FFmpeg
mpegvideodsp.c
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1 /*
2  * GMC (Global Motion Compensation), AltiVec-enabled
3  *
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/cpu.h"
24 #include "libavutil/mem.h"
25 #include "libavutil/ppc/cpu.h"
27 
29 
30 #if HAVE_ALTIVEC
31 /* AltiVec-enhanced gmc1. ATM this code assumes stride is a multiple of 8
32  * to preserve proper dst alignment. */
33 static void gmc1_altivec(uint8_t *dst /* align 8 */, uint8_t *src /* align1 */,
34  int stride, int h, int x16, int y16, int rounder)
35 {
36  int i;
37  const DECLARE_ALIGNED(16, unsigned short, rounder_a) = rounder;
38  const DECLARE_ALIGNED(16, unsigned short, ABCD)[8] = {
39  (16 - x16) * (16 - y16), /* A */
40  (x16) * (16 - y16), /* B */
41  (16 - x16) * (y16), /* C */
42  (x16) * (y16), /* D */
43  0, 0, 0, 0 /* padding */
44  };
45  register const vector unsigned char vczero =
46  (const vector unsigned char) vec_splat_u8(0);
47  register const vector unsigned short vcsr8 =
48  (const vector unsigned short) vec_splat_u16(8);
49  register vector unsigned char dstv, dstv2, srcvB, srcvC, srcvD;
50  register vector unsigned short tempB, tempC, tempD;
51  unsigned long dst_odd = (unsigned long) dst & 0x0000000F;
52  unsigned long src_really_odd = (unsigned long) src & 0x0000000F;
53  register vector unsigned short tempA =
54  vec_ld(0, (const unsigned short *) ABCD);
55  register vector unsigned short Av = vec_splat(tempA, 0);
56  register vector unsigned short Bv = vec_splat(tempA, 1);
57  register vector unsigned short Cv = vec_splat(tempA, 2);
58  register vector unsigned short Dv = vec_splat(tempA, 3);
59  register vector unsigned short rounderV =
60  vec_splat((vec_u16) vec_lde(0, &rounder_a), 0);
61 
62  /* we'll be able to pick-up our 9 char elements at src from those
63  * 32 bytes we load the first batch here, as inside the loop we can
64  * reuse 'src + stride' from one iteration as the 'src' of the next. */
65  register vector unsigned char src_0 = vec_ld(0, src);
66  register vector unsigned char src_1 = vec_ld(16, src);
67  register vector unsigned char srcvA = vec_perm(src_0, src_1,
68  vec_lvsl(0, src));
69 
70  if (src_really_odd != 0x0000000F)
71  /* If (src & 0xF) == 0xF, then (src + 1) is properly aligned
72  * on the second vector. */
73  srcvB = vec_perm(src_0, src_1, vec_lvsl(1, src));
74  else
75  srcvB = src_1;
76  srcvA = vec_mergeh(vczero, srcvA);
77  srcvB = vec_mergeh(vczero, srcvB);
78 
79  for (i = 0; i < h; i++) {
80  dst_odd = (unsigned long) dst & 0x0000000F;
81  src_really_odd = (((unsigned long) src) + stride) & 0x0000000F;
82 
83  dstv = vec_ld(0, dst);
84 
85  /* We'll be able to pick-up our 9 char elements at src + stride from
86  * those 32 bytes 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  srcvC = vec_mergeh(vczero, srcvC);
100  srcvD = vec_mergeh(vczero, srcvD);
101 
102  /* OK, now we (finally) do the math :-)
103  * Those four instructions replace 32 int muls & 32 int adds.
104  * Isn't AltiVec nice? */
105  tempA = vec_mladd((vector unsigned short) srcvA, Av, rounderV);
106  tempB = vec_mladd((vector unsigned short) srcvB, Bv, tempA);
107  tempC = vec_mladd((vector unsigned short) srcvC, Cv, tempB);
108  tempD = vec_mladd((vector unsigned short) srcvD, Dv, tempC);
109 
110  srcvA = srcvC;
111  srcvB = srcvD;
112 
113  tempD = vec_sr(tempD, vcsr8);
114 
115  dstv2 = vec_pack(tempD, (vector unsigned short) vczero);
116 
117  if (dst_odd)
118  dstv2 = vec_perm(dstv, dstv2, vcprm(0, 1, s0, s1));
119  else
120  dstv2 = vec_perm(dstv, dstv2, vcprm(s0, s1, 2, 3));
121 
122  vec_st(dstv2, 0, dst);
123 
124  dst += stride;
125  src += stride;
126  }
127 }
128 #endif /* HAVE_ALTIVEC */
129 
131 {
132 #if HAVE_ALTIVEC
134  return;
135 
136  c->gmc1 = gmc1_altivec;
137 #endif /* HAVE_ALTIVEC */
138 }
void(* gmc1)(uint8_t *dst, uint8_t *src, int srcStride, int h, int x16, int y16, int rounder)
translational global motion compensation.
Definition: mpegvideodsp.h:32
Memory handling functions.
#define src
Definition: vp8dsp.c:254
uint8_t
#define av_cold
Definition: attributes.h:82
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
#define DECLARE_ALIGNED(n, t, v)
Declare a variable that is aligned in memory.
Definition: mem.h:112
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define PPC_ALTIVEC(flags)
Definition: cpu.h:25
#define s0
Definition: regdef.h:37
#define s1
Definition: regdef.h:38
int av_get_cpu_flags(void)
Return the flags which specify extensions supported by the CPU.
Definition: cpu.c:93
Contains misc utility macros and inline functions.
GLint GLenum GLboolean GLsizei stride
Definition: opengl_enc.c:104
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default minimum maximum flags name is the option keep it simple and lowercase description are short
#define vec_u16
Definition: util_altivec.h:36
av_cold void ff_mpegvideodsp_init_ppc(MpegVideoDSPContext *c)
Definition: mpegvideodsp.c:130
#define stride