  3278889188817135834u, 1424047269444608885u }, {  8710297504448807696u, 1780059086805761106u }
};

fn uint32_t pow5_factor(uint64_t value)
{
  const uint64_t m_inv_5 = 14757395258967641293u; // 5 * m_inv_5 = 1 (mod 2^64)
  const uint64_t n_div_5 = 3689348814741910323u;  // #{ n | n = 0 (mod 2^64) } = 2^64 / 5
  uint32_t count = 0;
  for (;;) {
    assert(value != 0);
    value *= m_inv_5;
    if (value > n_div_5)
      break;
    ++count;
  }
  return count;
}

// Returns true if value is divisible by 5^p.
fn u8 multiple_of_power_of_5(const uint64_t value, const uint32_t p)
{
  // I tried a case distinction on p, but there was no performance difference.
  return pow5_factor(value) >= p;
}

// Returns true if value is divisible by 2^p.
fn u8 multiple_of_power_of_2(const u64 value, const u32 p) {
  assert(value != 0);
  assert(p < 64);
  // __builtin_ctzll doesn't appear to be faster here.
  return (value & ((1ull << p) - 1)) == 0;
}

fn inline uint64_t div5(const uint64_t x) {
  return x / 5;
}

fn inline uint64_t div10(const uint64_t x) {
  return x / 10;
}

fn inline uint64_t div100(const uint64_t x) {
  return x / 100;
}

fn inline uint64_t div1e8(const uint64_t x) {
  return x / 100000000;
}

fn inline uint64_t div1e9(const uint64_t x) {
  return x / 1000000000;
}

fn inline uint32_t mod1e9(const uint64_t x) {
  return (uint32_t) (x - 1000000000 * div1e9(x));
}

STRUCT(Double)
{
    u64 mantissa;
    s32 exponent;
};

may_be_unused fn Double double_transform(u64 ieee_mantissa, u32 ieee_exponent)
{
    u64 m2;
    s32 e2;
    if (ieee_exponent)
    {
        m2 = ((u64)1 << double_mantissa_bits) | ieee_mantissa;
        e2 = (s32)(ieee_exponent) - double_bias - double_mantissa_bits - 2;
    }
    else
    {
        m2 = ieee_mantissa;
        e2 = 1 - double_bias - double_mantissa_bits - 2;
    }

    u8 is_even = (m2 & 1) == 0;
    let(accept_bounds, is_even);

    u64 mv = 4 * m2;
    u32 mm_shift = (ieee_mantissa != 0) | (ieee_exponent <= 1);

    u64 vr, vp, vm;
    s32 e10;
    u8 vm_is_trailing_zeroes = 0;
    u8 vr_is_trailing_zeroes = 0;

    if (e2 >= 0)
    {
        u32 q = log10_pow2(e2) - (e2 > 3);
        e10 = (s32)q;
        s32 k = double_pow5_inv_bitcount + pow5_bits((s32)q) - 1;
        s32 i = -e2 + (s32)q + k;
        vr = mul_shift_all_64(m2, DOUBLE_POW5_INV_SPLIT[q], i, &vp, &vm, mm_shift);
        if (q <= 21)
        {
            u32 mv_mod_5 = ((u32)mv) - 5 * ((u32)div5(mv));
            if (mv_mod_5 == 0)
            {
                vr_is_trailing_zeroes = multiple_of_power_of_5(mv, q);
            }
            else if (accept_bounds)
            {
                vm_is_trailing_zeroes = multiple_of_power_of_5(mv - 1 - mm_shift, q);
            }
            else
            {
                vp -= multiple_of_power_of_5(mv + 2, q);
            }
        }
    }
    else
    {
        u32 q = log10_pow5(-e2) - (-e2 > 1);
        e10 = (s32) q + e2;
        s32 i = -e2 - (s32)q;
        s32 k = pow5_bits(i) - double_pow5_bitcount;
        s32 j = (s32)q - k;
        vr = mul_shift_all_64(m2, DOUBLE_POW5_SPLIT[i], j, &vp, &vm, mm_shift);

        if (q <= 1)
        {
            vr_is_trailing_zeroes = 1;
            if (accept_bounds)
            {
                vm_is_trailing_zeroes = mm_shift == 1;
            }
            else
            {
                vp -= 1;
            }
        }
        else if (q < 63)
        {
            vr_is_trailing_zeroes = multiple_of_power_of_2(mv, q);
        }
    }

