1 #include <lib9.h> 2 3 #define ULONG_MAX 4294967295UL 4 5 ulong 6 strtoul(char *nptr, char **endptr, int base) 7 { 8 char *p; 9 ulong n, nn, m; 10 int c, ovfl, neg, v, ndig; 11 12 p = (char*)nptr; 13 neg = 0; 14 n = 0; 15 ndig = 0; 16 ovfl = 0; 17 18 /* 19 * White space 20 */ 21 for(;;p++){ 22 switch(*p){ 23 case ' ': 24 case '\t': 25 case '\n': 26 case '\f': 27 case '\r': 28 case '\v': 29 continue; 30 } 31 break; 32 } 33 34 /* 35 * Sign 36 */ 37 if(*p=='-' || *p=='+') 38 if(*p++ == '-') 39 neg = 1; 40 41 /* 42 * Base 43 */ 44 if(base==0){ 45 if(*p != '0') 46 base = 10; 47 else{ 48 base = 8; 49 if(p[1]=='x' || p[1]=='X') 50 base = 16; 51 } 52 } 53 if(base<2 || 36<base) 54 goto Return; 55 if(base==16 && *p=='0'){ 56 if(p[1]=='x' || p[1]=='X') 57 if(('0' <= p[2] && p[2] <= '9') 58 ||('a' <= p[2] && p[2] <= 'f') 59 ||('A' <= p[2] && p[2] <= 'F')) 60 p += 2; 61 } 62 /* 63 * Non-empty sequence of digits 64 */ 65 n = 0; 66 m = ULONG_MAX/base; 67 for(;; p++,ndig++){ 68 c = *p; 69 v = base; 70 if('0'<=c && c<='9') 71 v = c - '0'; 72 else if('a'<=c && c<='z') 73 v = c - 'a' + 10; 74 else if('A'<=c && c<='Z') 75 v = c - 'A' + 10; 76 if(v >= base) 77 break; 78 if(n > m) 79 ovfl = 1; 80 nn = n*base + v; 81 if(nn < n) 82 ovfl = 1; 83 n = nn; 84 } 85 86 Return: 87 if(ndig == 0) 88 p = nptr; 89 if(endptr) 90 *endptr = p; 91 if(ovfl) 92 return ULONG_MAX; 93 if(neg) 94 return -n; 95 return n; 96 } 97