summaryrefslogtreecommitdiffstats
path: root/media/libjpeg/simd/i386/jccolext-mmx.asm
blob: 6357a42b2cf4887503da4067b35f09efcdb2e492 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
;
; jccolext.asm - colorspace conversion (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

%include "jcolsamp.inc"

; --------------------------------------------------------------------------
;
; Convert some rows of samples to the output colorspace.
;
; GLOBAL(void)
; jsimd_rgb_ycc_convert_mmx(JDIMENSION img_width, JSAMPARRAY input_buf,
;                           JSAMPIMAGE output_buf, JDIMENSION output_row,
;                           int num_rows);
;

%define img_width(b)   (b) + 8          ; JDIMENSION img_width
%define input_buf(b)   (b) + 12         ; JSAMPARRAY input_buf
%define output_buf(b)  (b) + 16         ; JSAMPIMAGE output_buf
%define output_row(b)  (b) + 20         ; JDIMENSION output_row
%define num_rows(b)    (b) + 24         ; int num_rows

%define original_ebp   ebp + 0
%define wk(i)          ebp - (WK_NUM - (i)) * SIZEOF_MMWORD
                                        ; mmword wk[WK_NUM]
%define WK_NUM         8
%define gotptr         wk(0) - SIZEOF_POINTER  ; void * gotptr

    align       32
    GLOBAL_FUNCTION(jsimd_rgb_ycc_convert_mmx)

EXTN(jsimd_rgb_ycc_convert_mmx):
    push        ebp
    mov         eax, esp                    ; eax = original ebp
    sub         esp, byte 4
    and         esp, byte (-SIZEOF_MMWORD)  ; align to 64 bits
    mov         [esp], eax
    mov         ebp, esp                    ; ebp = aligned ebp
    lea         esp, [wk(0)]
    pushpic     eax                     ; make a room for GOT address
    push        ebx
;   push        ecx                     ; need not be preserved
;   push        edx                     ; need not be preserved
    push        esi
    push        edi

    get_GOT     ebx                     ; get GOT address
    movpic      POINTER [gotptr], ebx   ; save GOT address

    mov         ecx, JDIMENSION [img_width(eax)]  ; num_cols
    test        ecx, ecx
    jz          near .return

    push        ecx

    mov         esi, JSAMPIMAGE [output_buf(eax)]
    mov         ecx, JDIMENSION [output_row(eax)]
    mov         edi, JSAMPARRAY [esi+0*SIZEOF_JSAMPARRAY]
    mov         ebx, JSAMPARRAY [esi+1*SIZEOF_JSAMPARRAY]
    mov         edx, JSAMPARRAY [esi+2*SIZEOF_JSAMPARRAY]
    lea         edi, [edi+ecx*SIZEOF_JSAMPROW]
    lea         ebx, [ebx+ecx*SIZEOF_JSAMPROW]
    lea         edx, [edx+ecx*SIZEOF_JSAMPROW]

    pop         ecx

    mov         esi, JSAMPARRAY [input_buf(eax)]
    mov         eax, INT [num_rows(eax)]
    test        eax, eax
    jle         near .return
    alignx      16, 7
.rowloop:
    pushpic     eax
    push        edx
    push        ebx
    push        edi
    push        esi
    push        ecx                     ; col

    mov         esi, JSAMPROW [esi]     ; inptr
    mov         edi, JSAMPROW [edi]     ; outptr0
    mov         ebx, JSAMPROW [ebx]     ; outptr1
    mov         edx, JSAMPROW [edx]     ; outptr2
    movpic      eax, POINTER [gotptr]   ; load GOT address (eax)

    cmp         ecx, byte SIZEOF_MMWORD
    jae         short .columnloop
    alignx      16, 7

