forked from KolibriOS/kolibrios
78 lines
1.2 KiB
C
78 lines
1.2 KiB
C
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/*
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* strntoumax.c
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*
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* The strntoumax() function and associated
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include <ctype.h>
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#include <inttypes.h>
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static inline int digitval(int ch)
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{
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if (ch >= '0' && ch <= '9') {
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return ch - '0';
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} else if (ch >= 'A' && ch <= 'Z') {
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return ch - 'A' + 10;
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} else if (ch >= 'a' && ch <= 'z') {
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return ch - 'a' + 10;
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} else {
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return -1;
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}
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}
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uintmax_t strntoumax(const char *nptr, char **endptr, int base, size_t n)
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{
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int minus = 0;
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uintmax_t v = 0;
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int d;
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while (n && isspace((unsigned char)*nptr)) {
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nptr++;
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n--;
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}
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/* Single optional + or - */
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if (n) {
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char c = *nptr;
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if (c == '-' || c == '+') {
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minus = (c == '-');
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nptr++;
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n--;
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}
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}
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if (base == 0) {
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if (n >= 2 && nptr[0] == '0' &&
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(nptr[1] == 'x' || nptr[1] == 'X')) {
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n -= 2;
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nptr += 2;
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base = 16;
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} else if (n >= 1 && nptr[0] == '0') {
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n--;
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nptr++;
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base = 8;
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} else {
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base = 10;
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}
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} else if (base == 16) {
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if (n >= 2 && nptr[0] == '0' &&
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(nptr[1] == 'x' || nptr[1] == 'X')) {
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n -= 2;
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nptr += 2;
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}
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}
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while (n && (d = digitval(*nptr)) >= 0 && d < base) {
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v = v * base + d;
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n--;
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nptr++;
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}
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if (endptr)
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*endptr = (char *)nptr;
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return minus ? -v : v;
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}
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