Help a 100% Newbie ?

[plenderj]

Hi there,

I have no experience in assembly...asm... or whatever.
But could you tell me what the following lines do :


for (i = 0; i < filesize; i += 32, j++) {
fread(&RomMemory[i], 32, 1, romfp);

_asm {
mov edx, dword ptr RomMemory
add edx, i

movq mm0, qword ptr [edx]
movq mm2, qword ptr [edx+8]
movq mm4, qword ptr [edx+16]
movq mm6, qword ptr [edx+24]

movq mm1, mm0
psrlw mm0, 8
psllw mm1, 8
por mm0, mm1

movq mm3, mm2
psrlw mm2, 8
psllw mm3, 8
por mm2, mm3

movq mm5, mm4
psrlw mm4, 8
psllw mm5, 8
por mm4, mm5

movq mm7, mm6
psrlw mm6, 8
psllw mm7, 8
por mm6, mm7

movq qword ptr [edx], mm0
movq qword ptr [edx+8], mm2
movq qword ptr [edx+16], mm4
movq qword ptr [edx+24], mm6
}


Im guessing they're swapping each two characters in a file or something, but im not quite sure.
Any ideas ?

- Jamie

[Darkwraith]

:confused:

What instruction set are you using?