aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/arm/dsputil_armv6.S
blob: 6eabeee7abc14d63d8f5684c5718d97bbb0024e1 (plain) (blame)
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
/*
 * Copyright (c) 2009 Mans Rullgard <mans@mansr.com>
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/arm/asm.S"

        preserve8

.macro  call_2x_pixels  type, subp
function ff_\type\()_pixels16\subp\()_armv6, export=1
        push            {r0-r3, lr}
        bl              ff_\type\()_pixels8\subp\()_armv6
        pop             {r0-r3, lr}
        add             r0,  r0,  #8
        add             r1,  r1,  #8
        b               ff_\type\()_pixels8\subp\()_armv6
endfunc
.endm

call_2x_pixels          avg
call_2x_pixels          put, _x2
call_2x_pixels          put, _y2
call_2x_pixels          put, _x2_no_rnd
call_2x_pixels          put, _y2_no_rnd

function ff_put_pixels16_armv6, export=1
        push            {r4-r11}
1:
        ldr             r5,  [r1, #4]
        ldr             r6,  [r1, #8]
        ldr             r7,  [r1, #12]
        ldr_post        r4,  r1,  r2
        strd            r6,  r7,  [r0, #8]
        ldr             r9,  [r1, #4]
        strd_post       r4,  r5,  r0,  r2
        ldr             r10, [r1, #8]
        ldr             r11, [r1, #12]
        ldr_post        r8,  r1,  r2
        strd            r10, r11, [r0, #8]
        subs            r3,  r3,  #2
        strd_post       r8,  r9,  r0,  r2
        bne             1b

        pop             {r4-r11}
        bx              lr
endfunc

function ff_put_pixels8_armv6, export=1
        push            {r4-r7}
1:
        ldr             r5,  [r1, #4]
        ldr_post        r4,  r1,  r2
        ldr             r7,  [r1, #4]
        strd_post       r4,  r5,  r0,  r2
        ldr_post        r6,  r1,  r2
        subs            r3,  r3,  #2
        strd_post       r6,  r7,  r0,  r2
        bne             1b

        pop             {r4-r7}
        bx              lr
endfunc

function ff_put_pixels8_x2_armv6, export=1
        push            {r4-r11, lr}
        mov             r12, #1
        orr             r12, r12, r12, lsl #8
        orr             r12, r12, r12, lsl #16
1:
        ldr             r4,  [r1]
        subs            r3,  r3,  #2
        ldr             r5,  [r1, #4]
        ldr             r7,  [r1, #5]
        lsr             r6,  r4,  #8
        ldr_pre         r8,  r1,  r2
        orr             r6,  r6,  r5,  lsl #24
        ldr             r9,  [r1, #4]
        ldr             r11, [r1, #5]
        lsr             r10, r8,  #8
        add             r1,  r1,  r2
        orr             r10, r10, r9,  lsl #24
        eor             r14, r4,  r6
        uhadd8          r4,  r4,  r6
        eor             r6,  r5,  r7
        uhadd8          r5,  r5,  r7
        and             r14, r14, r12
        and             r6,  r6,  r12
        uadd8           r4,  r4,  r14
        eor             r14, r8,  r10
        uadd8           r5,  r5,  r6
        eor             r6,  r9,  r11
        uhadd8          r8,  r8,  r10
        and             r14, r14, r12
        uhadd8          r9,  r9,  r11
        and             r6,  r6,  r12
        uadd8           r8,  r8,  r14
        strd_post       r4,  r5,  r0,  r2
        uadd8           r9,  r9,  r6
        strd_post       r8,  r9,  r0,  r2
        bne             1b

        pop             {r4-r11, pc}
endfunc

function ff_put_pixels8_y2_armv6, export=1
        push            {r4-r11}
        mov             r12, #1
        orr             r12, r12, r12, lsl #8
        orr             r12, r12, r12, lsl #16
        ldr             r4,  [r1]
        ldr             r5,  [r1, #4]
        ldr_pre         r6,  r1,  r2
        ldr             r7,  [r1, #4]
1:
        subs            r3,  r3,  #2
        uhadd8          r8,  r4,  r6
        eor             r10, r4,  r6
        uhadd8          r9,  r5,  r7
        eor             r11, r5,  r7
        and             r10, r10, r12
        ldr_pre         r4,  r1,  r2
        uadd8           r8,  r8,  r10
        and             r11, r11, r12
        uadd8           r9,  r9,  r11
        ldr             r5,  [r1, #4]
        uhadd8          r10, r4,  r6
        eor             r6,  r4,  r6
        uhadd8          r11, r5,  r7
        and             r6,  r6,  r12
        eor             r7,  r5,  r7
        uadd8           r10, r10, r6
        and             r7,  r7,  r12
        ldr_pre         r6,  r1,  r2
        uadd8           r11, r11, r7
        strd_post       r8,  r9,  r0,  r2
        ldr             r7,  [r1, #4]
        strd_post       r10, r11, r0,  r2
        bne             1b

