LuaJIT
/
LuaJIT
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
LuaJIT/src/lj_strfmt_num.c

593 lines
20 KiB
C
Raw Permalink Blame History

/*
** String formatting for floating-point numbers.
** Copyright (C) 2005-2022 Mike Pall. See Copyright Notice in luajit.h
** Contributed by Peter Cawley.
*/
#include <stdio.h>
#define lj_strfmt_num_c
#define LUA_CORE
#include "lj_obj.h"
#include "lj_buf.h"
#include "lj_str.h"
#include "lj_strfmt.h"
/* -- Precomputed tables -------------------------------------------------- */
/* Rescale factors to push the exponent of a number towards zero. */
#define RESCALE_EXPONENTS(P, N) \
P(308), P(289), P(270), P(250), P(231), P(212), P(193), P(173), P(154), \
P(135), P(115), P(96), P(77), P(58), P(38), P(0), P(0), P(0), N(39), N(58), \
N(77), N(96), N(116), N(135), N(154), N(174), N(193), N(212), N(231), \
N(251), N(270), N(289)
#define ONE_E_P(X) 1e+0 ## X
#define ONE_E_N(X) 1e-0 ## X
static const int16_t rescale_e[] = { RESCALE_EXPONENTS(-, +) };
static const double rescale_n[] = { RESCALE_EXPONENTS(ONE_E_P, ONE_E_N) };
#undef ONE_E_N
#undef ONE_E_P
/*
** For p in range -70 through 57, this table encodes pairs (m, e) such that
** 4*2^p <= (uint8_t)m*10^e, and is the smallest value for which this holds.
*/
static const int8_t four_ulp_m_e[] = {
34, -21, 68, -21, 14, -20, 28, -20, 55, -20, 2, -19, 3, -19, 5, -19, 9, -19,
-82, -18, 35, -18, 7, -17, -117, -17, 28, -17, 56, -17, 112, -16, -33, -16,
45, -16, 89, -16, -78, -15, 36, -15, 72, -15, -113, -14, 29, -14, 57, -14,
114, -13, -28, -13, 46, -13, 91, -12, -74, -12, 37, -12, 73, -12, 15, -11, 3,
-11, 59, -11, 2, -10, 3, -10, 5, -10, 1, -9, -69, -9, 38, -9, 75, -9, 15, -7,
3, -7, 6, -7, 12, -6, -17, -7, 48, -7, 96, -7, -65, -6, 39, -6, 77, -6, -103,
-5, 31, -5, 62, -5, 123, -4, -11, -4, 49, -4, 98, -4, -60, -3, 4, -2, 79, -3,
16, -2, 32, -2, 63, -2, 2, -1, 25, 0, 5, 1, 1, 2, 2, 2, 4, 2, 8, 2, 16, 2,
32, 2, 64, 2, -128, 2, 26, 2, 52, 2, 103, 3, -51, 3, 41, 4, 82, 4, -92, 4,
33, 4, 66, 4, -124, 5, 27, 5, 53, 5, 105, 6, 21, 6, 42, 6, 84, 6, 17, 7, 34,
7, 68, 7, 2, 8, 3, 8, 6, 8, 108, 9, -41, 9, 43, 10, 86, 9, -84, 10, 35, 10,
69, 10, -118, 11, 28, 11, 55, 12, 11, 13, 22, 13, 44, 13, 88, 13, -80, 13,
36, 13, 71, 13, -115, 14, 29, 14, 57, 14, 113, 15, -30, 15, 46, 15, 91, 15,
19, 16, 37, 16, 73, 16, 2, 17, 3, 17, 6, 17
};
/* min(2^32-1, 10^e-1) for e in range 0 through 10 */
static uint32_t ndigits_dec_threshold[] = {
0, 9U, 99U, 999U, 9999U, 99999U, 999999U,
9999999U, 99999999U, 999999999U, 0xffffffffU
};
/* -- Helper functions ---------------------------------------------------- */
