Scarfski/tinygltf
1
0
Fork 0
mirror of https://github.com/syoyo/tinygltf.git synced 2026-06-08 03:03:50 +00:00
Code Issues Packages Projects Releases Wiki Activity

Fix MSVC v3 C JSON float conversion

Browse Source
This commit is contained in:
Syoyo Fujita
2026-06-01 20:08:32 +09:00
parent 381daedaba
commit 2ff44b903c
1 changed files with 162 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

168
tinygltf_json_c.h
View File

@@ -129,6 +129,14 @@ char *tg3json_stringify_pretty(const tg3json_value *value, int indent, size_t *o
#ifndef TINYGLTF_JSON_NO_STDLIB
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <float.h>
#if defined(_MSC_VER) || (defined(LDBL_MANT_DIG) && LDBL_MANT_DIG <= 53)
#define TG3JSON_USE_STDLIB_FPCONV 1
#endif
#endif
#ifndef TG3JSON_USE_STDLIB_FPCONV
#define TG3JSON_USE_STDLIB_FPCONV 0
#endif
#ifdef TINYGLTF_JSON_NO_STDLIB
@@ -266,12 +274,6 @@ static uint64_t tg3json__double_bits(double v) {
return bits;
}
static double tg3json__double_from_bits(uint64_t bits) {
double v = 0.0;
TINYGLTF_JSON_MEMCPY(&v, &bits, sizeof(v));
return v;
}
static int tg3json__is_nan_bits(uint64_t bits) {
return ((bits & 0x7ff0000000000000ULL) == 0x7ff0000000000000ULL) &&
((bits & 0x000fffffffffffffULL) != 0);
@@ -281,6 +283,13 @@ static int tg3json__is_inf_bits(uint64_t bits) {
return (bits & 0x7fffffffffffffffULL) == 0x7ff0000000000000ULL;
}
#if !TG3JSON_USE_STDLIB_FPCONV
static double tg3json__double_from_bits(uint64_t bits) {
double v = 0.0;
TINYGLTF_JSON_MEMCPY(&v, &bits, sizeof(v));
return v;
}
static long double tg3json__pow10_ld(int exp10) {
long double v = 1.0L;
if (exp10 < 0) {
@@ -299,8 +308,30 @@ static long double tg3json__pow10_ld(int exp10) {
}
return v;
}
#endif
static int tg3json__parse_f64_c(const char *start, const char *end, double *out) {
#if TG3JSON_USE_STDLIB_FPCONV
size_t len = (size_t)(end - start);
char stack_buf[128];
char *buf = stack_buf;
char *parse_end = NULL;
double v;
if (len + 1 > sizeof(stack_buf)) {
buf = (char *)TINYGLTF_JSON_MALLOC(len + 1);
if (!buf) return 0;
}
if (len > 0) TINYGLTF_JSON_MEMCPY(buf, start, len);
buf[len] = '\0';
v = strtod(buf, &parse_end);
if (parse_end != buf + len || tg3json__is_inf_bits(tg3json__double_bits(v))) {
if (buf != stack_buf) TINYGLTF_JSON_FREE(buf);
return 0;
}
if (buf != stack_buf) TINYGLTF_JSON_FREE(buf);
*out = v;
return 1;
#else
const char *p = start;
int neg = 0;
int saw_digit = 0;
@@ -399,6 +430,7 @@ static int tg3json__parse_f64_c(const char *start, const char *end, double *out)
*out = (double)v;
if (tg3json__is_inf_bits(tg3json__double_bits(*out))) return 0;
return 1;
#endif
}
static char *tg3json__write_exp(char *p, int exp10) {
@@ -452,6 +484,97 @@ static int tg3json__same_f64(double a, double b) {
return tg3json__double_bits(a) == tg3json__double_bits(b);
}
#if TG3JSON_USE_STDLIB_FPCONV
static void tg3json__normalize_exponent(char *s) {
char *e = s;
char *dst;
int neg = 0;
while (*e && *e != 'e' && *e != 'E') ++e;
if (!*e) return;
*e++ = 'e';
dst = e;
