rockbox/apps/plugins/lua/strtoul.c
William Wilgus 1aa739e3c3 lua misc tweaks and cleanup
checks button_status in rockev
strpbrk_n custom implementation allows setting max search len in source string
add some branch prediction where appropriate
fix formatting in splash_scroller script

Change-Id: Id5d8e9d83f4b3e361ccb67b403af8f9a8a31b8f0
2020-10-04 04:00:54 -04:00

53 lines
1.2 KiB
C

#include "rocklibc.h"
unsigned long int strtoul(const char *ptr, char **endptr, int base)
{
int neg = 0, overflow = 0;
unsigned long int v=0;
const char* orig;
const char* nptr=ptr;
while(__unlikely(isspace(*nptr))) ++nptr;
if (*nptr == '-') { neg=1; nptr++; }
else if (*nptr == '+') ++nptr;
orig=nptr;
if (base==16 && nptr[0]=='0') goto skip0x;
if (base) {
register unsigned int b=base-2;
if (__unlikely(b>34)) { errno=EINVAL; return 0; }
} else {
if (*nptr=='0') {
base=8;
skip0x:
if ((nptr[1]=='x'||nptr[1]=='X') && isxdigit(nptr[2])) {
nptr+=2;
base=16;
}
} else
base=10;
}
while(__likely(*nptr)) {
register unsigned char c=*nptr;
c=(c>='a'?c-'a'+10:c>='A'?c-'A'+10:c<='9'?c-'0':0xff);
if (__unlikely(c>=base)) break; /* out of base */
{
register unsigned long x=(v&0xff)*base+c;
register unsigned long w=(v>>8)*base+(x>>8);
if (w>(ULONG_MAX>>8)) overflow=1;
v=(w<<8)+(x&0xff);
}
++nptr;
}
if (__unlikely(nptr==orig)) { /* no conversion done */
nptr=ptr;
errno=EINVAL;
v=0;
}
if (endptr) *endptr=(char *)nptr;
if (overflow) {
errno=ERANGE;
return ULONG_MAX;
}
return (neg?-v:v);
}