ref: 1018d7a7091fd5e0433f501a3474cdc3fec322cc
dir: /libkern/strtoul.c/
#include <lib9.h> #define ULONG_MAX 4294967295UL ulong strtoul(char *nptr, char **endptr, int base) { char *p; ulong n, nn, m; int c, ovfl, neg, v, ndig; p = (char*)nptr; neg = 0; n = 0; ndig = 0; ovfl = 0; /* * White space */ for(;;p++){ switch(*p){ case ' ': case '\t': case '\n': case '\f': case '\r': case '\v': continue; } break; } /* * Sign */ if(*p=='-' || *p=='+') if(*p++ == '-') neg = 1; /* * Base */ if(base==0){ if(*p != '0') base = 10; else{ base = 8; if(p[1]=='x' || p[1]=='X') base = 16; } } if(base<2 || 36<base) goto Return; if(base==16 && *p=='0'){ if(p[1]=='x' || p[1]=='X') if(('0' <= p[2] && p[2] <= '9') ||('a' <= p[2] && p[2] <= 'f') ||('A' <= p[2] && p[2] <= 'F')) p += 2; } /* * Non-empty sequence of digits */ n = 0; m = ULONG_MAX/base; for(;; p++,ndig++){ c = *p; v = base; if('0'<=c && c<='9') v = c - '0'; else if('a'<=c && c<='z') v = c - 'a' + 10; else if('A'<=c && c<='Z') v = c - 'A' + 10; if(v >= base) break; if(n > m) ovfl = 1; nn = n*base + v; if(nn < n) ovfl = 1; n = nn; } Return: if(ndig == 0) p = nptr; if(endptr) *endptr = p; if(ovfl) return ULONG_MAX; if(neg) return -n; return n; }