jcqntmmx.asm
;
; jcqntmmx.asm - sample data conversion and quantization (MMX)
;
; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
;
; Based on
; 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)
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)
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
