apps/codecs/libtta/filter.h

   1 /*
   2  * filter.h
   3  *
   4  * Description:  TTAv1 filter functions
   5  * Developed by: Alexander Djourik <ald@true-audio.com>
   6  *               Pavel Zhilin <pzh@true-audio.com>
   7  *
   8  * Copyright (c) 2004 True Audio Software. All rights reserved.
   9  *
  10  */
  11
  12 /*
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  *
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. Neither the name of the True Audio Software nor the names of its
  23  *    contributors may be used to endorse or promote products derived
  24  *    from this software without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  27  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  28  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  29  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  30  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  31  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  32  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  33  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  34  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  35  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  36  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  37  */
  38
  39 #ifndef FILTER_H
  40 #define FILTER_H
  41
  42 ///////// Filter Settings //////////
  43 static int flt_set[3] = {10, 9, 10};
  44
  45 #ifdef CPU_ARM
  46 int hybrid_filter(fltst *fs, int *in); /* implements in filter_arm.S */
  47
  48 #else
  49
  50 static inline void
  51 memshl (register int *pA) {
  52     register int *pB = pA + 16;
  53
  54     *pA++ = *pB++;
  55     *pA++ = *pB++;
  56     *pA++ = *pB++;
  57     *pA++ = *pB++;
  58     *pA++ = *pB++;
  59     *pA++ = *pB++;
  60     *pA++ = *pB++;
  61     *pA   = *pB;
  62 }
  63
  64 static inline void
  65 hybrid_filter (fltst *fs, int *in) {
  66     register int *pA = fs->dl + fs->index;
  67     register int *pB = fs->qm;
  68     register int *pM = fs->dx + fs->index;
  69     register int sum = fs->round;
  70
  71     if (!fs->error) {
  72         sum += *pA++ * *pB++;
  73         sum += *pA++ * *pB++;
  74         sum += *pA++ * *pB++;
  75         sum += *pA++ * *pB++;
  76         sum += *pA++ * *pB++;
  77         sum += *pA++ * *pB++;
  78         sum += *pA++ * *pB++;
  79         sum += *pA   * *pB;
  80         pM += 8;
  81     } else if (fs->error < 0) {
  82         sum += *pA++ * (*pB++ -= *pM++);
  83         sum += *pA++ * (*pB++ -= *pM++);
  84         sum += *pA++ * (*pB++ -= *pM++);
  85         sum += *pA++ * (*pB++ -= *pM++);
  86         sum += *pA++ * (*pB++ -= *pM++);
  87         sum += *pA++ * (*pB++ -= *pM++);
  88         sum += *pA++ * (*pB++ -= *pM++);
  89         sum += *pA   * (*pB   -= *pM++);
  90     } else {
  91         sum += *pA++ * (*pB++ += *pM++);
  92         sum += *pA++ * (*pB++ += *pM++);
  93         sum += *pA++ * (*pB++ += *pM++);
  94         sum += *pA++ * (*pB++ += *pM++);
  95         sum += *pA++ * (*pB++ += *pM++);
  96         sum += *pA++ * (*pB++ += *pM++);
  97         sum += *pA++ * (*pB++ += *pM++);
  98         sum += *pA   * (*pB   += *pM++);
  99     }
 100
 101     pB = pA++;
 102     fs->error = *in;
 103     *in += (sum >> fs->shift);
 104     *pA = *in;
 105
 106     *pM-- = ((*pB-- >> 30) | 1) << 2;
 107     *pM-- = ((*pB-- >> 30) | 1) << 1;
 108     *pM-- = ((*pB-- >> 30) | 1) << 1;
 109     *pM   = ((*pB   >> 30) | 1);
 110
 111     *(pA-1) = *(pA-0) - *(pA-1);
 112     *(pA-2) = *(pA-1) - *(pA-2);
 113     *(pA-3) = *(pA-2) - *(pA-3);
 114
 115     /*
 116      * Rockbox speciffic
 117      *     in order to make speed up, memshl() is executed at the rate once every 16 times.
 118      */
 119     if (++fs->index == 16)
 120     {
 121         memshl (fs->dl);
 122         memshl (fs->dx);
 123         fs->index = 0;
 124     }
 125 }
 126 #endif
 127
 128 static inline void
 129 filter_init (fltst *fs, int shift) {
 130     ci->memset (fs, 0, sizeof(fltst));
 131     fs->shift = shift;
 132     fs->round = 1 << (shift - 1);
 133     fs->index = 0;
 134 }
 135
 136 #endif /* FILTER_H */