194 lines
5.0 KiB
C
194 lines
5.0 KiB
C
/*
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* Copyright (c) 2011, 2013, 2014, 2015 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* stdlib/strtol.c
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* Converts integers represented as strings to binary representation.
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*/
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#ifndef STRTOL
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#define STRTOL strtol
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#define STRTOL_CHAR char
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#define STRTOL_UCHAR unsigned char
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#define STRTOL_L(x) x
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#define STRTOL_ISSPACE isspace
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#define STRTOL_INT long
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#define STRTOL_UNSIGNED_INT unsigned long
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#define STRTOL_INT_MIN LONG_MIN
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#define STRTOL_INT_MAX LONG_MAX
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#define STRTOL_INT_IS_UNSIGNED false
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#endif
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#include <assert.h>
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#include <ctype.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <limits.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <wchar.h>
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#include <wctype.h>
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// Convert a character into a digit.
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static int debase(STRTOL_CHAR c)
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{
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if ( STRTOL_L('0') <= c && c <= STRTOL_L('9') )
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return c - STRTOL_L('0');
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if ( STRTOL_L('a') <= c && c <= STRTOL_L('z') )
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return 10 + c - STRTOL_L('a');
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if ( STRTOL_L('A') <= c && c <= STRTOL_L('Z') )
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return 10 + c - STRTOL_L('A');
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return -1;
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}
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STRTOL_INT STRTOL(const STRTOL_CHAR* restrict str,
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STRTOL_CHAR** restrict end_ptr,
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int base)
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{
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// Reject bad bases.
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if ( base < 0 || base == 1 || 36 < base )
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{
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if ( end_ptr )
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*end_ptr = (STRTOL_CHAR*) str;
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return errno = EINVAL, 0;
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}
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const STRTOL_CHAR* original_str = str;
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// Skip any leading white space.
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while ( STRTOL_ISSPACE((STRTOL_UCHAR) *str) )
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str++;
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bool negative = false;
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STRTOL_CHAR c = *str;
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// Handle a leading sign character.
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if ( c == STRTOL_L('-') )
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str++, negative = true;
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else if ( c == STRTOL_L('+') )
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str++, negative = false;
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bool actually_negative = !STRTOL_INT_IS_UNSIGNED && negative;
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// Autodetect base if requested.
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if ( base == 0 )
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{
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if ( str[0] == STRTOL_L('0') &&
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(str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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(0 <= debase(str[2]) && debase(str[2]) < 16) )
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str += 2, base = 16;
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else if ( str[0] == STRTOL_L('0') &&
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0 <= debase(str[1]) && debase(str[1]) < 8 )
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str++, base = 8;
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else
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base = 10;
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}
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// Skip the leading '0x' prefix in base 16 for hexadecimal integers.
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else if ( base == 16 )
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{
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if ( str[0] == STRTOL_L('0') &&
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(str[1] == STRTOL_L('x') || str[1] == STRTOL_L('X')) &&
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(0 <= debase(str[2]) && debase(str[2]) < 16) )
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str += 2;
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}
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// Determine what value will be returned on overflow/underflow.
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STRTOL_INT overflow_value =
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actually_negative ? STRTOL_INT_MIN : STRTOL_INT_MAX;
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// Convert a single character at a time.
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STRTOL_INT result = 0;
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size_t num_converted_chars = 0;
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bool overflow_occured = false;
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while ( (c = *str ) )
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{
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// Stop if we encounter a character that doesn't fit in this base.
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int val = debase(c);
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if ( val < 0 || base <= val )
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break;
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str++;
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num_converted_chars++;
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if ( overflow_occured )
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continue;
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// Attempt to multiply the accumulator with the current base.
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if ( __builtin_mul_overflow(result, base, &result) )
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{
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overflow_occured = true;
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result = overflow_value;
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errno = ERANGE;
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continue;
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}
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// Nothing needs to be added if we are encountered a zero digit.
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if ( val == 0 )
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{
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}
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// Attempt to add the latest digit to the accumulator (positive).
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else if ( !actually_negative &&
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(STRTOL_INT) val <= (STRTOL_INT) (STRTOL_INT_MAX - result) )
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{
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result += (STRTOL_INT) val;
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}
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// Attempt to subtract the latest digit to the accumulator (negative).
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else if ( actually_negative &&
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(STRTOL_UNSIGNED_INT) val <
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((STRTOL_UNSIGNED_INT) result -
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(STRTOL_UNSIGNED_INT) STRTOL_INT_MIN) )
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{
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result -= (STRTOL_INT) val;
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}
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// Otherwise, the addition/subtract would overflow/underflow.
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else
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{
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overflow_occured = true;
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result = overflow_value;
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errno = ERANGE;
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continue;
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}
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}
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// If no characters were successfully converted, rewind to the start.
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if ( !num_converted_chars )
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{
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errno = EINVAL;
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str = original_str;
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}
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// Let the caller know where we got to.
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if ( end_ptr )
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*end_ptr = (STRTOL_CHAR*) str;
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// Handle the special case where we are creating an unsigned integer and the
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// string was negative. The result is the negation assuming no overflow.
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if ( STRTOL_INT_IS_UNSIGNED && negative )
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{
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if ( overflow_occured )
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result = STRTOL_INT_MAX;
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else
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result = -result;
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}
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return result;
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}
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