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annotate peck_fft.c @ 4:2d6c49fcafcb

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neon2 and neon4 support
author Peter Meerwald <p.meerwald@bct-electronic.com>
date Fri, 16 Sep 2011 14:04:19 +0200
parents cfec79393811
children c7237a7544eb
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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
Peter Meerwald <p.meerwald@bct-electronic.com>
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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_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
0
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52 peck_fft_cpx *tw1,*tw2,*tw3;
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53 peck_fft_cpx scratch[6];
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54 size_t k=m;
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55 const size_t m2=2*m;
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56 const size_t m3=3*m;
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57
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58 //printf("kf_bfly4\n");
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59
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60 tw3 = tw2 = tw1 = st->twiddles;
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61
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62 do {
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63 C_FIXDIV(*Fout, 4);
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64 C_FIXDIV(Fout[m], 4);
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65 C_FIXDIV(Fout[m2], 4);
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66 C_FIXDIV(Fout[m3], 4);
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67
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68 C_MUL(scratch[0], Fout[m], *tw1);
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69 C_MUL(scratch[1], Fout[m2], *tw2);
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70 C_MUL(scratch[2], Fout[m3], *tw3);
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71
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72 C_SUB(scratch[5], *Fout, scratch[1]);
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73 C_ADDTO(*Fout, scratch[1]);
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74 C_ADD(scratch[3], scratch[0], scratch[2]);
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75 C_SUB(scratch[4], scratch[0], scratch[2]);
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76 C_SUB(Fout[m2], *Fout, scratch[3]);
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77 tw1 += fstride;
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78 tw2 += fstride*2;
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79 tw3 += fstride*3;
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80 C_ADDTO(*Fout, scratch[3]);
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81
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82 if (st->inverse) {
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83 Fout[m].r = scratch[5].r - scratch[4].i;
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84 Fout[m].i = scratch[5].i + scratch[4].r;
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85 Fout[m3].r = scratch[5].r + scratch[4].i;
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86 Fout[m3].i = scratch[5].i - scratch[4].r;
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87 } else {
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88 Fout[m].r = scratch[5].r + scratch[4].i;
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89 Fout[m].i = scratch[5].i - scratch[4].r;
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90 Fout[m3].r = scratch[5].r - scratch[4].i;
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91 Fout[m3].i = scratch[5].i + scratch[4].r;
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92 }
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93 ++Fout;
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94 } while (--k);
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95 }
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96
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97 static void kf_bfly3(
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98 peck_fft_cpx * Fout,
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99 const size_t fstride,
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100 const peck_fft_cfg st,
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101 size_t m) {
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102
0
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103 size_t k=m;
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104 const size_t m2 = 2*m;
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105 peck_fft_cpx *tw1, *tw2;
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106 peck_fft_cpx scratch[5];
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107 peck_fft_cpx epi3;
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108 epi3 = st->twiddles[fstride*m];
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109
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110 printf("kf_bfly3\n");
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111
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112 tw1=tw2=st->twiddles;
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113
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114 do {
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115 C_FIXDIV(*Fout,3); C_FIXDIV(Fout[m],3); C_FIXDIV(Fout[m2],3);
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116
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117 C_MUL(scratch[1],Fout[m] , *tw1);
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118 C_MUL(scratch[2],Fout[m2] , *tw2);
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119
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120 C_ADD(scratch[3],scratch[1],scratch[2]);
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121 C_SUB(scratch[0],scratch[1],scratch[2]);
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122 tw1 += fstride;
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123 tw2 += fstride*2;
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124
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125 Fout[m].r = Fout->r - HALF_OF(scratch[3].r);
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126 Fout[m].i = Fout->i - HALF_OF(scratch[3].i);
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127
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128 C_MULBYSCALAR( scratch[0] , epi3.i );
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129
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130 C_ADDTO(*Fout,scratch[3]);
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131
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132 Fout[m2].r = Fout[m].r + scratch[0].i;
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133 Fout[m2].i = Fout[m].i - scratch[0].r;
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134
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135 Fout[m].r -= scratch[0].i;
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136 Fout[m].i += scratch[0].r;
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137
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138 ++Fout;
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139 } while (--k);
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140 }
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141
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142 static void kf_bfly5(
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143 peck_fft_cpx * Fout,
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144 const size_t fstride,
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145 const peck_fft_cfg st,
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146 int m
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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 Fout0=Fout;
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160 Fout1=Fout0+m;
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161 Fout2=Fout0+2*m;
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162 Fout3=Fout0+3*m;
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163 Fout4=Fout0+4*m;
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164
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165 tw=st->twiddles;
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166 for (u = 0; u < m; ++u) {
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167 C_FIXDIV( *Fout0,5); C_FIXDIV( *Fout1,5); C_FIXDIV( *Fout2,5); C_FIXDIV( *Fout3,5); C_FIXDIV( *Fout4,5);
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168 scratch[0] = *Fout0;
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169
