| ; |
| ; jquant.asm - sample data conversion and quantization (MMX) |
| ; |
| ; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB |
| ; |
| ; Based on the x86 SIMD extension for IJG JPEG library |
| ; Copyright (C) 1999-2006, MIYASAKA Masaru. |
| ; For conditions of distribution and use, see copyright notice in jsimdext.inc |
| ; |
| ; This file should be assembled with NASM (Netwide Assembler), |
| ; can *not* be assembled with Microsoft's MASM or any compatible |
| ; assembler (including Borland's Turbo Assembler). |
| ; NASM is available from http://nasm.sourceforge.net/ or |
| ; http://sourceforge.net/project/showfiles.php?group_id=6208 |
| ; |
| ; [TAB8] |
| |
| %include "jsimdext.inc" |
| %include "jdct.inc" |
| |
| ; -------------------------------------------------------------------------- |
| SECTION SEG_TEXT |
| BITS 32 |
| ; |
| ; Load data into workspace, applying unsigned->signed conversion |
| ; |
| ; GLOBAL(void) |
| ; jsimd_convsamp_mmx (JSAMPARRAY sample_data, JDIMENSION start_col, |
| ; DCTELEM *workspace); |
| ; |
| |
| %define sample_data ebp+8 ; JSAMPARRAY sample_data |
| %define start_col ebp+12 ; JDIMENSION start_col |
| %define workspace ebp+16 ; DCTELEM *workspace |
| |
| align 16 |
| global EXTN(jsimd_convsamp_mmx) PRIVATE |
| |
| EXTN(jsimd_convsamp_mmx): |
| push ebp |
| mov ebp,esp |
| push ebx |
| ; push ecx ; need not be preserved |
| ; push edx ; need not be preserved |
| push esi |
| push edi |
| |
| pxor mm6,mm6 ; mm6=(all 0's) |
| pcmpeqw mm7,mm7 |
| psllw mm7,7 ; mm7={0xFF80 0xFF80 0xFF80 0xFF80} |
| |
| mov esi, JSAMPARRAY [sample_data] ; (JSAMPROW *) |
| mov eax, JDIMENSION [start_col] |
| mov edi, POINTER [workspace] ; (DCTELEM *) |
| mov ecx, DCTSIZE/4 |
| alignx 16,7 |
| .convloop: |
| mov ebx, JSAMPROW [esi+0*SIZEOF_JSAMPROW] ; (JSAMPLE *) |
| mov edx, JSAMPROW [esi+1*SIZEOF_JSAMPROW] ; (JSAMPLE *) |
| |
| movq mm0, MMWORD [ebx+eax*SIZEOF_JSAMPLE] ; mm0=(01234567) |
| movq mm1, MMWORD [edx+eax*SIZEOF_JSAMPLE] ; mm1=(89ABCDEF) |
| |
| mov ebx, JSAMPROW [esi+2*SIZEOF_JSAMPROW] ; (JSAMPLE *) |
| mov edx, JSAMPROW [esi+3*SIZEOF_JSAMPROW] ; (JSAMPLE *) |
| |
| movq mm2, MMWORD [ebx+eax*SIZEOF_JSAMPLE] ; mm2=(GHIJKLMN) |
| movq mm3, MMWORD [edx+eax*SIZEOF_JSAMPLE] ; mm3=(OPQRSTUV) |
| |
| movq mm4,mm0 |
| punpcklbw mm0,mm6 ; mm0=(0123) |
| punpckhbw mm4,mm6 ; mm4=(4567) |
| movq mm5,mm1 |
| punpcklbw mm1,mm6 ; mm1=(89AB) |
| punpckhbw mm5,mm6 ; mm5=(CDEF) |
| |
| paddw mm0,mm7 |
| paddw mm4,mm7 |
| paddw mm1,mm7 |
| paddw mm5,mm7 |
| |
| movq MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0 |
| movq MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm4 |
| movq MMWORD [MMBLOCK(1,0,edi,SIZEOF_DCTELEM)], mm1 |