        pop             {r4-r11}
        bx              lr
endfunc

function ff_put_pixels8_x2_no_rnd_armv6, export=1
        push            {r4-r9, lr}
1:
        subs            r3,  r3,  #2
        ldr             r4,  [r1]
        ldr             r5,  [r1, #4]
        ldr             r7,  [r1, #5]
        ldr_pre         r8,  r1,  r2
        ldr             r9,  [r1, #4]
        ldr             r14, [r1, #5]
        add             r1,  r1,  r2
        lsr             r6,  r4,  #8
        orr             r6,  r6,  r5,  lsl #24
        lsr             r12, r8,  #8
        orr             r12, r12, r9,  lsl #24
        uhadd8          r4,  r4,  r6
        uhadd8          r5,  r5,  r7
        uhadd8          r8,  r8,  r12
        uhadd8          r9,  r9,  r14
        stm             r0,  {r4,r5}
        add             r0,  r0,  r2
        stm             r0,  {r8,r9}
        add             r0,  r0,  r2
        bne             1b

        pop             {r4-r9, pc}
endfunc

function ff_put_pixels8_y2_no_rnd_armv6, export=1
        push            {r4-r9, lr}
        ldr             r4,  [r1]
        ldr             r5,  [r1, #4]
        ldr_pre         r6,  r1,  r2
        ldr             r7,  [r1, #4]
1:
        subs            r3,  r3,  #2
        uhadd8          r8,  r4,  r6
        ldr_pre         r4,  r1,  r2
        uhadd8          r9,  r5,  r7
        ldr             r5,  [r1, #4]
        uhadd8          r12, r4,  r6
        ldr_pre         r6,  r1,  r2
        uhadd8          r14, r5,  r7
        ldr             r7,  [r1, #4]
        stm             r0,  {r8,r9}
        add             r0,  r0,  r2
        stm             r0,  {r12,r14}
        add             r0,  r0,  r2
        bne             1b

        pop             {r4-r9, pc}
endfunc

function ff_avg_pixels8_armv6, export=1
        pld             [r1, r2]
        push            {r4-r10, lr}
        mov             lr,  #1
        orr             lr,  lr,  lr,  lsl #8
        orr             lr,  lr,  lr,  lsl #16
        ldrd            r4,  r5,  [r0]
        ldr             r10, [r1, #4]
        ldr_post        r9,  r1,  r2
        subs            r3,  r3,  #2
1:
        pld             [r1, r2]
        eor             r8,  r4,  r9
        uhadd8          r4,  r4,  r9
        eor             r12, r5,  r10
        ldrd_reg        r6,  r7,  r0,  r2
        uhadd8          r5,  r5,  r10
        and             r8,  r8,  lr
        ldr             r10, [r1, #4]
        and             r12, r12, lr
        uadd8           r4,  r4,  r8
        ldr_post        r9,  r1,  r2
        eor             r8,  r6,  r9
        uadd8           r5,  r5,  r12
        pld             [r1, r2,  lsl #1]
        eor             r12, r7,  r10
        uhadd8          r6,  r6,  r9
        strd_post       r4,  r5,  r0,  r2
        uhadd8          r7,  r7,  r10
        beq             2f
        and             r8,  r8,  lr
        ldrd_reg        r4,  r5,  r0,  r2
        uadd8           r6,  r6,  r8
        ldr             r10, [r1, #4]
        and             r12, r12, lr
        subs            r3,  r3,  #2
        uadd8           r7,  r7,  r12
        ldr_post        r9,  r1,  r2
        strd_post       r6,  r7,  r0,  r2
        b               1b
2:
        and             r8,  r8,  lr
        and             r12, r12, lr
        uadd8           r6,  r6,  r8
        uadd8           r7,  r7,  r12
        strd_post       r6,  r7,  r0,  r2