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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) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
251 peck_fft_cpx *Fout_beg = Fout;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
252 const int p = *factors++; /* the radix */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
253 const int m = *factors++; /* stage's FFT length / p */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
254 const peck_fft_cpx *Fout_end = Fout + p*m;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
255
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
256 // printf("kf_work\n");
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
257
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
258 if (m == 1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
259 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
260 *Fout = *f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
261 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
262 } while (++Fout != Fout_end);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
263 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
264 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
265 // recursive call:
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
266 // DFT of size m*p performed by doing
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
267 // p instances of smaller DFTs of size m,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
268 // each one takes a decimated version of the input
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
269 kf_work(Fout, f, fstride*p, factors, st);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
270 f += fstride;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
271 } while ((Fout += m) != Fout_end);
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 Fout=Fout_beg;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
275
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
276 // recombine the p smaller DFTs
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
277 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
278 case 2: kf_bfly2(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
279 case 3: kf_bfly3(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
280 case 4: kf_bfly4(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
281 case 5: kf_bfly5(Fout, fstride, st, m); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
282 default: kf_bfly_generic(Fout, fstride, st, m, p); break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
283 }
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 * facbuf is populated by p1, m1, p2, m2, ...
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
288 * where
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
289 * p[i] * m[i] = m[i-1]
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
290 * m0 = n
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
291 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
292 static void kf_factor(int n, int * facbuf) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
293 int p = 4;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
294 float floor_sqrt;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
295 floor_sqrt = floorf(sqrtf(n));
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
296
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
297 /* factor out powers of 4, powers of 2, then any remaining primes */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
298 do {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
299 while (n % p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
300 switch (p) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
301 case 4: p = 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
302 case 2: p = 3; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
303 default: p += 2; break;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
304 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
305 if (p > floor_sqrt)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
306 p = n; /* no more factors, skip to end */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
307 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
308 n /= p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
309 *facbuf++ = p;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
310 *facbuf++ = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
311 } while (n > 1);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
312 }
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 * User-callable function to allocate all necessary storage space for the fft.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
316 * The return value is a contiguous block of memory, allocated with malloc. As such,
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
317 * it can be freed with free(), rather than a peck_fft-specific function.
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
318 */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
319 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
320 peck_fft_cfg st = NULL;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
321 size_t memneeded = sizeof(struct peck_fft_state)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
322 + sizeof(peck_fft_cpx)*(nfft-1); /* twiddle factors */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
323
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
324 if (lenmem == NULL) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
325 st = ( peck_fft_cfg)PECK_FFT_MALLOC(memneeded);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
326 } else {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
327 if (mem != NULL && *lenmem >= memneeded)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
328 st = (peck_fft_cfg)mem;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
329 *lenmem = memneeded;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
330 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
331
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
332 if (st) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
333 int i;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
334 st->nfft=nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
335 st->inverse = inverse_fft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
336
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
337 for (i = 0; i < nfft; ++i) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
338 const float pi = 3.14159265359f;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
339 float phase = -2*pi*i / nfft;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
340 if (st->inverse)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
341 phase *= -1;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
342 kf_cexp(st->twiddles+i, phase);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
343 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
344
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
345 kf_factor(nfft, st->factors);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
346 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
347 return st;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
348 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
349
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
350 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
351 kf_work(fout, fin, 1, cfg->factors, cfg);
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
352 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
353
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
354 void peck_fft_cleanup(void) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
355 /* nothing needed any more */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
356 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
357
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
358 int peck_fft_next_fast_size(int n) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
359 while (1) {
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
360 int m = n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
361 while ((m % 2) == 0) m /= 2;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
362 while ((m % 3) == 0) m /= 3;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
363 while ((m % 5) == 0) m /= 5;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
364 if (m <= 1)
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
365 break; /* n is completely factorable by twos, threes, and fives */
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
366 n++;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
367 }
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
368 return n;
Peter Meerwald <p.meerwald@bct-electronic.com>
parents:
diff changeset
369 }

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