/* Compute the number of digits in the decimal representation of x. */
static MSize ndigits_dec(uint32_t x)
{
MSize t = ((lj_fls(x | 1) * 77) >> 8) + 1; /* 2^8/77 is roughly log2(10) */
return t + (x > ndigits_dec_threshold[t]);
}
#define WINT_R(x, sh, sc) \
{ uint32_t d = (x*(((1<<sh)+sc-1)/sc))>>sh; x -= d*sc; *p++ = (char)('0'+d); }
/* Write 9-digit unsigned integer to buffer. */
static char *lj_strfmt_wuint9(char *p, uint32_t u)
{
uint32_t v = u / 10000, w;
u -= v * 10000;
w = v / 10000;
v -= w * 10000;
*p++ = (char)('0'+w);
WINT_R(v, 23, 1000)
WINT_R(v, 12, 100)
WINT_R(v, 10, 10)
*p++ = (char)('0'+v);
WINT_R(u, 23, 1000)
WINT_R(u, 12, 100)
WINT_R(u, 10, 10)
*p++ = (char)('0'+u);
return p;
}
#undef WINT_R
/* -- Extended precision arithmetic --------------------------------------- */
/*
** The "nd" format is a fixed-precision decimal representation for numbers. It
** consists of up to 64 uint32_t values, with each uint32_t storing a value
** in the range [0, 1e9). A number in "nd" format consists of three variables:
**
** uint32_t nd[64];
** uint32_t ndlo;
** uint32_t ndhi;
**
** The integral part of the number is stored in nd[0 ... ndhi], the value of
** which is sum{i in [0, ndhi] | nd[i] * 10^(9*i)}. If the fractional part of
** the number is zero, ndlo is zero. Otherwise, the fractional part is stored
** in nd[ndlo ... 63], the value of which is taken to be
** sum{i in [ndlo, 63] | nd[i] * 10^(9*(i-64))}.
**
** If the array part had 128 elements rather than 64, then every double would
** have an exact representation in "nd" format. With 64 elements, all integral
** doubles have an exact representation, and all non-integral doubles have
** enough digits to make both %.99e and %.99f do the right thing.
*/
#if LJ_64
#define ND_MUL2K_MAX_SHIFT 29
#define ND_MUL2K_DIV1E9(val) ((uint32_t)((val) / 1000000000))
#else
#define ND_MUL2K_MAX_SHIFT 11
#define ND_MUL2K_DIV1E9(val) ((uint32_t)((val) >> 9) / 1953125)
#endif
/* Multiply nd by 2^k and add carry_in (ndlo is assumed to be zero). */
static uint32_t nd_mul2k(uint32_t* nd, uint32_t ndhi, uint32_t k,
uint32_t carry_in, SFormat sf)
{
uint32_t i, ndlo = 0, start = 1;
/* Performance hacks. */
if (k > ND_MUL2K_MAX_SHIFT*2 && STRFMT_FP(sf) != STRFMT_FP(STRFMT_T_FP_F)) {
start = ndhi - (STRFMT_PREC(sf) + 17) / 8;
}
/* Real logic. */
while (k >= ND_MUL2K_MAX_SHIFT) {
for (i = ndlo; i <= ndhi; i++) {
uint64_t val = ((uint64_t)nd[i] << ND_MUL2K_MAX_SHIFT) | carry_in;
carry_in = ND_MUL2K_DIV1E9(val);
nd[i] = (uint32_t)val - carry_in * 1000000000;
}
if (carry_in) {
nd[++ndhi] = carry_in; carry_in = 0;
if (start++ == ndlo) ++ndlo;
}
k -= ND_MUL2K_MAX_SHIFT;
}
if (k) {
