summaryrefslogtreecommitdiffstats
path: root/third_party/dav1d/src/x86/msac.asm
blob: 92a3a731d328dd6811368c3fd669f18ec0e18829 (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
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
; Copyright © 2019, VideoLAN and dav1d authors
; Copyright © 2019, Two Orioles, LLC
; All rights reserved.
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions are met:
;
; 1. Redistributions of source code must retain the above copyright notice, this
;    list of conditions and the following disclaimer.
;
; 2. Redistributions in binary form must reproduce the above copyright notice,
;    this list of conditions and the following disclaimer in the documentation
;    and/or other materials provided with the distribution.
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
; ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
; DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
; ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

%include "config.asm"
%include "ext/x86/x86inc.asm"

SECTION_RODATA 64 ; avoids cacheline splits

min_prob:  dw 60, 56, 52, 48, 44, 40, 36, 32, 28, 24, 20, 16, 12, 8, 4, 0
pw_0xff00: times 8 dw 0xff00
pw_32:     times 8 dw 32

%if ARCH_X86_64
%define resp   resq
%define movp   movq
%define c_shuf q3333
%macro DECODE_SYMBOL_ADAPT_INIT 0-1
%endmacro
%else
%define resp   resd
%define movp   movd
%define c_shuf q1111
%macro DECODE_SYMBOL_ADAPT_INIT 0-1 0 ; hi_tok
    mov            t0, r0m
    mov            t1, r1m
%if %1 == 0
    mov            t2, r2m
%endif
%if STACK_ALIGNMENT >= 16
    sub           esp, 40-%1*4
%else
    mov           eax, esp
    and           esp, ~15
    sub           esp, 40-%1*4
    mov         [esp], eax
%endif
%endmacro
%endif

struc msac
    .buf:        resp 1
    .end:        resp 1
    .dif:        resp 1
    .rng:        resd 1
    .cnt:        resd 1
    .update_cdf: resd 1
endstruc

%define m(x, y) mangle(private_prefix %+ _ %+ x %+ y)

SECTION .text

%if WIN64
DECLARE_REG_TMP 0, 1, 2, 3, 4, 5, 7, 3, 8
%define buf rsp+stack_offset+8 ; shadow space
%elif UNIX64
DECLARE_REG_TMP 0, 1, 2, 3, 4, 5, 7, 0, 8
%define buf rsp-40 ; red zone
%else
DECLARE_REG_TMP 2, 3, 4, 1, 5, 6, 5, 2, 3
%define buf esp+8
%endif

INIT_XMM sse2
cglobal msac_decode_symbol_adapt4, 0, 6, 6
    DECODE_SYMBOL_ADAPT_INIT
    LEA           rax, pw_0xff00
    movd           m2, [t0+msac.rng]
    movq           m1, [t1]
    movp           m3, [t0+msac.dif]
    mov           t3d, [t0+msac.update_cdf]
    mov           t4d, t2d
    not            t2     ; -(n_symbols + 1)
    pshuflw        m2, m2, q0000
    movd     [buf+12], m2
    pand           m2, [rax]
    mova           m0, m1
    psrlw          m1, 6
    psllw          m1, 7
    pmulhuw        m1, m2
    movq           m2, [rax+t2*2]
    pshuflw        m3, m3, c_shuf
    paddw          m1, m2
    mova     [buf+16], m1
    psubusw        m1, m3
    pxor           m2, m2
    pcmpeqw        m1, m2 ; c >= v
    pmovmskb      eax, m1
    test          t3d, t3d
    jz .renorm ; !allow_update_cdf

; update_cdf:
    movzx         t3d, word [t1+t4*2] ; count
    pcmpeqw        m2, m2
    mov           t2d, t3d
    shr           t3d, 4
    cmp           t4d, 3
    sbb           t3d, -5 ; (count >> 4) + (n_symbols > 2) + 4
    cmp           t2d, 32
    adc           t2d, 0  ; count + (count < 32)
    movd           m3, t3d
    pavgw          m2, m1 ; i >= val ? -1 : 32768
    psubw          m2, m0 ; for (i = 0; i < val; i++)
    psubw          m0, m1 ;     cdf[i] += (32768 - cdf[i]) >> rate;
    psraw          m2, m3 ; for (; i < n_symbols; i++)
    paddw          m0, m2 ;     cdf[i] += ((  -1 - cdf[i]) >> rate) + 1;
    movq         [t1], m0
    mov     [t1+t4*2], t2w