        pop             {r4-r10, pc}
endfunc

function ff_add_pixels_clamped_armv6, export=1
        push            {r4-r8,lr}
        mov             r3,  #8
1:
        ldm             r0!, {r4,r5,r12,lr}
        ldrd            r6,  r7,  [r1]
        pkhbt           r8,  r4,  r5,  lsl #16
        pkhtb           r5,  r5,  r4,  asr #16
        pkhbt           r4,  r12, lr,  lsl #16
        pkhtb           lr,  lr,  r12, asr #16
        pld             [r1, r2]
        uxtab16         r8,  r8,  r6
        uxtab16         r5,  r5,  r6,  ror #8
        uxtab16         r4,  r4,  r7
        uxtab16         lr,  lr,  r7,  ror #8
        usat16          r8,  #8,  r8
        usat16          r5,  #8,  r5
        usat16          r4,  #8,  r4
        usat16          lr,  #8,  lr
        orr             r6,  r8,  r5,  lsl #8
        orr             r7,  r4,  lr,  lsl #8
        subs            r3,  r3,  #1
        strd_post       r6,  r7,  r1,  r2
        bgt             1b
        pop             {r4-r8,pc}
endfunc

function ff_get_pixels_armv6, export=1
        pld             [r1, r2]
        push            {r4-r8, lr}
        mov             lr,  #8
1:
        ldrd_post       r4,  r5,  r1,  r2
        subs            lr,  lr,  #1
        uxtb16          r6,  r4
        uxtb16          r4,  r4,  ror #8
        uxtb16          r12, r5
        uxtb16          r8,  r5,  ror #8
        pld             [r1, r2]
        pkhbt           r5,  r6,  r4,  lsl #16
        pkhtb           r6,  r4,  r6,  asr #16
        pkhbt           r7,  r12, r8,  lsl #16
        pkhtb           r12, r8,  r12, asr #16
        stm             r0!, {r5,r6,r7,r12}
        bgt             1b

        pop             {r4-r8, pc}
endfunc

function ff_diff_pixels_armv6, export=1
        pld             [r1, r3]
        pld             [r2, r3]
        push            {r4-r9, lr}
        mov             lr,  #8
1:
        ldrd_post       r4,  r5,  r1,  r3
        ldrd_post       r6,  r7,  r2,  r3
        uxtb16          r8,  r4
        uxtb16          r4,  r4,  ror #8
        uxtb16          r9,  r6
        uxtb16          r6,  r6,  ror #8
        pld             [r1, r3]
        ssub16          r9,  r8,  r9
        ssub16          r6,  r4,  r6
        uxtb16          r8,  r5
        uxtb16          r5,  r5,  ror #8
        pld             [r2, r3]
        pkhbt           r4,  r9,  r6,  lsl #16
        pkhtb           r6,  r6,  r9,  asr #16
        uxtb16          r9,  r7
        uxtb16          r7,  r7,  ror #8
        ssub16          r9,  r8,  r9
        ssub16          r5,  r5,  r7
        subs            lr,  lr,  #1
        pkhbt           r8,  r9,  r5,  lsl #16
        pkhtb           r9,  r5,  r9,  asr #16
        stm             r0!, {r4,r6,r8,r9}
        bgt             1b

        pop             {r4-r9, pc}
endfunc

function ff_pix_abs16_armv6, export=1
        ldr             r0,  [sp]
        push            {r4-r9, lr}
        mov             r12, #0
        mov             lr,  #0
        ldm             r1,  {r4-r7}
        ldr             r8,  [r2]
1:
        ldr             r9,  [r2, #4]
        pld             [r1, r3]
        usada8          r12, r4,  r8,  r12
        ldr             r8,  [r2, #8]
        pld             [r2, r3]
        usada8          lr,  r5,  r9,  lr
        ldr             r9,  [r2, #12]
        usada8          r12, r6,  r8,  r12
        subs            r0,  r0,  #1
        usada8          lr,  r7,  r9,  lr
        beq             2f
        add             r1,  r1,  r3
        ldm             r1,  {r4-r7}
        add             r2,  r2,  r3
        ldr             r8,  [r2]
        b               1b
2:
        add             r0,  r12, lr
        pop             {r4-r9, pc}
endfunc

