tumbledemerald-legacy/tools/gbagfx/rl.c
2022-05-19 17:14:13 +00:00

150 lines
3.5 KiB
C

// Copyright (c) 2016 YamaArashi
#include <stdlib.h>
#include <stdbool.h>
#include "global.h"
#include "rl.h"
unsigned char *RLDecompress(unsigned char *src, int srcSize, int *uncompressedSize)
{
if (srcSize < 4)
goto fail;
int destSize = (src[3] << 16) | (src[2] << 8) | src[1];
unsigned char *dest = malloc(destSize);
if (dest == NULL)
goto fail;
int srcPos = 4;
int destPos = 0;
for (;;)
{
if (srcPos >= srcSize)
goto fail;
unsigned char flags = src[srcPos++];
bool compressed = ((flags & 0x80) != 0);
if (compressed)
{
int length = (flags & 0x7F) + 3;
unsigned char data = src[srcPos++];
if (destPos + length > destSize)
goto fail;
for (int i = 0; i < length; i++)
dest[destPos++] = data;
}
else
{
int length = (flags & 0x7F) + 1;
if (destPos + length > destSize)
goto fail;
for (int i = 0; i < length; i++)
dest[destPos++] = src[srcPos++];
}
if (destPos == destSize)
{
*uncompressedSize = destSize;
return dest;
}
}
fail:
FATAL_ERROR("Fatal error while decompressing RL file.\n");
}
unsigned char *RLCompress(unsigned char *src, int srcSize, int *compressedSize)
{
if (srcSize <= 0)
goto fail;
int worstCaseDestSize = 4 + srcSize * 2;
// Round up to the next multiple of four.
worstCaseDestSize = (worstCaseDestSize + 3) & ~3;
unsigned char *dest = malloc(worstCaseDestSize);
if (dest == NULL)
goto fail;
// header
dest[0] = 0x30; // RL compression type
dest[1] = (unsigned char)srcSize;
dest[2] = (unsigned char)(srcSize >> 8);
dest[3] = (unsigned char)(srcSize >> 16);
int srcPos = 0;
int destPos = 4;
for (;;)
{
bool compress = false;
int uncompressedStart = srcPos;
int uncompressedLength = 0;
while (srcPos < srcSize && uncompressedLength < (0x7F + 1))
{
compress = (srcPos + 2 < srcSize && src[srcPos] == src[srcPos + 1] && src[srcPos] == src[srcPos + 2]);
if (compress)
break;
srcPos++;
uncompressedLength++;
}
if (uncompressedLength > 0)
{
dest[destPos++] = uncompressedLength - 1;
for (int i = 0; i < uncompressedLength; i++)
dest[destPos++] = src[uncompressedStart + i];
}
if (compress)
{
unsigned char data = src[srcPos];
int compressedLength = 0;
while (compressedLength < (0x7F + 3)
&& srcPos + compressedLength < srcSize
&& src[srcPos + compressedLength] == data)
{
compressedLength++;
}
dest[destPos++] = 0x80 | (compressedLength - 3);
dest[destPos++] = data;
srcPos += compressedLength;
}
if (srcPos == srcSize)
{
// Pad to multiple of 4 bytes.
int remainder = destPos % 4;
if (remainder != 0)
{
for (int i = 0; i < 4 - remainder; i++)
dest[destPos++] = 0;
}
*compressedSize = destPos;
return dest;
}
}
fail:
FATAL_ERROR("Fatal error while compressing RL file.\n");
}