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annotate peck_fft.c @ 6:fee54f1878f7

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kill FIXED_POINT stuff, simplify
author Peter Meerwald <p.meerwald@bct-electronic.com>
date Fri, 16 Sep 2011 15:18:28 +0200
parents c7237a7544eb
children 707be088ccc3
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Peter Meerwald <p.meerwald@bct-electronic.com>
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1 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
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2 Copyright (c) 2003-2010, Mark Borgerding
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3
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4 All rights reserved.
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5
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6 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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7
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8 * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
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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.
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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.
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11
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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.
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13 */
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14
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15
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16 #include "_peck_fft_guts.h"
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17 /* The guts header contains all the multiplication and addition macros that are defined for
1
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18 * fixed or floating point complex numbers. It also delares the kf_ internal functions.
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19 */
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20
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21 static void kf_bfly2(
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22 peck_fft_cpx *Fout,
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23 const size_t fstride,
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24 const peck_fft_cfg st,
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25 int m) {
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26
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27 //printf("kf_bfly2\n");
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28
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29 peck_fft_cpx *Fout2;
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30 peck_fft_cpx *tw1 = st->twiddles;
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31 peck_fft_cpx t;
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32 Fout2 = Fout + m;
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33 do {
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34 C_MUL(t, *Fout2, *tw1);
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35 tw1 += fstride;
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36 C_SUB(*Fout2, *Fout, t);
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37 C_ADDTO(*Fout, t);
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38 ++Fout2;
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39 ++Fout;
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40 } while (--m);
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41 }
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42
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43 static void kf_bfly4(
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44 peck_fft_cpx * Fout,
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45 const size_t fstride,
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46 const peck_fft_cfg st,
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47 const size_t m) {
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48
0
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49 peck_fft_cpx *tw1,*tw2,*tw3;
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50 peck_fft_cpx scratch[6];
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51 size_t k=m;
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52 const size_t m2=2*m;
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53 const size_t m3=3*m;
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54
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55 //printf("kf_bfly4\n");
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56
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57 tw3 = tw2 = tw1 = st->twiddles;
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58
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59 do {
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60 C_MUL(scratch[0], Fout[m], *tw1);
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61 C_MUL(scratch[1], Fout[m2], *tw2);
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62 C_MUL(scratch[2], Fout[m3], *tw3);
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63
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64 C_SUB(scratch[5], *Fout, scratch[1]);
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65 C_ADDTO(*Fout, scratch[1]);
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66 C_ADD(scratch[3], scratch[0], scratch[2]);
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67 C_SUB(scratch[4], scratch[0], scratch[2]);
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68 C_SUB(Fout[m2], *Fout, scratch[3]);
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69 tw1 += fstride;
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70 tw2 += fstride*2;
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71 tw3 += fstride*3;
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72 C_ADDTO(*Fout, scratch[3]);
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73
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74 if (st->inverse) {
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75 Fout[m].r = scratch[5].r - scratch[4].i;
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76 Fout[m].i = scratch[5].i + scratch[4].r;
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77 Fout[m3].r = scratch[5].r + scratch[4].i;
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78 Fout[m3].i = scratch[5].i - scratch[4].r;
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79 } else {
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80 Fout[m].r = scratch[5].r + scratch[4].i;
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81 Fout[m].i = scratch[5].i - scratch[4].r;
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82 Fout[m3].r = scratch[5].r - scratch[4].i;
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83 Fout[m3].i = scratch[5].i + scratch[4].r;
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84 }
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85 ++Fout;
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86 } while (--k);
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87 }
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88
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89 static void kf_bfly3(
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90 peck_fft_cpx * Fout,
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91 const size_t fstride,
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92 const peck_fft_cfg st,
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93 size_t m) {
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94
0
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95 size_t k=m;
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96 const size_t m2 = 2*m;
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97 peck_fft_cpx *tw1, *tw2;
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98 peck_fft_cpx scratch[5];
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99 peck_fft_cpx epi3;
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100 epi3 = st->twiddles[fstride*m];
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101
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102 printf("kf_bfly3\n");
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103
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104 tw1 = tw2 = st->twiddles;
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105
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106 do {
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107 C_MUL(scratch[1],Fout[m] , *tw1);
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108 C_MUL(scratch[2],Fout[m2] , *tw2);
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109
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110 C_ADD(scratch[3],scratch[1],scratch[2]);
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111 C_SUB(scratch[0],scratch[1],scratch[2]);
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112 tw1 += fstride;
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113 tw2 += fstride*2;
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114
