Mercurial > hg > peckfft

annotate peck_fft.c @ 1:cfec79393811

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cleanup
author Peter Meerwald <p.meerwald@bct-electronic.com>
date Fri, 16 Sep 2011 12:57:27 +0200
parents 723f588b82ac
children 2d6c49fcafcb
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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
Peter Meerwald <p.meerwald@bct-electronic.com>
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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
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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_FIXDIV(*Fout, 2);
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35 C_FIXDIV(*Fout2, 2);
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36
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37 C_MUL(t, *Fout2, *tw1);
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38 tw1 += fstride;
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39 C_SUB(*Fout2, *Fout, t);
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40 C_ADDTO(*Fout, t);
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41 ++Fout2;
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42 ++Fout;
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43 } while (--m);
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44 }
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45
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46 static void kf_bfly4(
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47 peck_fft_cpx * Fout,
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48 const size_t fstride,
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49 const peck_fft_cfg st,
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50 const size_t m) {
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51 peck_fft_cpx *tw1,*tw2,*tw3;
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52 peck_fft_cpx scratch[6];
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53 size_t k=m;
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54 const size_t m2=2*m;
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55 const size_t m3=3*m;
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56
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57 //printf("kf_bfly4\n");
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58
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59 tw3 = tw2 = tw1 = st->twiddles;
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60
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61 do {
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62 C_FIXDIV(*Fout, 4);
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63 C_FIXDIV(Fout[m], 4);
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64 C_FIXDIV(Fout[m2], 4);
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65 C_FIXDIV(Fout[m3], 4);
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66
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67 C_MUL(scratch[0], Fout[m], *tw1);
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68 C_MUL(scratch[1], Fout[m2], *tw2);
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69 C_MUL(scratch[2], Fout[m3], *tw3);
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70
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71 C_SUB(scratch[5], *Fout, scratch[1]);
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72 C_ADDTO(*Fout, scratch[1]);
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73 C_ADD(scratch[3], scratch[0], scratch[2]);
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74 C_SUB(scratch[4], scratch[0], scratch[2]);
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75 C_SUB(Fout[m2], *Fout, scratch[3]);
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76 tw1 += fstride;
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77 tw2 += fstride*2;
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78 tw3 += fstride*3;
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79 C_ADDTO(*Fout, scratch[3]);
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80
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81 if (st->inverse) {
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82 Fout[m].r = scratch[5].r - scratch[4].i;
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83 Fout[m].i = scratch[5].i + scratch[4].r;
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84 Fout[m3].r = scratch[5].r + scratch[4].i;
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85 Fout[m3].i = scratch[5].i - scratch[4].r;
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86 } else {
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87 Fout[m].r = scratch[5].r + scratch[4].i;
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88 Fout[m].i = scratch[5].i - scratch[4].r;
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89 Fout[m3].r = scratch[5].r - scratch[4].i;
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90 Fout[m3].i = scratch[5].i + scratch[4].r;
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91 }
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92 ++Fout;
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93 } while (--k);
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94 }
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95
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96 static void kf_bfly3(
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97 peck_fft_cpx * Fout,
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98 const size_t fstride,
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99 const peck_fft_cfg st,
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100 size_t m) {
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101 size_t k=m;
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102 const size_t m2 = 2*m;
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103 peck_fft_cpx *tw1, *tw2;
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104 peck_fft_cpx scratch[5];
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105 peck_fft_cpx epi3;
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106 epi3 = st->twiddles[fstride*m];
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107
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108 printf("kf_bfly3\n");
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109
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110
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111 tw1=tw2=st->twiddles;
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112
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113 do {
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114 C_FIXDIV(*Fout,3); C_FIXDIV(Fout[m],3); C_FIXDIV(Fout[m2],3);
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115
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116 C_MUL(scratch[1],Fout[m] , *tw1);
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117 C_MUL(scratch[2],Fout[m2] , *tw2);
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118
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119 C_ADD(scratch[3],scratch[1],scratch[2]);
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120 C_SUB(scratch[0],scratch[1],scratch[2]);
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121 tw1 += fstride;
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122 tw2 += fstride*2;
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123
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124 Fout[m].r = Fout->r - HALF_OF(scratch[3].r);
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125 Fout[m].i = Fout->i - HALF_OF(scratch[3].i);
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126
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127 C_MULBYSCALAR( scratch[0] , epi3.i );
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128
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129 C_ADDTO(*Fout,scratch[3]);
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130
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131 Fout[m2].r = Fout[m].r + scratch[0].i;
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132 Fout[m2].i = Fout[m].i - scratch[0].r;
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133
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134 Fout[m].r -= scratch[0].i;
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135 Fout[m].i += scratch[0].r;
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136
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137 ++Fout;
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138 } while (--k);
