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gmc_altivec.c
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1 /*
2  * GMC (Global Motion Compensation)
3  * AltiVec-enabled
4  * Copyright (c) 2003 Romain Dolbeau <romain@dolbeau.org>
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include "libavutil/mem.h"
26 #include "dsputil_altivec.h"
27 
28 /*
29  altivec-enhanced gmc1. ATM this code assume stride is a multiple of 8,
30  to preserve proper dst alignment.
31 */
32 void ff_gmc1_altivec(uint8_t *dst /* align 8 */, uint8_t *src /* align1 */, int stride, int h, int x16, int y16, int rounder)
33 {
34  const DECLARE_ALIGNED(16, unsigned short, rounder_a) = rounder;
35  const DECLARE_ALIGNED(16, unsigned short, ABCD)[8] =
36  {
37  (16-x16)*(16-y16), /* A */
38  ( x16)*(16-y16), /* B */
39  (16-x16)*( y16), /* C */
40  ( x16)*( y16), /* D */
41  0, 0, 0, 0 /* padding */
42  };
43  register const vector unsigned char vczero = (const vector unsigned char)vec_splat_u8(0);
44  register const vector unsigned short vcsr8 = (const vector unsigned short)vec_splat_u16(8);
45  register vector unsigned char dstv, dstv2, src_0, src_1, srcvA, srcvB, srcvC, srcvD;
46  register vector unsigned short Av, Bv, Cv, Dv, rounderV, tempA, tempB, tempC, tempD;
47  int i;
48  unsigned long dst_odd = (unsigned long)dst & 0x0000000F;
49  unsigned long src_really_odd = (unsigned long)src & 0x0000000F;
50 
51  tempA = vec_ld(0, (const unsigned short*)ABCD);
52  Av = vec_splat(tempA, 0);
53  Bv = vec_splat(tempA, 1);
54  Cv = vec_splat(tempA, 2);
55  Dv = vec_splat(tempA, 3);
56 
57  rounderV = vec_splat((vec_u16)vec_lde(0, &rounder_a), 0);
58 
59  // we'll be able to pick-up our 9 char elements
60  // at src from those 32 bytes
61  // we load the first batch here, as inside the loop
62  // we can re-use 'src+stride' from one iteration
63  // as the 'src' of the next.
64  src_0 = vec_ld(0, src);
65  src_1 = vec_ld(16, src);
66  srcvA = vec_perm(src_0, src_1, vec_lvsl(0, src));
67 
68  if (src_really_odd != 0x0000000F) {
69  // if src & 0xF == 0xF, then (src+1) is properly aligned
70  // on the second vector.
71  srcvB = vec_perm(src_0, src_1, vec_lvsl(1, src));
72  } else {
73  srcvB = src_1;
74  }
75  srcvA = vec_mergeh(vczero, srcvA);
76  srcvB = vec_mergeh(vczero, srcvB);
77 
78  for(i=0; i<h; i++) {
79  dst_odd = (unsigned long)dst & 0x0000000F;
80  src_really_odd = (((unsigned long)src) + stride) & 0x0000000F;
81 
82  dstv = vec_ld(0, dst);
83 
84  // we we'll be able to pick-up our 9 char elements
85  // at src + stride from those 32 bytes
86  // then reuse the resulting 2 vectors srvcC and srcvD
87  // as the next srcvA and srcvB
88  src_0 = vec_ld(stride + 0, src);
89  src_1 = vec_ld(stride + 16, src);
90  srcvC = vec_perm(src_0, src_1, vec_lvsl(stride + 0, src));
91 
92  if (src_really_odd != 0x0000000F) {
93  // if src & 0xF == 0xF, then (src+1) is properly aligned
94  // on the second vector.
95  srcvD = vec_perm(src_0, src_1, vec_lvsl(stride + 1, src));
96  } else {
97  srcvD = src_1;
98  }
99 
100  srcvC = vec_mergeh(vczero, srcvC);
101  srcvD = vec_mergeh(vczero, srcvD);
102 
103 
104  // OK, now we (finally) do the math :-)
105  // those four instructions replaces 32 int muls & 32 int adds.
106  // isn't AltiVec nice ?
107  tempA = vec_mladd((vector unsigned short)srcvA, Av, rounderV);
108  tempB = vec_mladd((vector unsigned short)srcvB, Bv, tempA);
109  tempC = vec_mladd((vector unsigned short)srcvC, Cv, tempB);
110  tempD = vec_mladd((vector unsigned short)srcvD, Dv, tempC);
111 
112  srcvA = srcvC;
113  srcvB = srcvD;
114 
115  tempD = vec_sr(tempD, vcsr8);
116 
117  dstv2 = vec_pack(tempD, (vector unsigned short)vczero);
118 
119  if (dst_odd) {
120  dstv2 = vec_perm(dstv, dstv2, vcprm(0,1,s0,s1));
121  } else {
122  dstv2 = vec_perm(dstv, dstv2, vcprm(s0,s1,2,3));
123  }
124 
125  vec_st(dstv2, 0, dst);
126 
127  dst += stride;
128  src += stride;
129  }
130 }