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#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
static int valid_exp(const unsigned char *s)
{
return isdigit(*s) || ((s[0]=='+'||s[0]=='-') && isdigit(s[1]));
}
long double strtold(const char *s1, char **p)
{
const unsigned char *s = (void *)s1;
long double x = 0;
long double frac;
int sign = 0;
int nonzero = 0;
int radix = '.';
long e;
int saved_errno = errno;
if (!p) p = (char **)&s1;
/* Initial whitespace */
for (; isspace(*s); s++);
/* Optional sign */
if (*s == '-') sign = *s++;
else if (*s == '+') s++;
/* Handle infinities and NaNs. */
if ((s[0]|32)=='i' && (s[1]|32)=='n' && (s[2]|32)=='f') {
*p = (char *)s + 3;
return sign ? -1.0/0.0 : 1.0/0.0;
} else if ((s[0]|32)=='n' && (s[1]|32)=='a' && (s[2]|32)=='n') {
*p = (char *)s + 3;
return 0.0/0.0;
}
/* Possible hex float */
if (s[0]=='0' && (s[1]|32)=='x') {
/* Mantissa must be non-degenerate */
if (!isxdigit(s[2]) && (s[2]!=radix || !isxdigit(s[3]))) {
/* Decimal float 0, 'x' extraneous */
*p = (char *)++s;
return 0;
}
/* We have a real hex float */
s += 2;
for (; isxdigit(*s); s++) {
x = 16*x + (isdigit(*s)?*s-'0':(*s|32)-'a'+10);
if (*s!='0') nonzero=1;
}
if (*s == radix) {
frac = 1.0/16.0;
for (s++; isxdigit(*s); s++) {
x += frac * (isdigit(*s)?*s-'0':(*s|32)-'a'+10);
frac *= 1.0/16.0;
if (*s!='0') nonzero=1;
}
}
if ((*s|32) == 'p' && valid_exp(s+1)) {
e = strtol((void *)(s+1), (void *)&s, 10);
for (; e>0; e--) x *= 2.0;
for (; e<0; e++) x *= 0.5;
}
goto finish;
}
/* Mantissa must be non-degenerate */
if (!isdigit(s[0]) && (s[0]!=radix || !isdigit(s[1]))) {
*p = (char *)s1;
return 0;
}
for (; isdigit(*s); s++) {
x = 10*x + *s-'0';
if (*s!='0') nonzero=1;
}
if (*s == radix) {
frac = 10.0;
for (s++; isdigit(*s); s++) {
x += (*s-'0') / frac;
frac *= 10.0;
if (*s!='0') nonzero=1;
}
}
if ((*s|32)=='e' && valid_exp(s+1)) {
e = strtol((void *)++s, (void *)&s, 10);
for (; e>0; e--) x *= 10.0;
for (; e<0; e++) x /= 10.0;
}
finish:
errno = ((nonzero && !x) || !(1.0/x)) ? ERANGE : saved_errno;
*p = (char*)s;
return sign ? -x : x;
}
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