1 files changed, 149 insertions, 0 deletions
diff --git a/tools/gbagfx/rl.c b/tools/gbagfx/rl.c
new file mode 100644
index 0000000..968c934
--- /dev/null
+++ b/tools/gbagfx/rl.c
@@ -0,0 +1,149 @@
+// 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");
+}