From 267eb077a79b85638598e1a872ffab9e60da7dfe Mon Sep 17 00:00:00 2001
From: Linus Nielsen Feltzing <linus@haxx.se>
Date: Thu, 14 Apr 2005 11:51:31 +0000
Subject: New API for buffered PCM playback

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@6284 a1c6a512-1295-4272-9138-f99709370657
---
 apps/debug_menu.c              |  57 +++++++++++++-------
 firmware/export/pcm_playback.h |  10 ++++
 firmware/pcm_playback.c        | 119 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 167 insertions(+), 19 deletions(-)

diff --git a/apps/debug_menu.c b/apps/debug_menu.c
index 3969972..f140295 100644
--- a/apps/debug_menu.c
+++ b/apps/debug_menu.c
@@ -63,8 +63,8 @@
 #include "pcm_playback.h"
 #include "buffer.h"
 
-#define CHUNK_SIZE      44100    /* Transfer CHUNK_SIZE bytes on
-                                    each DMA transfer */
+#define CHUNK_SIZE      0x100000    /* Transfer CHUNK_SIZE bytes on
+                                       each DMA transfer */
 
 static unsigned char line = 0;
 static unsigned char *audio_buffer;
@@ -95,9 +95,9 @@ static void puts(const char *fmt, ...)
 /* Very basic WAVE-file support.. Just for testing purposes.. */
 int load_wave(char *filename)
 {
-    int f, i;
+    int f, i, num;
     unsigned char buf[32];
-    unsigned short *p;
+    unsigned short *p, *end;
 
     puts("Loading %s..", filename);
 
@@ -136,10 +136,18 @@ int load_wave(char *filename)
     close(f);
 
     puts("Changing byte order..");
+    end = (unsigned short *)(audio_buffer + audio_size);
     p = (unsigned short *)audio_buffer;
-    for (i=0; i<audio_size/2; i++, p++)
+    while(p < end)
     {
-        *p = SWAB16(*p);
+        /* Swap 128k at a time, to allow the other threads to run */
+        num = MIN(0x20000, (int)(end - p));
+        for(i = 0;i < num;i++)
+        {
+            *p = SWAB16(*p);
+            p++;
+        }
+        yield();
     }
 
     return 0;
@@ -152,20 +160,14 @@ int load_wave(char *filename)
 
 */
 
-static void test_get_more(unsigned char **ptr, long *size)
+int test_tracknum;
+static void test_trackchange(void)
 {
-    static long last_chunk_size = 0;
-
-    audio_pos += last_chunk_size;
-    
-    if(audio_pos < audio_size)
-    {
-        last_chunk_size = MIN(CHUNK_SIZE, (audio_size - audio_pos));
-        *ptr = &audio_buffer[audio_pos];
-        *size = last_chunk_size;
-    }
+    test_tracknum++;
 }
 
+extern int pcmbuf_unplayed_bytes;
+
 bool uda1380_test(void)
 {
     long button;
@@ -173,11 +175,15 @@ bool uda1380_test(void)
     bool done = false;
     char buf[80];
     bool play = true;
+    int sz;
+    char *ptr;
 
     lcd_setmargins(0, 0);
     lcd_clear_display(); 
     lcd_update();
 
+    test_tracknum = 1;
+    
     line = 0;
     
     if (load_wave("/sample.wav") == -1)
@@ -188,10 +194,19 @@ bool uda1380_test(void)
     puts("Playing..");
 
     audio_pos = 0;
+    pcm_play_init();
     pcm_set_frequency(44100);
     pcm_set_volume(0xff - vol);
-    pcm_play_data(audio_buffer, CHUNK_SIZE,
-                  test_get_more);
+
+    ptr = audio_buffer;
+    for(sz = 0;sz < audio_size;sz += CHUNK_SIZE)
+    {
+        if(!pcm_play_add_chunk(ptr, CHUNK_SIZE, test_trackchange))
+            break;
+        ptr += MIN(CHUNK_SIZE, (audio_size - sz));
+    }
+
+    pcm_play_start();
 
     while(!done)
     {
@@ -205,6 +220,10 @@ bool uda1380_test(void)
         lcd_puts(0, line+3, buf);
         snprintf(buf, sizeof(buf), "DSR0: %02x", DSR0);
         lcd_puts(0, line+4, buf);
+        snprintf(buf, sizeof(buf), "Track: %d", test_tracknum);
+        lcd_puts(0, line+5, buf);
+        snprintf(buf, sizeof(buf), "Unplayed: %08x", pcmbuf_unplayed_bytes);
+        lcd_puts(0, line+6, buf);
         lcd_update();
 
         button = button_get_w_tmo(HZ/2);
diff --git a/firmware/export/pcm_playback.h b/firmware/export/pcm_playback.h
index f661209..23ec1fe 100644
--- a/firmware/export/pcm_playback.h
+++ b/firmware/export/pcm_playback.h
@@ -21,11 +21,21 @@
 
 void pcm_init(void);
 void pcm_set_frequency(unsigned int frequency);
+
+/* This is for playing "raw" PCM data */
 void pcm_play_data(const unsigned char* start, int size,
                    void (*get_more)(unsigned char** start, long* size));
+
 void pcm_play_stop(void);
 void pcm_play_pause(bool play);
 bool pcm_is_playing(void);
 void pcm_set_volume(int volume);
 