for (i = ndlo; i <= ndhi; i++) {
uint64_t val = ((uint64_t)nd[i] << k) | carry_in;
carry_in = ND_MUL2K_DIV1E9(val);
nd[i] = (uint32_t)val - carry_in * 1000000000;
}
if (carry_in) nd[++ndhi] = carry_in;
}
return ndhi;
}
/* Divide nd by 2^k (ndlo is assumed to be zero). */
static uint32_t nd_div2k(uint32_t* nd, uint32_t ndhi, uint32_t k, SFormat sf)
{
uint32_t ndlo = 0, stop1 = ~0, stop2 = ~0;
/* Performance hacks. */
if (!ndhi) {
if (!nd[0]) {
return 0;
} else {
uint32_t s = lj_ffs(nd[0]);
if (s >= k) { nd[0] >>= k; return 0; }
nd[0] >>= s; k -= s;
}
}
if (k > 18) {
if (STRFMT_FP(sf) == STRFMT_FP(STRFMT_T_FP_F)) {
stop1 = 63 - (int32_t)STRFMT_PREC(sf) / 9;
} else {
int32_t floorlog2 = ndhi * 29 + lj_fls(nd[ndhi]) - k;
int32_t floorlog10 = (int32_t)(floorlog2 * 0.30102999566398114);
stop1 = 62 + (floorlog10 - (int32_t)STRFMT_PREC(sf)) / 9;
stop2 = 61 + ndhi - (int32_t)STRFMT_PREC(sf) / 8;
}
}
/* Real logic. */
while (k >= 9) {
uint32_t i = ndhi, carry = 0;
for (;;) {
uint32_t val = nd[i];
nd[i] = (val >> 9) + carry;
carry = (val & 0x1ff) * 1953125;
if (i == ndlo) break;
i = (i - 1) & 0x3f;
}
if (ndlo != stop1 && ndlo != stop2) {
if (carry) { ndlo = (ndlo - 1) & 0x3f; nd[ndlo] = carry; }
if (!nd[ndhi]) { ndhi = (ndhi - 1) & 0x3f; stop2--; }
} else if (!nd[ndhi]) {
if (ndhi != ndlo) { ndhi = (ndhi - 1) & 0x3f; stop2--; }
else return ndlo;
}
k -= 9;
}
if (k) {
uint32_t mask = (1U << k) - 1, mul = 1000000000 >> k, i = ndhi, carry = 0;
for (;;) {
uint32_t val = nd[i];
nd[i] = (val >> k) + carry;
carry = (val & mask) * mul;
if (i == ndlo) break;
i = (i - 1) & 0x3f;
}
if (carry) { ndlo = (ndlo - 1) & 0x3f; nd[ndlo] = carry; }
}
return ndlo;
}
/* Add m*10^e to nd (assumes ndlo <= e/9 <= ndhi and 0 <= m <= 9). */
static uint32_t nd_add_m10e(uint32_t* nd, uint32_t ndhi, uint8_t m, int32_t e)
{
uint32_t i, carry;
if (e >= 0) {
i = (uint32_t)e/9;
carry = m * (ndigits_dec_threshold[e - (int32_t)i*9] + 1);
} else {
int32_t f = (e-8)/9;
i = (uint32_t)(64 + f);
carry = m * (ndigits_dec_threshold[e - f*9] + 1);
}
for (;;) {
uint32_t val = nd[i] + carry;
if (LJ_UNLIKELY(val >= 1000000000)) {
val -= 1000000000;
nd[i] = val;
if (LJ_UNLIKELY(i == ndhi)) {
ndhi = (ndhi + 1) & 0x3f;
nd[ndhi] = 1;
break;
}
carry = 1;
i = (i + 1) & 0x3f;
} else {
nd[i] = val;
break;
}
}
return ndhi;
}
/* Test whether two "nd" values are equal in their most significant digits. */
static int nd_similar(uint32_t* nd, uint32_t ndhi, uint32_t* ref, MSize hilen,
MSize prec)
{
char nd9[9], ref9[9];
if (hilen <= prec) {
if (LJ_UNLIKELY(nd[ndhi] != *ref)) return 0;
prec -= hilen; ref--; ndhi = (ndhi - 1) & 0x3f;
if (prec >= 9) {
