FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/rdft.c
Date: 2023-03-22 23:59:29
Exec Total Coverage
Lines: 38 40 95.0%
Functions: 3 3 100.0%
Branches: 24 32 75.0%
Line Branch Exec Source
1 /*
2 * (I)RDFT transforms
3 * Copyright (c) 2009 Alex Converse <alex dot converse at gmail dot com>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21 #include <stdlib.h>
22 #include <math.h>
23 #include "libavutil/error.h"
24 #include "libavutil/mathematics.h"
25 #include "rdft.h"
26
27 /**
28 * @file
29 * (Inverse) Real Discrete Fourier Transforms.
30 */
31
32 /** Map one real FFT into two parallel real even and odd FFTs. Then interleave
33 * the two real FFTs into one complex FFT. Unmangle the results.
34 * ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM
35 */
36 39298 static void rdft_calc_c(RDFTContext *s, FFTSample *data)
37 {
38 int i, i1, i2;
39 FFTComplex ev, od, odsum;
40 39298 const int n = 1 << s->nbits;
41 39298 const float k1 = 0.5;
42 39298 const float k2 = 0.5 - s->inverse;
43 39298 const FFTSample *tcos = s->tcos;
44 39298 const FFTSample *tsin = s->tsin;
45
46
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 39298 if (!s->inverse) {
47 28070 s->fft.fft_permute(&s->fft, (FFTComplex*)data);
48 28070 s->fft.fft_calc(&s->fft, (FFTComplex*)data);
49 }
50 /* i=0 is a special case because of packing, the DC term is real, so we
51 are going to throw the N/2 term (also real) in with it. */
52 39298 ev.re = data[0];
53 39298 data[0] = ev.re+data[1];
54 39298 data[1] = ev.re-data[1];
55
56 #define RDFT_UNMANGLE(sign0, sign1) \
57 for (i = 1; i < (n>>2); i++) { \
58 i1 = 2*i; \
59 i2 = n-i1; \
60 /* Separate even and odd FFTs */ \
61 ev.re = k1*(data[i1 ]+data[i2 ]); \
62 od.im = k2*(data[i2 ]-data[i1 ]); \
63 ev.im = k1*(data[i1+1]-data[i2+1]); \
64 od.re = k2*(data[i1+1]+data[i2+1]); \
65 /* Apply twiddle factors to the odd FFT and add to the even FFT */ \
66 odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \
67 odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \
68 data[i1 ] = ev.re + odsum.re; \
69 data[i1+1] = ev.im + odsum.im; \
70 data[i2 ] = ev.re - odsum.re; \
71 data[i2+1] = odsum.im - ev.im; \
72 }
73
74
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 39298 if (s->negative_sin) {
75
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 718592 RDFT_UNMANGLE(+,-)
76 } else {
77
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 359296 RDFT_UNMANGLE(-,+)
78 }
79
80 39298 data[2*i+1]=s->sign_convention*data[2*i+1];
81
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 39298 if (s->inverse) {
82 11228 data[0] *= k1;
83 11228 data[1] *= k1;
84 11228 s->fft.fft_permute(&s->fft, (FFTComplex*)data);
85 11228 s->fft.fft_calc(&s->fft, (FFTComplex*)data);
86 }
87 39298 }
88
89 32 av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans)
90 {
91 32 int n = 1 << nbits;
92 int ret;
93
94 32 s->nbits = nbits;
95
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 32 s->inverse = trans == IDFT_C2R || trans == DFT_C2R;
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 32 s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1;
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 32 s->negative_sin = trans == DFT_C2R || trans == DFT_R2C;
98
99
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 32 if (nbits < 4 || nbits > 16)
100 ✗ return AVERROR(EINVAL);
101
102
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 32 if ((ret = ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C)) < 0)
103 ✗ return ret;
104
105 32 ff_init_ff_cos_tabs(nbits);
106 32 s->tcos = ff_cos_tabs[nbits];
107 32 s->tsin = ff_cos_tabs[nbits] + (n >> 2);
108 32 s->rdft_calc = rdft_calc_c;
109
110 #if ARCH_ARM
111 ff_rdft_init_arm(s);
112 #endif
113
114 32 return 0;
115 }
116
117 32 av_cold void ff_rdft_end(RDFTContext *s)
118 {
119 32 ff_fft_end(&s->fft);
120 32 }
121