Kodewerx

unsigned int get_decompressed_data_size (const unsigned char* sourceData, unsigned int headerBottom) {
   unsigned int decompressedLength;
   decompressedLength = (((unsigned int*)sourceData)[headerBottom / 4 - 1]) + headerBottom;
   return decompressedLength;
}

void decompress_ARM9_binary (const unsigned char* sourceData, unsigned int headerBottom, unsigned char* destData) {
   
   int srcPos, destPos;

   int controlByte;

   int runsLeft;
   unsigned int srcLength, destLength;
   int srcStart;

   srcLength = ((unsigned int*)sourceData)[headerBottom / 4 - 2];
   destLength = (((unsigned int*)sourceData)[headerBottom / 4 - 1]) + headerBottom;

   srcPos = headerBottom - (srcLength >> 24);
   destPos = destLength;
   srcStart = headerBottom - (srcLength & 0x00FFFFFF);

   while (srcPos > srcStart) {
      controlByte = sourceData[--srcPos];

      for (runsLeft = 0x08; (runsLeft > 0) && (srcPos >= 0) && (destPos >=0); --runsLeft) {

         if (controlByte & 0x80) {
            // copy data run from decompressed buffer
            int runRepeats, runLength;   
            unsigned char temp;

            runRepeats = sourceData[--srcPos];
            runLength = ((sourceData[--srcPos] | (runRepeats << 8)) & 0x0fff) + 0x02;
            runRepeats = (runRepeats >> 4) + 0x2;
   
            for ( ; runRepeats >= 0; runRepeats-= 0x1) {
               temp = destData[destPos + runLength];
               destData[--destPos] = temp;
            }
         } else {
            // copy byte from source compressed data
            destData[--destPos] = sourceData[--srcPos];
         }

         controlByte = controlByte << 1;
      }
   }

   while ((srcPos >= 0) && (destPos >= 0)) {
      destData[--destPos] = sourceData[--srcPos];
   }
}