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;
; jquant.asm - sample data conversion and quantization (MMX)
;
; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
; Copyright (C) 2016, 2024, D. R. Commander.
;
; 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) or Yasm.
%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 32
GLOBAL_FUNCTION(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
; "Optimizing subroutines in assembly language:
;
; 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 32
GLOBAL_FUNCTION(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 32