function ff_pix_abs16_x2_armv6, export=1
        ldr             r12, [sp]
        push            {r4-r11, lr}
        mov             r0,  #0
        mov             lr,  #1
        orr             lr,  lr,  lr,  lsl #8
        orr             lr,  lr,  lr,  lsl #16
1:
        ldr             r8,  [r2]
        ldr             r9,  [r2, #4]
        lsr             r10, r8,  #8
        ldr             r4,  [r1]
        lsr             r6,  r9,  #8
        orr             r10, r10, r9,  lsl #24
        ldr             r5,  [r2, #8]
        eor             r11, r8,  r10
        uhadd8          r7,  r8,  r10
        orr             r6,  r6,  r5,  lsl #24
        and             r11, r11, lr
        uadd8           r7,  r7,  r11
        ldr             r8,  [r1, #4]
        usada8          r0,  r4,  r7,  r0
        eor             r7,  r9,  r6
        lsr             r10, r5,  #8
        and             r7,  r7,  lr
        uhadd8          r4,  r9,  r6
        ldr             r6,  [r2, #12]
        uadd8           r4,  r4,  r7
        pld             [r1, r3]
        orr             r10, r10, r6,  lsl #24
        usada8          r0,  r8,  r4,  r0
        ldr             r4,  [r1, #8]
        eor             r11, r5,  r10
        ldrb            r7,  [r2, #16]
        and             r11, r11, lr
        uhadd8          r8,  r5,  r10
        ldr             r5,  [r1, #12]
        uadd8           r8,  r8,  r11
        pld             [r2, r3]
        lsr             r10, r6,  #8
        usada8          r0,  r4,  r8,  r0
        orr             r10, r10, r7,  lsl #24
        subs            r12,  r12,  #1
        eor             r11, r6,  r10
        add             r1,  r1,  r3
        uhadd8          r9,  r6,  r10
        and             r11, r11, lr
        uadd8           r9,  r9,  r11
        add             r2,  r2,  r3
        usada8          r0,  r5,  r9,  r0
        bgt             1b

        pop             {r4-r11, pc}
endfunc

.macro  usad_y2         p0,  p1,  p2,  p3,  n0,  n1,  n2,  n3
        ldr             \n0, [r2]
        eor             \n1, \p0, \n0
        uhadd8          \p0, \p0, \n0
        and             \n1, \n1, lr
        ldr             \n2, [r1]
        uadd8           \p0, \p0, \n1
        ldr             \n1, [r2, #4]
        usada8          r0,  \p0, \n2, r0
        pld             [r1,  r3]
        eor             \n3, \p1, \n1
        uhadd8          \p1, \p1, \n1
        and             \n3, \n3, lr
        ldr             \p0, [r1, #4]
        uadd8           \p1, \p1, \n3
        ldr             \n2, [r2, #8]
        usada8          r0,  \p1, \p0, r0
        pld             [r2,  r3]
        eor             \p0, \p2, \n2
        uhadd8          \p2, \p2, \n2
        and             \p0, \p0, lr
        ldr             \p1, [r1, #8]
        uadd8           \p2, \p2, \p0
        ldr             \n3, [r2, #12]
        usada8          r0,  \p2, \p1, r0
        eor             \p1, \p3, \n3
        uhadd8          \p3, \p3, \n3
        and             \p1, \p1, lr
        ldr             \p0,  [r1, #12]
        uadd8           \p3, \p3, \p1
        add             r1,  r1,  r3
        usada8          r0,  \p3, \p0,  r0
        add             r2,  r2,  r3
.endm

function ff_pix_abs16_y2_armv6, export=1
        pld             [r1]
        pld             [r2]
        ldr             r12, [sp]
        push            {r4-r11, lr}
        mov             r0,  #0
        mov             lr,  #1
        orr             lr,  lr,  lr,  lsl #8
        orr             lr,  lr,  lr,  lsl #16
        ldr             r4,  [r2]
        ldr             r5,  [r2, #4]
        ldr             r6,  [r2, #8]
        ldr             r7,  [r2, #12]
        add             r2,  r2,  r3
1:
        usad_y2         r4,  r5,  r6,  r7,  r8,  r9,  r10, r11
        subs            r12, r12, #2
        usad_y2         r8,  r9,  r10, r11, r4,  r5,  r6,  r7
        bgt             1b

