drivers/sound/gus

/* */
This source file includes following definitions.
gus_adagio_vol
gus_linear_vol
   1 /*
   2  * gus_vol.c - Compute volume for GUS.
   3  */
   4 /*
   5  * Copyright by Hannu Savolainen 1993-1996
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are
   9  * met: 1. Redistributions of source code must retain the above copyright
  10  * notice, this list of conditions and the following disclaimer. 2.
  11  * Redistributions in binary form must reproduce the above copyright notice,
  12  * this list of conditions and the following disclaimer in the documentation
  13  * and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
  16  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  17  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  18  * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
  19  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  21  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  22  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25  * SUCH DAMAGE.
  26  */
  27 #include <linux/config.h>
  28 
  29 #include "sound_config.h"
  30 #ifdef CONFIG_GUS
  31 #include "gus_linearvol.h"
  32 
  33 #define GUS_VOLUME      gus_wave_volume
  34 
  35 
  36 extern int      gus_wave_volume;
  37 
  38 /*
  39  * Calculate gus volume from note velocity, main volume, expression, and
  40  * intrinsic patch volume given in patch library.  Expression is multiplied
  41  * in, so it emphasizes differences in note velocity, while main volume is
  42  * added in -- I don't know whether this is right, but it seems reasonable to
  43  * me.  (In the previous stage, main volume controller messages were changed
  44  * to expression controller messages, if they were found to be used for
  45  * dynamic volume adjustments, so here, main volume can be assumed to be
  46  * constant throughout a song.)
  47  *
  48  * Intrinsic patch volume is added in, but if over 64 is also multiplied in, so
  49  * we can give a big boost to very weak voices like nylon guitar and the
  50  * basses.  The normal value is 64.  Strings are assigned lower values.
  51  */
  52 unsigned short
  53 gus_adagio_vol (int vel, int mainv, int xpn, int voicev)
     /*  */
  54 {
  55   int             i, m, n, x;
  56 
  57 
  58   /*
  59    * A voice volume of 64 is considered neutral, so adjust the main volume if
  60    * something other than this neutral value was assigned in the patch
  61    * library.
  62    */
  63   x = 256 + 6 * (voicev - 64);
  64 
  65   /*
  66    * Boost expression by voice volume above neutral.
  67    */
  68   if (voicev > 65)
  69     xpn += voicev - 64;
  70   xpn += (voicev - 64) / 2;
  71 
  72   /*
  73    * Combine multiplicative and level components.
  74    */
  75   x = vel * xpn * 6 + (voicev / 4) * x;
  76 
  77 #ifdef GUS_VOLUME
  78   /*
  79    * Further adjustment by installation-specific master volume control
  80    * (default 60).
  81    */
  82   x = (x * GUS_VOLUME * GUS_VOLUME) / 10000;
  83 #endif
  84 
  85 #ifdef GUS_USE_CHN_MAIN_VOLUME
  86   /*
  87    * Experimental support for the channel main volume
  88    */
  89 
  90   mainv = (mainv / 2) + 64;     /* Scale to 64 to 127 */
  91   x = (x * mainv * mainv) / 16384;
  92 #endif
  93 
  94   if (x < 2)
  95     return (0);
  96   else if (x >= 65535)
  97     return ((15 << 8) | 255);
  98 
  99   /*
 100    * Convert to gus's logarithmic form with 4 bit exponent i and 8 bit
 101    * mantissa m.
 102    */
 103   n = x;
 104   i = 7;
 105   if (n < 128)
 106     {
 107       while (i > 0 && n < (1 << i))
 108         i--;
 109     }
 110   else
 111     while (n > 255)
 112       {
 113         n >>= 1;
 114         i++;
 115       }
 116   /*
 117    * Mantissa is part of linear volume not expressed in exponent.  (This is
 118    * not quite like real logs -- I wonder if it's right.)
 119    */
 120   m = x - (1 << i);
 121 
 122   /*
 123    * Adjust mantissa to 8 bits.
 124    */
 125   if (m > 0)
 126     {
 127       if (i > 8)
 128         m >>= i - 8;
 129       else if (i < 8)
 130         m <<= 8 - i;
 131     }
 132 
 133   return ((i << 8) + m);
 134 }
 135 
 136 /*
 137  * Volume-values are interpreted as linear values. Volume is based on the
 138  * value supplied with SEQ_START_NOTE(), channel main volume (if compiled in)
 139  * and the volume set by the mixer-device (default 60%).
 140  */
 141 
 142 unsigned short
 143 gus_linear_vol (int vol, int mainvol)
     /*  */
 144 {
 145   int             mixer_mainvol;
 146 
 147   if (vol <= 0)
 148     vol = 0;
 149   else if (vol >= 127)
 150     vol = 127;
 151 
 152 #ifdef GUS_VOLUME
 153   mixer_mainvol = GUS_VOLUME;
 154 #else
 155   mixer_mainvol = 100;
 156 #endif
 157 
 158 #ifdef GUS_USE_CHN_MAIN_VOLUME
 159   if (mainvol <= 0)
 160     mainvol = 0;
 161   else if (mainvol >= 127)
 162     mainvol = 127;
 163 #else
 164   mainvol = 127;
 165 #endif
 166 
 167   return gus_linearvol[(((vol * mainvol) / 127) * mixer_mainvol) / 100];
 168 }
 169 
 170 #endif
/* */
root/drivers/sound/gus_vol.c

DEFINITIONS
