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5
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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * fir.h - General telephony FIR routines
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2002 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: fir.h,v 1.8 2006/10/24 13:45:28 steveu Exp $
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26 */
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27
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28 /*! \page fir_page FIR filtering
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29 \section fir_page_sec_1 What does it do?
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30 ???.
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31
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32 \section fir_page_sec_2 How does it work?
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33 ???.
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34 */
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35
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36 #if !defined(_FIR_H_)
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37 #define _FIR_H_
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38
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39 /*
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40 Blackfin NOTES & IDEAS:
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41
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42 A simple dot product function is used to implement the filter. This performs
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43 just one MAC/cycle which is inefficient but was easy to implement as a first
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44 pass. The current Blackfin code also uses an unrolled form of the filter
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45 history to avoid 0 length hardware loop issues. This is wasteful of
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46 memory.
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47
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48 Ideas for improvement:
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49
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50 1/ Rewrite filter for dual MAC inner loop. The issue here is handling
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51 history sample offsets that are 16 bit aligned - the dual MAC needs
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52 32 bit aligmnent. There are some good examples in libbfdsp.
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53
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54 2/ Use the hardware circular buffer facility tohalve memory usage.
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55
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56 3/ Consider using internal memory.
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57
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58 Using less memory might also improve speed as cache misses will be
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59 reduced. A drop in MIPs and memory approaching 50% should be
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60 possible.
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61
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62 The foreground and background filters currenlty use a total of
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63 about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
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64 can.
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65 */
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66
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67 #if defined(USE_MMX) || defined(USE_SSE2)
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68 #include "mmx.h"
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69 #endif
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70
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71 /*!
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72 16 bit integer FIR descriptor. This defines the working state for a single
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73 instance of an FIR filter using 16 bit integer coefficients.
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74 */
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75 typedef struct
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76 {
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77 int taps;
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78 int curr_pos;
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79 const int16_t *coeffs;
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80 int16_t *history;
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81 } fir16_state_t;
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82
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83 /*!
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84 32 bit integer FIR descriptor. This defines the working state for a single
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85 instance of an FIR filter using 32 bit integer coefficients, and filtering
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86 16 bit integer data.
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87 */
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88 typedef struct
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89 {
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90 int taps;
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91 int curr_pos;
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92 const int32_t *coeffs;
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93 int16_t *history;
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94 } fir32_state_t;
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95
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96 /*!
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97 Floating point FIR descriptor. This defines the working state for a single
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98 instance of an FIR filter using floating point coefficients and data.
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99 */
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100 typedef struct
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101 {
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102 int taps;
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103 int curr_pos;
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104 const float *coeffs;
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105 float *history;
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106 } fir_float_state_t;
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107
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108 #ifdef __cplusplus
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109 extern "C" {
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110 #endif
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111
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112 static __inline__ const int16_t *fir16_create(fir16_state_t *fir,
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113 const int16_t *coeffs,
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114 int taps)
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115 {
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116 fir->taps = taps;
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117 fir->curr_pos = taps - 1;
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118 fir->coeffs = coeffs;
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119 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
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120 if ((fir->history = malloc(2*taps*sizeof(int16_t))))
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121 memset(fir->history, 0, 2*taps*sizeof(int16_t));
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122 #else
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123 if ((fir->history = (int16_t *) malloc(taps*sizeof(int16_t))))
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124 memset(fir->history, 0, taps*sizeof(int16_t));
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125 #endif
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126 return fir->history;
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127 }
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128 /*- End of function --------------------------------------------------------*/
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129
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130 static __inline__ void fir16_flush(fir16_state_t *fir)
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131 {
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132 #if defined(USE_MMX) || defined(USE_SSE2) || defined(__BLACKFIN_ASM__)
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133 memset(fir->history, 0, 2*fir->taps*sizeof(int16_t));
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134 #else
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135 memset(fir->history, 0, fir->taps*sizeof(int16_t));
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136 #endif
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137 }
