// 3D Sort Assembler code
// Aug 2016 
// See http://tropicalcoder.com/3dBubbleSort.htm

// Reads colours as bgr
void Graphics::Do3DSort(Image *pImage, int limit)
{
 unsigned counter = limit;

 unsigned width = (unsigned)pImage->imageWidth;
 unsigned widthMinusOne = width - 1;
 unsigned widthTimesFour = width * 4;
 unsigned widthMinusOneTimesFour = widthMinusOne * 4;
 unsigned widthPlusOneTimesFour = (width + 1) * 4;
 unsigned height = (unsigned)pImage->imageHeight;
 unsigned ModVal = (height-1) * width;


 LPVOID pvBits = pImage->pImageDWordAligned;



 // Compare RED
 _asm{
		 // Pick a pixel at random coordinates x, y where x = {0 thru W - 1)}, y = {0 thru (H - 2)}
		 // x = rand() % width;
		 // y = rand() % (height - 1);
		 // dwPixelA = pImage->getColour(x, y);
LOOP_IT:
	mov eax, counter
	dec eax
	mov counter, eax
        test eax, eax
        jz  DONE

        call        randomMT  // Get random offset in eax
        xor         edx,edx
        mov         ecx,ModVal   // do mod (height-1) * width (skipping last line))
        div         ecx       // edx has remainder
        shl         edx,2     // * 4 to make it a DWORD offset
        mov         esi,dword ptr [pvBits]
        add         esi,edx
        mov         edi,esi

	mov ecx, dword ptr [edi]

	// If amount of red in pixel below (at x, y+1) is greater than red in current pixel, swap pixels
	// dwPixelB = pImage->getColour(x, y+1);

        // Second offset can be derived from the first...
        add esi, widthTimesFour  // add width * 4 to make dword offset
	mov edx, dword ptr [esi] // pixel below (at x, y+1)

	cmp	 dl, cl // sort red up
	jbe	NEXT0

	mov dword ptr [esi], ecx
	mov dword ptr [edi], edx
}

NEXT0:

 // Compare GREEN
 _asm{
/*
		 // Pick another pixel at random coordinates x, y where x = {0 thru (W - 2)}, y = {0 thru (H - 2)}
		 x = rand() % (width - 1);
		 y = rand() % (height - 1);
		 dwPixelA = pImage->getColour(x, y);
*/
GREEN_REPEAT:
        call        randomMT    // Get random offset in eax
        mov         ebx,eax     // Stored for later
        xor         edx,edx
        mov         ecx,ModVal  // do mod (height-1) * width (skipping last line))
        div         ecx         // edx has remainder
        // We now have in edx the offset to some pixel between 0 and (height-1) * width
	// We cannot allow a pixel on any given line at (width-1)
	// x must be from 0 thru (width - 2)


	// Do if x == (width-1) try again
        mov         esi,edx // store temporarily in ebx

	// do x % width and compare reaminder to (width-1)
	mov         eax,ebx
        xor         edx,edx
        mov         ecx,width  // do mod width
        div         ecx        // edx has remainder
        cmp         edx,  widthMinusOne
        jge         GREEN_REPEAT

	// Get the original offset back
        mov         edx,esi // was stored temporarily in esi
        shl         edx,2   // * 4 to make it a DWORD offset
        mov         esi,dword ptr [pvBits]
        add         esi,edx
        mov         edi,esi

	mov         ecx,dword ptr [edi]

        // If amount of green in pixel to the lower right (at x+1, y+1) is less than green in current pixel, swap pixels
	// dwPixelB = pImage->getColour(x+1, y+1);
        add esi, widthPlusOneTimesFour // (width + 1) * 4 to make dword offset 
	mov edx, dword ptr [esi]
        cmp    ch, dh
        jbe    NEXT1
 
        mov dword ptr [esi], ecx
        mov dword ptr [edi], edx

 }

NEXT1:

 // Compare BLUE
 _asm{
		 // Pick another pixel at random coordinates x, y where x = {1 thru (W - 1)}, y = {0 thru (H - 2)}
		 // x = 1 + (rand() % (width-1));
		 // y = rand() % (height - 1);
		 // dwPixelA = pImage->getColour(x, y);
BLUE_REPEAT:
        call        randomMT    // Get random offset in eax
        mov         ebx,eax
        xor         edx,edx
        mov         ecx,ModVal  // do mod (height-1) * width (skipping last line))
        div         ecx         // edx has remainder
        // We now have in edx the offset to some pixel between 0 and (height-1) * width
	// We cannot allow a pixel on any given line at 0
	// x must be from 1 thru (width - 1)
	// Do if x == 0 try again
        mov         esi,edx // store temporarily in esi
	mov         eax,ebx
        xor         edx,edx
	// do x % width and compare reaminder to 0
        mov         ecx,width  // do mod width
        div         ecx        // edx has remainder
        cmp         edx,  0
        je          BLUE_REPEAT

	// Get the original offset back
        mov         edx,esi // was stored temporarily in esi
        shl         edx,2       // * 4 to make it a DWORD offset
        mov         esi,dword ptr [pvBits]
        add         esi,edx
        mov         edi,esi

	mov         ecx,dword ptr [edi]

	// If amount of blue in pixel to the lower left (at x-1, y+1) is less than blue in current pixel, swap pixels
	// dwPixelB = pImage->getColour(x-1, y+1);
        add esi, widthMinusOneTimesFour
	mov edx, dword ptr [esi]

	mov ebx, ecx
	and	ecx, 0x00FF0000

	mov eax, edx
	and	edx, 0x00FF0000

	cmp	ecx, edx
	jbe	LOOP_IT

	mov dword ptr [esi], ebx
	mov dword ptr [edi], eax
	jmp LOOP_IT
 }
 DONE:
 counter = 0;
}