.renorm:
    tzcnt         eax, eax
    mov            t4, [t0+msac.dif]
    movzx         t1d, word [buf+rax+16] ; v
    movzx         t2d, word [buf+rax+14] ; u
    shr           eax, 1
.renorm2:
%if ARCH_X86_64 == 0
%if STACK_ALIGNMENT >= 16
    add           esp, 40
%else
    mov           esp, [esp]
%endif
%endif
    not            t4
    sub           t2d, t1d ; rng
    shl            t1, gprsize*8-16
    add            t4, t1  ; ~dif
.renorm3:
    mov           t1d, [t0+msac.cnt]
    movifnidn      t7, t0
.renorm4:
    bsr           ecx, t2d
    xor           ecx, 15  ; d
.renorm5:
    shl           t2d, cl
    shl            t4, cl
    mov [t7+msac.rng], t2d
    not            t4
    sub           t1d, ecx
    jae .end ; no refill required

; refill:
    mov            t2, [t7+msac.buf]
    mov           rcx, [t7+msac.end]
%if ARCH_X86_64 == 0
    push           t5
%endif
    lea            t5, [t2+gprsize]
    cmp            t5, rcx
    ja .refill_eob
    mov            t2, [t2]
    lea           ecx, [t1+23]
    add           t1d, 16
    shr           ecx, 3   ; shift_bytes
    bswap          t2
    sub            t5, rcx
    shl           ecx, 3   ; shift_bits
    shr            t2, cl
    sub           ecx, t1d ; shift_bits - 16 - cnt
    mov           t1d, gprsize*8-16
    shl            t2, cl
    mov [t7+msac.buf], t5
    sub           t1d, ecx ; cnt + gprsize*8 - shift_bits
    xor            t4, t2
%if ARCH_X86_64 == 0
    pop            t5
%endif
.end:
    mov [t7+msac.cnt], t1d
    mov [t7+msac.dif], t4
    RET
.refill_eob: ; avoid overreading the input buffer
    mov            t5, rcx
    mov           ecx, gprsize*8-24
    sub           ecx, t1d ; c
.refill_eob_loop:
    cmp            t2, t5
    jae .refill_eob_end    ; eob reached
    movzx         t1d, byte [t2]
    inc            t2
    shl            t1, cl
    xor            t4, t1
    sub           ecx, 8
    jge .refill_eob_loop
.refill_eob_end:
    mov           t1d, gprsize*8-24
%if ARCH_X86_64 == 0
    pop            t5
%endif
    sub           t1d, ecx
    mov [t7+msac.buf], t2
    mov [t7+msac.dif], t4
    mov [t7+msac.cnt], t1d
    RET

cglobal msac_decode_symbol_adapt8, 0, 6, 6
    DECODE_SYMBOL_ADAPT_INIT
    LEA           rax, pw_0xff00
    movd           m2, [t0+msac.rng]
    mova           m1, [t1]
    movp           m3, [t0+msac.dif]
    mov           t3d, [t0+msac.update_cdf]
    mov           t4d, t2d
    not            t2
    pshuflw        m2, m2, q0000
    movd     [buf+12], m2
    punpcklqdq     m2, m2
    mova           m0, m1
    psrlw          m1, 6
    pand           m2, [rax]
    psllw          m1, 7
    pmulhuw        m1, m2
    movu           m2, [rax+t2*2]
    pshuflw        m3, m3, c_shuf
    paddw          m1, m2
    punpcklqdq     m3, m3
    mova     [buf+16], m1
    psubusw        m1, m3
    pxor           m2, m2
    pcmpeqw        m1, m2
    pmovmskb      eax, m1
    test          t3d, t3d
    jz m(msac_decode_symbol_adapt4, SUFFIX).renorm
    movzx         t3d, word [t1+t4*2]
    pcmpeqw        m2, m2
    mov           t2d, t3d
    shr           t3d, 4
    cmp           t4d, 3 ; may be called with n_symbols <= 2
    sbb           t3d, -5
    cmp           t2d, 32
    adc           t2d, 0
    movd           m3, t3d
    pavgw          m2, m1
    psubw          m2, m0
    psubw          m0, m1
    psraw          m2, m3
    paddw          m0, m2
    mova         [t1], m0
    mov     [t1+t4*2], t2w
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm

cglobal msac_decode_symbol_adapt16, 0, 6, 6
    DECODE_SYMBOL_ADAPT_INIT
    LEA           rax, pw_0xff00
    movd           m4, [t0+msac.rng]
    mova           m2, [t1]
    mova           m3, [t1+16]
    movp           m5, [t0+msac.dif]
    mov           t3d, [t0+msac.update_cdf]
    mov           t4d, t2d
    not            t2
%if WIN64
    sub           rsp, 48 ; need 36 bytes, shadow space is only 32
%endif
    pshuflw        m4, m4, q0000
    movd      [buf-4], m4
    punpcklqdq     m4, m4
    mova           m0, m2
    psrlw          m2, 6
    mova           m1, m3
    psrlw          m3, 6
    pand           m4, [rax]
    psllw          m2, 7
    psllw          m3, 7
    pmulhuw        m2, m4
    pmulhuw        m3, m4
    movu           m4, [rax+t2*2]
    pshuflw        m5, m5, c_shuf
    paddw          m2, m4
    psubw          m4, [rax-pw_0xff00+pw_32]
    punpcklqdq     m5, m5
    paddw          m3, m4
    mova        [buf], m2
    psubusw        m2, m5
    mova     [buf+16], m3
    psubusw        m3, m5
    pxor           m4, m4
    pcmpeqw        m2, m4
    pcmpeqw        m3, m4
    packsswb       m5, m2, m3
    pmovmskb      eax, m5
    test          t3d, t3d
    jz .renorm
    movzx         t3d, word [t1+t4*2]
    pcmpeqw        m4, m4
    mova           m5, m4
    lea           t2d, [t3+80] ; only support n_symbols > 2
    shr           t2d, 4
    cmp           t3d, 32
    adc           t3d, 0
    pavgw          m4, m2
    pavgw          m5, m3
    psubw          m4, m0
    psubw          m0, m2
    movd           m2, t2d
    psubw          m5, m1
    psubw          m1, m3
    psraw          m4, m2
    psraw          m5, m2
    paddw          m0, m4
    paddw          m1, m5
    mova         [t1], m0
    mova      [t1+16], m1
    mov     [t1+t4*2], t3w
.renorm:
    tzcnt         eax, eax
    mov            t4, [t0+msac.dif]
    movzx         t1d, word [buf+rax*2]
    movzx         t2d, word [buf+rax*2-2]
%if WIN64
    add           rsp, 48
%endif
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm2

cglobal msac_decode_bool_adapt, 0, 6, 0
    movifnidn      t1, r1mp
    movifnidn      t0, r0mp
    movzx         eax, word [t1]
    movzx         t3d, byte [t0+msac.rng+1]
    mov            t4, [t0+msac.dif]
    mov           t2d, [t0+msac.rng]
%if ARCH_X86_64
    mov           t5d, eax
%endif
    and           eax, ~63
    imul          eax, t3d
%if UNIX64
    mov            t6, t4
%endif
    shr           eax, 7
    add           eax, 4            ; v
    mov           t3d, eax
    shl           rax, gprsize*8-16 ; vw
    sub           t2d, t3d          ; r - v
    sub            t4, rax          ; dif - vw
    setb           al
    cmovb         t2d, t3d
    mov           t3d, [t0+msac.update_cdf]
%if UNIX64
    cmovb          t4, t6
%else
    cmovb          t4, [t0+msac.dif]
%endif
%if ARCH_X86_64 == 0
    movzx         eax, al
%endif
    not            t4
    test          t3d, t3d
    jz m(msac_decode_symbol_adapt4, SUFFIX).renorm3
%if UNIX64 == 0
    push           t6
%endif
    movzx         t6d, word [t1+2]
%if ARCH_X86_64 == 0
    push           t5
    movzx         t5d, word [t1]
%endif
    movifnidn      t7, t0
    lea           ecx, [t6+64]
    cmp           t6d, 32
    adc           t6d, 0
    mov        [t1+2], t6w
    imul          t6d, eax, -32769
    shr           ecx, 4   ; rate
    add           t6d, t5d ; if (bit)
    sub           t5d, eax ;     cdf[0] -= ((cdf[0] - 32769) >> rate) + 1;
    sar           t6d, cl  ; else
    sub           t5d, t6d ;     cdf[0] -= cdf[0] >> rate;
    mov          [t1], t5w
%if WIN64
    mov           t1d, [t7+msac.cnt]
    pop            t6
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm4
%else
%if ARCH_X86_64 == 0
    pop            t5
    pop            t6
%endif
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm3
%endif