| movq MMWORD [MMBLOCK(1,1,edi,SIZEOF_DCTELEM)], mm5 |
| |
| movq mm0,mm2 |
| punpcklbw mm2,mm6 ; mm2=(GHIJ) |
| punpckhbw mm0,mm6 ; mm0=(KLMN) |
| movq mm4,mm3 |
| punpcklbw mm3,mm6 ; mm3=(OPQR) |
| punpckhbw mm4,mm6 ; mm4=(STUV) |
| |
| paddw mm2,mm7 |
| paddw mm0,mm7 |
| paddw mm3,mm7 |
| paddw mm4,mm7 |
| |
| movq MMWORD [MMBLOCK(2,0,edi,SIZEOF_DCTELEM)], mm2 |
| movq MMWORD [MMBLOCK(2,1,edi,SIZEOF_DCTELEM)], mm0 |
| movq MMWORD [MMBLOCK(3,0,edi,SIZEOF_DCTELEM)], mm3 |
| movq MMWORD [MMBLOCK(3,1,edi,SIZEOF_DCTELEM)], mm4 |
| |
| add esi, byte 4*SIZEOF_JSAMPROW |
| add edi, byte 4*DCTSIZE*SIZEOF_DCTELEM |
| dec ecx |
| jnz short .convloop |
| |
| emms ; empty MMX state |
| |
| pop edi |
| pop esi |
| ; pop edx ; need not be preserved |
| ; pop ecx ; need not be preserved |
| pop ebx |
| pop ebp |
| ret |
| |
| ; -------------------------------------------------------------------------- |
| ; |
| ; Quantize/descale the coefficients, and store into coef_block |
| ; |
| ; This implementation is based on an algorithm described in |
| ; "How to optimize for the Pentium family of microprocessors" |
| ; (http://www.agner.org/assem/). |
| ; |
| ; GLOBAL(void) |
| ; jsimd_quantize_mmx (JCOEFPTR coef_block, DCTELEM *divisors, |
| ; DCTELEM *workspace); |
| ; |
| |
| %define RECIPROCAL(m,n,b) MMBLOCK(DCTSIZE*0+(m),(n),(b),SIZEOF_DCTELEM) |
| %define CORRECTION(m,n,b) MMBLOCK(DCTSIZE*1+(m),(n),(b),SIZEOF_DCTELEM) |
| %define SCALE(m,n,b) MMBLOCK(DCTSIZE*2+(m),(n),(b),SIZEOF_DCTELEM) |
| %define SHIFT(m,n,b) MMBLOCK(DCTSIZE*3+(m),(n),(b),SIZEOF_DCTELEM) |
| |
| %define coef_block ebp+8 ; JCOEFPTR coef_block |
| %define divisors ebp+12 ; DCTELEM *divisors |
| %define workspace ebp+16 ; DCTELEM *workspace |
| |
| align 16 |
| global EXTN(jsimd_quantize_mmx) PRIVATE |
| |
| EXTN(jsimd_quantize_mmx): |
| push ebp |
| mov ebp,esp |
| ; push ebx ; unused |
| ; push ecx ; unused |
| ; push edx ; need not be preserved |
| push esi |
| push edi |
| |
| mov esi, POINTER [workspace] |
| mov edx, POINTER [divisors] |
| mov edi, JCOEFPTR [coef_block] |
| mov ah, 2 |
| alignx 16,7 |
| .quantloop1: |
| mov al, DCTSIZE2/8/2 |
| alignx 16,7 |
| .quantloop2: |
| movq mm2, MMWORD [MMBLOCK(0,0,esi,SIZEOF_DCTELEM)] |
| movq mm3, MMWORD [MMBLOCK(0,1,esi,SIZEOF_DCTELEM)] |
| |
| movq mm0,mm2 |
| movq mm1,mm3 |
| |
| psraw mm2,(WORD_BIT-1) ; -1 if value < 0, 0 otherwise |
| psraw mm3,(WORD_BIT-1) |
| |
| pxor mm0,mm2 ; val = -val |
| pxor mm1,mm3 |
| psubw mm0,mm2 |
| psubw mm1,mm3 |
| |
| ; |
| ; MMX is an annoyingly crappy instruction set. It has two |
| ; misfeatures that are causing problems here: |
| ; |
| ; - All multiplications are signed. |
| ; |