    s32 removed = 0;
    u64 output;
    u8 last_removed_digit = 0;

    if (vm_is_trailing_zeroes | vr_is_trailing_zeroes)
    {
        while (1)
        {
            u64 vp_div10 = div10(vp);
            u64 vm_div10 = div10(vm);

            if (vp_div10 <= vm_div10)
            {
                break;
            }

            u32 vm_mod10 = ((u32)vm) - 10 * ((u32)vm_div10);
            u32 vr_div10 = div10(vr);
            u32 vr_mod10 = ((u32)vr) - 10 * ((u32)vr_div10);
            vm_is_trailing_zeroes &= vm_mod10 == 0;
            vr_is_trailing_zeroes &= last_removed_digit == 0;
            last_removed_digit = (u8)vr_mod10;
            vr = vr_div10;
            vp = vp_div10;
            vm = vm_div10;
            removed += 1;
        }

        if (vm_is_trailing_zeroes)
        {
            while (1)
            {
                const uint64_t vm_div10 = div10(vm);
                const uint32_t vm_mod10 = ((uint32_t) vm) - 10 * ((uint32_t) vm_div10);

                if (vm_mod10 != 0)
                {
                    break;
                }

                const uint64_t vp_div10 = div10(vp);
                const uint64_t vr_div10 = div10(vr);
                const uint32_t vr_mod10 = ((uint32_t) vr) - 10 * ((uint32_t) vr_div10);
                vr_is_trailing_zeroes &= last_removed_digit == 0;
                last_removed_digit = (uint8_t) vr_mod10;
                vr = vr_div10;
                vp = vp_div10;
                vm = vm_div10;
                removed += 1;
            }
        }

        if (vr_is_trailing_zeroes && last_removed_digit == 5 && vr % 2 == 0)
        {
            // Round even if the exact number is .....50..0.
            last_removed_digit = 4;
        }
        // We need to take vr + 1 if vr is outside bounds or we need to round up.
        output = vr + ((vr == vm && (!accept_bounds || !vm_is_trailing_zeroes)) || last_removed_digit >= 5);
    }
    else
    {
        u8 round_up = 0;
        u64 vp_div100 = div100(vp);
        u64 vm_div100 = div100(vm);

        if (vp_div100 > vm_div100)
        {
            u64 vr_div100 = div100(vr);
            u32 vr_mod100 = ((u32)vr) - 100 * ((u32)vr_div100);
            round_up = vr_mod100 >= 50;
            vr = vr_div100;
            vp = vp_div100;
            vm = vm_div100;
            removed += 2;
        }

        while (1)
        {
            u64 vp_div10 = div10(vp);
            u64 vm_div10 = div10(vm);
            if (vp_div10 <= vm_div10)
            {
                break;
            }
            u64 vr_div10 = div10(vr);
            u32 vr_mod10 = ((u32)vr) - 10 * ((u32) vr_div10);
            round_up = vr_mod10 >= 5;
            vr = vr_div10;
            vp = vp_div10;
            vm = vm_div10;
            removed += 1;
        }

        output = vr + ((vr == vm) | round_up);
    }

    s32 exp = e10 + removed;

    return (Double)
    {
        .mantissa = output,
        .exponent = exp,
    };
}

may_be_unused fn SmallIntResult small_int(u64 ieee_mantissa, u32 ieee_exponent)
{
    SmallIntResult result = {};
    let(m2, ((u64)1 << double_mantissa_bits) | ieee_mantissa);
    let(e2, (s32)ieee_exponent - double_bias - double_mantissa_bits);

    if (e2 > 0)
    {
        return result;
    }

    if (e2 < -52)
    {
        return result;
    }

    u64 mask = ((u64)1 << -e2) - 1;
    u64 fraction = m2 & mask;
    if (fraction != 0)
    {
        return result;
    }

    result.mantissa = m2 >> -e2;
    result.exponent = 0;
    result.is_small_int = 1;

