Mercurial > hg > peckfft

annotate peck_fft.c @ 5:c7237a7544eb

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
cleanup
author Peter Meerwald <p.meerwald@bct-electronic.com>
date Fri, 16 Sep 2011 15:08:29 +0200
parents 2d6c49fcafcb
children fee54f1878f7
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
1 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
2 Copyright (c) 2003-2010, Mark Borgerding
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
3
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
4 All rights reserved.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
5
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
6 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
7
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
8 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
9 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
10 * Neither the author nor the names of any contributors may be used to endorse or promote products derived from this software without specific prior written permission.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
11
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
12 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
13 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
14
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
15
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
16 #include "_peck_fft_guts.h"
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
17 /* The guts header contains all the multiplication and addition macros that are defined for
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
18 * fixed or floating point complex numbers. It also delares the kf_ internal functions.
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
19 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
20
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
21 static void kf_bfly2(
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
22 peck_fft_cpx *Fout,
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
23 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
24 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
25 int m) {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
26
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
27 //printf("kf_bfly2\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
28
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
29 peck_fft_cpx *Fout2;
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
30 peck_fft_cpx *tw1 = st->twiddles;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
31 peck_fft_cpx t;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
32 Fout2 = Fout + m;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
33 do {
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
34 C_FIXDIV(*Fout, 2);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
35 C_FIXDIV(*Fout2, 2);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
36
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
37 C_MUL(t, *Fout2, *tw1);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
38 tw1 += fstride;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
39 C_SUB(*Fout2, *Fout, t);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
40 C_ADDTO(*Fout, t);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
41 ++Fout2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
42 ++Fout;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
43 } while (--m);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
44 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
45
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
46 static void kf_bfly4(
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
47 peck_fft_cpx * Fout,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
48 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
49 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
50 const size_t m) {
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
51
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
52 peck_fft_cpx *tw1,*tw2,*tw3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
53 peck_fft_cpx scratch[6];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
54 size_t k=m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
55 const size_t m2=2*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
56 const size_t m3=3*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
57
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
58 //printf("kf_bfly4\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
59
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
60 tw3 = tw2 = tw1 = st->twiddles;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
61
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
62 do {
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
63 C_FIXDIV(*Fout, 4);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
64 C_FIXDIV(Fout[m], 4);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
65 C_FIXDIV(Fout[m2], 4);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
66 C_FIXDIV(Fout[m3], 4);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
67
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
68 C_MUL(scratch[0], Fout[m], *tw1);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
69 C_MUL(scratch[1], Fout[m2], *tw2);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
70 C_MUL(scratch[2], Fout[m3], *tw3);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
71
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
72 C_SUB(scratch[5], *Fout, scratch[1]);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
73 C_ADDTO(*Fout, scratch[1]);
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
74 C_ADD(scratch[3], scratch[0], scratch[2]);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
75 C_SUB(scratch[4], scratch[0], scratch[2]);
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
76 C_SUB(Fout[m2], *Fout, scratch[3]);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
77 tw1 += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
78 tw2 += fstride*2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
79 tw3 += fstride*3;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
80 C_ADDTO(*Fout, scratch[3]);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
81
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
82 if (st->inverse) {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
83 Fout[m].r = scratch[5].r - scratch[4].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
84 Fout[m].i = scratch[5].i + scratch[4].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
85 Fout[m3].r = scratch[5].r + scratch[4].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
86 Fout[m3].i = scratch[5].i - scratch[4].r;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
87 } else {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
88 Fout[m].r = scratch[5].r + scratch[4].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
89 Fout[m].i = scratch[5].i - scratch[4].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
90 Fout[m3].r = scratch[5].r - scratch[4].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
91 Fout[m3].i = scratch[5].i + scratch[4].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
92 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
93 ++Fout;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
94 } while (--k);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
95 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
96
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
97 static void kf_bfly3(
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
98 peck_fft_cpx * Fout,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
99 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
100 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
101 size_t m) {
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
102
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
103 size_t k=m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
104 const size_t m2 = 2*m;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
105 peck_fft_cpx *tw1, *tw2;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
106 peck_fft_cpx scratch[5];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
107 peck_fft_cpx epi3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
108 epi3 = st->twiddles[fstride*m];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
109
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
110 printf("kf_bfly3\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
111
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
112 tw1 = tw2 = st->twiddles;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
113
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
114 do {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
115 C_FIXDIV(*Fout,3); C_FIXDIV(Fout[m],3); C_FIXDIV(Fout[m2],3);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
116
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
117 C_MUL(scratch[1],Fout[m] , *tw1);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
118 C_MUL(scratch[2],Fout[m2] , *tw2);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
119
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
120 C_ADD(scratch[3],scratch[1],scratch[2]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
121 C_SUB(scratch[0],scratch[1],scratch[2]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
122 tw1 += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
123 tw2 += fstride*2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
124
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
