76 lines
1.3 KiB
C
76 lines
1.3 KiB
C
/*
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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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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 && *nptr == '-' ) {
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minus = 1;
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nptr++;
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n--;
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} else if ( n && *nptr == '+' ) {
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nptr++;
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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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