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/*
* frame.c - frame implementation
*
* Copyright (C) 2019 Emmanuel Marty
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
/*
* Uses the libdivsufsort library Copyright (c) 2003-2008 Yuta Mori
*
* Inspired by LZ4 by Yann Collet. https://github.com/lz4/lz4
* With help, ideas, optimizations and speed measurements by spke <zxintrospec@gmail.com>
* With ideas from Lizard by Przemyslaw Skibinski and Yann Collet. https://github.com/inikep/lizard
* Also with ideas from smallz4 by Stephan Brumme. https://create.stephan-brumme.com/smallz4/
*
*/
#include <stdlib.h>
#include <string.h>
#include "frame.h"
#define LZSA_ID_0 0x7b
#define LZSA_ID_1 0x9e
/**
* Get compressed file header size
*
* @return file header size
*/
int lzsa_get_header_size(void) {
return 3;
}
/**
* Get compressed frame header size
*
* @return frame header size
*/
int lzsa_get_frame_size(void) {
return 3;
}
/**
* Encode file header
*
* @param pFrameData encoding buffer
* @param nMaxFrameDataSize max encoding buffer size, in bytes
*
* @return number of encoded bytes, or -1 for failure
*/
int lzsa_encode_header(unsigned char *pFrameData, const int nMaxFrameDataSize, int nFormatVersion) {
if (nMaxFrameDataSize >= 3 && (nFormatVersion == 1 || nFormatVersion == 2)) {
pFrameData[0] = LZSA_ID_0; /* Magic number */
pFrameData[1] = LZSA_ID_1;
pFrameData[2] = (nFormatVersion == 2) ? 0x20 : 0; /* Format version 1 */
return 3;
}
else {
return -1;
}
}
/**
* Encode compressed block frame header
*
* @param pFrameData encoding buffer
* @param nMaxFrameDataSize max encoding buffer size, in bytes
* @param nBlockDataSize compressed block's data size, in bytes
*
* @return number of encoded bytes, or -1 for failure
*/
int lzsa_encode_compressed_block_frame(unsigned char *pFrameData, const int nMaxFrameDataSize, const int nBlockDataSize) {
if (nMaxFrameDataSize >= 3 && nBlockDataSize <= 0x7fffff) {
pFrameData[0] = nBlockDataSize & 0xff;
pFrameData[1] = (nBlockDataSize >> 8) & 0xff;
pFrameData[2] = (nBlockDataSize >> 16) & 0x7f;
return 3;
}
else {
return -1;
}
}
/**
* Encode uncompressed block frame header
*
* @param pFrameData encoding buffer
* @param nMaxFrameDataSize max encoding buffer size, in bytes
* @param nBlockDataSize uncompressed block's data size, in bytes
*
* @return number of encoded bytes, or -1 for failure
*/
int lzsa_encode_uncompressed_block_frame(unsigned char *pFrameData, const int nMaxFrameDataSize, const int nBlockDataSize) {
if (nMaxFrameDataSize >= 3 && nBlockDataSize <= 0x7fffff) {
pFrameData[0] = nBlockDataSize & 0xff;
pFrameData[1] = (nBlockDataSize >> 8) & 0xff;
pFrameData[2] = ((nBlockDataSize >> 16) & 0x7f) | 0x80; /* Uncompressed block */
return 3;
}
else {
return -1;
}
}
/**
* Encode terminal frame header
*
* @param pFrameData encoding buffer
* @param nMaxFrameDataSize max encoding buffer size, in bytes
*
* @return number of encoded bytes, or -1 for failure
*/
int lzsa_encode_footer_frame(unsigned char *pFrameData, const int nMaxFrameDataSize) {
if (nMaxFrameDataSize >= 3) {
pFrameData[0] = 0x00; /* EOD frame */
pFrameData[1] = 0x00;
pFrameData[2] = 0x00;
return 3;
}
else {
return -1;
}
}
/**
* Decode file header
*
* @param pFrameData data bytes
* @param nFrameDataSize number of bytes to decode
*
* @return 0 for success, or -1 for failure
*/
int lzsa_decode_header(const unsigned char *pFrameData, const int nFrameDataSize, int *nFormatVersion) {
if (nFrameDataSize != 3 ||
pFrameData[0] != LZSA_ID_0 ||
pFrameData[1] != LZSA_ID_1 ||
(pFrameData[2] & 0x1f) != 0 ||
((pFrameData[2] & 0xe0) != 0x00 && (pFrameData[2] & 0xe0) != 0x20)) {
return -1;
}
else {
*nFormatVersion = (pFrameData[2] & 0xe0) ? 2 : 1;
return 0;
}
}
/**
* Decode frame header
*
* @param pFrameData data bytes
* @param nFrameDataSize number of bytes to decode
* @param nBlockSize pointer to block size, updated if this function succeeds (set to 0 if this is the terminal frame)
* @param nIsUncompressed pointer to compressed block flag, updated if this function succeeds
*
* @return 0 for success, or -1 for failure
*/
int lzsa_decode_frame(const unsigned char *pFrameData, const int nFrameDataSize, unsigned int *nBlockSize, int *nIsUncompressed) {
if (nFrameDataSize == 3) {
*nBlockSize = ((unsigned int)pFrameData[0]) |
(((unsigned int)pFrameData[1]) << 8) |
(((unsigned int)pFrameData[2]) << 16);
*nIsUncompressed = ((*nBlockSize & 0x800000) != 0) ? 1 : 0;
*nBlockSize &= 0x7fffff;
return 0;
}
else {
return -1;
}
}
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