1 files changed, 155 insertions, 0 deletions
diff --git a/tools/gbagfx/lz.c b/tools/gbagfx/lz.c
new file mode 100644
index 0000000..c2ba3e3
--- /dev/null
+++ b/tools/gbagfx/lz.c
@@ -0,0 +1,155 @@
+// Copyright (c) 2015 YamaArashi
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include "global.h"
+#include "lz.h"
+
+unsigned char *LZDecompress(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++];
+
+		for (int i = 0; i < 8; i++) {
+			if (flags & 0x80) {
+				if (srcPos + 1 >= srcSize)
+					goto fail;
+
+				int blockSize = (src[srcPos] >> 4) + 3;
+				int blockDistance = (((src[srcPos] & 0xF) << 8) | src[srcPos + 1]) + 1;
+
+				srcPos += 2;
+
+				int blockPos = destPos - blockDistance;
+
+				// Some Ruby/Sapphire tilesets overflow.
+				if (destPos + blockSize > destSize) {
+					blockSize = destSize - destPos;
+					fprintf(stderr, "Destination buffer overflow.\n");
+				}
+
+				if (blockPos < 0)
+					goto fail;
+
+				for (int j = 0; j < blockSize; j++)
+					dest[destPos++] = dest[blockPos + j];
+			} else {
+				if (srcPos >= srcSize || destPos >= destSize)
+					goto fail;
+
+				dest[destPos++] = src[srcPos++];
+			}
+
+			if (destPos == destSize) {
+				*uncompressedSize = destSize;
+				return dest;
+			}
+
+			flags <<= 1;
+		}
+	}
+
+fail:
+	FATAL_ERROR("Fatal error while decompressing LZ file.\n");
+}
+
+unsigned char *LZCompress(unsigned char *src, int srcSize, int *compressedSize)
+{
+	const int minDistance = 2; // for compatibility with LZ77UnCompVram()
+
+	if (srcSize <= 0)
+		goto fail;
+
+	int worstCaseDestSize = 4 + srcSize + ((srcSize + 7) / 8);
+
+	// 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] = 0x10; // LZ 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 (;;) {
+		unsigned char *flags = &dest[destPos++];
+		*flags = 0;
+
+		for (int i = 0; i < 8; i++) {
+			int bestBlockDistance = 0;
+			int bestBlockSize = 0;
+			int blockDistance = minDistance;
+
+			while (blockDistance <= srcPos && blockDistance <= 0x1000) {
+				int blockStart = srcPos - blockDistance;
+				int blockSize = 0;
+
+				while (blockSize < 18
+				    && srcPos + blockSize < srcSize
+				    && src[blockStart + blockSize] == src[srcPos + blockSize])
+					blockSize++;
+
+				if (blockSize > bestBlockSize) {
+					bestBlockDistance = blockDistance;
+					bestBlockSize = blockSize;
+
+					if (blockSize == 18)
+						break;
+				}
+
+				blockDistance++;
+			}
+
+			if (bestBlockSize >= 3) {
+				*flags |= (0x80 >> i);
+				srcPos += bestBlockSize;
+				bestBlockSize -= 3;
+				bestBlockDistance--;
+				dest[destPos++] = (bestBlockSize << 4) | ((unsigned int)bestBlockDistance >> 8);
+				dest[destPos++] = (unsigned char)bestBlockDistance;
+			} else {
+				dest[destPos++] = src[srcPos++];
+			}
+
+			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 LZ file.\n");
+}