workbench/devs/AHI/Device/dspecho.c

   1 /*
   2      AHI - Hardware independent audio subsystem
   3      Copyright (C) 1996-2005 Martin Blom <martin@blom.org>
   4
   5      This library is free software; you can redistribute it and/or
   6      modify it under the terms of the GNU Library General Public
   7      License as published by the Free Software Foundation; either
   8      version 2 of the License, or (at your option) any later version.
   9
  10      This library is distributed in the hope that it will be useful,
  11      but WITHOUT ANY WARRANTY; without even the implied warranty of
  12      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13      Library General Public License for more details.
  14
  15      You should have received a copy of the GNU Library General Public
  16      License along with this library; if not, write to the
  17      Free Software Foundation, Inc., 59 Temple Place - Suite 330, Cambridge,
  18      MA 02139, USA.
  19 */
  20
  21 #include <config.h>
  22
  23 #include "ahi_def.h"
  24 #include "dsp.h"
  25 #include "dspecho.h"
  26 #include "dspechofuncs.h"
  27
  28 #define min(a,b) (((a)<(b))?(a):(b))
  29 #define max(a,b) (((a)>(b))?(a):(b))
  30
  31 /**************
  32 * Inputs: ahiede_Delay, ahiede_Feedback, ahiede_Mix, ahiede_Cross
  33 *
  34 * Delay      = ahide_Delay
  35 * MixN       = 1-ahide_Mix
  36 * MixD       = ahide_Mix
  37 * FeedbackDO = ahide_Feedback*ahide_Cross
  38 * FeedbackDS = ahide_Feedback*(1-ahide_Cross)
  39 * FeedbackNO = (1-ahide_Feedback)*ahide_Cross
  40 * FeedbackNS = (1-ahide_Feedback)*(1-ahide_Cross)
  41 *
  42 *                                               |\
  43 * left in ->---+----------+---------------------| >---->(+)----> left out
  44 *              |          |                MixN |/       ^
  45 *  FeedbackNO \¯/        \¯/ FeedbackNS                  |
  46 *              v          v                              |
  47 *              |          |                              |
  48 *              |          v    |¯¯¯|            |\       |
  49 *              |    +--->(+)-->| T |----+-------| >------+
  50 *              |    |     ^    |___|    |  MixD |/
  51 *              |    |     |    Delay    |
  52 *              |    |     |             |
  53 *              |    |     |      /|     |
  54 *              |    |     +-----< |-----+
  55 *              |    | FeedbackDS \|     |
  56 *              |    |                   |
  57 *              |    |            /|     |
  58 *             (+)<--(-----------< |-----+
  59 *              |    |            \| FeedbackDO
  60 *              |    |
  61 *              |    |
  62 *              |    |
  63 *              |    |            /| FeedbackDO
  64 *              |   (+)<---------< |-----+
  65 *              |    |            \|     |
  66 *              |    |                   |
  67 *              |    | FeedbackDS /|     |
  68 *              |    |     +-----< |-----+
  69 *              |    |     |      \|     |
  70 *              |    |     |             |
  71 *              |    |     v    |¯¯¯|    |       |\
  72 *              +----(--->(+)-->| T |----+-------| >------+
  73 *                   |     ^    |___|       MixD |/       |
  74 *                   |     |    Delay                     |
  75 *                   ^     ^                              |
  76 *       FeedbackNO /_\   /_\ FeedbackNS                  |
  77 *                   |     |                     |\       v
  78 * right in ->-------+-----+---------------------| >---->(+)----> right out
  79 *                                          MixN |/
  80 *
  81 *
  82 **************
  83 *
  84 * The delay buffer: (BuffSamples = 5, Delay = 8 Total size = 13
  85 *
  86 *  1) Delay times
  87 *
  88 *  +---------+
  89 *  |         |
  90 *  v         ^
  91 * |_|_|_|_|_|_|_|_|_|_|_|_|_|
  92 * *---------*
  93 *
  94 *  2) BuffSamples times
  95 *
  96 *  +-Mix-----------+
  97 *  |               |
  98 *  ^               v
  99 * |_|_|_|_|_|_|_|_|_|_|_|_|_|
 100 * *---------*
 101 *
 102 * Or optimized using a circular buffer:
 103 *
 104 *
 105 * Offset<BuffSamples => BuffSamples-Offset times:
 106 *
 107 *  +-Mix-----------+
 108 *  |               |
 109 *  ^               v
 110 * |_|_|_|_|_|_|_|_|_|_|_|_|_|
 111 * *---------*
 112 *
 113 * BuffSamples<=Offset<=Delay => BuffSamples times:
 114 *
 115 *  +-Mix-----+
 116 *  |         |
 117 *  v         ^
 118 * |_|_|_|_|_|_|_|_|_|_|_|_|_|
 119 *           *---------*