%if RGB_PIXELSIZE == 3  ; ---------------

.column_ld1:
    push        eax
    push        edx
    lea         ecx, [ecx+ecx*2]        ; imul ecx,RGB_PIXELSIZE
    test        cl, SIZEOF_BYTE
    jz          short .column_ld2
    sub         ecx, byte SIZEOF_BYTE
    xor         eax, eax
    mov         al, byte [esi+ecx]
.column_ld2:
    test        cl, SIZEOF_WORD
    jz          short .column_ld4
    sub         ecx, byte SIZEOF_WORD
    xor         edx, edx
    mov         dx, word [esi+ecx]
    shl         eax, WORD_BIT
    or          eax, edx
.column_ld4:
    movd        mmA, eax
    pop         edx
    pop         eax
    test        cl, SIZEOF_DWORD
    jz          short .column_ld8
    sub         ecx, byte SIZEOF_DWORD
    movd        mmG, dword [esi+ecx]
    psllq       mmA, DWORD_BIT
    por         mmA, mmG
.column_ld8:
    test        cl, SIZEOF_MMWORD
    jz          short .column_ld16
    movq        mmG, mmA
    movq        mmA, MMWORD [esi+0*SIZEOF_MMWORD]
    mov         ecx, SIZEOF_MMWORD
    jmp         short .rgb_ycc_cnv
.column_ld16:
    test        cl, 2*SIZEOF_MMWORD
    mov         ecx, SIZEOF_MMWORD
    jz          short .rgb_ycc_cnv
    movq        mmF, mmA
    movq        mmA, MMWORD [esi+0*SIZEOF_MMWORD]
    movq        mmG, MMWORD [esi+1*SIZEOF_MMWORD]
    jmp         short .rgb_ycc_cnv
    alignx      16, 7

.columnloop:
    movq        mmA, MMWORD [esi+0*SIZEOF_MMWORD]
    movq        mmG, MMWORD [esi+1*SIZEOF_MMWORD]
    movq        mmF, MMWORD [esi+2*SIZEOF_MMWORD]

.rgb_ycc_cnv:
    ; mmA=(00 10 20 01 11 21 02 12)
    ; mmG=(22 03 13 23 04 14 24 05)
    ; mmF=(15 25 06 16 26 07 17 27)

    movq        mmD, mmA
    psllq       mmA, 4*BYTE_BIT         ; mmA=(-- -- -- -- 00 10 20 01)
    psrlq       mmD, 4*BYTE_BIT         ; mmD=(11 21 02 12 -- -- -- --)

    punpckhbw   mmA, mmG                ; mmA=(00 04 10 14 20 24 01 05)
    psllq       mmG, 4*BYTE_BIT         ; mmG=(-- -- -- -- 22 03 13 23)

    punpcklbw   mmD, mmF                ; mmD=(11 15 21 25 02 06 12 16)
    punpckhbw   mmG, mmF                ; mmG=(22 26 03 07 13 17 23 27)

    movq        mmE, mmA
    psllq       mmA, 4*BYTE_BIT         ; mmA=(-- -- -- -- 00 04 10 14)
    psrlq       mmE, 4*BYTE_BIT         ; mmE=(20 24 01 05 -- -- -- --)

    punpckhbw   mmA, mmD                ; mmA=(00 02 04 06 10 12 14 16)
    psllq       mmD, 4*BYTE_BIT         ; mmD=(-- -- -- -- 11 15 21 25)

    punpcklbw   mmE, mmG                ; mmE=(20 22 24 26 01 03 05 07)
    punpckhbw   mmD, mmG                ; mmD=(11 13 15 17 21 23 25 27)

    pxor        mmH, mmH

    movq        mmC, mmA
    punpcklbw   mmA, mmH                ; mmA=(00 02 04 06)
    punpckhbw   mmC, mmH                ; mmC=(10 12 14 16)

    movq        mmB, mmE
    punpcklbw   mmE, mmH                ; mmE=(20 22 24 26)
    punpckhbw   mmB, mmH                ; mmB=(01 03 05 07)

    movq        mmF, mmD
    punpcklbw   mmD, mmH                ; mmD=(11 13 15 17)
    punpckhbw   mmF, mmH                ; mmF=(21 23 25 27)

%else  ; RGB_PIXELSIZE == 4 ; -----------

.column_ld1:
    test        cl, SIZEOF_MMWORD/8
    jz          short .column_ld2
    sub         ecx, byte SIZEOF_MMWORD/8
    movd        mmA, dword [esi+ecx*RGB_PIXELSIZE]
.column_ld2:
    test        cl, SIZEOF_MMWORD/4
    jz          short .column_ld4
    sub         ecx, byte SIZEOF_MMWORD/4
    movq        mmF, mmA
    movq        mmA, MMWORD [esi+ecx*RGB_PIXELSIZE]
.column_ld4:
    test        cl, SIZEOF_MMWORD/2
    mov         ecx, SIZEOF_MMWORD
    jz          short .rgb_ycc_cnv
    movq        mmD, mmA
    movq        mmC, mmF
    movq        mmA, MMWORD [esi+0*SIZEOF_MMWORD]
    movq        mmF, MMWORD [esi+1*SIZEOF_MMWORD]
    jmp         short .rgb_ycc_cnv
    alignx      16, 7

.columnloop:
    movq        mmA, MMWORD [esi+0*SIZEOF_MMWORD]
    movq        mmF, MMWORD [esi+1*SIZEOF_MMWORD]
    movq        mmD, MMWORD [esi+2*SIZEOF_MMWORD]
    movq        mmC, MMWORD [esi+3*SIZEOF_MMWORD]

