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stdlib: Improve SDL_strtod

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- Handle leading whitespace
- Handle positive sign
- Parse integer part as unsigned long long
- Handle signed zero (this also applies to printf)
This commit is contained in:
Carl Åstholm
2024-09-12 01:23:56 +02:00
committed by Sam Lantinga
parent a78f612d4b
commit 8092e35287
1 changed files with 29 additions and 26 deletions
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55
src/stdlib/SDL_string.c
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@@ -540,7 +540,7 @@ static size_t SDL_ScanLongW(const wchar_t *text, int count, int radix, long *val
} }
#endif #endif
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOUL) || !defined(HAVE_STRTOD) #if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOUL)
static size_t SDL_ScanUnsignedLong(const char *text, int count, int radix, unsigned long *valuep) static size_t SDL_ScanUnsignedLong(const char *text, int count, int radix, unsigned long *valuep)
{ {
const unsigned long ulong_max = ~0UL; const unsigned long ulong_max = ~0UL;
@@ -608,7 +608,7 @@ static size_t SDL_ScanLongLong(const char *text, int count, int radix, long long
} }
#endif #endif
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOULL) #if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOULL) || !defined(HAVE_STRTOD)
static size_t SDL_ScanUnsignedLongLong(const char *text, int count, int radix, unsigned long long *valuep) static size_t SDL_ScanUnsignedLongLong(const char *text, int count, int radix, unsigned long long *valuep)
{ {
const unsigned long long ullong_max = ~0ULL; const unsigned long long ullong_max = ~0ULL;
@@ -628,35 +628,40 @@ static size_t SDL_ScanUnsignedLongLong(const char *text, int count, int radix, u
#if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOD) #if !defined(HAVE_VSSCANF) || !defined(HAVE_STRTOD)
static size_t SDL_ScanFloat(const char *text, double *valuep) static size_t SDL_ScanFloat(const char *text, double *valuep)
{ {
const char *textstart = text; const char *text_start = text;
unsigned long lvalue = 0; const char *number_start = text_start;
double value = 0.0; double value = 0.0;
bool negative = false; bool negative = false;
if (*text == '-') { while (SDL_isspace(*text)) {
negative = true;
++text; ++text;
} }
text += SDL_ScanUnsignedLong(text, 0, 10, &lvalue); if (*text == '-' || *text == '+') {
value += lvalue; negative = *text == '-';
if (*text == '.') {
int mult = 10;
++text; ++text;
while (SDL_isdigit((unsigned char)*text)) { }
lvalue = *text - '0'; number_start = text;
value += (double)lvalue / mult; if (SDL_isdigit(*text)) {
mult *= 10; value += SDL_strtoull(text, (char **)(&text), 10);
if (*text == '.') {
double denom = 10;
++text; ++text;
while (SDL_isdigit(*text)) {
value += (double)(*text - '0') / denom;
denom *= 10;
++text;
}
} }
} }
if (valuep && text > textstart) { if (text == number_start) {
if (negative && value != 0.0) { // no number was parsed, and thus no characters were consumed
*valuep = -value; text = text_start;
} else {
*valuep = value;
}
} }
return text - textstart; if (negative) {
value = -value;
}
*valuep = value;
return text - text_start;
} }
#endif #endif
@@ -1302,10 +1307,8 @@ double SDL_strtod(const char *string, char **endp)
#ifdef HAVE_STRTOD #ifdef HAVE_STRTOD
return strtod(string, endp); return strtod(string, endp);
#else #else
size_t len; double value;
double value = 0.0; size_t len = SDL_ScanFloat(string, &value);
len = SDL_ScanFloat(string, &value);
if (endp) { if (endp) {
*endp = (char *)string + len; *endp = (char *)string + len;
} }
@@ -1977,7 +1980,7 @@ static size_t SDL_PrintFloat(char *text, size_t maxlen, SDL_FormatInfo *info, do
// This isn't especially accurate, but hey, it's easy. :) // This isn't especially accurate, but hey, it's easy. :)
unsigned long long value; unsigned long long value;
if (arg < 0) { if (arg < 0.0 || (arg == 0.0 && 1.0 / arg < 0.0)) { // additional check for signed zero
num[length++] = '-'; num[length++] = '-';
arg = -arg; arg = -arg;
} else if (info->force_sign) { } else if (info->force_sign) {