3685l1100664 1007 330 11260 6774745715 10537 0ustar darcyljedit;------------------------------------------------------------------ ; C prototype ; AMDXYGRAD(float *data, int row_sz, float *result, float *quarter_vec) ; ; Computes squared gradient in 4 directions (2 horizontal, 2 vertical) ; using implementation that efficiently utilizes 3DNow! capability ; Implemented by J. Bush and T. Newman, UAH Computer Science. ; Input parameters: ; data - pointer to input image ; row_sz - number of elements per row of data ; result - pointer to output (result) image ; quarter_vec - constant array for division by 4 ; Register usage: ; eax - points to pixels in previous row of input data ("bottom row") ; ebx - points to pixels in next row of input data ("top row") ; ecx - points to pixels in current row of input data ("middle row") ; edx - points to pixels in output (result) image (these are output ; pixels corresponding to current input pixels at ecx) ; ebp - eventually used to store row_sz ; ebx,edx are also used as a temporary scratch registers during init. ;------------------------------------------------------------------ global AMDXYGRAD align 16 AMDXYGRAD: push ebp ;save stack pointer mov ebp, esp femms ;clear MMX registers and switch to MMX/3DNow mode mov ebx, [ebp+20] ;get quarter_vec pointer movq mm7, [ebx] ;load quarter_vec contents mov eax, [ebp+8] ;bottom row of data mov edx, [ebp+12] ;load row_sz, then shl edx, 2 ;adjust for data element size (float = 4 bytes) mov ecx, eax ;duplicate pointer to start of row mov ebx, eax ;duplicate pointer add eax, 4 ;add offset of a word (no x dir. grad. at start) add ecx, edx ;determine middle row start shl edx, 1 ;get offset to top row add ebx, edx ;top row of data add ebx, 4 ;add offset of a word to top row mov edx, [ebp+16] ;load pointer to result mov ebp, [ebp+12] ;row_sz equals no. of pixels processed by loop add edx, 4 ;add offset of a word to result pointer gradcalcxy_loop: movq mm0, [ecx] ;get 4 middle row pixels into MM0 movq mm1, [ecx+8] ;and MM1 movq mm2, [ebx] ;get first 2 bottom row pixels movq mm4, [eax] ;get first 2 top row pixels movq mm3, [ebx+8] ;get next 2 bottom row pixels movq mm5, [eax+8] ;get next 2 top row pixels pfsub mm0, mm1 ;x directional subtr. of middle row pixel values movq mm6, [ecx+16] ;move next 2 middle row pixels into MM6 pfsub mm2, mm4 ;subtr. pixels in top & bottom row (y dir.) pfmul mm0, mm0 ;square x direction diff. ( delta(x) ) pfsub mm3, mm5 ;subtr. next pixels in y dir. pfmul mm2, mm2 ;square ( delta(y) ) pfadd mm0, mm2 ;add delta(x) and delta(y) pfmul mm3, mm3 ;square delta(y) for next pixels pfmul mm0, mm7 ;divide results by 4 movq [edx], mm0 ;store first 2 pixels pfsub mm1, mm6 ;subtr. next pixels in x direct. pfmul mm1, mm1 ;square delta(x) for next pixels pfadd mm1, mm3 ;add next delta(x) and delta(y) pfmul mm1, mm7 ;divide by 4 movq [edx+8], mm1 ;store next 2 pixels add eax, 16 ;increment pointers add ebx, 16 add ecx, 16 add edx, 16 sub ebp, 4 ;decrement counter jz mv_previous ;if ebp==0, jump cmp ebp, 4 jl remainder ;else, if ebp<4, jump jmp gradcalcxy_loop ;else, repeat loop remainder: ;process the last pixel(s) in the row specially ;calculate gradient one pixel at a time to ;avoid going beyond row boundary movq mm0, [ecx] movq mm1, [ecx+8] movq mm2, [ebx] movq mm4, [eax] pfsub mm0, mm1 pfsub mm2, mm4 pfmul mm0, mm0 pfmul mm2, mm2 pfadd mm0, mm2 pfmul mm0, mm7 ;divide by 4 movq [edx], mm0 sub ebp, 2 add eax, 8 add ebx, 8 add edx, 8 add ecx, 8 cmp ebp , 1 jg remainder ;if ebp>1, repeat loop jle zero_out ;else, jump mv_previous: ;if boundary was already reached, back up sub edx, 4 ;to last pixel in the row zero_out: pfsub mm7, mm7 ;zero out the last movd [edx], mm7 ;pixel femms pop ebp ret