.rgb_ycc_cnv:
    ; mmA=(00 10 20 30 01 11 21 31)
    ; mmF=(02 12 22 32 03 13 23 33)
    ; mmD=(04 14 24 34 05 15 25 35)
    ; mmC=(06 16 26 36 07 17 27 37)

    movq        mmB, mmA
    punpcklbw   mmA, mmF                ; mmA=(00 02 10 12 20 22 30 32)
    punpckhbw   mmB, mmF                ; mmB=(01 03 11 13 21 23 31 33)

    movq        mmG, mmD
    punpcklbw   mmD, mmC                ; mmD=(04 06 14 16 24 26 34 36)
    punpckhbw   mmG, mmC                ; mmG=(05 07 15 17 25 27 35 37)

    movq        mmE, mmA
    punpcklwd   mmA, mmD                ; mmA=(00 02 04 06 10 12 14 16)
    punpckhwd   mmE, mmD                ; mmE=(20 22 24 26 30 32 34 36)

    movq        mmH, mmB
    punpcklwd   mmB, mmG                ; mmB=(01 03 05 07 11 13 15 17)
    punpckhwd   mmH, mmG                ; mmH=(21 23 25 27 31 33 35 37)

    pxor        mmF, mmF

    movq        mmC, mmA
    punpcklbw   mmA, mmF                ; mmA=(00 02 04 06)
    punpckhbw   mmC, mmF                ; mmC=(10 12 14 16)

    movq        mmD, mmB
    punpcklbw   mmB, mmF                ; mmB=(01 03 05 07)
    punpckhbw   mmD, mmF                ; mmD=(11 13 15 17)

    movq        mmG, mmE
    punpcklbw   mmE, mmF                ; mmE=(20 22 24 26)
    punpckhbw   mmG, mmF                ; mmG=(30 32 34 36)

    punpcklbw   mmF, mmH
    punpckhbw   mmH, mmH
    psrlw       mmF, BYTE_BIT           ; mmF=(21 23 25 27)
    psrlw       mmH, BYTE_BIT           ; mmH=(31 33 35 37)

%endif  ; RGB_PIXELSIZE ; ---------------

    ; mm0=(R0 R2 R4 R6)=RE, mm2=(G0 G2 G4 G6)=GE, mm4=(B0 B2 B4 B6)=BE
    ; mm1=(R1 R3 R5 R7)=RO, mm3=(G1 G3 G5 G7)=GO, mm5=(B1 B3 B5 B7)=BO

    ; (Original)
    ; Y  =  0.29900 * R + 0.58700 * G + 0.11400 * B
    ; Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
    ; Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE
    ;
    ; (This implementation)
    ; Y  =  0.29900 * R + 0.33700 * G + 0.11400 * B + 0.25000 * G
    ; Cb = -0.16874 * R - 0.33126 * G + 0.50000 * B + CENTERJSAMPLE
    ; Cr =  0.50000 * R - 0.41869 * G - 0.08131 * B + CENTERJSAMPLE

    movq        MMWORD [wk(0)], mm0     ; wk(0)=RE
    movq        MMWORD [wk(1)], mm1     ; wk(1)=RO
    movq        MMWORD [wk(2)], mm4     ; wk(2)=BE
    movq        MMWORD [wk(3)], mm5     ; wk(3)=BO

    movq        mm6, mm1
    punpcklwd   mm1, mm3
    punpckhwd   mm6, mm3
    movq        mm7, mm1
    movq        mm4, mm6
    pmaddwd     mm1, [GOTOFF(eax,PW_F0299_F0337)]  ; mm1=ROL*FIX(0.299)+GOL*FIX(0.337)
    pmaddwd     mm6, [GOTOFF(eax,PW_F0299_F0337)]  ; mm6=ROH*FIX(0.299)+GOH*FIX(0.337)
    pmaddwd     mm7, [GOTOFF(eax,PW_MF016_MF033)]  ; mm7=ROL*-FIX(0.168)+GOL*-FIX(0.331)
    pmaddwd     mm4, [GOTOFF(eax,PW_MF016_MF033)]  ; mm4=ROH*-FIX(0.168)+GOH*-FIX(0.331)

    movq        MMWORD [wk(4)], mm1     ; wk(4)=ROL*FIX(0.299)+GOL*FIX(0.337)
    movq        MMWORD [wk(5)], mm6     ; wk(5)=ROH*FIX(0.299)+GOH*FIX(0.337)