cglobal msac_decode_bool_equi, 0, 6, 0
    movifnidn      t0, r0mp
    mov           t1d, [t0+msac.rng]
    mov            t4, [t0+msac.dif]
    mov           t2d, t1d
    mov           t1b, 8
    mov            t3, t4
    mov           eax, t1d
    shr           t1d, 1            ; v
    shl           rax, gprsize*8-17 ; vw
    sub           t2d, t1d          ; r - v
    sub            t4, rax          ; dif - vw
    cmovb         t2d, t1d
    mov           t1d, [t0+msac.cnt]
    cmovb          t4, t3
    movifnidn      t7, t0
    mov           ecx, 0xbfff
    setb           al ; the upper 32 bits contains garbage but that's OK
    sub           ecx, t2d
    not            t4
    ; In this case of this function, (d =) 16 - clz(v) = 2 - (v >> 14)
    ;   i.e. (0 <= d <= 2) and v < (3 << 14)
    shr           ecx, 14           ; d
%if ARCH_X86_64 == 0
    movzx         eax, al
%endif
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm5

cglobal msac_decode_bool, 0, 6, 0
    movifnidn      t0, r0mp
    movifnidn     t1d, r1m
    movzx         eax, byte [t0+msac.rng+1] ; r >> 8
    mov            t4, [t0+msac.dif]
    mov           t2d, [t0+msac.rng]
    and           t1d, ~63
    imul          eax, t1d
    mov            t3, t4
    shr           eax, 7
    add           eax, 4            ; v
    mov           t1d, eax
    shl           rax, gprsize*8-16 ; vw
    sub           t2d, t1d          ; r - v
    sub            t4, rax          ; dif - vw
    cmovb         t2d, t1d
    cmovb          t4, t3
    setb           al
    not            t4
%if ARCH_X86_64 == 0
    movzx         eax, al
%endif
    jmp m(msac_decode_symbol_adapt4, SUFFIX).renorm3

%macro HI_TOK 1 ; update_cdf
%if ARCH_X86_64 == 0
    mov           eax, -24
%endif
%%loop:
%if %1
    movzx         t2d, word [t1+3*2]
%endif
    mova           m1, m0
    pshuflw        m2, m2, q0000
    psrlw          m1, 6
    movd     [buf+12], m2
    pand           m2, m4
    psllw          m1, 7
    pmulhuw        m1, m2
%if ARCH_X86_64 == 0
    add           eax, 5
    mov       [buf+8], eax
%endif
    pshuflw        m3, m3, c_shuf
    paddw          m1, m5
    movq     [buf+16], m1
    psubusw        m1, m3
    pxor           m2, m2
    pcmpeqw        m1, m2
    pmovmskb      eax, m1
%if %1
    lea           ecx, [t2+80]
    pcmpeqw        m2, m2
    shr           ecx, 4
    cmp           t2d, 32
    adc           t2d, 0
    movd           m3, ecx
    pavgw          m2, m1
    psubw          m2, m0
    psubw          m0, m1
    psraw          m2, m3
    paddw          m0, m2
    movq         [t1], m0
    mov      [t1+3*2], t2w
%endif
    tzcnt         eax, eax
    movzx         ecx, word [buf+rax+16]
    movzx         t2d, word [buf+rax+14]
    not            t4
%if ARCH_X86_64
    add           t6d, 5
%endif
    sub           eax, 5   ; setup for merging the tok_br and tok branches
    sub           t2d, ecx
    shl           rcx, gprsize*8-16
    add            t4, rcx
    bsr           ecx, t2d
    xor           ecx, 15
    shl           t2d, cl
    shl            t4, cl
    movd           m2, t2d
    mov [t7+msac.rng], t2d
    not            t4
    sub           t5d, ecx
    jae %%end
    mov            t2, [t7+msac.buf]
    mov           rcx, [t7+msac.end]
%if UNIX64 == 0
    push           t8
%endif
    lea            t8, [t2+gprsize]
    cmp            t8, rcx
    ja %%refill_eob
    mov            t2, [t2]
    lea           ecx, [t5+23]
    add           t5d, 16
    shr           ecx, 3
    bswap          t2
    sub            t8, rcx
    shl           ecx, 3
    shr            t2, cl
    sub           ecx, t5d
    mov           t5d, gprsize*8-16
    shl            t2, cl
    mov [t7+msac.buf], t8
%if UNIX64 == 0
    pop            t8
%endif
    sub           t5d, ecx
    xor            t4, t2
%%end:
    movp           m3, t4
%if ARCH_X86_64
    add           t6d, eax ; CF = tok_br < 3 || tok == 15
    jnc %%loop
    lea           eax, [t6+30]
%else
    add           eax, [buf+8]
    jnc %%loop
    add           eax, 30
%if STACK_ALIGNMENT >= 16
    add           esp, 36
%else
    mov           esp, [esp]
%endif
%endif
    mov [t7+msac.dif], t4
    shr           eax, 1
    mov [t7+msac.cnt], t5d
    RET
%%refill_eob:
    mov            t8, rcx
    mov           ecx, gprsize*8-24
    sub           ecx, t5d
%%refill_eob_loop:
    cmp            t2, t8
    jae %%refill_eob_end
    movzx         t5d, byte [t2]
    inc            t2
    shl            t5, cl
    xor            t4, t5
    sub           ecx, 8
    jge %%refill_eob_loop
%%refill_eob_end:
%if UNIX64 == 0
    pop            t8
%endif
    mov           t5d, gprsize*8-24
    mov [t7+msac.buf], t2
    sub           t5d, ecx
    jmp %%end
%endmacro