 120 *
 121 * Offset>Delay => BuffSamples+Delay-Offset times:
 122 *
 123 *          +-Mix-----+
 124 *          |         |
 125 *          v         ^
 126 * |_|_|_|_|_|_|_|_|_|_|_|_|_|
 127 * --*               *--------
 128 *
 129 * The delay buffer: (BuffSamples = 5, Delay = 3 Total size = 8
 130 *
 131 * Offset<BuffSamples => BuffSamples-Offset times:
 132 *
 133 *  +-Mix-+
 134 *  |     |
 135 *  ^     v
 136 * |_|_|_|_|_|_|_|_|
 137 * *---------*
 138 *
 139 * Offset>=BuffSamples => BuffSamples+Delay-Offset times:
 140 *
 141 *  +-----Mix-+
 142 *  |         |
 143 *  v         ^
 144 * |_|_|_|_|_|_|_|_|
 145 * ----*     *------
 146 *
 147 *
 148 *
 149 * Algoritm:
 150 *
 151 *   LoopsLeft=BuffSamples
 152 *   Offset=0
 153 *   Src=E
 154 *   Dst=E+Delay
 155 * Loop:
 156 *   If LoopsLeft <= 0 GOTO Exit
 157 *   IF Src >= (E + MaxBuffSamples + Delay) THEN Src = Src - (MaxBuffSamples + Delay)
 158 *   IF Dst >= (E + MaxBuffSamples + Delay) THEN Dst = Dst - (MaxBuffSamples + Delay)
 159 *   IF Offset >= (MaxBuffSamples + Delay) THEN Offset = Offset - (MaxBuffSamples + Delay)
 160 *
 161 *   IF Offset < MaxBuffSamples THEN LoopTimes = MaxBuffSamples-Offset : GOTO Echo
 162 *   IF Offset <= Delay THEN LoopTimes = MaxBuffSamples : GOTO Echo
 163 *   LoopTimes = MaxBuffSamples+Delay-Offset
 164 * Echo:
 165 *   LoopTimes = min(LoopTimes,LoopsLeft)
 166 *   Echo LoopTimes samples
 167 *
 168 *   Src = Src + LoopTimes
 169 *   Dst = Dst + LoopTimes
 170 *   Offset = Offset + LoopTimes
 171 *   LoopsLeft = LoopsLeft - LoopTimes
 172 *   GOTO Loop
 173 * Exit:
 174 *
 175 */
 176
 177 static void
 178 do_DSPEcho ( struct Echo *es,
 179              void *buf,
 180              struct AHIPrivAudioCtrl *audioctrl,
 181              void (*echofunc)(LONG, struct Echo *, void **, void **, void **) )
 182 {
 183   LONG  samples, loops;
 184   ULONG offset;
 185   void *srcptr, *dstptr;
 186
 187   samples = audioctrl->ac.ahiac_BuffSamples;
 188   offset  = es->ahiecho_Offset;
 189   srcptr  = es->ahiecho_SrcPtr;
 190   dstptr  = es->ahiecho_DstPtr;
 191
 192   while(samples > 0)
 193   {
 194     /* Circular buffer stuff */
 195
 196     if(srcptr >= es->ahiecho_EndPtr)
 197     {
 198       srcptr = (char *) srcptr - es->ahiecho_BufferSize;
 199     }
 200
 201     if(dstptr >= es->ahiecho_EndPtr)
 202     {
 203       dstptr = (char *) dstptr - es->ahiecho_BufferSize;
 204     }
 205
 206     if(offset >= es->ahiecho_BufferLength)
 207     {
 208       offset -= es->ahiecho_BufferLength;
 209     }
 210
 211
 212
 213     if(offset < audioctrl->ac.ahiac_MaxBuffSamples)
 214     {
 215       loops = audioctrl->ac.ahiac_MaxBuffSamples - offset;
 216     }
 217     else if(offset <= es->ahiecho_Delay)
 218     {
 219       loops = audioctrl->ac.ahiac_MaxBuffSamples;
 220     }
 221     else
 222     {
 223       loops = audioctrl->ac.ahiac_MaxBuffSamples + es->ahiecho_Delay - offset;
 224     }
 225
 226     loops = min(loops, samples);
 227
 228     samples -= loops;
 229     offset  += loops;
 230
 231     /* Call echo function */
 232
 233     echofunc(loops, es, &buf, &srcptr, &dstptr);
 234
 235   } // while(samples > 0)
 236
 237   es->ahiecho_Offset = offset;
 238   es->ahiecho_SrcPtr = srcptr;
 239   es->ahiecho_DstPtr = dstptr;
 240 }
 241
 242
 243
 244
 245 /* Entry points **************************************************************/
 246
 247 void
 248 do_DSPEchoMono16( struct Echo *es,
 249                   void *buf,
 250                   struct AHIPrivAudioCtrl *audioctrl )
 251 {
 252   do_DSPEcho( es, buf, audioctrl, EchoMono16 );
 253 }
 254
 255
 256 void
 257 do_DSPEchoStereo16( struct Echo *es,
 258                     void *buf,
 259                     struct AHIPrivAudioCtrl *audioctrl )
 260 {
 261   do_DSPEcho( es, buf, audioctrl, EchoStereo16 );
 262 }
 263
 264
 265 void
 266 do_DSPEchoMono32 ( struct Echo *es,
 267                    void *buf,
 268                    struct AHIPrivAudioCtrl *audioctrl )
 269 {
 270   do_DSPEcho( es, buf, audioctrl, EchoMono32 );
 271 }
 272
 273
 274 void
 275 do_DSPEchoStereo32( struct Echo *es,
 276                     void *buf,
 277                     struct AHIPrivAudioCtrl *audioctrl )
 278 {
 279   do_DSPEcho( es, buf, audioctrl, EchoStereo32 );
 280 }
 281
 282
 283 void
 284 do_DSPEchoMulti32( struct Echo *es,
 285                    void *buf,
 286                    struct AHIPrivAudioCtrl *audioctrl )
 287 {
 288   do_DSPEcho( es, buf, audioctrl, EchoMulti32 );
 289 }
 290