apps/beep.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (c) 2011 Michael Sevakis
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "config.h"
  22 #include "system.h"
  23 #include "settings.h"
  24 #include "dsp.h"
  25 #include "pcm.h"
  26 #include "pcm_mixer.h"
  27 #include "misc.h"
  28
  29 static int32_t beep_phase;      /* Phase of square wave generator */
  30 static uint32_t beep_step;      /* Step of square wave generator on each sample */
  31 static uint32_t beep_amplitude; /* Amplitude of square wave generator */
  32 static int beep_count;          /* Number of samples remaining to generate */
  33
  34 /* Reserve enough static space for keyclick to fit */
  35 #define BEEP_BUF_COUNT (NATIVE_FREQUENCY / 1000 * KEYCLICK_DURATION)
  36 static uint32_t beep_buf[BEEP_BUF_COUNT] IBSS_ATTR;
  37
  38 /* Actually output samples into beep_buf */
  39 #if defined(CPU_ARM)
  40 static FORCE_INLINE void beep_generate(int count)
  41 {
  42     uint32_t *out = beep_buf;
  43     uint32_t s;
  44
  45     asm volatile (
  46     "1:                            \n"
  47         "eor   %3, %5, %1, asr #31 \n"
  48         "subs  %2, %2, #1          \n"
  49         "str   %3, [%0], #4        \n"
  50         "add   %1, %1, %4          \n"
  51         "bgt   1b                  \n"
  52         : "+r"(out), "+r"(beep_phase), "+r"(count),
  53           "=&r"(s)
  54         : "r"(beep_step), "r"(beep_amplitude));
  55 }
  56 #elif defined (CPU_COLDFIRE)
  57 static FORCE_INLINE void beep_generate(int count)
  58 {
  59     uint32_t *out = beep_buf;
  60     uint32_t s;
  61
  62     asm volatile (
  63     "1:                   \n"
  64         "move.l %1, %3    \n"
  65         "add.l  %4, %1    \n"
  66         "add.l  %3, %3    \n"
  67         "subx.l %3, %3    \n"
  68         "eor.l  %5, %3    \n"
  69         "move.l %3, (%0)+ \n"
  70         "subq.l #1, %2    \n"
  71         "bgt.b  1b        \n"
  72         : "+a"(out), "+d"(beep_phase), "+d"(count),
  73           "=&d"(s)
  74         : "r"(beep_step), "d"(beep_amplitude));
  75 }
  76 #else
  77 static FORCE_INLINE void beep_generate(int count)
  78 {
  79     uint32_t *out = beep_buf;
  80     uint32_t amplitude = beep_amplitude;
  81     uint32_t step = beep_step;
  82     int32_t phase = beep_phase;
  83
  84     do
  85     {
  86         *out++ = (phase >> 31) ^ amplitude;
  87         phase += step;
  88     }
  89     while (--count > 0);
  90
  91     beep_phase = phase;
  92 }
  93 #endif
  94
  95 /* Callback to generate the beep frames - also don't want inlining of
  96    call below in beep_play */
  97 static void __attribute__((noinline))
  98 beep_get_more(unsigned char **start, size_t *size)
  99 {
 100     int count = beep_count;
 101
 102     if (count > 0)
 103     {
 104         count = MIN(count, BEEP_BUF_COUNT);
 105         beep_count -= count;
 106         *start = (unsigned char *)beep_buf;
 107         *size = count * sizeof(uint32_t);
 108         beep_generate(count);
 109     }
 110 }
 111
 112 /* Generates a constant square wave sound with a given frequency in Hertz for
 113    a duration in milliseconds */
 114 void beep_play(unsigned int frequency, unsigned int duration,
 115                unsigned int amplitude)
 116 {
 117     mixer_channel_stop(PCM_MIXER_CHAN_BEEP);
 118
 119     if (frequency == 0 || duration == 0 || amplitude == 0)
 120         return;
 121
 122     if (amplitude > INT16_MAX)
 123         amplitude = INT16_MAX;
 124
 125     /* Setup the parameters for the square wave generator */
 126     beep_phase = 0;
 127     beep_step = 0xffffffffu / NATIVE_FREQUENCY * frequency;
 128     beep_count = NATIVE_FREQUENCY / 1000 * duration;
 129     beep_amplitude = amplitude | (amplitude << 16); /* Word:|AMP16|AMP16| */
 130
 131     /* If it fits - avoid cb overhead */
 132     unsigned char *start;
 133     size_t size;
 134
 135     /* Generate first frame here */
 136     beep_get_more(&start, &size);
 137
 138     mixer_channel_set_amplitude(PCM_MIXER_CHAN_BEEP, MIX_AMP_UNITY);
 139     mixer_channel_play_data(PCM_MIXER_CHAN_BEEP,
 140                             beep_count ? beep_get_more : NULL,
 141                             start, size);
 142 }