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fft_altivec.c
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1 /*
2  * FFT/IFFT transforms
3  * AltiVec-enabled
4  * Copyright (c) 2009 Loren Merritt
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 "config.h"
24 #include "libavutil/cpu.h"
25 #include "libavutil/ppc/cpu.h"
28 #include "libavcodec/fft.h"
29 
30 /**
31  * Do a complex FFT with the parameters defined in ff_fft_init().
32  * The input data must be permuted before with s->revtab table.
33  * No 1.0 / sqrt(n) normalization is done.
34  * AltiVec-enabled:
35  * This code assumes that the 'z' pointer is 16 bytes-aligned.
36  * It also assumes all FFTComplex are 8 bytes-aligned pairs of floats.
37  */
38 
39 #if HAVE_VSX
40 #include "fft_vsx.h"
41 #else
44 #endif
45 
46 #if HAVE_GNU_AS && HAVE_ALTIVEC
47 static void imdct_half_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
48 {
49  int j, k;
50  int n = 1 << s->mdct_bits;
51  int n4 = n >> 2;
52  int n8 = n >> 3;
53  int n32 = n >> 5;
54  const uint16_t *revtabj = s->revtab;
55  const uint16_t *revtabk = s->revtab+n4;
56  const vec_f *tcos = (const vec_f*)(s->tcos+n8);
57  const vec_f *tsin = (const vec_f*)(s->tsin+n8);
58  const vec_f *pin = (const vec_f*)(input+n4);
59  vec_f *pout = (vec_f*)(output+n4);
60 
61  /* pre rotation */
62  k = n32-1;
63  do {
64  vec_f cos,sin,cos0,sin0,cos1,sin1,re,im,r0,i0,r1,i1,a,b,c,d;
65 #define CMULA(p,o0,o1,o2,o3)\
66  a = pin[ k*2+p]; /* { z[k].re, z[k].im, z[k+1].re, z[k+1].im } */\
67  b = pin[-k*2-p-1]; /* { z[-k-2].re, z[-k-2].im, z[-k-1].re, z[-k-1].im } */\
68  re = vec_perm(a, b, vcprm(0,2,s0,s2)); /* { z[k].re, z[k+1].re, z[-k-2].re, z[-k-1].re } */\
69  im = vec_perm(a, b, vcprm(s3,s1,3,1)); /* { z[-k-1].im, z[-k-2].im, z[k+1].im, z[k].im } */\
70  cos = vec_perm(cos0, cos1, vcprm(o0,o1,s##o2,s##o3)); /* { cos[k], cos[k+1], cos[-k-2], cos[-k-1] } */\
71  sin = vec_perm(sin0, sin1, vcprm(o0,o1,s##o2,s##o3));\
72  r##p = im*cos - re*sin;\
73  i##p = re*cos + im*sin;
74 #define STORE2(v,dst)\
75  j = dst;\
76  vec_ste(v, 0, output+j*2);\
77  vec_ste(v, 4, output+j*2);
78 #define STORE8(p)\
79  a = vec_perm(r##p, i##p, vcprm(0,s0,0,s0));\
80  b = vec_perm(r##p, i##p, vcprm(1,s1,1,s1));\
81  c = vec_perm(r##p, i##p, vcprm(2,s2,2,s2));\
82  d = vec_perm(r##p, i##p, vcprm(3,s3,3,s3));\
83  STORE2(a, revtabk[ p*2-4]);\
84  STORE2(b, revtabk[ p*2-3]);\
85  STORE2(c, revtabj[-p*2+2]);\
86  STORE2(d, revtabj[-p*2+3]);
87 
88  cos0 = tcos[k];
89  sin0 = tsin[k];
90  cos1 = tcos[-k-1];
91  sin1 = tsin[-k-1];
92  CMULA(0, 0,1,2,3);
93  CMULA(1, 2,3,0,1);
94  STORE8(0);
95  STORE8(1);
96  revtabj += 4;
97  revtabk -= 4;
98  k--;
99  } while(k >= 0);
100 
101 #if HAVE_VSX
102  ff_fft_calc_vsx(s, (FFTComplex*)output);
103 #else
104  ff_fft_calc_altivec(s, (FFTComplex*)output);
105 #endif
106 
107  /* post rotation + reordering */
108  j = -n32;
109  k = n32-1;
110  do {
111  vec_f cos,sin,re,im,a,b,c,d;
112 #define CMULB(d0,d1,o)\
113  re = pout[o*2];\
114  im = pout[o*2+1];\
115  cos = tcos[o];\
116  sin = tsin[o];\
117  d0 = im*sin - re*cos;\
118  d1 = re*sin + im*cos;
119 
120  CMULB(a,b,j);
121  CMULB(c,d,k);
122  pout[2*j] = vec_perm(a, d, vcprm(0,s3,1,s2));
123  pout[2*j+1] = vec_perm(a, d, vcprm(2,s1,3,s0));
124  pout[2*k] = vec_perm(c, b, vcprm(0,s3,1,s2));
125  pout[2*k+1] = vec_perm(c, b, vcprm(2,s1,3,s0));
126  j++;
127  k--;
128  } while(k >= 0);
129 }
130 
131 static void imdct_calc_altivec(FFTContext *s, FFTSample *output, const FFTSample *input)
132 {
133  int k;
134  int n = 1 << s->mdct_bits;
135  int n4 = n >> 2;
136  int n16 = n >> 4;
137  vec_u32 sign = {1U<<31,1U<<31,1U<<31,1U<<31};
138  vec_u32 *p0 = (vec_u32*)(output+n4);
139  vec_u32 *p1 = (vec_u32*)(output+n4*3);
140 
141  imdct_half_altivec(s, output + n4, input);
142 
143  for (k = 0; k < n16; k++) {
144  vec_u32 a = p0[k] ^ sign;
145  vec_u32 b = p1[-k-1];
146  p0[-k-1] = vec_perm(a, a, vcprm(3,2,1,0));
147  p1[k] = vec_perm(b, b, vcprm(3,2,1,0));
148  }
149 }
150 #endif /* HAVE_GNU_AS && HAVE_ALTIVEC */
151 
153 {
154 #if HAVE_GNU_AS && HAVE_ALTIVEC
156  return;
157 
158 #if HAVE_VSX
159  s->fft_calc = ff_fft_calc_interleave_vsx;
160 #else
162 #endif
163  if (s->mdct_bits >= 5) {
164  s->imdct_calc = imdct_calc_altivec;
165  s->imdct_half = imdct_half_altivec;
166  }
167 #endif /* HAVE_GNU_AS && HAVE_ALTIVEC */
168 }