    return result;
}

fn u32 decimalLength17(const u64 v) {
    // This is slightly faster than a loop.
    // The average output length is 16.38 digits, so we check high-to-low.
    // Function precondition: v is not an 18, 19, or 20-digit number.
    // (17 digits are sufficient for round-tripping.)
    assert(v < 100000000000000000L);
    if (v >= 10000000000000000L) { return 17; }
    if (v >= 1000000000000000L) { return 16; }
    if (v >= 100000000000000L) { return 15; }
    if (v >= 10000000000000L) { return 14; }
    if (v >= 1000000000000L) { return 13; }
    if (v >= 100000000000L) { return 12; }
    if (v >= 10000000000L) { return 11; }
    if (v >= 1000000000L) { return 10; }
    if (v >= 100000000L) { return 9; }
    if (v >= 10000000L) { return 8; }
    if (v >= 1000000L) { return 7; }
    if (v >= 100000L) { return 6; }
    if (v >= 10000L) { return 5; }
    if (v >= 1000L) { return 4; }
    if (v >= 100L) { return 3; }
    if (v >= 10L) { return 2; }
    return 1;
}

// A floating decimal representing m * 10^e.
STRUCT(floating_decimal_64)
{
  uint64_t mantissa;
  // Decimal exponent's range is -324 to 308
  // inclusive, and can fit in a short if needed.
  int32_t exponent;
};

fn u8* digits2(u64 value)
{
    String str = strlit("00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899");
    return str.pointer + (value * 2);
}

fn void write_float_decimal(String buffer, u64* value, u64 count)
{
    u64 i = 0;

    while (i + 2 < count)
    {
        let_cast(u8, c, *value % 100);
        *value /= 100;
        let(ptr, digits2(c));
        buffer.pointer[count - i - 1] = ptr[1];
        buffer.pointer[count - i - 2] = ptr[0];
        i += 2;
    }

    while (i < count)
    {
        let(c, cast_to(u8, *value % 10));
        *value /= 10;
        buffer.pointer[count - i - 1] = '0' + c;

        i += 1;
    }
}

fn u64 format_float(String buffer, f64 value_double)
{
    let(value_int, *(u64*)&value_double);
    u64 buffer_i = 0;

    const u8 ieee_sign = ((value_int >> (double_mantissa_bits + double_exponent_bits)) & 1) != 0;
    let(ieee_mantissa, value_int & (((u64)1 << double_mantissa_bits) - 1));
    let(ieee_exponent, (u32)((value_int >> double_mantissa_bits) & (((u32)1 << double_exponent_bits) - 1)));

    if (ieee_exponent == (((u32)1 << double_exponent_bits) - 1) || (ieee_exponent == 0 && ieee_mantissa == 0))
    {
        if (ieee_mantissa)
        {
            String nan = strlit("NaN");
            memcpy(&buffer.pointer[buffer_i], nan.pointer, nan.length);
            buffer_i += nan.length;
        }
        else
        {
            if (ieee_sign)
            {
                buffer.pointer[buffer_i] = '-';
                buffer_i += 1;
            }

            if (ieee_exponent)
            {
                String inf = strlit("Infinity");
                memcpy(&buffer.pointer[buffer_i], inf.pointer, inf.length);
                buffer_i += inf.length;
            }
            else
            {
                String e0 = strlit("0E0");
                memcpy(&buffer.pointer[buffer_i], e0.pointer, e0.length);
                buffer_i += e0.length;
            }
        }
    }
    else
    {
        let(small_int_result, small_int(ieee_mantissa, ieee_exponent));
        Double result;
        if (small_int_result.is_small_int)
        {
            while (1)
            {
                u64 q = div10(small_int_result.mantissa);
                u32 r = ((u32)small_int_result.mantissa) - 10 * ((u32)q);

                if (r != 0)
                {
                    break;
                }

                small_int_result.mantissa = q;
                small_int_result.exponent += 1;
            }
        }
        else
        {
            result = double_transform(ieee_mantissa, ieee_exponent);
        }

        typedef enum FloatFormat
        {
            FLOAT_FORMAT_DECIMAL,
            FLOAT_FORMAT_SCIENTIFIC,
        } FloatFormat;

        FloatFormat format = FLOAT_FORMAT_DECIMAL;
        u64 output = result.mantissa;
        u32 olength = decimalLength17(output);

        // Sign
        buffer.pointer[buffer_i] = '-';
        buffer_i += ieee_sign;

        switch (format)
        {
            case FLOAT_FORMAT_SCIENTIFIC:
                {
                    u32 i = 0;

                    if ((output >> 32) != 0)
                    {
                        u64 q = div1e8(output);
                        u32 output2 = ((u32)output) - 100000000 * ((u32)q);
                        output = q;