125 Fout[m].r = Fout->r - HALF_OF(scratch[3].r);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
126 Fout[m].i = Fout->i - HALF_OF(scratch[3].i);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
127
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
128 C_MULBYSCALAR( scratch[0] , epi3.i );
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
129
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
130 C_ADDTO(*Fout,scratch[3]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
131
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
132 Fout[m2].r = Fout[m].r + scratch[0].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
133 Fout[m2].i = Fout[m].i - scratch[0].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
134
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
135 Fout[m].r -= scratch[0].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
136 Fout[m].i += scratch[0].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
137
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
138 ++Fout;
1
cfec79393811 cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 0
diff changeset
139 } while (--k);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
140 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
141
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
142 static void kf_bfly5(
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
143 peck_fft_cpx * Fout,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
144 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
145 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
146 int m
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
147 ) {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
148 peck_fft_cpx *Fout0,*Fout1,*Fout2,*Fout3,*Fout4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
149 int u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
150 peck_fft_cpx scratch[13];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
151 peck_fft_cpx * twiddles = st->twiddles;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
152 peck_fft_cpx *tw;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
153 peck_fft_cpx ya,yb;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
154 ya = twiddles[fstride*m];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
155 yb = twiddles[fstride*2*m];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
156
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
157 printf("kf_bfly5\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
158
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
159 Fout0 = Fout;
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
160 Fout1 = Fout0 + m;
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
161 Fout2 = Fout0 + 2*m;
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
162 Fout3 = Fout0 + 3*m;
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
163 Fout4 = Fout0 + 4*m;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
164
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
165 tw=st->twiddles;
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
166 for (u = 0; u < m; ++u) {
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
167 C_FIXDIV( *Fout0,5); C_FIXDIV( *Fout1,5); C_FIXDIV( *Fout2,5); C_FIXDIV( *Fout3,5); C_FIXDIV( *Fout4,5);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
168 scratch[0] = *Fout0;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
169
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
170 C_MUL(scratch[1] ,*Fout1, tw[u*fstride]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
171 C_MUL(scratch[2] ,*Fout2, tw[2*u*fstride]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
172 C_MUL(scratch[3] ,*Fout3, tw[3*u*fstride]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
173 C_MUL(scratch[4] ,*Fout4, tw[4*u*fstride]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
174
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
175 C_ADD( scratch[7],scratch[1],scratch[4]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
176 C_SUB( scratch[10],scratch[1],scratch[4]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
177 C_ADD( scratch[8],scratch[2],scratch[3]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
178 C_SUB( scratch[9],scratch[2],scratch[3]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
179
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
180 Fout0->r += scratch[7].r + scratch[8].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
181 Fout0->i += scratch[7].i + scratch[8].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
182
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
183 scratch[5].r = scratch[0].r + S_MUL(scratch[7].r,ya.r) + S_MUL(scratch[8].r,yb.r);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
184 scratch[5].i = scratch[0].i + S_MUL(scratch[7].i,ya.r) + S_MUL(scratch[8].i,yb.r);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
185
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
186 scratch[6].r = S_MUL(scratch[10].i,ya.i) + S_MUL(scratch[9].i,yb.i);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
187 scratch[6].i = -S_MUL(scratch[10].r,ya.i) - S_MUL(scratch[9].r,yb.i);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
188
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
189 C_SUB(*Fout1,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
190 C_ADD(*Fout4,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
191
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
192 scratch[11].r = scratch[0].r + S_MUL(scratch[7].r,yb.r) + S_MUL(scratch[8].r,ya.r);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
193 scratch[11].i = scratch[0].i + S_MUL(scratch[7].i,yb.r) + S_MUL(scratch[8].i,ya.r);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
194 scratch[12].r = - S_MUL(scratch[10].i,yb.i) + S_MUL(scratch[9].i,ya.i);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
195 scratch[12].i = S_MUL(scratch[10].r,yb.i) - S_MUL(scratch[9].r,ya.i);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
196
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
197 C_ADD(*Fout2,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
198 C_SUB(*Fout3,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
199
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
200 ++Fout0;++Fout1;++Fout2;++Fout3;++Fout4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
201 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
202 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
203
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
204 /* perform the butterfly for one stage of a mixed radix FFT */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
205 static void kf_bfly_generic(
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
206 peck_fft_cpx * Fout,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
207 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
208 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
209 int m,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
210 int p) {
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
211
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
212 int u,k,q1,q;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
213 peck_fft_cpx * twiddles = st->twiddles;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
214 peck_fft_cpx t;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
215 int Norig = st->nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
216
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
217 printf("kf_bfly_generic\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
218
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
219 peck_fft_cpx * scratch = (peck_fft_cpx*)PECK_FFT_TMP_ALLOC(sizeof(peck_fft_cpx)*p);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
220
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
221 for ( u=0; u<m; ++u ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
222 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
223 for (q1 = 0; q1 < p; ++q1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
224 scratch[q1] = Fout[k];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
225 C_FIXDIV(scratch[q1], p);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
226 k += m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
227 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
228
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
229 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
230 for ( q1=0 ; q1<p ; ++q1 ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
231 int twidx=0;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
232 Fout[ k ] = scratch[0];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
233 for (q=1;q<p;++q ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
234 twidx += fstride * k;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
235 if (twidx>=Norig) twidx-=Norig;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
236 C_MUL(t,scratch[q] , twiddles[twidx] );
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
237 C_ADDTO( Fout[ k ] ,t);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
238 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
239 k += m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
240 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
241 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
242 PECK_FFT_TMP_FREE(scratch);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
243 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
244
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
245 static void kf_work(
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