        pop             {r4-r11, pc}
endfunc

function ff_pix_abs8_armv6, export=1
        pld             [r2, r3]
        ldr             r12, [sp]
        push            {r4-r9, lr}
        mov             r0,  #0
        mov             lr,  #0
        ldrd_post       r4,  r5,  r1,  r3
1:
        subs            r12, r12, #2
        ldr             r7,  [r2, #4]
        ldr_post        r6,  r2,  r3
        ldrd_post       r8,  r9,  r1,  r3
        usada8          r0,  r4,  r6,  r0
        pld             [r2, r3]
        usada8          lr,  r5,  r7,  lr
        ldr             r7,  [r2, #4]
        ldr_post        r6,  r2,  r3
        beq             2f
        ldrd_post       r4,  r5,  r1,  r3
        usada8          r0,  r8,  r6,  r0
        pld             [r2, r3]
        usada8          lr,  r9,  r7,  lr
        b               1b
2:
        usada8          r0,  r8,  r6,  r0
        usada8          lr,  r9,  r7,  lr
        add             r0,  r0,  lr
        pop             {r4-r9, pc}
endfunc

function ff_sse16_armv6, export=1
        ldr             r12, [sp]
        push            {r4-r9, lr}
        mov             r0,  #0
1:
        ldrd            r4,  r5,  [r1]
        ldr             r8,  [r2]
        uxtb16          lr,  r4
        uxtb16          r4,  r4,  ror #8
        uxtb16          r9,  r8
        uxtb16          r8,  r8,  ror #8
        ldr             r7,  [r2, #4]
        usub16          lr,  lr,  r9
        usub16          r4,  r4,  r8
        smlad           r0,  lr,  lr,  r0
        uxtb16          r6,  r5
        uxtb16          lr,  r5,  ror #8
        uxtb16          r8,  r7
        uxtb16          r9,  r7,  ror #8
        smlad           r0,  r4,  r4,  r0
        ldrd            r4,  r5,  [r1, #8]
        usub16          r6,  r6,  r8
        usub16          r8,  lr,  r9
        ldr             r7,  [r2, #8]
        smlad           r0,  r6,  r6,  r0
        uxtb16          lr,  r4
        uxtb16          r4,  r4,  ror #8
        uxtb16          r9,  r7
        uxtb16          r7,  r7, ror #8
        smlad           r0,  r8,  r8,  r0
        ldr             r8,  [r2, #12]
        usub16          lr,  lr,  r9
        usub16          r4,  r4,  r7
        smlad           r0,  lr,  lr,  r0
        uxtb16          r6,  r5
        uxtb16          r5,  r5,  ror #8
        uxtb16          r9,  r8
        uxtb16          r8,  r8,  ror #8
        smlad           r0,  r4,  r4,  r0
        usub16          r6,  r6,  r9
        usub16          r5,  r5,  r8
        smlad           r0,  r6,  r6,  r0
        add             r1,  r1,  r3
        add             r2,  r2,  r3
        subs            r12, r12, #1
        smlad           r0,  r5,  r5,  r0
        bgt             1b

        pop             {r4-r9, pc}
endfunc

function ff_pix_norm1_armv6, export=1
        push            {r4-r6, lr}
        mov             r12, #16
        mov             lr,  #0
1:
        ldm             r0,  {r2-r5}
        uxtb16          r6,  r2
        uxtb16          r2,  r2,  ror #8
        smlad           lr,  r6,  r6,  lr
        uxtb16          r6,  r3
        smlad           lr,  r2,  r2,  lr
        uxtb16          r3,  r3,  ror #8
        smlad           lr,  r6,  r6,  lr
        uxtb16          r6,  r4
        smlad           lr,  r3,  r3,  lr
        uxtb16          r4,  r4,  ror #8
        smlad           lr,  r6,  r6,  lr
        uxtb16          r6,  r5
        smlad           lr,  r4,  r4,  lr
        uxtb16          r5,  r5,  ror #8
        smlad           lr,  r6,  r6,  lr
        subs            r12, r12, #1
        add             r0,  r0,  r1
        smlad           lr,  r5,  r5,  lr
        bgt             1b

        mov             r0,  lr
        pop             {r4-r6, pc}
endfunc

function ff_pix_sum_armv6, export=1
        push            {r4-r7, lr}
        mov             r12, #16
        mov             r2,  #0
        mov             r3,  #0
        mov             lr,  #0
        ldr             r4,  [r0]
1:
        subs            r12, r12, #1
        ldr             r5,  [r0, #4]
        usada8          r2,  r4,  lr,  r2
        ldr             r6,  [r0, #8]
        usada8          r3,  r5,  lr,  r3
        ldr             r7,  [r0, #12]
        usada8          r2,  r6,  lr,  r2
        beq             2f
        ldr_pre         r4,  r0,  r1
        usada8          r3,  r7,  lr,  r3
        bgt             1b
2:
        usada8          r3,  r7,  lr,  r3
        add             r0,  r2,  r3
        pop             {r4-r7, pc}
endfunc