    pxor        mm1, mm1
    pxor        mm6, mm6
    punpcklwd   mm1, mm5                ; mm1=BOL
    punpckhwd   mm6, mm5                ; mm6=BOH
    psrld       mm1, 1                  ; mm1=BOL*FIX(0.500)
    psrld       mm6, 1                  ; mm6=BOH*FIX(0.500)

    movq        mm5, [GOTOFF(eax,PD_ONEHALFM1_CJ)]  ; mm5=[PD_ONEHALFM1_CJ]

    paddd       mm7, mm1
    paddd       mm4, mm6
    paddd       mm7, mm5
    paddd       mm4, mm5
    psrld       mm7, SCALEBITS          ; mm7=CbOL
    psrld       mm4, SCALEBITS          ; mm4=CbOH
    packssdw    mm7, mm4                ; mm7=CbO

    movq        mm1, MMWORD [wk(2)]     ; mm1=BE

    movq        mm6, mm0
    punpcklwd   mm0, mm2
    punpckhwd   mm6, mm2
    movq        mm5, mm0
    movq        mm4, mm6
    pmaddwd     mm0, [GOTOFF(eax,PW_F0299_F0337)]  ; mm0=REL*FIX(0.299)+GEL*FIX(0.337)
    pmaddwd     mm6, [GOTOFF(eax,PW_F0299_F0337)]  ; mm6=REH*FIX(0.299)+GEH*FIX(0.337)
    pmaddwd     mm5, [GOTOFF(eax,PW_MF016_MF033)]  ; mm5=REL*-FIX(0.168)+GEL*-FIX(0.331)
    pmaddwd     mm4, [GOTOFF(eax,PW_MF016_MF033)]  ; mm4=REH*-FIX(0.168)+GEH*-FIX(0.331)

    movq        MMWORD [wk(6)], mm0     ; wk(6)=REL*FIX(0.299)+GEL*FIX(0.337)
    movq        MMWORD [wk(7)], mm6     ; wk(7)=REH*FIX(0.299)+GEH*FIX(0.337)

    pxor        mm0, mm0
    pxor        mm6, mm6
    punpcklwd   mm0, mm1                ; mm0=BEL
    punpckhwd   mm6, mm1                ; mm6=BEH
    psrld       mm0, 1                  ; mm0=BEL*FIX(0.500)
    psrld       mm6, 1                  ; mm6=BEH*FIX(0.500)

    movq        mm1, [GOTOFF(eax,PD_ONEHALFM1_CJ)]  ; mm1=[PD_ONEHALFM1_CJ]

    paddd       mm5, mm0
    paddd       mm4, mm6
    paddd       mm5, mm1
    paddd       mm4, mm1
    psrld       mm5, SCALEBITS          ; mm5=CbEL
    psrld       mm4, SCALEBITS          ; mm4=CbEH
    packssdw    mm5, mm4                ; mm5=CbE

    psllw       mm7, BYTE_BIT
    por         mm5, mm7                ; mm5=Cb
    movq        MMWORD [ebx], mm5       ; Save Cb

    movq        mm0, MMWORD [wk(3)]     ; mm0=BO
    movq        mm6, MMWORD [wk(2)]     ; mm6=BE
    movq        mm1, MMWORD [wk(1)]     ; mm1=RO

    movq        mm4, mm0
    punpcklwd   mm0, mm3
    punpckhwd   mm4, mm3
    movq        mm7, mm0
    movq        mm5, mm4
    pmaddwd     mm0, [GOTOFF(eax,PW_F0114_F0250)]  ; mm0=BOL*FIX(0.114)+GOL*FIX(0.250)
    pmaddwd     mm4, [GOTOFF(eax,PW_F0114_F0250)]  ; mm4=BOH*FIX(0.114)+GOH*FIX(0.250)
    pmaddwd     mm7, [GOTOFF(eax,PW_MF008_MF041)]  ; mm7=BOL*-FIX(0.081)+GOL*-FIX(0.418)
    pmaddwd     mm5, [GOTOFF(eax,PW_MF008_MF041)]  ; mm5=BOH*-FIX(0.081)+GOH*-FIX(0.418)

    movq        mm3, [GOTOFF(eax,PD_ONEHALF)]  ; mm3=[PD_ONEHALF]

    paddd       mm0, MMWORD [wk(4)]
    paddd       mm4, MMWORD [wk(5)]
    paddd       mm0, mm3
    paddd       mm4, mm3
    psrld       mm0, SCALEBITS          ; mm0=YOL
    psrld       mm4, SCALEBITS          ; mm4=YOH
    packssdw    mm0, mm4                ; mm0=YO