246 peck_fft_cpx * Fout,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
247 const peck_fft_cpx * f,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
248 const size_t fstride,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
249 int *factors,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
250 const peck_fft_cfg st) {
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
251
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
252 peck_fft_cpx *Fout_beg = Fout;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
253 const int p = *factors++; /* the radix */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
254 const int m = *factors++; /* stage's FFT length / p */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
255 const peck_fft_cpx *Fout_end = Fout + p*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
256
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
257 // printf("kf_work\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
258
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
259 if (m == 1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
260 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
261 *Fout = *f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
262 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
263 } while (++Fout != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
264 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
265 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
266 // recursive call:
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
267 // DFT of size m*p performed by doing
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
268 // p instances of smaller DFTs of size m,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
269 // each one takes a decimated version of the input
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
270 kf_work(Fout, f, fstride*p, factors, st);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
271 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
272 } while ((Fout += m) != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
273 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
274
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
275 Fout = Fout_beg;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
276
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
277 // recombine the p smaller DFTs
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
278 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
279 case 2: kf_bfly2(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
280 case 3: kf_bfly3(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
281 case 4: kf_bfly4(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
282 case 5: kf_bfly5(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
283 default: kf_bfly_generic(Fout, fstride, st, m, p); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
284 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
285 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
286
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
287 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
288 * facbuf is populated by p1, m1, p2, m2, ...
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
289 * where
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
290 * p[i] * m[i] = m[i-1]
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
291 * m0 = n
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
292 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
293 static void kf_factor(int n, int * facbuf) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
294 int p = 4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
295 float floor_sqrt;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
296 floor_sqrt = floorf(sqrtf(n));
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
297
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
298 /* factor out powers of 4, powers of 2, then any remaining primes */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
299 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
300 while (n % p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
301 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
302 case 4: p = 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
303 case 2: p = 3; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
304 default: p += 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
305 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
306 if (p > floor_sqrt)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
307 p = n; /* no more factors, skip to end */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
308 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
309 n /= p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
310 *facbuf++ = p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
311 *facbuf++ = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
312 } while (n > 1);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
313 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
314
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
315 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
316 * User-callable function to allocate all necessary storage space for the fft.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
317 * The return value is a contiguous block of memory, allocated with malloc. As such,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
318 * it can be freed with free(), rather than a peck_fft-specific function.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
319 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
320 peck_fft_cfg peck_fft_alloc(int nfft, int inverse_fft, void * mem, size_t * lenmem) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
321 peck_fft_cfg st = NULL;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
322 size_t memneeded = sizeof(struct peck_fft_state)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
323 + sizeof(peck_fft_cpx)*(nfft-1); /* twiddle factors */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
324
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
325 if (lenmem == NULL) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
326 st = ( peck_fft_cfg)PECK_FFT_MALLOC(memneeded);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
327 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
328 if (mem != NULL && *lenmem >= memneeded)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
329 st = (peck_fft_cfg)mem;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
330 *lenmem = memneeded;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
331 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
332
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
333 if (st) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
334 int i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
335 st->nfft=nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
336 st->inverse = inverse_fft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
337
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
338 for (i = 0; i < nfft; ++i) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
339 const float pi = 3.14159265359f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
340 float phase = -2*pi*i / nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
341 if (st->inverse)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
342 phase *= -1;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
343 kf_cexp(st->twiddles+i, phase);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
344 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
345
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
346 kf_factor(nfft, st->factors);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
347 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
348 return st;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
349 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
350
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
351 void peck_fft(peck_fft_cfg cfg, const peck_fft_cpx *fin, peck_fft_cpx *fout) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
352 kf_work(fout, fin, 1, cfg->factors, cfg);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
353 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
354
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
355 void peck_fft_cleanup(void) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
356 /* nothing needed any more */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
357 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
358
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
359 int peck_fft_next_fast_size(int n) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
360 while (1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
361 int m = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
362 while ((m % 2) == 0) m /= 2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
363 while ((m % 3) == 0) m /= 3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
364 while ((m % 5) == 0) m /= 5;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
365 if (m <= 1)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
366 break; /* n is completely factorable by twos, threes, and fives */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
367 n++;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
368 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
369 return n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
370 }

Repositories maintained by Peter Meerwald, pmeerw@pmeerw.net.