                        u32 c = output % 10000;
                        output2 /= 10000;

                        const uint32_t d = output2 % 10000;
                        const uint32_t c0 = (c % 100) << 1;
                        const uint32_t c1 = (c / 100) << 1;
                        const uint32_t d0 = (d % 100) << 1;
                        const uint32_t d1 = (d / 100) << 1;

                        let(base_index, buffer_i + olength);
                        let(base, buffer.pointer + base_index);
                        memcpy(base - 1, DIGIT_TABLE + c0, 2);
                        memcpy(base - 3, DIGIT_TABLE + c1, 2);
                        memcpy(base - 5, DIGIT_TABLE + d0, 2);
                        memcpy(base - 7, DIGIT_TABLE + d1, 2);

                        i += 8;
                    }

                    let(output2, (u32)output);

                    while (output2 >= 10000)
                    {
#ifdef __clang__
                        const u32 c = output2 - 10000 * (output2 / 10000);
#else
                        const uint32_t c = output2 % 10000;
#endif
                        output2 /= 10000;
                        const u32 c0 = (c % 100) << 1;
                        const u32 c1 = (c / 100) << 1;
                        let(base_index, buffer_i + olength - i);
                        memcpy(buffer.pointer + base_index - 1, DIGIT_TABLE + c0, 2);
                        memcpy(buffer.pointer + base_index - 3, DIGIT_TABLE + c1, 2);

                        i += 4;
                    }

                    if (output2 >= 100)
                    {
                        const u32 c = (output2 % 100) << 1;
                        output2 /= 100;
                        memcpy(buffer.pointer + buffer_i + olength - i - 1, DIGIT_TABLE + c, 2);
                        i += 2;
                    }

                    if (output2 >= 10)
                    {
                        const uint32_t c = output2 << 1;
                        // We can't use memcpy here: the decimal dot goes between these two digits.
                        buffer.pointer[buffer_i + olength - i] = DIGIT_TABLE[c + 1];
                        buffer.pointer[buffer_i] = DIGIT_TABLE[c];
                    }
                    else
                    {
                        buffer.pointer[buffer_i] = (u8)output2 + '0';
                    }

                    // Print decimal point if needed.
                    if (olength > 1)
                    {
                        buffer.pointer[buffer_i + 1] = '.';
                        buffer_i += olength + 1;
                    } else {
                        buffer_i += 1;
                    }

                    // Print the exponent.
                    buffer.pointer[buffer_i] = 'E';
                    buffer_i += 1;
                    int32_t exp = result.exponent + (int32_t) olength - 1;
                    if (exp < 0) {
                        buffer.pointer[buffer_i] = '-';
                        buffer_i += 1;
                        exp = -exp;
                    }

                    if (exp >= 100)
                    {
                        const int32_t c = exp % 10;
                        memcpy(buffer.pointer + buffer_i, DIGIT_TABLE + 2 * (exp / 10), 2);
                        buffer.pointer[buffer_i + 2] = (u8)c + '0';
                        buffer_i += 3;
                    }
                    else if (exp >= 10)
                    {
                        memcpy(buffer.pointer + buffer_i, DIGIT_TABLE + 2 * exp, 2);
                        buffer_i += 2;
                    }
                    else
                    {
                        buffer.pointer[buffer_i] = (u8)exp + '0';
                        buffer_i += 1;
                    }
                } break;
            case FLOAT_FORMAT_DECIMAL:
                {
                    let(dp_offset, result.exponent + cast_to(s32, olength));

                    if (dp_offset <= 0)
                    {
                        buffer.pointer[buffer_i] = '0';
                        buffer.pointer[buffer_i + 1] = '.';
                        buffer_i += 2;

                        // let(dp_index, buffer_i);