if (LJ_UNLIKELY(nd[ndhi] != *ref)) return 0;
prec -= 9; ref--; ndhi = (ndhi - 1) & 0x3f;
}
} else {
prec -= hilen - 9;
}
lj_assertX(prec < 9, "bad precision %d", prec);
lj_strfmt_wuint9(nd9, nd[ndhi]);
lj_strfmt_wuint9(ref9, *ref);
return !memcmp(nd9, ref9, prec) && (nd9[prec] < '5') == (ref9[prec] < '5');
}
/* -- Formatted conversions to buffer ------------------------------------- */
/* Write formatted floating-point number to either sb or p. */
static char *lj_strfmt_wfnum(SBuf *sb, SFormat sf, lua_Number n, char *p)
{
MSize width = STRFMT_WIDTH(sf), prec = STRFMT_PREC(sf), len;
TValue t;
t.n = n;
if (LJ_UNLIKELY((t.u32.hi << 1) >= 0xffe00000)) {
/* Handle non-finite values uniformly for %a, %e, %f, %g. */
int prefix = 0, ch = (sf & STRFMT_F_UPPER) ? 0x202020 : 0;
if (((t.u32.hi & 0x000fffff) | t.u32.lo) != 0) {
ch ^= ('n' << 16) | ('a' << 8) | 'n';
if ((sf & STRFMT_F_SPACE)) prefix = ' ';
} else {
ch ^= ('i' << 16) | ('n' << 8) | 'f';
if ((t.u32.hi & 0x80000000)) prefix = '-';
else if ((sf & STRFMT_F_PLUS)) prefix = '+';
else if ((sf & STRFMT_F_SPACE)) prefix = ' ';
}
len = 3 + (prefix != 0);
if (!p) p = lj_buf_more(sb, width > len ? width : len);
if (!(sf & STRFMT_F_LEFT)) while (width-- > len) *p++ = ' ';
if (prefix) *p++ = prefix;
*p++ = (char)(ch >> 16); *p++ = (char)(ch >> 8); *p++ = (char)ch;
} else if (STRFMT_FP(sf) == STRFMT_FP(STRFMT_T_FP_A)) {
/* %a */
const char *hexdig = (sf & STRFMT_F_UPPER) ? "0123456789ABCDEFPX"
: "0123456789abcdefpx";
int32_t e = (t.u32.hi >> 20) & 0x7ff;
char prefix = 0, eprefix = '+';
if (t.u32.hi & 0x80000000) prefix = '-';
else if ((sf & STRFMT_F_PLUS)) prefix = '+';
else if ((sf & STRFMT_F_SPACE)) prefix = ' ';
t.u32.hi &= 0xfffff;
if (e) {
t.u32.hi |= 0x100000;
e -= 1023;
} else if (t.u32.lo | t.u32.hi) {
/* Non-zero denormal - normalise it. */
uint32_t shift = t.u32.hi ? 20-lj_fls(t.u32.hi) : 52-lj_fls(t.u32.lo);
e = -1022 - shift;
t.u64 <<= shift;
}
/* abs(n) == t.u64 * 2^(e - 52) */
/* If n != 0, bit 52 of t.u64 is set, and is the highest set bit. */
if ((int32_t)prec < 0) {
/* Default precision: use smallest precision giving exact result. */
prec = t.u32.lo ? 13-lj_ffs(t.u32.lo)/4 : 5-lj_ffs(t.u32.hi|0x100000)/4;
} else if (prec < 13) {
/* Precision is sufficiently low as to maybe require rounding. */
t.u64 += (((uint64_t)1) << (51 - prec*4));
}
if (e < 0) {
eprefix = '-';
e = -e;
}
len = 5 + ndigits_dec((uint32_t)e) + prec + (prefix != 0)
+ ((prec | (sf & STRFMT_F_ALT)) != 0);
if (!p) p = lj_buf_more(sb, width > len ? width : len);
if (!(sf & (STRFMT_F_LEFT | STRFMT_F_ZERO))) {
while (width-- > len) *p++ = ' ';
}
if (prefix) *p++ = prefix;
*p++ = '0';