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138 /*- End of function --------------------------------------------------------*/
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139
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140 static __inline__ void fir16_free(fir16_state_t *fir)
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141 {
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142 free(fir->history);
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143 }
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144 /*- End of function --------------------------------------------------------*/
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145
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146 #ifdef __BLACKFIN_ASM__
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147 static inline int32_t dot_asm(short *x, short *y, int len)
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148 {
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149 int dot;
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150
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151 len--;
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152
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153 __asm__
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154 (
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155 "I0 = %1;\n\t"
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156 "I1 = %2;\n\t"
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157 "A0 = 0;\n\t"
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158 "R0.L = W[I0++] || R1.L = W[I1++];\n\t"
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159 "LOOP dot%= LC0 = %3;\n\t"
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160 "LOOP_BEGIN dot%=;\n\t"
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161 "A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
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162 "LOOP_END dot%=;\n\t"
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163 "A0 += R0.L*R1.L (IS);\n\t"
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164 "R0 = A0;\n\t"
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165 "%0 = R0;\n\t"
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166 : "=&d" (dot)
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167 : "a" (x), "a" (y), "a" (len)
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168 : "I0", "I1", "A1", "A0", "R0", "R1"
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169 );
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170
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171 return dot;
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172 }
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173 #endif
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174 /*- End of function --------------------------------------------------------*/
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175
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176 static __inline__ int16_t fir16(fir16_state_t *fir, int16_t sample)
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177 {
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178 int32_t y;
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179 #if defined(USE_MMX)
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180 int i;
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181 mmx_t *mmx_coeffs;
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182 mmx_t *mmx_hist;
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183
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184 fir->history[fir->curr_pos] = sample;
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185 fir->history[fir->curr_pos + fir->taps] = sample;
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186
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187 mmx_coeffs = (mmx_t *) fir->coeffs;
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188 mmx_hist = (mmx_t *) &fir->history[fir->curr_pos];
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189 i = fir->taps;
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190 pxor_r2r(mm4, mm4);
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191 /* 8 samples per iteration, so the filter must be a multiple of 8 long. */
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192 while (i > 0)
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193 {
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194 movq_m2r(mmx_coeffs[0], mm0);
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195 movq_m2r(mmx_coeffs[1], mm2);
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196 movq_m2r(mmx_hist[0], mm1);
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197 movq_m2r(mmx_hist[1], mm3);
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198 mmx_coeffs += 2;
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199 mmx_hist += 2;
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200 pmaddwd_r2r(mm1, mm0);
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201 pmaddwd_r2r(mm3, mm2);
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202 paddd_r2r(mm0, mm4);
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203 paddd_r2r(mm2, mm4);
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204 i -= 8;
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205 }
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206 movq_r2r(mm4, mm0);
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207 psrlq_i2r(32, mm0);
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208 paddd_r2r(mm0, mm4);
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209 movd_r2m(mm4, y);
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210 emms();
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211 #elif defined(USE_SSE2)
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212 int i;
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213 xmm_t *xmm_coeffs;
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214 xmm_t *xmm_hist;
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215
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216 fir->history[fir->curr_pos] = sample;
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217 fir->history[fir->curr_pos + fir->taps] = sample;
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218
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219 xmm_coeffs = (xmm_t *) fir->coeffs;
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220 xmm_hist = (xmm_t *) &fir->history[fir->curr_pos];
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221 i = fir->taps;
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222 pxor_r2r(xmm4, xmm4);
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223 /* 16 samples per iteration, so the filter must be a multiple of 16 long. */
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224 while (i > 0)
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225 {
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226 movdqu_m2r(xmm_coeffs[0], xmm0);
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227 movdqu_m2r(xmm_coeffs[1], xmm2);
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228 movdqu_m2r(xmm_hist[0], xmm1);
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229 movdqu_m2r(xmm_hist[1], xmm3);
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230 xmm_coeffs += 2;
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231 xmm_hist += 2;
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232 pmaddwd_r2r(xmm1, xmm0);
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233 pmaddwd_r2r(xmm3, xmm2);
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234 paddd_r2r(xmm0, xmm4);
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235 paddd_r2r(xmm2, xmm4);
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236 i -= 16;
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237 }
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238 movdqa_r2r(xmm4, xmm0);
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239 psrldq_i2r(8, xmm0);
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240 paddd_r2r(xmm0, xmm4);
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241 movdqa_r2r(xmm4, xmm0);
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242 psrldq_i2r(4, xmm0);
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243 paddd_r2r(xmm0, xmm4);
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244 movd_r2m(xmm4, y);
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245 #elif defined(__BLACKFIN_ASM__)
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246 fir->history[fir->curr_pos] = sample;
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247 fir->history[fir->curr_pos + fir->taps] = sample;
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248 y = dot_asm((int16_t*)fir->coeffs, &fir->history[fir->curr_pos], fir->taps);
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249 #else
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250 int i;
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251 int offset1;
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252 int offset2;
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253
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254 fir->history[fir->curr_pos] = sample;
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255
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256 offset2 = fir->curr_pos;
