apps/plugins/pacbox/wsg3.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Pacbox - a Pacman Emulator for Rockbox
  11  *
  12  * Based on PIE - Pacman Instructional Emulator
  13  *
  14  * Namco custom waveform sound generator 3 (Pacman hardware)
  15  *
  16  * Copyright (c) 2003,2004 Alessandro Scotti
  17  * http://www.ascotti.org/
  18  *
  19  * This program is free software; you can redistribute it and/or
  20  * modify it under the terms of the GNU General Public License
  21  * as published by the Free Software Foundation; either version 2
  22  * of the License, or (at your option) any later version.
  23  *
  24  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  25  * KIND, either express or implied.
  26  *
  27  ****************************************************************************/
  28 #include "plugin.h"
  29 #include "wsg3.h"
  30
  31 struct wsg3 wsg3;
  32
  33 static bool wsg3_get_voice(struct wsg3_voice *voice, int index)
  34 {
  35     int base = 5*index;
  36     const unsigned char *regs = wsg3.sound_regs;
  37     unsigned x;
  38
  39     x = regs[0x15 + base] & 0x0F;
  40
  41     if (x == 0)
  42         return false;
  43
  44     voice->volume = x;
  45
  46     x =            (regs[0x14 + base] & 0x0F);
  47     x = (x << 4) | (regs[0x13 + base] & 0x0F);
  48     x = (x << 4) | (regs[0x12 + base] & 0x0F);
  49     x = (x << 4) | (regs[0x11 + base] & 0x0F);
  50     x = (x << 4);
  51
  52     if (index == 0)
  53     {
  54         /* The first voice has an extra 4-bit of data */
  55         x |= regs[0x10 + base] & 0x0F;
  56     }
  57
  58     if (x == 0)
  59         return false;
  60
  61     voice->frequency = x;
  62
  63     voice->waveform = regs[0x05 + base] & 0x07;
  64
  65     return true;
  66 }
  67
  68 void wsg3_play_sound(int * buf, int len)
  69 {
  70     struct wsg3_voice voice;
  71
  72     if (wsg3_get_voice(&voice, 0))
  73     {
  74         unsigned offset = wsg3.wave_offset[0];
  75         unsigned step = voice.frequency * wsg3.resample_step;
  76         int * wave_data = wsg3.sound_wave_data + 32 * voice.waveform;
  77         int volume = voice.volume;
  78         int i;
  79
  80         for (i = 0; i < len; i++)
  81         {
  82             /* Should be shifted right by 15, but we must also get rid
  83              * of the 10 bits used for decimals */
  84             buf[i] += wave_data[(offset >> 25) & 0x1F] * volume;
  85             offset += step;
  86         }
  87
  88         wsg3.wave_offset[0] = offset;
  89     }
  90
  91     if (wsg3_get_voice(&voice, 1))
  92     {
  93         unsigned offset = wsg3.wave_offset[1];
  94         unsigned step = voice.frequency * wsg3.resample_step;
  95         int * wave_data = wsg3.sound_wave_data + 32 * voice.waveform;
  96         int volume = voice.volume;
  97         int i;
  98
  99         for (i = 0; i < len; i++)
 100         {
 101             /* Should be shifted right by 15, but we must also get rid
 102              * of the 10 bits used for decimals */
 103             buf[i] += wave_data[(offset >> 25) & 0x1F] * volume;
 104             offset += step;
 105         }
 106
 107         wsg3.wave_offset[1] = offset;
 108     }
 109
 110     if (wsg3_get_voice(&voice, 2))
 111     {
 112         unsigned offset = wsg3.wave_offset[2];
 113         unsigned step = voice.frequency * wsg3.resample_step;
 114         int * wave_data = wsg3.sound_wave_data + 32 * voice.waveform;
 115         int volume = voice.volume;
 116         int i;
 117
 118         for (i = 0; i < len; i++)
 119         {
 120             /* Should be shifted right by 15, but we must also get rid
 121              * of the 10 bits used for decimals */
 122             buf[i] += wave_data[(offset >> 25) & 0x1F] * volume;
 123             offset += step;
 124         }
 125
 126         wsg3.wave_offset[2] = offset;
 127     }
 128 }
 129
 130 void wsg3_set_sampling_rate(unsigned sampling_rate)
 131 {
 132     wsg3.sampling_rate = sampling_rate;
 133     wsg3.resample_step = (wsg3.master_clock << 10) / sampling_rate;
 134 }
 135
 136 void wsg3_set_sound_prom( const unsigned char * prom )
 137 {
 138     int i;
 139
 140     for (i = 0; i < 32*8; i++)
 141         wsg3.sound_wave_data[i] = (int)*prom++ - 8;
 142 }
 143
 144 void wsg3_init(unsigned master_clock)
 145 {
 146     memset(&wsg3, 0, sizeof (struct wsg3));
 147     wsg3.master_clock = master_clock;
 148 }