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mozjpeg/simd/i386/jquant-mmx.asm
DRC 19c791cdac Improve code formatting consistency 
With rare exceptions ...
- Always separate line continuation characters by one space from
  preceding code.
- Always use two-space indentation.  Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
  function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
  with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
  function name.
- Always precede pointer symbols ('*' and '**') by a space in type
  casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
  API libraries (using min() from tjutil.h is still necessary for
  TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
  line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.

The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions.  This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree.  The
new convention is more consistent with the formatting of other OSS code
bases.

This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.

NOTES:
- Although it is no longer necessary for the function name in function
  declarations to begin in Column 1 (this was historically necessary
  because of the ansi2knr utility, which allowed libjpeg to be built
  with non-ANSI compilers), we retain that formatting for the libjpeg
  code because it improves readability when using libjpeg's function
  attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
  Uncrustify, although neither was completely up to the task, and thus
  a great deal of manual tweaking was required.  Note to developers of
  code formatting utilities:  the libjpeg-turbo code base is an
  excellent test bed, because AFAICT, it breaks every single one of the
  utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
  formatted to match the SSE2 code (refer to
  ff5685d5344273df321eb63a005eaae19d2496e3.)  I hadn't intended to
  bother with this, but the Loongson MMI implementation demonstrated
  that there is still academic value to the MMX implementation, as an
  algorithmic model for other 64-bit vector implementations.  Thus, it
  is desirable to improve its readability in the same manner as that of
  the SSE2 implementation.
2018-03-16 02:14:34 -05:00

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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, 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),
; 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 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
; "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 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
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