if (*e == '+' || *e == '-') {
neg = (*e == '-');
++e;
}
while (*e == '0') ++e;
if (neg) *dst++ = '-';
if (!*e) {
*dst++ = '0';
} else {
while (*e) *dst++ = *e++;
}
*dst = '\0';
}
static void tg3json__expand_short_plain_decimal(char *s) {
char *p = s;
char *e;
char digits[32];
char out[96];
int negative = 0;
int ndigits = 0;
int int_digits = 0;
int exp10 = 0;
int new_point;
int i;
char *q = out;
if (*p == '-') {
negative = 1;
++p;
}
e = p;
while (*e && *e != 'e') ++e;
if (!*e) return;
for (; p < e; ++p) {
if (*p == '.') {
int_digits = ndigits;
} else {
if (ndigits < (int)(sizeof(digits) - 1)) digits[ndigits++] = *p;
}
}
if (int_digits == 0) int_digits = ndigits;
++e;
if (*e == '-') {
int sign = -1;
++e;
while (*e >= '0' && *e <= '9') exp10 = exp10 * 10 + (*e++ - '0');
exp10 *= sign;
} else {
while (*e >= '0' && *e <= '9') exp10 = exp10 * 10 + (*e++ - '0');
}
if (exp10 < -4 || exp10 >= 16) return;
new_point = int_digits + exp10;
if (negative) *q++ = '-';
if (new_point <= 0) {
*q++ = '0';
*q++ = '.';
for (i = 0; i < -new_point; ++i) *q++ = '0';
for (i = 0; i < ndigits; ++i) *q++ = digits[i];
} else if (new_point >= ndigits) {
for (i = 0; i < ndigits; ++i) *q++ = digits[i];
for (i = ndigits; i < new_point; ++i) *q++ = '0';
} else {
for (i = 0; i < new_point; ++i) *q++ = digits[i];
*q++ = '.';
for (; i < ndigits; ++i) *q++ = digits[i];
}
*q = '\0';
if (q > out) {
char *dot = out;
while (*dot && *dot != '.') ++dot;
if (*dot == '.') {
char *end = q - 1;
while (end > dot && *end == '0') *end-- = '\0';
if (end == dot) *end = '\0';
}
}
TINYGLTF_JSON_MEMCPY(s, out, (size_t)(TINYGLTF_JSON_STRLEN(out) + 1));
}
#endif
static char *tg3json__dtoa_c(double value, char *buf) {
uint64_t bits = tg3json__double_bits(value);
int negative = (int)(bits >> 63);
@@ -490,6 +613,39 @@ static char *tg3json__dtoa_c(double value, char *buf) {
return buf;
}
#if TG3JSON_USE_STDLIB_FPCONV
{
int precision;
char candidate[96];
char shortest[96];
shortest[0] = '\0';
for (precision = 1; precision <= 17; ++precision) {
char fmt[8];
double parsed = 0.0;
int n;
n = snprintf(fmt, sizeof(fmt), "%%.%dg", precision);
if (n <= 0 || n >= (int)sizeof(fmt)) continue;
n = snprintf(candidate, sizeof(candidate), fmt, value);
if (n <= 0 || n >= (int)sizeof(candidate)) continue;
tg3json__normalize_exponent(candidate);
tg3json__expand_short_plain_decimal(candidate);
if (tg3json__parse_f64_c(candidate, candidate + TINYGLTF_JSON_STRLEN(candidate), &parsed) &&
tg3json__same_f64(parsed, value)) {
TINYGLTF_JSON_MEMCPY(shortest, candidate, TINYGLTF_JSON_STRLEN(candidate) + 1);
break;
}
}
if (!shortest[0]) {
int n = snprintf(shortest, sizeof(shortest), "%.17g", value);
if (n <= 0 || n >= (int)sizeof(shortest)) return buf;
tg3json__normalize_exponent(shortest);
tg3json__expand_short_plain_decimal(shortest);
}
TINYGLTF_JSON_MEMCPY(buf, shortest, TINYGLTF_JSON_STRLEN(shortest));
return buf + TINYGLTF_JSON_STRLEN(shortest);
}
#endif
x = negative ? -(long double)value : (long double)value;
while (x >= 1.0e16L) {
x *= 1.0e-16L;