| ; - The second operand for the shifts is not treated as packed. |
| ; |
| ; |
| ; We work around the first problem by implementing this algorithm: |
| ; |
| ; unsigned long unsigned_multiply(unsigned short x, unsigned short y) |
| ; { |
| ; enum { SHORT_BIT = 16 }; |
| ; signed short sx = (signed short) x; |
| ; signed short sy = (signed short) y; |
| ; signed long sz; |
| ; |
| ; sz = (long) sx * (long) sy; /* signed multiply */ |
| ; |
| ; if (sx < 0) sz += (long) sy << SHORT_BIT; |
| ; if (sy < 0) sz += (long) sx << SHORT_BIT; |
| ; |
| ; return (unsigned long) sz; |
| ; } |
| ; |
| ; (note that a negative sx adds _sy_ and vice versa) |
| ; |
| ; For the second problem, we replace the shift by a multiplication. |
| ; Unfortunately that means we have to deal with the signed issue again. |
| ; |
| |
| paddw mm0, MMWORD [CORRECTION(0,0,edx)] ; correction + roundfactor |
| paddw mm1, MMWORD [CORRECTION(0,1,edx)] |
| |
| movq mm4,mm0 ; store current value for later |
| movq mm5,mm1 |
| pmulhw mm0, MMWORD [RECIPROCAL(0,0,edx)] ; reciprocal |
| pmulhw mm1, MMWORD [RECIPROCAL(0,1,edx)] |
| paddw mm0,mm4 ; reciprocal is always negative (MSB=1), |
| paddw mm1,mm5 ; so we always need to add the initial value |
| ; (input value is never negative as we |
| ; inverted it at the start of this routine) |
| |
| ; here it gets a bit tricky as both scale |
| ; and mm0/mm1 can be negative |
| movq mm6, MMWORD [SCALE(0,0,edx)] ; scale |
| movq mm7, MMWORD [SCALE(0,1,edx)] |
| movq mm4,mm0 |
| movq mm5,mm1 |
| pmulhw mm0,mm6 |
| pmulhw mm1,mm7 |
| |
| psraw mm6,(WORD_BIT-1) ; determine if scale is negative |
| psraw mm7,(WORD_BIT-1) |
| |
| pand mm6,mm4 ; and add input if it is |
| pand mm7,mm5 |
| paddw mm0,mm6 |
| paddw mm1,mm7 |
| |
| psraw mm4,(WORD_BIT-1) ; then check if negative input |
| psraw mm5,(WORD_BIT-1) |
| |
| pand mm4, MMWORD [SCALE(0,0,edx)] ; and add scale if it is |
| pand mm5, MMWORD [SCALE(0,1,edx)] |
| paddw mm0,mm4 |
| paddw mm1,mm5 |
| |
| pxor mm0,mm2 ; val = -val |
| pxor mm1,mm3 |
| psubw mm0,mm2 |
| psubw mm1,mm3 |
| |
| movq MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0 |
| movq MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm1 |
| |
| add esi, byte 8*SIZEOF_DCTELEM |
| add edx, byte 8*SIZEOF_DCTELEM |
| add edi, byte 8*SIZEOF_JCOEF |
| dec al |
| jnz near .quantloop2 |
| dec ah |
| jnz near .quantloop1 ; to avoid branch misprediction |
| |
| emms ; empty MMX state |
| |
| pop edi |
| pop esi |
| ; pop edx ; need not be preserved |
| ; pop ecx ; unused |
| ; pop ebx ; unused |
| pop ebp |
| ret |
| |
| ; For some reason, the OS X linker does not honor the request to align the |
| ; segment unless we do this. |
| align 16 |