                        let(dp_poffset, (u32)(-dp_offset));
                        memset(buffer.pointer + buffer_i, '0', dp_poffset);
                        buffer_i += dp_poffset;
                        write_float_decimal(s_get_slice(u8, buffer, buffer_i, buffer.length), &output, olength);
                        buffer_i += olength;
                    }
                    else
                    {
                        let(dp_uoffset, (u64)dp_offset);
                        if (dp_uoffset >= olength)
                        {
                            write_float_decimal(s_get_slice(u8, buffer, buffer_i, buffer.length), &output, olength);
                            buffer_i += olength;
                            let(length, dp_uoffset - olength);
                            String memset_slice = s_get_slice(u8, buffer, buffer_i, buffer_i + length);
                            memset(memset_slice.pointer, 0, length);
                            buffer_i += length;
                        }
                        else
                        {
                            write_float_decimal(s_get_slice(u8, buffer, buffer_i + dp_uoffset + 1, buffer.length), &output, olength - dp_uoffset);
                            buffer.pointer[buffer_i + dp_uoffset] = '.';
                            // let(dp_index, buffer_i + dp_uoffset + 1);
                            write_float_decimal(s_get_slice(u8, buffer, buffer_i, buffer.length), &output, dp_uoffset);
                            buffer_i += olength + 1;
                        }
                    }
                } break;
        }
    }

    return buffer_i;
}

fn String format_string_va(String buffer, const char* format, va_list args)
{
    u8* it = (u8*)format;
    u64 buffer_i = 0;

    while (*it)
    {
        while (*it && *it != brace_open)
        {
            s_get(buffer, buffer_i) = *it;
            buffer_i += 1;
            it += 1;
        }

        if (*it == brace_open)
        {
            it += 1;
            let(next_ch, *it);

            if (next_ch == brace_open)
            {
                todo();
            }
            else
            {
                switch (next_ch)
                {
                    case 'c':
                        {
                            int done = 0;
                            it += 1;
                            if (*it == 's')
                            {
                                it += 1;
                                if (*it == 't')
                                {
                                    it += 1;
                                    if (*it == 'r')
                                    {
                                        it += 1;
                                        done = 1;
                                        let_va_arg(const u8*, cstring, args);
                                        while (*cstring)
                                        {
                                            buffer.pointer[buffer_i] = *cstring;
                                            buffer_i += 1;
                                            cstring += 1;
                                        }
                                    }
                                }
                            }
                            else
                            {
                                let_cast(u8, character, cast_to(u8, va_arg(args, u32)));
                                buffer.pointer[buffer_i] = character;
                                buffer_i += 1;
                                done = 1;
                            }

                            assert(done);
                        } break;
                    case 'f':
                        {
                            it += 1;
                            f64 value_double;
                            switch (*it)
                            {
                                case '3':
                                    it += 1;
                                    if (*it != '2')
                                    {
                                        failed_execution();
                                    }
                                    it += 1;
                                    value_double = va_arg(args, f64);
                                    break;
                                case '6':
                                    it += 1;
                                    if (*it != '4')
                                    {
                                        failed_execution();
                                    }
                                    it += 1;
                                    value_double = va_arg(args, f64);
                                    break;
                                default:
                                    failed_execution();
                            }

                            buffer_i += format_float(s_get_slice(u8, buffer, buffer_i, buffer.length), value_double);
                        } break;
                    case 's':
                        {
                            it += 1;

                            if (is_decimal_digit(*it))
                            {
                                u8* bit_count_start = it;
                                while (is_decimal_digit(*it))
                                {
                                    it += 1;
                                }

                                u8* bit_count_end = it;
                                u64 bit_count = parse_decimal(slice_from_pointer_range(u8, (u8*)bit_count_start, (u8*)bit_count_end));

                                typedef enum IntegerFormat
                                {
                                    INTEGER_FORMAT_HEXADECIMAL,
                                    INTEGER_FORMAT_DECIMAL,
                                    INTEGER_FORMAT_OCTAL,
                                    INTEGER_FORMAT_BINARY,
                                } IntegerFormat;

                                IntegerFormat format = INTEGER_FORMAT_DECIMAL;

                                if (*it == ':')
                                {
                                    it += 1;
                                    switch (*it)
                                    {
                                        case 'x':
                                            format = INTEGER_FORMAT_HEXADECIMAL;
                                            break;
                                        case 'd':
                                            format = INTEGER_FORMAT_DECIMAL;
                                            break;
                                        case 'o':
                                            format = INTEGER_FORMAT_OCTAL;
                                            break;
                                        case 'b':
                                            format = INTEGER_FORMAT_BINARY;
                                            break;
                                        default:
                                            unreachable();
                                    }

                                    it += 1;
                                }

                                s64 original_value;
                                switch (bit_count)
                                {
                                    case 8:
                                    case 16:
                                    case 32:
                                        original_value = va_arg(args, s32);
                                        break;
                                    case 64:
                                        original_value = va_arg(args, s64);
                                        break;
                                    default:
                                        unreachable();
                                }

