1 /* 2 * strntoumax.c 3 * 4 * The strntoumax() function and associated 5 */ 6 7 #include <stddef.h> 8 #include <stdint.h> 9 #include <ctype.h> 10 11 static inline int digitval(int ch) 12 { 13 if (ch >= '0' && ch <= '9') { 14 return ch - '0'; 15 } else if (ch >= 'A' && ch <= 'Z') { 16 return ch - 'A' + 10; 17 } else if (ch >= 'a' && ch <= 'z') { 18 return ch - 'a' + 10; 19 } else { 20 return -1; 21 } 22 } 23 24 uintmax_t strntoumax(const char *nptr, char **endptr, int base, size_t n) 25 { 26 int minus = 0; 27 uintmax_t v = 0; 28 int d; 29 30 while (n && isspace((unsigned char)*nptr)) { 31 nptr++; 32 n--; 33 } 34 35 /* Single optional + or - */ 36 if (n && *nptr == '-') { 37 minus = 1; 38 nptr++; 39 n--; 40 } else if (n && *nptr == '+') { 41 nptr++; 42 } 43 44 if (base == 0) { 45 if (n >= 2 && nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) { 46 n -= 2; 47 nptr += 2; 48 base = 16; 49 } else if (n >= 1 && nptr[0] == '0') { 50 n--; 51 nptr++; 52 base = 8; 53 } else { 54 base = 10; 55 } 56 } else if (base == 16) { 57 if (n >= 2 && nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) { 58 n -= 2; 59 nptr += 2; 60 } 61 } 62 63 while (n && (d = digitval(*nptr)) >= 0 && d < base) { 64 v = v * base + d; 65 n--; 66 nptr++; 67 } 68 69 if (endptr) 70 *endptr = (char *)nptr; 71 72 return minus ? -v : v; 73 } 74
