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/*
* Copyright (C) 2014 Andreas Steffen
* HSR Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY;https://www.hsr.ch/HSR-intern-Anmeldung.4409.0.html?&no_cache=1 without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include "bliss_bitpacker.h"
typedef struct private_bliss_bitpacker_t private_bliss_bitpacker_t;
/**
* Private data structure for bliss_bitpacker_t object
*/
struct private_bliss_bitpacker_t {
/**
* Public interface.
*/
bliss_bitpacker_t public;
/**
* Current number of bits written to buffer
*/
size_t bits;
/**
* Bit buffer for up to 32 bits
*/
uint32_t bits_buf;
/**
* Bits left in the bit buffer
*/
size_t bits_left;
/**
* Buffer
*/
chunk_t buf;
/**
* Read/Write pointer into buffer
*/
chunk_t pos;
};
METHOD(bliss_bitpacker_t, get_bits, size_t,
private_bliss_bitpacker_t *this)
{
return this->bits;
}
METHOD(bliss_bitpacker_t, write_bits, bool,
private_bliss_bitpacker_t *this, uint32_t value, size_t bits)
{
if (bits == 0)
{
return TRUE;
}
if (bits > 32)
{
return FALSE;
}
if (bits < 32)
{
value &= (1 << bits) - 1;
}
this->bits += bits;
while (TRUE)
{
if (bits <= this->bits_left)
{
this->bits_buf |= value << (this->bits_left - bits);
this->bits_left -= bits;
return TRUE;
}
this->bits_buf |= value >> (bits - this->bits_left);
value &= (1 << (bits - this->bits_left)) - 1;
bits -= this->bits_left;
if (this->pos.len < 8)
{
return FALSE;
}
htoun32(this->pos.ptr, this->bits_buf);
this->pos = chunk_skip(this->pos, 4);
this->bits_buf = 0;
this->bits_left = 32;
}
}
METHOD(bliss_bitpacker_t, read_bits, bool,
private_bliss_bitpacker_t *this, uint32_t *value, size_t bits)
{
if (bits > 32)
{
return FALSE;
}
*value = 0;
while (TRUE)
{
if (this->bits_left == 0)
{
if (this->pos.len < 4)
{
return FALSE;
}
this->bits_buf = untoh32(this->pos.ptr);
this->pos = chunk_skip(this->pos, 4);
this->bits_left = 32;
}
if (bits <= this->bits_left)
{
*value |= this->bits_buf >> (this->bits_left - bits);
this->bits_buf &= (1 << (this->bits_left - bits)) - 1;
this->bits_left -= bits;
return TRUE;
}
*value |= this->bits_buf << (bits - this->bits_left);
bits -= this->bits_left;
this->bits_left = 0;
}
}
METHOD(bliss_bitpacker_t, extract_buf, chunk_t,
private_bliss_bitpacker_t *this)
{
chunk_t buf;
htoun32(this->pos.ptr, this->bits_buf);
this->pos.len -= 4;
buf = this->buf;
buf.len = this->buf.len - this->pos.len - this->bits_left/8;
this->buf = this->pos = chunk_empty;
return buf;
}
METHOD(bliss_bitpacker_t, destroy, void,
private_bliss_bitpacker_t *this)
{
free(this->buf.ptr);
free(this);
}
/**
* See header.
*/
bliss_bitpacker_t *bliss_bitpacker_create(uint16_t max_bits)
{
private_bliss_bitpacker_t *this;
INIT(this,
.public = {
.get_bits = _get_bits,
.write_bits = _write_bits,
.read_bits = _read_bits,
.extract_buf = _extract_buf,
.destroy = _destroy,
},
.bits_left = 32,
.buf = chunk_alloc(round_up(max_bits, 32)/8),
);
this->pos = this->buf;
return &this->public;
}
/**
* See header.
*/
bliss_bitpacker_t *bliss_bitpacker_create_from_data(chunk_t data)
{
private_bliss_bitpacker_t *this;
INIT(this,
.public = {
.get_bits = _get_bits,
.write_bits = _write_bits,
.read_bits = _read_bits,
.extract_buf = _extract_buf,
.destroy = _destroy,
},
.bits = 8 * data.len,
.buf = chunk_alloc(round_up(data.len, 4)),
);
memset(this->buf.ptr + this->buf.len - 4, 0x00, 4);
memcpy(this->buf.ptr, data.ptr, data.len);
this->pos = this->buf;
return &this->public;
}
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