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sortix--sortix/libc/integer.cpp
2013-12-17 14:30:23 +01:00

90 lines
2.9 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011.
This file is part of the Sortix C Library.
The Sortix C Library is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at your
option) any later version.
The Sortix C Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
integer.cpp
Converts integers represented as strings to binary representation.
*******************************************************************************/
#include <ctype.h>
#include <stddef.h>
#include <stdlib.h>
static int Debase(char c)
{
if ( '0' <= c && c <= '9' ) { return c - '0'; }
if ( 'a' <= c && c <= 'z' ) { return 10 + c - 'a'; }
if ( 'A' <= c && c <= 'Z' ) { return 10 + c - 'A'; }
return -1;
}
template <class INT, bool UNSIGNED> INT ParseInteger(const char* str, char** endptr, int base)
{
const char* origstr = str;
int origbase = base;
while ( isspace(*str) ) { str++; }
if ( base < 0 || 36 < base ) { if ( endptr ) { *endptr = (char*) str; } return 0; }
INT result = 0;
bool negative = false;
char c = *str;
if ( !UNSIGNED && c == '-' ) { str++; negative = true; }
if ( !UNSIGNED && c == '+' ) { str++; negative = false; }
if ( !base && str[0] == '0' )
{
if ( str[1] == 'x' || str[1] == 'X' ) { str += 2; base = 16; }
else if ( 0 <= Debase(str[1]) && Debase(str[1]) < 8 ) { str++; base = 8; }
}
if ( !base ) { base = 10; }
if ( origbase == 16 && str[0] == '0' && (str[1] == 'x' || str[1] == 'X') ) { str += 2; }
size_t numconvertedchars = 0;
while ( (c = *str ) )
{
int val = Debase(c);
if ( val < 0 ) { break; }
if ( base <= val ) { break; }
if ( !UNSIGNED && negative ) { val = -val; }
// TODO: Detect overflow!
result = result * (INT) base + (INT) val;
str++;
numconvertedchars++;
}
if ( !numconvertedchars ) { str = origstr; result = 0; }
if ( endptr ) { *endptr = (char*) str; }
return result;
}
extern "C" long strtol(const char* str, char** endptr, int base)
{
return ParseInteger<long, false>(str, endptr, base);
}
extern "C" long long strtoll(const char* str, char** endptr, int base)
{
return ParseInteger<long long, false>(str, endptr, base);
}
extern "C" unsigned long strtoul(const char* str, char** endptr, int base)
{
return ParseInteger<unsigned long, true>(str, endptr, base);
}
extern "C" unsigned long long strtoull(const char* str, char** endptr, int base)
{
return ParseInteger<unsigned long long, true>(str, endptr, base);
}