cglobal msac_decode_hi_tok, 0, 7 + ARCH_X86_64, 6
    DECODE_SYMBOL_ADAPT_INIT 1
%if ARCH_X86_64 == 0 && PIC
    LEA            t2, min_prob+12*2
    %define base t2-(min_prob+12*2)
%else
    %define base 0
%endif
    movq           m0, [t1]
    movd           m2, [t0+msac.rng]
    mov           eax, [t0+msac.update_cdf]
    movq           m4, [base+pw_0xff00]
    movp           m3, [t0+msac.dif]
    movq           m5, [base+min_prob+12*2]
    mov            t4, [t0+msac.dif]
    mov           t5d, [t0+msac.cnt]
%if ARCH_X86_64
    mov           t6d, -24
%endif
    movifnidn      t7, t0
    test          eax, eax
    jz .no_update_cdf
    HI_TOK          1
.no_update_cdf:
    HI_TOK          0

%if ARCH_X86_64
INIT_YMM avx2
cglobal msac_decode_symbol_adapt16, 3, 6, 6
    lea           rax, [pw_0xff00]
    vpbroadcastw   m2, [t0+msac.rng]
    mova           m0, [t1]
    vpbroadcastw   m3, [t0+msac.dif+6]
    vbroadcasti128 m4, [rax]
    mov           t3d, [t0+msac.update_cdf]
    mov           t4d, t2d
    not            t2
%if STACK_ALIGNMENT < 32
    mov            r5, rsp
%if WIN64
    and           rsp, ~31
    sub           rsp, 40
%else
    and            r5, ~31
    %define buf r5-32
%endif
%elif WIN64
    sub           rsp, 64
%else
    %define buf rsp-56
%endif
    psrlw          m1, m0, 6
    movd      [buf-4], xm2
    pand           m2, m4
    psllw          m1, 7
    pmulhuw        m1, m2
    paddw          m1, [rax+t2*2]
    mova        [buf], m1
    pmaxuw         m1, m3
    pcmpeqw        m1, m3
    pmovmskb      eax, m1
    test          t3d, t3d
    jz .renorm
    movzx         t3d, word [t1+t4*2]
    pcmpeqw        m2, m2
    lea           t2d, [t3+80]
    shr           t2d, 4
    cmp           t3d, 32
    adc           t3d, 0
    movd          xm3, t2d
    pavgw          m2, m1
    psubw          m2, m0
    psubw          m0, m1
    psraw          m2, xm3
    paddw          m0, m2
    mova         [t1], m0
    mov     [t1+t4*2], t3w
.renorm:
    tzcnt         eax, eax
    mov            t4, [t0+msac.dif]
    movzx         t1d, word [buf+rax-0]
    movzx         t2d, word [buf+rax-2]
    shr           eax, 1
%if WIN64
%if STACK_ALIGNMENT < 32
    mov           rsp, r5
%else
    add           rsp, 64
%endif
%endif
    vzeroupper
    jmp m(msac_decode_symbol_adapt4, _sse2).renorm2
%endif