*p++ = hexdig[17]; /* x or X */
if ((sf & (STRFMT_F_LEFT | STRFMT_F_ZERO)) == STRFMT_F_ZERO) {
while (width-- > len) *p++ = '0';
}
*p++ = '0' + (t.u32.hi >> 20); /* Usually '1', sometimes '0' or '2'. */
if ((prec | (sf & STRFMT_F_ALT))) {
/* Emit fractional part. */
char *q = p + 1 + prec;
*p = '.';
if (prec < 13) t.u64 >>= (52 - prec*4);
else while (prec > 13) p[prec--] = '0';
while (prec) { p[prec--] = hexdig[t.u64 & 15]; t.u64 >>= 4; }
p = q;
}
*p++ = hexdig[16]; /* p or P */
*p++ = eprefix; /* + or - */
p = lj_strfmt_wint(p, e);
} else {
/* %e or %f or %g - begin by converting n to "nd" format. */
uint32_t nd[64];
uint32_t ndhi = 0, ndlo, i;
int32_t e = (t.u32.hi >> 20) & 0x7ff, ndebias = 0;
char prefix = 0, *q;
if (t.u32.hi & 0x80000000) prefix = '-';
else if ((sf & STRFMT_F_PLUS)) prefix = '+';
else if ((sf & STRFMT_F_SPACE)) prefix = ' ';
prec += ((int32_t)prec >> 31) & 7; /* Default precision is 6. */
if (STRFMT_FP(sf) == STRFMT_FP(STRFMT_T_FP_G)) {
/* %g - decrement precision if non-zero (to make it like %e). */
prec--;
prec ^= (uint32_t)((int32_t)prec >> 31);
}
if ((sf & STRFMT_T_FP_E) && prec < 14 && n != 0) {
/* Precision is sufficiently low that rescaling will probably work. */
if ((ndebias = rescale_e[e >> 6])) {
t.n = n * rescale_n[e >> 6];
if (LJ_UNLIKELY(!e)) t.n *= 1e10, ndebias -= 10;
t.u64 -= 2; /* Convert 2ulp below (later we convert 2ulp above). */
nd[0] = 0x100000 | (t.u32.hi & 0xfffff);
e = ((t.u32.hi >> 20) & 0x7ff) - 1075 - (ND_MUL2K_MAX_SHIFT < 29);
goto load_t_lo; rescale_failed:
t.n = n;
e = (t.u32.hi >> 20) & 0x7ff;
ndebias = ndhi = 0;
}
}
nd[0] = t.u32.hi & 0xfffff;
if (e == 0) e++; else nd[0] |= 0x100000;
e -= 1043;
if (t.u32.lo) {
e -= 32 + (ND_MUL2K_MAX_SHIFT < 29); load_t_lo:
#if ND_MUL2K_MAX_SHIFT >= 29
nd[0] = (nd[0] << 3) | (t.u32.lo >> 29);
ndhi = nd_mul2k(nd, ndhi, 29, t.u32.lo & 0x1fffffff, sf);
#elif ND_MUL2K_MAX_SHIFT >= 11
ndhi = nd_mul2k(nd, ndhi, 11, t.u32.lo >> 21, sf);
ndhi = nd_mul2k(nd, ndhi, 11, (t.u32.lo >> 10) & 0x7ff, sf);
ndhi = nd_mul2k(nd, ndhi, 11, (t.u32.lo << 1) & 0x7ff, sf);
#else
#error "ND_MUL2K_MAX_SHIFT too small"
#endif
}
if (e >= 0) {
ndhi = nd_mul2k(nd, ndhi, (uint32_t)e, 0, sf);
ndlo = 0;
} else {
ndlo = nd_div2k(nd, ndhi, (uint32_t)-e, sf);
if (ndhi && !nd[ndhi]) ndhi--;
}
/* abs(n) == nd * 10^ndebias (for slightly loose interpretation of ==) */
if ((sf & STRFMT_T_FP_E)) {
/* %e or %g - assume %e and start by calculating nd's exponent (nde). */
char eprefix = '+';
int32_t nde = -1;
MSize hilen;
if (ndlo && !nd[ndhi]) {
ndhi = 64; do {} while (!nd[--ndhi]);
nde -= 64 * 9;
}
hilen = ndigits_dec(nd[ndhi]);
nde += ndhi * 9 + hilen;
