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////////////////////////////////////////////////////////////////////////////////
///
/// @file decompress.c
///
/// @project
///
/// @brief Decompression Routines
///
////////////////////////////////////////////////////////////////////////////////
///
////////////////////////////////////////////////////////////////////////////////
///
/// @copyright Copyright (c) 2019, Evan Lojewski
/// @cond
///
/// All rights reserved.
///
/// Redistribution and use in source and binary forms, with or without
/// modification, are permitted provided that the following conditions are met:
/// 1. Redistributions of source code must retain the above copyright notice,
/// this list of conditions and the following disclaimer.
/// 2. Redistributions in binary form must reproduce the above copyright notice,
/// this list of conditions and the following disclaimer in the documentation
/// and/or other materials provided with the distribution.
/// 3. Neither the name of the copyright holder nor the
/// names of its contributors may be used to endorse or promote products
/// derived from this software without specific prior written permission.
///
////////////////////////////////////////////////////////////////////////////////
///
/// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
/// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
/// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
/// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
/// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
/// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
/// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
/// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
/// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
/// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
/// POSSIBILITY OF SUCH DAMAGE.
/// @endcond
////////////////////////////////////////////////////////////////////////////////
#include <Compress.h>
#include <stdio.h>
#define DICTIONARY_INIT_0x20 (0x20)
#define DICTIONARY_INIT_0x00 (0x00)
#define DICTIONARY_INIT_INDEX (2014)
#define DICTIONARY_SIZE (2048)
#define LITERAL_TYPE (1)
#define REFERENCE_TYPE (0)
static struct {
uint8_t dictionary[DICTIONARY_SIZE];
uint32_t cursor;
const uint8_t* inBuffer;
int32_t inBytes;
uint8_t* outBuffer;
int32_t outRemaining;
int32_t outSent;
} g_DecompressorState;
static void state_init(const uint8_t* inBuffer, int32_t inBytes)
{
g_DecompressorState.cursor = DICTIONARY_INIT_INDEX;
int i = 0;
for(; i < g_DecompressorState.cursor; i++)
{
g_DecompressorState.dictionary[i] = DICTIONARY_INIT_0x20;
}
for(; i < DICTIONARY_SIZE; i++)
{
g_DecompressorState.dictionary[i] = DICTIONARY_INIT_0x00;
}
g_DecompressorState.inBuffer = inBuffer;
g_DecompressorState.inBytes = inBytes;
}
static void state_insert(uint8_t byte)
{
g_DecompressorState.dictionary[g_DecompressorState.cursor] = byte;
// Increment and wrap.
g_DecompressorState.cursor = (g_DecompressorState.cursor + 1) % DICTIONARY_SIZE;
}
static uint8_t state_get_dictionary(uint16_t offset)
{
offset = offset % DICTIONARY_SIZE;
return g_DecompressorState.dictionary[offset];
}
static uint8_t state_get_byte(void)
{
// uint8_t bytesLeft = g_DecompressorState.inBytes;
uint8_t byte = 0;
// if(bytesLeft > 0)
// {
byte = *g_DecompressorState.inBuffer;
g_DecompressorState.inBuffer++;
g_DecompressorState.inBytes--;
// }
return byte;
}
int32_t state_bytes_left(void)
{
return g_DecompressorState.inBytes;
}
int32_t decompress(uint8_t* outBuffer, int32_t outBytes,
const uint8_t* inBuffer, int32_t inBytes)
{
int32_t actualSize = 0;
state_init(inBuffer, inBytes);
while(state_bytes_left() > 0)
{
uint8_t control = state_get_byte();
for(int i = 0; i < 8; i++)
{
if(actualSize >= outBytes || !state_bytes_left())
{
// We have no bytes left, or we've filled up the output buffer
break;
}
if((control & (1 << i)) == REFERENCE_TYPE)
{
// Read in two reference bytes
uint8_t B0 = state_get_byte();
uint8_t B1 = state_get_byte();
uint16_t offset = (((uint16_t)B1 & 0xE0u) << 3u) | B0;
uint16_t length = (B1 & 0x1Fu) + 3u;
while(length && actualSize < outBytes)
{
uint8_t literal = state_get_dictionary(offset);
state_insert(literal);
offset++;
length--;
outBuffer[actualSize++] = literal;
}
}
else /* LITERAL_TYPE */
{
uint8_t literal = state_get_byte();;
state_insert(literal);
// Output
outBuffer[actualSize++] = literal;
}
}
}
// printf("inBytes: %d (%d left), outBytes: %d, actualSize: %d\n", inBytes, state_bytes_left(), outBytes, actualSize);
// while(1);
return actualSize;
}
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