Function ILAPIENTRY iluColoursUsed

DevIL/src-ILU/src/ilu_manip.cpp:533–639

typedef struct BUCKET { ILubyte Colours[4];  struct BUCKET *Next; } BUCKET;

ILuint ILAPIENTRY iluColoursUsed()
{
	ILuint i, c, Bpp, ColVal, SizeData, BucketPos = 0, NumCols = 0;
	BUCKET Buckets[8192], *Temp;
	ILubyte ColTemp[4];
	ILboolean Matched;
	BUCKET *Heap[9];
	ILuint HeapPos = 0, HeapPtr = 0, HeapSize;

	imemclear(Buckets, sizeof(BUCKET) * 8192);
	for (c = 0; c < 9; c++) {
		Heap[c] = 0;
	}

	iluCurImage = ilGetCurImage();
	if (iluCurImage == NULL) {
		ilSetError(ILU_ILLEGAL_OPERATION);
		return 0;
	}

	Bpp = iluCurImage->Bpp;
	SizeData = iluCurImage->SizeOfData;

	// Create our miniature memory heap.
	// I have determined that the average number of colours versus
	//	the number of pixels is about a 1:8 ratio, so divide by 8.
	HeapSize = IL_MAX(1, iluCurImage->SizeOfData / iluCurImage->Bpp / 8);
	Heap[0] = (BUCKET*)ialloc(HeapSize * sizeof(BUCKET));
	if (Heap[0] == NULL)
		return IL_FALSE;

	for (i = 0; i < SizeData; i += Bpp) {
		*(ILuint*)ColTemp = 0;
		/*for (c = 0; c < Bpp; c++) {
			ColTemp[c] = iluCurImage->Data[i + c];
		}*/
		ColTemp[0] = iluCurImage->Data[i];
		if (Bpp > 1) {
			ColTemp[1] = iluCurImage->Data[i + 1];
			ColTemp[2] = iluCurImage->Data[i + 2];
		}
		if (Bpp > 3)
			ColTemp[3] = iluCurImage->Data[i + 3];

		BucketPos = *(ILuint*)ColTemp % 8192;

		// Add to hash table
		if (Buckets[BucketPos].Next == NULL) {
			NumCols++;
			//Buckets[BucketPos].Next = (BUCKET*)ialloc(sizeof(BUCKET));
			Buckets[BucketPos].Next = Heap[HeapPos] + HeapPtr++;
			if (HeapPtr >= HeapSize) {
				Heap[++HeapPos] = (BUCKET*)ialloc(HeapSize * sizeof(BUCKET));
				if (Heap[HeapPos] == NULL)
					goto alloc_error;
				HeapPtr = 0;
			}
			*(ILuint*)Buckets[BucketPos].Next->Colours = *(ILuint*)ColTemp;