if (ndebias) {
/*
** Rescaling was performed, but this introduced some error, and might
** have pushed us across a rounding boundary. We check whether this
** error affected the result by introducing even more error (2ulp in
** either direction), and seeing whether a rounding boundary was
** crossed. Having already converted the -2ulp case, we save off its
** most significant digits, convert the +2ulp case, and compare them.
*/
int32_t eidx = e + 70 + (ND_MUL2K_MAX_SHIFT < 29)
+ (t.u32.lo >= 0xfffffffe && !(~t.u32.hi << 12));
const int8_t *m_e = four_ulp_m_e + eidx * 2;
lj_assertG_(G(sbufL(sb)), 0 <= eidx && eidx < 128, "bad eidx %d", eidx);
nd[33] = nd[ndhi];
nd[32] = nd[(ndhi - 1) & 0x3f];
nd[31] = nd[(ndhi - 2) & 0x3f];
nd_add_m10e(nd, ndhi, (uint8_t)*m_e, m_e[1]);
if (LJ_UNLIKELY(!nd_similar(nd, ndhi, nd + 33, hilen, prec + 1))) {
goto rescale_failed;
}
}
if ((int32_t)(prec - nde) < (0x3f & -(int32_t)ndlo) * 9) {
/* Precision is sufficiently low as to maybe require rounding. */
ndhi = nd_add_m10e(nd, ndhi, 5, nde - prec - 1);
nde += (hilen != ndigits_dec(nd[ndhi]));
}
nde += ndebias;
if ((sf & STRFMT_T_FP_F)) {
/* %g */
if ((int32_t)prec >= nde && nde >= -4) {
if (nde < 0) ndhi = 0;
prec -= nde;
goto g_format_like_f;
} else if (!(sf & STRFMT_F_ALT) && prec && width > 5) {
/* Decrease precision in order to strip trailing zeroes. */
char tail[9];
uint32_t maxprec = hilen - 1 + ((ndhi - ndlo) & 0x3f) * 9;
if (prec >= maxprec) prec = maxprec;
else ndlo = (ndhi - (((int32_t)(prec - hilen) + 9) / 9)) & 0x3f;
i = prec - hilen - (((ndhi - ndlo) & 0x3f) * 9) + 10;
lj_strfmt_wuint9(tail, nd[ndlo]);
while (prec && tail[--i] == '0') {
prec--;
if (!i) {
if (ndlo == ndhi) { prec = 0; break; }
lj_strfmt_wuint9(tail, nd[++ndlo]);
i = 9;
}
}
}
}
if (nde < 0) {
/* Make nde non-negative. */
eprefix = '-';
nde = -nde;
}
len = 3 + prec + (prefix != 0) + ndigits_dec((uint32_t)nde) + (nde < 10)
+ ((prec | (sf & STRFMT_F_ALT)) != 0);
if (!p) p = lj_buf_more(sb, (width > len ? width : len) + 5);
if (!(sf & (STRFMT_F_LEFT | STRFMT_F_ZERO))) {
while (width-- > len) *p++ = ' ';
}
if (prefix) *p++ = prefix;
if ((sf & (STRFMT_F_LEFT | STRFMT_F_ZERO)) == STRFMT_F_ZERO) {
while (width-- > len) *p++ = '0';
}
q = lj_strfmt_wint(p + 1, nd[ndhi]);
p[0] = p[1]; /* Put leading digit in the correct place. */
if ((prec | (sf & STRFMT_F_ALT))) {
/* Emit fractional part. */
p[1] = '.'; p += 2;
prec -= (MSize)(q - p); p = q; /* Account for digits already emitted. */
/* Then emit chunks of 9 digits (this may emit 8 digits too many). */
for (i = ndhi; (int32_t)prec > 0 && i != ndlo; prec -= 9) {
i = (i - 1) & 0x3f;
p = lj_strfmt_wuint9(p, nd[i]);
}
if ((sf & STRFMT_T_FP_F) && !(sf & STRFMT_F_ALT)) {
/* %g (and not %#g) - strip trailing zeroes. */
p += (int32_t)prec & ((int32_t)prec >> 31);
while (p[-1] == '0') p--;