    pxor        mm3, mm3
    pxor        mm4, mm4
    punpcklwd   mm3, mm1                ; mm3=ROL
    punpckhwd   mm4, mm1                ; mm4=ROH
    psrld       mm3, 1                  ; mm3=ROL*FIX(0.500)
    psrld       mm4, 1                  ; mm4=ROH*FIX(0.500)

    movq        mm1, [GOTOFF(eax,PD_ONEHALFM1_CJ)]  ; mm1=[PD_ONEHALFM1_CJ]

    paddd       mm7, mm3
    paddd       mm5, mm4
    paddd       mm7, mm1
    paddd       mm5, mm1
    psrld       mm7, SCALEBITS          ; mm7=CrOL
    psrld       mm5, SCALEBITS          ; mm5=CrOH
    packssdw    mm7, mm5                ; mm7=CrO

    movq        mm3, MMWORD [wk(0)]     ; mm3=RE

    movq        mm4, mm6
    punpcklwd   mm6, mm2
    punpckhwd   mm4, mm2
    movq        mm1, mm6
    movq        mm5, mm4
    pmaddwd     mm6, [GOTOFF(eax,PW_F0114_F0250)]  ; mm6=BEL*FIX(0.114)+GEL*FIX(0.250)
    pmaddwd     mm4, [GOTOFF(eax,PW_F0114_F0250)]  ; mm4=BEH*FIX(0.114)+GEH*FIX(0.250)
    pmaddwd     mm1, [GOTOFF(eax,PW_MF008_MF041)]  ; mm1=BEL*-FIX(0.081)+GEL*-FIX(0.418)
    pmaddwd     mm5, [GOTOFF(eax,PW_MF008_MF041)]  ; mm5=BEH*-FIX(0.081)+GEH*-FIX(0.418)

    movq        mm2, [GOTOFF(eax,PD_ONEHALF)]      ; mm2=[PD_ONEHALF]

    paddd       mm6, MMWORD [wk(6)]
    paddd       mm4, MMWORD [wk(7)]
    paddd       mm6, mm2
    paddd       mm4, mm2
    psrld       mm6, SCALEBITS          ; mm6=YEL
    psrld       mm4, SCALEBITS          ; mm4=YEH
    packssdw    mm6, mm4                ; mm6=YE

    psllw       mm0, BYTE_BIT
    por         mm6, mm0                ; mm6=Y
    movq        MMWORD [edi], mm6       ; Save Y

    pxor        mm2, mm2
    pxor        mm4, mm4
    punpcklwd   mm2, mm3                ; mm2=REL
    punpckhwd   mm4, mm3                ; mm4=REH
    psrld       mm2, 1                  ; mm2=REL*FIX(0.500)
    psrld       mm4, 1                  ; mm4=REH*FIX(0.500)

    movq        mm0, [GOTOFF(eax,PD_ONEHALFM1_CJ)]  ; mm0=[PD_ONEHALFM1_CJ]

    paddd       mm1, mm2
    paddd       mm5, mm4
    paddd       mm1, mm0
    paddd       mm5, mm0
    psrld       mm1, SCALEBITS          ; mm1=CrEL
    psrld       mm5, SCALEBITS          ; mm5=CrEH
    packssdw    mm1, mm5                ; mm1=CrE

    psllw       mm7, BYTE_BIT
    por         mm1, mm7                ; mm1=Cr
    movq        MMWORD [edx], mm1       ; Save Cr

    sub         ecx, byte SIZEOF_MMWORD
    add         esi, byte RGB_PIXELSIZE*SIZEOF_MMWORD  ; inptr
    add         edi, byte SIZEOF_MMWORD                ; outptr0
    add         ebx, byte SIZEOF_MMWORD                ; outptr1
    add         edx, byte SIZEOF_MMWORD                ; outptr2
    cmp         ecx, byte SIZEOF_MMWORD
    jae         near .columnloop
    test        ecx, ecx
    jnz         near .column_ld1

    pop         ecx                     ; col
    pop         esi
    pop         edi
    pop         ebx
    pop         edx
    poppic      eax

    add         esi, byte SIZEOF_JSAMPROW  ; input_buf
    add         edi, byte SIZEOF_JSAMPROW
    add         ebx, byte SIZEOF_JSAMPROW
    add         edx, byte SIZEOF_JSAMPROW
    dec         eax                        ; num_rows
    jg          near .rowloop

    emms                                ; empty MMX state

.return:
    pop         edi
    pop         esi
;   pop         edx                     ; need not be preserved
;   pop         ecx                     ; need not be preserved
    pop         ebx
    mov         esp, ebp                ; esp <- aligned ebp
    pop         esp                     ; esp <- original ebp
    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