                                String buffer_slice = s_get_slice(u8, buffer, buffer_i, buffer.length);

                                switch (format)
                                {
                                    case INTEGER_FORMAT_HEXADECIMAL:
                                        {
                                            let(written_characters, format_hexadecimal(buffer_slice, original_value));
                                            buffer_i += written_characters;
                                        } break;
                                    case INTEGER_FORMAT_DECIMAL:
                                        {
                                            u64 value;
                                            if (original_value < 0)
                                            {
                                                buffer_slice.pointer[0] = '-';
                                                buffer_slice.pointer += 1;
                                                buffer_slice.length -= 1;
                                                buffer_i += 1;
                                                value = (u64)(-(original_value - (original_value == INT64_MIN))) + (original_value == INT64_MIN);
                                            }
                                            else
                                            {
                                                value = (u64)original_value;
                                            }

                                            let(written_characters, format_decimal(buffer_slice, value));
                                            buffer_i += written_characters;
                                        } break;
                                    case INTEGER_FORMAT_OCTAL:
                                        {
                                            todo();
                                        } break;
                                    case INTEGER_FORMAT_BINARY:
                                        {
                                            todo();
                                        } break;
                                }
                            }
                            else
                            {
                                String string = va_arg(args, String);
                                memcpy(buffer.pointer + buffer_i, string.pointer, string.length);
                                buffer_i += string.length;
                            }

                        } break;
                    case 'u':
                        {
                            it += 1;

                            u8* bit_count_start = it;
                            while (is_decimal_digit(*it))
                            {
                                it += 1;
                            }

                            u8* bit_count_end = it;
                            u64 bit_count = parse_decimal(slice_from_pointer_range(u8, (u8*)bit_count_start, (u8*)bit_count_end));

                            typedef enum IntegerFormat
                            {
                                INTEGER_FORMAT_HEXADECIMAL,
                                INTEGER_FORMAT_DECIMAL,
                                INTEGER_FORMAT_OCTAL,
                                INTEGER_FORMAT_BINARY,
                            } IntegerFormat;

                            IntegerFormat format = INTEGER_FORMAT_DECIMAL;

                            if (*it == ':')
                            {
                                it += 1;
                                switch (*it)
                                {
                                    case 'x':
                                        format = INTEGER_FORMAT_HEXADECIMAL;
                                        break;
                                    case 'd':
                                        format = INTEGER_FORMAT_DECIMAL;
                                        break;
                                    case 'o':
                                        format = INTEGER_FORMAT_OCTAL;
                                        break;
                                    case 'b':
                                        format = INTEGER_FORMAT_BINARY;
                                        break;
                                    default:
                                        unreachable();
                                }

                                it += 1;
                            }

                            u64 original_value;
                            switch (bit_count)
                            {
                                case 8:
                                case 16:
                                case 32:
                                    original_value = va_arg(args, u32);
                                    break;
                                case 64:
                                    original_value = va_arg(args, u64);
                                    break;
                                default:
                                    unreachable();
                            }

                            let(buffer_slice, s_get_slice(u8, buffer, buffer_i, buffer.length));

                            switch (format)
                            {
                                case INTEGER_FORMAT_HEXADECIMAL:
                                    {
                                        let(written_characters, format_hexadecimal(buffer_slice, original_value));
                                        buffer_i += written_characters;
                                    } break;
                                case INTEGER_FORMAT_DECIMAL:
                                    {
                                        let(written_characters, format_decimal(buffer_slice, original_value));
                                        buffer_i += written_characters;
                                    } break;
                                case INTEGER_FORMAT_OCTAL:
                                    {
                                        todo();
                                    } break;
                                case INTEGER_FORMAT_BINARY:
                                    {
                                        todo();
                                    } break;
                            }
                        } break;
                    default:
                        buffer.pointer[buffer_i] = '{';
                        buffer_i += 1;
                        continue;
                }

                if (*it != brace_close)
                {
                    failed_execution();
                }

                it += 1;
            }
        }
    }

    return (String) { .pointer = buffer.pointer, .length = buffer_i };
}

fn String format_string(String buffer, const char* format, ...)
{
    va_list args;
    va_start(args, format);
    let(result, format_string_va(buffer, format, args));
    va_end(args);
    return result;
}