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115 Fout[m].r = Fout->r - HALF_OF(scratch[3].r);
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116 Fout[m].i = Fout->i - HALF_OF(scratch[3].i);
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117
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118 C_MULBYSCALAR( scratch[0] , epi3.i );
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119
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120 C_ADDTO(*Fout,scratch[3]);
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121
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122 Fout[m2].r = Fout[m].r + scratch[0].i;
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123 Fout[m2].i = Fout[m].i - scratch[0].r;
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124
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125 Fout[m].r -= scratch[0].i;
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126 Fout[m].i += scratch[0].r;
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127
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128 ++Fout;
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129 } while (--k);
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130 }
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131
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132 static void kf_bfly5(
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133 peck_fft_cpx * Fout,
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134 const size_t fstride,
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135 const peck_fft_cfg st,
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136 int m
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137 ) {
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138 peck_fft_cpx *Fout0,*Fout1,*Fout2,*Fout3,*Fout4;
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139 int u;
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140 peck_fft_cpx scratch[13];
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141 peck_fft_cpx * twiddles = st->twiddles;
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142 peck_fft_cpx *tw;
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143 peck_fft_cpx ya,yb;
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144 ya = twiddles[fstride*m];
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145 yb = twiddles[fstride*2*m];
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146
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147 printf("kf_bfly5\n");
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148
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149 Fout0 = Fout;
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150 Fout1 = Fout0 + m;
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151 Fout2 = Fout0 + 2*m;
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152 Fout3 = Fout0 + 3*m;
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153 Fout4 = Fout0 + 4*m;
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154
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155 tw=st->twiddles;
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156 for (u = 0; u < m; ++u) {
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157 scratch[0] = *Fout0;
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158
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159 C_MUL(scratch[1], *Fout1, tw[u*fstride]);
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160 C_MUL(scratch[2], *Fout2, tw[2*u*fstride]);
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161 C_MUL(scratch[3], *Fout3, tw[3*u*fstride]);
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162 C_MUL(scratch[4], *Fout4, tw[4*u*fstride]);
0
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163
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164 C_ADD(scratch[7], scratch[1], scratch[4]);
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165 C_SUB(scratch[10], scratch[1], scratch[4]);
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166 C_ADD(scratch[8], scratch[2], scratch[3]);
fee54f1878f7 kill FIXED_POINT stuff, simplify
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 5
diff changeset
167 C_SUB(scratch[9], scratch[2], scratch[3]);
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
168
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
169 Fout0->r += scratch[7].r + scratch[8].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
170 Fout0->i += scratch[7].i + scratch[8].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
171
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
172 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
173 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
174
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
175 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
176 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
177
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
178 C_SUB(*Fout1,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
179 C_ADD(*Fout4,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
180
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
181 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
182 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
183 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
184 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
185
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
186 C_ADD(*Fout2,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
187 C_SUB(*Fout3,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
188
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
189 ++Fout0;++Fout1;++Fout2;++Fout3;++Fout4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
190 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
191 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
192
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
193 /* perform the butterfly for one stage of a mixed radix FFT */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
194 static void kf_bfly_generic(
4
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
195 peck_fft_cpx * Fout,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
196 const size_t fstride,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
197 const peck_fft_cfg st,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
198 int m,
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
199 int p) {
2d6c49fcafcb neon2 and neon4 support
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 1
diff changeset
200
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
201 int u,k,q1,q;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
202 peck_fft_cpx * twiddles = st->twiddles;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
203 peck_fft_cpx t;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
204 int Norig = st->nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
205
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
206 printf("kf_bfly_generic\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
207
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
208 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
209
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
210 for ( u=0; u<m; ++u ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
211 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
212 for (q1 = 0; q1 < p; ++q1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
213 scratch[q1] = Fout[k];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
214 k += m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
215 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
216
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
217 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
218 for ( q1=0 ; q1<p ; ++q1 ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
219 int twidx=0;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
220 Fout[ k ] = scratch[0];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
221 for (q=1;q<p;++q ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
222 twidx += fstride * k;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
223 if (twidx>=Norig) twidx-=Norig;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
224 C_MUL(t,scratch[q] , twiddles[twidx] );
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
225 C_ADDTO( Fout[ k ] ,t);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
226 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
227 k += m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
228 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
229 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
230 PECK_FFT_TMP_FREE(scratch);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
231 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
232
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
233 static void kf_work(
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
234 peck_fft_cpx * Fout,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
235 const peck_fft_cpx * f,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
236 const size_t fstride,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
