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sortix--sortix/libc/wchar/mbrtowc.cpp
2013-12-17 14:30:36 +01:00

105 lines
3 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012.
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/>.
wchar/mbrtowc.cpp
Convert a multibyte sequence to a wide character.
*******************************************************************************/
#include <errno.h>
#include <stdint.h>
#include <wchar.h>
extern "C"
size_t mbrtowc(wchar_t* restrict pwc, const char* restrict s, size_t n,
mbstate_t* restrict /*ps*/)
{
if ( !s )
{
// TODO: Restore ps to initial state if currently valid.
return 0;
}
uint8_t* buf = (uint8_t*) s;
wchar_t ret = 0;
size_t numbytes = 0;
size_t sequence_len = 1;
while ( numbytes < sequence_len )
{
if ( numbytes == n )
{
// TODO: Support restore through the mbstate_t!
return (size_t) -2;
}
uint8_t b = buf[numbytes++];
bool is_continuation = b >> (8-2) == 0b10;
if ( 1 == numbytes && is_continuation )
return errno = EILSEQ, (size_t) -1;
if ( 2 <= numbytes && !is_continuation )
return errno = EILSEQ, (size_t) -1;
wchar_t new_bits;
size_t new_bits_num;
if ( b >> (8-1) == 0b0 )
new_bits = b & 0b01111111,
new_bits_num = 7,
sequence_len = 1;
else if ( b >> (8-2) == 0b10 )
new_bits = b & 0b00111111,
new_bits_num = 6,
sequence_len = 2;
else if ( b >> (8-3) == 0b110 )
new_bits = b & 0b00011111,
new_bits_num = 5,
sequence_len = 3;
else if ( b >> (8-4) == 0b1110 )
new_bits = b & 0b00001111,
new_bits_num = 4,
sequence_len = 4;
else if ( b >> (8-5) == 0b11110 )
new_bits = b & 0b00000111,
new_bits_num = 3,
sequence_len = 5;
else if ( b >> (8-6) == 0b111110 )
new_bits = b & 0b00000011,
new_bits_num = 2,
sequence_len = 6;
else if ( b >> (8-7) == 0b1111110 )
new_bits = b & 0b00000001,
new_bits_num = 1,
sequence_len = 7;
else
return errno = EILSEQ, (size_t) -1;
ret = ret >> new_bits_num | new_bits;
}
if ( !ret )
{
// TODO: Reset ps to initial state.
return 0;
}
if ( (numbytes == 2 && ret <= 0x007F) ||
(numbytes == 3 && ret <= 0x07FF) ||
(numbytes == 4 && ret <= 0xFFFF) ||
(numbytes == 5 && ret <= 0x1FFFFF) ||
(numbytes == 6 && ret <= 0x3FFFFFF) )
return errno = EILSEQ, (size_t) -1;
if ( pwc )
*pwc = ret;
return numbytes;
}