Image en niveaux de gris
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;// compilation : ;// "as toto.s -o toto.o ;// "ld toto.o -o toto ;// The _fill function is juste to have predictive result when debugging with gdb in Eclipse ;// And so to be able to verify operations and pixel results in memory .section .data .align 16 ; // to ensure 16bytes alignement image: .space 256*256*4; // 256*256*(4 bytes/pixel) format : RGBARGBARGBA.... imagelen: .long 256*256*4; // take care to have size multiple of 4pixels // take care to have @image 128bits aligned, if not change all "movdqa" with "movdqu" // "movdqa = move doublequad aligned", "movdqu = move doublequad unaligned" charmaskinlong: .long 0x000000FF; // we compute all coefficients as 65536th coefR: .long 77; // 0.3 *256 coefG: .long 151; // 0.59 *256 coefB: .long 28; // 0.11 *256 // 77+151+28 = 256 ok, we shouldn't overflow 255 .section .text .global _start _start: call _fill; movd charmaskinlong,%xmm7; // load charmask in XMM7=[000000000000000000000000000000FF] pshufd $0,%xmm7,%xmm7; // copy charmask on each packeted 32bits // XMM7==[000000FF000000FF000000FF000000FF] movd coefR,%xmm6; // load coefR in XMM6=[000000000000000000000000000000cR] pshufd $0,%xmm6,%xmm6; // XMM6.D=[cR cR cR cR] , XMM7.W=[0 cR 0 cR 0 cR 0 cR] movd coefG,%xmm5; // load coefG in XMM5=[000000000000000000000000000000cG] pshufd $0,%xmm5,%xmm5; // XMM5.D=[cG cG cG cG] , XMM5.W=[0 cG 0 cG 0 cG 0 cG] pslld $16,%xmm5; // XMM5.W=[cG 0 cG 0 cG 0 cG 0] por %xmm5,%xmm6; // XMM6.W=[cG cR cG cR cG cR cG cR] movd coefB,%xmm4; // load coefB in XMM7=[000000000000000000000000000000cB] pshufd $0,%xmm4,%xmm4; // XMM4.D=[cB cB cB cB] , XMM4.W=[0 cB 0 cB 0 cB 0 cB] movdqa %xmm7,%xmm5; // XMM5.D=[255 255 255 255] pslld $16,%xmm4; // XMM4.W=[cB 0 cB 0 cB 0 cB 0] por %xmm4,%xmm5; // XMM5.W=[cB 255 cB 255 cB 255 cB 255] movl $image,%eax; // put ptr image in EAX movl imagelen,%ecx; // put size in ECX sar $4,%ecx; // divide size by 16 (4 pixels / pass) _loop4: // the goal is (R*cR+G*cG+B*cB)/256 (cR,cG,cB are *256) // we will do ( [(R*cR + G*cG)/256]*255 + B*cB)/256 -> 2 Packed MultiplyAdd operation movdqa (%eax),%xmm0; // load 4pixels in XMM0 (4 * 32bits = 128bits) pshufd $0xE4,%xmm7,%xmm1; // copy XMM7 to XMM1 (using shifting SSE unit not load unit) pand %xmm0,%xmm1; // XMM1.B=[00 00 00 RR 00 00 00 RR 00 00 00 RR 00 00 00 RR] pshufd $0xE4,%xmm7,%xmm2; // copy XMM7 to XMM2 (using shifting SSE unit not load unit) pslld $8,%xmm2; // XMM2.B=[00 00 FF 00 00 00 FF 00 00 00 FF 00 00 00 FF 00] pand %xmm0,%xmm2; // XMM1.B=[00 00 GG 00 00 00 GG 00 00 00 GG 00 00 00 GG 00] pslld $8,%xmm2; // XMM1.B=[00 GG 00 00 00 GG 00 00 00 GG 00 00 00 GG 00 00] por %xmm2,%xmm1; // XMM1.W=[G R G R G R G R] pmaddwd %xmm6,%xmm1; // XMM1.D=[g*cG+R*cR g*cG+R*cR g*cG+R*cR g*cG+R*cR] psrad $8,%xmm1; // XMM1.W=[0 (g*cG+R*cR)/256 4x] movdqa %xmm7,%xmm2; // Copy XMM7 to XMM2 using load SSE unit pslld $16,%xmm2; // XMM2.B=[00 FF 00 00 00 FF 00 00 00 FF 00 00 00 FF 00 00] pand %xmm0,%xmm2; // XMM2.B=[00 BB 00 00 00 BB 00 00 00 BB 00 00 00 BB 00 00] por %xmm2,%xmm1; // XMM1.W=[BB (g*cG+R*cR)/256 BB 4x] pmaddwd %xmm5,%xmm1; // XMM1.D=[((g*cG+R*cR)/256)*255+B*cB 4x] // XMM1.D~=[(g*cG+R*cR+B*cB) 4x] psrad $8,%xmm1; // XMM1.D~=[(g*cG+R*cR+B*cB)/256 4x] movdqa %xmm7,%xmm2; // Copy XMM7 to XMM2 using load SSE unit pslld $24,%xmm2; // XMM2.B=[FF 00 00 00 FF 00 00 00 FF 00 00 00 FF 00 00 00] pand %xmm0,%xmm2; // XMM2.B=[AA 00 00 00 AA 00 00 00 AA 00 00 00 AA 00 00 00] por %xmm1,%xmm2; // XMM2.B=[AA 00 00 Gr AA 00 00 Gr AA 00 00 Gr AA 00 00 Gr] movdqa %xmm1,%xmm3; // XMM3.D~=[Grey Grey Grey Grey] pslld $8,%xmm3; // XMM3.B=[00 00 Gr 00 00 00 Gr 00 00 00 Gr 00 00 00 Gr 00] por %xmm3,%xmm2; // XMM2.B=[AA 00 Gr Gr AA 00 Gr Gr AA 00 Gr Gr AA 00 Gr Gr] pslld $8,%xmm3; // XMM3.B=[00 Gr 00 00 00 Gr 00 00 00 Gr 00 00 00 Gr 00 00] por %xmm3,%xmm2; // XMM2.B=[AA Gr Gr Gr AA Gr Gr Gr AA Gr Gr Gr AA Gr Gr Gr] movdqa %xmm2,(%eax); // store 4pixels packed Grey converted add $16,%eax; // next frame is 4*4bytes=16bytes further dec %ecx; // decrement 4pixels packed count jnz _loop4; // continue works :) _end: mov $1,%eax; // 1 => exit mov $0,%ebx; // 0 return code int $0x80; // bye bye :) ;// Addon function to fill the picture _fill: movl $image,%eax; // put ptr image in EAX xor %ebx,%ebx; // clear EBX movl imagelen,%ecx; // put size in ECX _loop2: movb %bl,(%eax); // put counter in pixel component inc %bl; // increment counter inc %eax; // increment pixel component pointer dec %ecx; // decrement byte count jnz _loop2; // continue if not finished ret; // come back to the main code
Compatibilité : Assembleur x86
Disponible dans d'autres langages :
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