237 int *factors,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
238 const peck_fft_cfg st) {
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
239
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
240 peck_fft_cpx *Fout_beg = Fout;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
241 const int p = *factors++; /* the radix */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
242 const int m = *factors++; /* stage's FFT length / p */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
243 const peck_fft_cpx *Fout_end = Fout + p*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
244
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
245 // printf("kf_work\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
246
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
247 if (m == 1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
248 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
249 *Fout = *f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
250 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
251 } while (++Fout != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
252 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
253 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
254 // recursive call:
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
255 // DFT of size m*p performed by doing
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
256 // p instances of smaller DFTs of size m,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
257 // each one takes a decimated version of the input
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
258 kf_work(Fout, f, fstride*p, factors, st);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
259 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
260 } while ((Fout += m) != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
261 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
262
5
c7237a7544eb cleanup
Peter Meerwald <p.meerwald@bct-electronic.com>
parents: 4
diff changeset
263 Fout = Fout_beg;
0
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
264
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
265 // recombine the p smaller DFTs
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
266 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
267 case 2: kf_bfly2(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
268 case 3: kf_bfly3(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
269 case 4: kf_bfly4(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
270 case 5: kf_bfly5(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
271 default: kf_bfly_generic(Fout, fstride, st, m, p); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
272 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
273 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
274
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
275 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
276 * facbuf is populated by p1, m1, p2, m2, ...
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
277 * where
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
278 * p[i] * m[i] = m[i-1]
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
279 * m0 = n
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
280 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
281 static void kf_factor(int n, int * facbuf) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
282 int p = 4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
283 float floor_sqrt;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
284 floor_sqrt = floorf(sqrtf(n));
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
285
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
286 /* factor out powers of 4, powers of 2, then any remaining primes */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
287 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
288 while (n % p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
289 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
290 case 4: p = 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
291 case 2: p = 3; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
292 default: p += 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
293 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
294 if (p > floor_sqrt)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
295 p = n; /* no more factors, skip to end */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
296 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
297 n /= p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
298 *facbuf++ = p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
299 *facbuf++ = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
300 } while (n > 1);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
301 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
302
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
303 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
304 * User-callable function to allocate all necessary storage space for the fft.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
305 * The return value is a contiguous block of memory, allocated with malloc. As such,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
306 * it can be freed with free(), rather than a peck_fft-specific function.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
307 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
308 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
309 peck_fft_cfg st = NULL;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
310 size_t memneeded = sizeof(struct peck_fft_state)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
311 + sizeof(peck_fft_cpx)*(nfft-1); /* twiddle factors */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
312
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
313 if (lenmem == NULL) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
314 st = ( peck_fft_cfg)PECK_FFT_MALLOC(memneeded);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
315 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
316 if (mem != NULL && *lenmem >= memneeded)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
317 st = (peck_fft_cfg)mem;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
318 *lenmem = memneeded;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
319 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
320
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
321 if (st) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
322 int i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
323 st->nfft=nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
324 st->inverse = inverse_fft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
325
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
326 for (i = 0; i < nfft; ++i) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
327 const float pi = 3.14159265359f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
328 float phase = -2*pi*i / nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
329 if (st->inverse)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
330 phase *= -1;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
331 kf_cexp(st->twiddles+i, phase);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
332 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
333
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
334 kf_factor(nfft, st->factors);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
335 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
336 return st;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
337 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
338
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
339 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
340 kf_work(fout, fin, 1, cfg->factors, cfg);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
341 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
342
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
343 void peck_fft_cleanup(void) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
344 /* nothing needed any more */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
345 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
346
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
347 int peck_fft_next_fast_size(int n) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
348 while (1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
349 int m = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
350 while ((m % 2) == 0) m /= 2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
351 while ((m % 3) == 0) m /= 3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
352 while ((m % 5) == 0) m /= 5;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
353 if (m <= 1)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
354 break; /* n is completely factorable by twos, threes, and fives */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
355 n++;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
356 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
357 return n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
358 }

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