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_core.h" /* for NATIVE_FREQUENCY */
  25 #include "pcm.h"
  26 #include "pcm_mixer.h"
  27 #include "misc.h"
  28
  29 /** Beep generation, CPU optimized **/
  30 #include "asm/beep.c"
  31
  32 static uint32_t beep_phase;     /* Phase of square wave generator */
  33 static uint32_t beep_step;      /* Step of square wave generator on each sample */
  34 #ifdef BEEP_GENERIC
  35 static int16_t  beep_amplitude; /* Amplitude of square wave generator */
  36 #else
  37 /* Optimized routines do XOR with phase sign bit in both channels at once */
  38 static uint32_t beep_amplitude; /* Amplitude of square wave generator */
  39 #endif
  40 static int beep_count;          /* Number of samples remaining to generate */
  41
  42 /* Reserve enough static space for keyclick to fit */
  43 #define BEEP_BUF_COUNT (NATIVE_FREQUENCY / 1000 * KEYCLICK_DURATION)
  44 static int16_t beep_buf[BEEP_BUF_COUNT*2] IBSS_ATTR __attribute__((aligned(4)));
  45
  46 /* Callback to generate the beep frames - also don't want inlining of
  47    call below in beep_play */
  48 static void __attribute__((noinline))
  49 beep_get_more(const void **start, size_t *size)
  50 {
  51     int count = beep_count;
  52
  53     if (count > 0)
  54     {
  55         count = MIN(count, BEEP_BUF_COUNT);
  56         beep_count -= count;
  57         *start = beep_buf;
  58         *size = count * 2 * sizeof (int16_t);
  59         beep_generate((void *)beep_buf, count, &beep_phase,
  60                       beep_step, beep_amplitude);
  61     }
  62 }
  63
  64 /* Generates a constant square wave sound with a given frequency in Hertz for
  65    a duration in milliseconds */
  66 void beep_play(unsigned int frequency, unsigned int duration,
  67                unsigned int amplitude)
  68 {
  69     mixer_channel_stop(PCM_MIXER_CHAN_BEEP);
  70
  71     if (frequency == 0 || duration == 0 || amplitude == 0)
  72         return;
  73
  74     if (amplitude > INT16_MAX)
  75         amplitude = INT16_MAX;
  76
  77     /* Setup the parameters for the square wave generator */
  78     beep_phase = 0;
  79     beep_step = 0xffffffffu / NATIVE_FREQUENCY * frequency;
  80     beep_count = NATIVE_FREQUENCY / 1000 * duration;
  81
  82 #ifdef BEEP_GENERIC
  83     beep_amplitude = amplitude;
  84 #else
  85     /* Optimized routines do XOR with phase sign bit in both channels at once */
  86     beep_amplitude = amplitude | (amplitude << 16); /* Word:|AMP16|AMP16| */
  87 #endif
  88
  89     /* If it fits - avoid cb overhead */
  90     const void *start;
  91     size_t size;
  92
  93     /* Generate first frame here */
  94     beep_get_more(&start, &size);
  95
  96     mixer_channel_set_amplitude(PCM_MIXER_CHAN_BEEP, MIX_AMP_UNITY);
  97     mixer_channel_play_data(PCM_MIXER_CHAN_BEEP,
  98                             beep_count ? beep_get_more : NULL,
  99                             start, size);
 100 }