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139 }
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140
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141 static void kf_bfly5(
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142 peck_fft_cpx * Fout,
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143 const size_t fstride,
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144 const peck_fft_cfg st,
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145 int m
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146 )
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147 {
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148 peck_fft_cpx *Fout0,*Fout1,*Fout2,*Fout3,*Fout4;
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149 int u;
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150 peck_fft_cpx scratch[13];
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151 peck_fft_cpx * twiddles = st->twiddles;
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152 peck_fft_cpx *tw;
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153 peck_fft_cpx ya,yb;
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154 ya = twiddles[fstride*m];
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155 yb = twiddles[fstride*2*m];
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156
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157 printf("kf_bfly5\n");
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158
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159
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160 Fout0=Fout;
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161 Fout1=Fout0+m;
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162 Fout2=Fout0+2*m;
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163 Fout3=Fout0+3*m;
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164 Fout4=Fout0+4*m;
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165
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166 tw=st->twiddles;
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167 for ( u=0; u<m; ++u ) {
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168 C_FIXDIV( *Fout0,5); C_FIXDIV( *Fout1,5); C_FIXDIV( *Fout2,5); C_FIXDIV( *Fout3,5); C_FIXDIV( *Fout4,5);
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169 scratch[0] = *Fout0;
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170
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171 C_MUL(scratch[1] ,*Fout1, tw[u*fstride]);
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172 C_MUL(scratch[2] ,*Fout2, tw[2*u*fstride]);
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173 C_MUL(scratch[3] ,*Fout3, tw[3*u*fstride]);
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174 C_MUL(scratch[4] ,*Fout4, tw[4*u*fstride]);
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175
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176 C_ADD( scratch[7],scratch[1],scratch[4]);
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diff changeset
177 C_SUB( scratch[10],scratch[1],scratch[4]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
178 C_ADD( scratch[8],scratch[2],scratch[3]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
179 C_SUB( scratch[9],scratch[2],scratch[3]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
180
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
181 Fout0->r += scratch[7].r + scratch[8].r;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
182 Fout0->i += scratch[7].i + scratch[8].i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
183
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
184 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
185 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
186
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
187 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
188 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
189
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
190 C_SUB(*Fout1,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
191 C_ADD(*Fout4,scratch[5],scratch[6]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
192
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
193 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
194 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
195 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
196 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
197
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
198 C_ADD(*Fout2,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
199 C_SUB(*Fout3,scratch[11],scratch[12]);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
200
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
201 ++Fout0;++Fout1;++Fout2;++Fout3;++Fout4;
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
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
205 /* perform the butterfly for one stage of a mixed radix FFT */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
206 static void kf_bfly_generic(
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
207 peck_fft_cpx * Fout,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
208 const size_t fstride,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
209 const peck_fft_cfg st,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
210 int m,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
211 int p
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
212 )
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
213 {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
214 int u,k,q1,q;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
215 peck_fft_cpx * twiddles = st->twiddles;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
216 peck_fft_cpx t;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
217 int Norig = st->nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
218
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
219 printf("kf_bfly_generic\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
220
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
221
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
222 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
223
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
224 for ( u=0; u<m; ++u ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
225 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
226 for (q1 = 0; q1 < p; ++q1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
227 scratch[q1] = Fout[k];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
228 C_FIXDIV(scratch[q1], p);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
229 k += m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
230 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
231
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
232 k=u;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
233 for ( q1=0 ; q1<p ; ++q1 ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
234 int twidx=0;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
235 Fout[ k ] = scratch[0];
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
236 for (q=1;q<p;++q ) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
237 twidx += fstride * k;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
238 if (twidx>=Norig) twidx-=Norig;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
239 C_MUL(t,scratch[q] , twiddles[twidx] );
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
240 C_ADDTO( Fout[ k ] ,t);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
241 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
242 k += m;
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 PECK_FFT_TMP_FREE(scratch);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
246 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
247
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
248 static void kf_work(
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
249 peck_fft_cpx * Fout,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
250 const peck_fft_cpx * f,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
251 const size_t fstride,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
252 int *factors,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
253 const peck_fft_cfg st) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
254 peck_fft_cpx *Fout_beg = Fout;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
255 const int p = *factors++; /* the radix */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
256 const int m = *factors++; /* stage's FFT length / p */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
