111 lines
2.8 KiB
C
111 lines
2.8 KiB
C
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/*
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This source code was extracted from the Q8 package created and
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placed in the PUBLIC DOMAIN by Doug Gwyn <gwyn@arl.mil>
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last edit: 1999/11/05 gwyn@arl.mil
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Implements subclause 7.8.2 of ISO/IEC 9899:1999 (E).
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This particular implementation requires the matching <inttypes.h>.
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It also assumes that character codes for A..Z and a..z are in
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contiguous ascending order; this is true for ASCII but not EBCDIC.
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <ctype.h>
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#include <inttypes.h>
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/* Helper macros */
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/* convert digit character to number, in any base */
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#define ToNumber(c) (isdigit(c) ? (c) - '0' : \
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isupper(c) ? (c) - 'A' + 10 : \
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islower(c) ? (c) - 'a' + 10 : \
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-1 /* "invalid" flag */ \
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)
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/* validate converted digit character for specific base */
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#define valid(n, b) ((n) >= 0 && (n) < (b))
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uintmax_t
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strtoumax(nptr, endptr, base)
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register const char * __restrict__ nptr;
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char ** __restrict__ endptr;
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register int base;
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{
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register uintmax_t accum; /* accumulates converted value */
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register uintmax_t next; /* for computing next value of accum */
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register int n; /* numeral from digit character */
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int minus; /* set iff minus sign seen (yes!) */
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int toobig; /* set iff value overflows */
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if ( endptr != NULL )
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*endptr = (char *)nptr; /* in case no conversion's performed */
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if ( base < 0 || base == 1 || base > 36 )
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{
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errno = EDOM;
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return 0; /* unspecified behavior */
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}
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/* skip initial, possibly empty sequence of white-space characters */
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while ( isspace(*nptr) )
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++nptr;
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/* process subject sequence: */
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/* optional sign (yes!) */
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if ( (minus = *nptr == '-') || *nptr == '+' )
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++nptr;
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if ( base == 0 )
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{
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if ( *nptr == '0' )
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{
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if ( nptr[1] == 'X' || nptr[1] == 'x' )
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base = 16;
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else
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base = 8;
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}
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else
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base = 10;
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}
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/* optional "0x" or "0X" for base 16 */
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if ( base == 16 && *nptr == '0' && (nptr[1] == 'X' || nptr[1] == 'x') )
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nptr += 2; /* skip past this prefix */
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/* check whether there is at least one valid digit */
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n = ToNumber(*nptr);
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++nptr;
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if ( !valid(n, base) )
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return 0; /* subject seq. not of expected form */
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accum = n;
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for ( toobig = 0; n = ToNumber(*nptr), valid(n, base); ++nptr )
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if ( accum > UINTMAX_MAX / base + 1 /* major wrap-around */
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|| (next = base * accum + n) < accum /* minor wrap-around */
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)
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toobig = 1; /* but keep scanning */
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else
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accum = next;
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if ( endptr != NULL )
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*endptr = (char *)nptr; /* points to first not-valid-digit */
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if ( toobig )
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{
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errno = ERANGE;
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return UINTMAX_MAX;
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}
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else
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return minus ? -accum : accum; /* (yes!) */
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}
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unsigned long long __attribute__ ((alias ("strtoumax")))
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strtoull (const char* __restrict__ nptr, char ** __restrict__ endptr, int base);
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