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257 offset1 = fir->taps - offset2;
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258 y = 0;
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259 for (i = fir->taps - 1; i >= offset1; i--)
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260 y += fir->coeffs[i]*fir->history[i - offset1];
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261 for ( ; i >= 0; i--)
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262 y += fir->coeffs[i]*fir->history[i + offset2];
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263 #endif
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264 if (fir->curr_pos <= 0)
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265 fir->curr_pos = fir->taps;
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266 fir->curr_pos--;
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267 return (int16_t) (y >> 15);
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268 }
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269 /*- End of function --------------------------------------------------------*/
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270
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271 static __inline__ const int16_t *fir32_create(fir32_state_t *fir,
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272 const int32_t *coeffs,
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273 int taps)
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274 {
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275 fir->taps = taps;
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276 fir->curr_pos = taps - 1;
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277 fir->coeffs = coeffs;
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278 fir->history = (int16_t *) malloc(taps*sizeof(int16_t));
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279 if (fir->history)
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280 memset(fir->history, '\0', taps*sizeof(int16_t));
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281 return fir->history;
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282 }
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283 /*- End of function --------------------------------------------------------*/
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284
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285 static __inline__ void fir32_flush(fir32_state_t *fir)
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286 {
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287 memset(fir->history, 0, fir->taps*sizeof(int16_t));
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288 }
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289 /*- End of function --------------------------------------------------------*/
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290
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291 static __inline__ void fir32_free(fir32_state_t *fir)
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292 {
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293 free(fir->history);
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294 }
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295 /*- End of function --------------------------------------------------------*/
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296
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297 static __inline__ int16_t fir32(fir32_state_t *fir, int16_t sample)
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298 {
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299 int i;
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300 int32_t y;
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301 int offset1;
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302 int offset2;
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303
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304 fir->history[fir->curr_pos] = sample;
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305 offset2 = fir->curr_pos;
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306 offset1 = fir->taps - offset2;
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307 y = 0;
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308 for (i = fir->taps - 1; i >= offset1; i--)
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309 y += fir->coeffs[i]*fir->history[i - offset1];
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310 for ( ; i >= 0; i--)
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311 y += fir->coeffs[i]*fir->history[i + offset2];
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312 if (fir->curr_pos <= 0)
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313 fir->curr_pos = fir->taps;
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314 fir->curr_pos--;
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315 return (int16_t) (y >> 15);
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316 }
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317 /*- End of function --------------------------------------------------------*/
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318
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319 #ifndef __KERNEL__
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320 static __inline__ const float *fir_float_create(fir_float_state_t *fir,
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321 const float *coeffs,
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322 int taps)
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323 {
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324 fir->taps = taps;
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325 fir->curr_pos = taps - 1;
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326 fir->coeffs = coeffs;
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327 fir->history = (float *) malloc(taps*sizeof(float));
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328 if (fir->history)
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329 memset(fir->history, '\0', taps*sizeof(float));
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330 return fir->history;
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331 }
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332 /*- End of function --------------------------------------------------------*/
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333
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334 static __inline__ void fir_float_free(fir_float_state_t *fir)
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335 {
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336 free(fir->history);
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337 }
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338 /*- End of function --------------------------------------------------------*/
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339
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340 static __inline__ int16_t fir_float(fir_float_state_t *fir, int16_t sample)
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341 {
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342 int i;
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343 float y;
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344 int offset1;
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345 int offset2;
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346
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347 fir->history[fir->curr_pos] = sample;
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348
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349 offset2 = fir->curr_pos;
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350 offset1 = fir->taps - offset2;
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351 y = 0;
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352 for (i = fir->taps - 1; i >= offset1; i--)
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353 y += fir->coeffs[i]*fir->history[i - offset1];
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354 for ( ; i >= 0; i--)
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355 y += fir->coeffs[i]*fir->history[i + offset2];
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356 if (fir->curr_pos <= 0)
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357 fir->curr_pos = fir->taps;
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358 fir->curr_pos--;
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359 return (int16_t) y;
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360 }
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361 /*- End of function --------------------------------------------------------*/
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362 #endif
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363
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364 #ifdef __cplusplus
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365 }
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366 #endif
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367
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368 #endif
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369 /*- End of file ------------------------------------------------------------*/
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