if (p[-1] == '.') p--;
} else {
/* %e (or %#g) - emit trailing zeroes. */
while ((int32_t)prec > 0) { *p++ = '0'; prec--; }
p += (int32_t)prec;
}
} else {
p++;
}
*p++ = (sf & STRFMT_F_UPPER) ? 'E' : 'e';
*p++ = eprefix; /* + or - */
if (nde < 10) *p++ = '0'; /* Always at least two digits of exponent. */
p = lj_strfmt_wint(p, nde);
} else {
/* %f (or, shortly, %g in %f style) */
if (prec < (MSize)(0x3f & -(int32_t)ndlo) * 9) {
/* Precision is sufficiently low as to maybe require rounding. */
ndhi = nd_add_m10e(nd, ndhi, 5, 0 - prec - 1);
}
g_format_like_f:
if ((sf & STRFMT_T_FP_E) && !(sf & STRFMT_F_ALT) && prec && width) {
/* Decrease precision in order to strip trailing zeroes. */
if (ndlo) {
/* nd has a fractional part; we need to look at its digits. */
char tail[9];
uint32_t maxprec = (64 - ndlo) * 9;
if (prec >= maxprec) prec = maxprec;
else ndlo = 64 - (prec + 8) / 9;
i = prec - ((63 - ndlo) * 9);
lj_strfmt_wuint9(tail, nd[ndlo]);
while (prec && tail[--i] == '0') {
prec--;
if (!i) {
if (ndlo == 63) { prec = 0; break; }
lj_strfmt_wuint9(tail, nd[++ndlo]);
i = 9;
}
}
} else {
/* nd has no fractional part, so precision goes straight to zero. */
prec = 0;
}
}
len = ndhi * 9 + ndigits_dec(nd[ndhi]) + prec + (prefix != 0)
+ ((prec | (sf & STRFMT_F_ALT)) != 0);
if (!p) p = lj_buf_more(sb, (width > len ? width : len) + 8);
if (!(sf & (STRFMT_F_LEFT | STRFMT_F_ZERO))) {
while (width-- > len) *p++ = ' ';
}
if (prefix) *p++ = prefix;
if ((sf & (STRFMT_F_LEFT | STRFMT_F_ZERO)) == STRFMT_F_ZERO) {
while (width-- > len) *p++ = '0';
}
/* Emit integer part. */
p = lj_strfmt_wint(p, nd[ndhi]);
i = ndhi;
while (i) p = lj_strfmt_wuint9(p, nd[--i]);
if ((prec | (sf & STRFMT_F_ALT))) {
/* Emit fractional part. */
*p++ = '.';
/* Emit chunks of 9 digits (this may emit 8 digits too many). */
while ((int32_t)prec > 0 && i != ndlo) {
i = (i - 1) & 0x3f;
p = lj_strfmt_wuint9(p, nd[i]);
prec -= 9;
}
if ((sf & STRFMT_T_FP_E) && !(sf & STRFMT_F_ALT)) {
/* %g (and not %#g) - strip trailing zeroes. */
p += (int32_t)prec & ((int32_t)prec >> 31);
while (p[-1] == '0') p--;
if (p[-1] == '.') p--;
} else {
/* %f (or %#g) - emit trailing zeroes. */
while ((int32_t)prec > 0) { *p++ = '0'; prec--; }
p += (int32_t)prec;
}
}
}
}
if ((sf & STRFMT_F_LEFT)) while (width-- > len) *p++ = ' ';
return p;
}
/* Add formatted floating-point number to buffer. */
SBuf *lj_strfmt_putfnum(SBuf *sb, SFormat sf, lua_Number n)
{
sb->w = lj_strfmt_wfnum(sb, sf, n, NULL);
return sb;
}
/* -- Conversions to strings ---------------------------------------------- */
/* Convert number to string. */
GCstr * LJ_FASTCALL lj_strfmt_num(lua_State *L, cTValue *o)
{
char buf[STRFMT_MAXBUF_NUM];
MSize len = (MSize)(lj_strfmt_wfnum(NULL, STRFMT_G14, o->n, buf) - buf);
return lj_str_new(L, buf, len);
}
Reference in New Issue View Git Blame Copy Permalink