257 const peck_fft_cpx *Fout_end = Fout + p*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
258
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
259 // printf("kf_work\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
260
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
261 if (m == 1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
262 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
263 *Fout = *f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
264 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
265 } while (++Fout != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
266 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
267 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
268 // recursive call:
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
269 // DFT of size m*p performed by doing
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
270 // p instances of smaller DFTs of size m,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
271 // each one takes a decimated version of the input
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
272 kf_work(Fout, f, fstride*p, factors, st);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
273 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
274 } while ((Fout += m) != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
275 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
276
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
277 Fout=Fout_beg;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
278
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
279 // recombine the p smaller DFTs
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
280 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
281 case 2: kf_bfly2(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
282 case 3: kf_bfly3(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
283 case 4: kf_bfly4(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
284 case 5: kf_bfly5(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
285 default: kf_bfly_generic(Fout, fstride, st, m, p); break;
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
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
289 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
290 * facbuf is populated by p1, m1, p2, m2, ...
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
291 * where
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
292 * p[i] * m[i] = m[i-1]
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
293 * m0 = n
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
294 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
295 static void kf_factor(int n, int * facbuf) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
296 int p = 4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
297 float floor_sqrt;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
298 floor_sqrt = floorf(sqrtf(n));
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
299
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
300 /* factor out powers of 4, powers of 2, then any remaining primes */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
301 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
302 while (n % p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
303 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
304 case 4: p = 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
305 case 2: p = 3; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
306 default: p += 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
307 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
308 if (p > floor_sqrt)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
309 p = n; /* no more factors, skip to end */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
310 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
311 n /= p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
312 *facbuf++ = p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
313 *facbuf++ = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
314 } while (n > 1);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
315 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
316
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
317 /*
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
318 * User-callable function to allocate all necessary storage space for the fft.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
319 * The return value is a contiguous block of memory, allocated with malloc. As such,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
320 * it can be freed with free(), rather than a peck_fft-specific function.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
321 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
322 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
323 peck_fft_cfg st = NULL;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
324 size_t memneeded = sizeof(struct peck_fft_state)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
325 + sizeof(peck_fft_cpx)*(nfft-1); /* twiddle factors */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
326
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
327 if (lenmem == NULL) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
328 st = ( peck_fft_cfg)PECK_FFT_MALLOC(memneeded);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
329 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
330 if (mem != NULL && *lenmem >= memneeded)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
331 st = (peck_fft_cfg)mem;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
332 *lenmem = memneeded;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
333 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
334
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
335 if (st) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
336 int i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
337 st->nfft=nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
338 st->inverse = inverse_fft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
339
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
340 for (i = 0; i < nfft; ++i) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
341 const float pi = 3.14159265359f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
342 float phase = -2*pi*i / nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
343 if (st->inverse)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
344 phase *= -1;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
345 kf_cexp(st->twiddles+i, phase);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
346 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
347
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
348 kf_factor(nfft, st->factors);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
349 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
350 return st;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
351 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
352
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
353 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
354 kf_work(fout, fin, 1, cfg->factors, cfg);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
355 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
356
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
357 void peck_fft_cleanup(void) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
358 /* nothing needed any more */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
359 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
360
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
361 int peck_fft_next_fast_size(int n) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
362 while (1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
363 int m = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
364 while ((m % 2) == 0) m /= 2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
365 while ((m % 3) == 0) m /= 3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
366 while ((m % 5) == 0) m /= 5;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
367 if (m <= 1)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
368 break; /* n is completely factorable by twos, threes, and fives */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
369 n++;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
370 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
371 return n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
372 }

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