drivers/staging/echo/fir.h

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