Commit FS#12150 - Fully-functional audio mixer - and finally whip old limitations about playback of voice and other sounds when paused. Channels are independent in state and amplitude. Fade on stop/pause is handled by the channel's volume control rather than global volume which means it now works from anywhere. Opens up the possibility of plugin sounds during music playback by merely adding an additional channel enum. If any PCM drivers were not properly modified, see one of the last comments in the task for a description of the simple change that is expected. Some params are tunable in firmware/export/pcm-mixer.h as well.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30097 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 142 insertions, 0 deletions

diff --git a/apps/beep.c b/apps/beep.c
new file mode 100644
index 0000000000..716847263e
--- /dev/null
+++ b/apps/beep.c
@@ -0,0 +1,142 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (c) 2011 Michael Sevakis
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+#include "config.h"
+#include "system.h"
+#include "settings.h"
+#include "dsp.h"
+#include "pcm.h"
+#include "pcm_mixer.h"
+#include "misc.h"
+
+static int32_t beep_phase;      /* Phase of square wave generator */
+static uint32_t beep_step;      /* Step of square wave generator on each sample */
+static uint32_t beep_amplitude; /* Amplitude of square wave generator */
+static int beep_count;          /* Number of samples remaining to generate */
+
+/* Reserve enough static space for keyclick to fit */
+#define BEEP_BUF_COUNT (NATIVE_FREQUENCY / 1000 * KEYCLICK_DURATION)
+static uint32_t beep_buf[BEEP_BUF_COUNT] IBSS_ATTR;
+
+/* Actually output samples into beep_buf */
+#if defined(CPU_ARM)
+static FORCE_INLINE void beep_generate(int count)
+{
+    uint32_t *out = beep_buf;
+    uint32_t s;
+
+    asm volatile (
+    "1:                            \n"
+        "eor   %3, %5, %1, asr #31 \n"
+        "subs  %2, %2, #1          \n"
+        "str   %3, [%0], #4        \n"
+        "add   %1, %1, %4          \n"
+        "bgt   1b                  \n"
+        : "+r"(out), "+r"(beep_phase), "+r"(count),
+          "=&r"(s)
+        : "r"(beep_step), "r"(beep_amplitude));
+}
+#elif defined (CPU_COLDFIRE)
+static FORCE_INLINE void beep_generate(int count)
+{
+    uint32_t *out = beep_buf;
+    uint32_t s;
+
+    asm volatile (
+    "1:                   \n"
+        "move.l %1, %3    \n"
+        "add.l  %4, %1    \n"
+        "add.l  %3, %3    \n"
+        "subx.l %3, %3    \n"
+        "eor.l  %5, %3    \n"
+        "move.l %3, (%0)+ \n"
+        "subq.l #1, %2    \n"
+        "bgt.b  1b        \n"
+        : "+a"(out), "+d"(beep_phase), "+d"(count),
+          "=&d"(s)
+        : "r"(beep_step), "d"(beep_amplitude));
+}
+#else
+static FORCE_INLINE void beep_generate(int count)
+{
+    uint32_t *out = beep_buf;
+    uint32_t amplitude = beep_amplitude;
+    uint32_t step = beep_step;
+    int32_t phase = beep_phase;
+
+    do
+    {
+        *out++ = (phase >> 31) ^ amplitude;
+        phase += step;
+    }
+    while (--count > 0);
+
+    beep_phase = phase;
+}
+#endif
+
+/* Callback to generate the beep frames - also don't want inlining of
+   call below in beep_play */
+static void __attribute__((noinline)) ICODE_ATTR
+beep_get_more(unsigned char **start, size_t *size)
+{
+    int count = beep_count;
+
+    if (count > 0)
+    {
+        count = MIN(count, BEEP_BUF_COUNT);
+        beep_count -= count;
+        *start = (unsigned char *)beep_buf;
+        *size = count * sizeof(uint32_t);
+        beep_generate(count);
+    }
+}
+
+/* Generates a constant square wave sound with a given frequency in Hertz for
+   a duration in milliseconds */
+void beep_play(unsigned int frequency, unsigned int duration,
+               unsigned int amplitude)
+{
+    mixer_channel_stop(PCM_MIXER_CHAN_BEEP);
+
+    if (frequency == 0 || duration == 0 || amplitude == 0)
+        return;
+
+    if (amplitude > INT16_MAX)
+        amplitude = INT16_MAX;
+
+    /* Setup the parameters for the square wave generator */
+    beep_phase = 0;
+    beep_step = 0xffffffffu / NATIVE_FREQUENCY * frequency;
+    beep_count = NATIVE_FREQUENCY / 1000 * duration;
+    beep_amplitude = amplitude | (amplitude << 16); /* Word:|AMP16|AMP16| */
+
+    /* If it fits - avoid cb overhead */
+    unsigned char *start;
+    size_t size;
+
+    /* Generate first frame here */
+    beep_get_more(&start, &size);
+
+    mixer_channel_set_amplitude(PCM_MIXER_CHAN_BEEP, MIX_AMP_UNITY);
+    mixer_channel_play_data(PCM_MIXER_CHAN_BEEP,
+                            beep_count ? beep_get_more : NULL,
+                            start, size);
+}