+/* These functions are for playing chained buffers of PCM data */
+void pcm_play_init(void);
+void pcm_play_start(void);
+bool pcm_play_add_chunk(void *addr, int size, void (*callback)(void));
+int pcm_play_num_used_buffers(void);
+void pcm_play_set_watermark(int numbytes, void (*callback)(int bytes_left));
+
 #endif
diff --git a/firmware/pcm_playback.c b/firmware/pcm_playback.c
index e1afea9..f5fc5e7 100644
--- a/firmware/pcm_playback.c
+++ b/firmware/pcm_playback.c
@@ -207,3 +207,122 @@ void pcm_init(void)
 
     pcm_set_frequency(44100);
 }
+
+
+#define NUM_PCM_BUFFERS 16 /* Must be a power of 2 */
+#define NUM_PCM_BUFFERS_MASK (NUM_PCM_BUFFERS - 1)
+
+struct pcmbufdesc
+{
+    void *addr;
+    int size;
+    void (*callback)(void); /* Call this when the buffer has been played */
+} pcmbuffers[NUM_PCM_BUFFERS];
+
+int pcmbuf_read_index;
+int pcmbuf_write_index;
+int pcmbuf_unplayed_bytes;
+int pcmbuf_watermark;
+void (*pcmbuf_watermark_callback)(int bytes_left);
+
+int pcm_play_num_used_buffers(void)
+{
+    return (pcmbuf_write_index - pcmbuf_read_index) & NUM_PCM_BUFFERS_MASK;
+}
+
+void pcm_play_set_watermark(int numbytes, void (*callback)(int bytes_left))
+{
+    pcmbuf_watermark = numbytes;
+    pcmbuf_watermark_callback = callback;
+}
+
+bool pcm_play_add_chunk(void *addr, int size, void (*callback)(void))
+{
+    /* We don't use the last buffer, since we can't see the difference
+       between the full and empty condition */
+    if(pcm_play_num_used_buffers() < (NUM_PCM_BUFFERS - 1))
+    {
+        pcmbuffers[pcmbuf_write_index].addr = addr;
+        pcmbuffers[pcmbuf_write_index].size = size;
+        pcmbuffers[pcmbuf_write_index].callback = callback;
+        pcmbuf_write_index = (pcmbuf_write_index+1) & NUM_PCM_BUFFERS_MASK;
+        pcmbuf_unplayed_bytes += size;
+        return true;
+    }
+    else
+        return false;
+}
+
+void pcm_play_init(void)
+{
+    pcmbuf_read_index = 0;
+    pcmbuf_write_index = 0;
+    pcmbuf_unplayed_bytes = 0;
+    pcm_play_set_watermark(0x10000, NULL);
+}
+
+static int last_chunksize = 0;
+
+static void pcm_play_callback(unsigned char** start, long* size)
+{
+    struct pcmbufdesc *desc = &pcmbuffers[pcmbuf_read_index];
+    int sz;
+
+    pcmbuf_unplayed_bytes -= last_chunksize;
+    
+    if(desc->size == 0)
+    {
+        /* The buffer is finished, call the callback function */
+        if(desc->callback)
+            desc->callback();
+
+        /* Advance to the next buffer */
+        pcmbuf_read_index = (pcmbuf_read_index + 1) & NUM_PCM_BUFFERS_MASK;
+        desc = &pcmbuffers[pcmbuf_read_index];
+    }
+    
+    if(pcm_play_num_used_buffers())
+    {
+        /* Play max 64K at a time */
+        sz = MIN(desc->size, 32768);
+        *start = desc->addr;
+        *size = sz;
+
+        /* Update the buffer descriptor */
+        desc->size -= sz;
+        desc->addr += sz;
+
+        last_chunksize = sz;
+    }
+    else
+    {
+        /* No more buffers */
+        *size = 0;
+    }
+#if 0
+    if(pcmbuf_unplayed_bytes <= pcmbuf_watermark)
+    {
+        if(pcmbuf_watermark_callback)
+        {
+            pcmbuf_watermark_callback(pcmbuf_unplayed_bytes);
+        }
+    }
+#endif
+}
+
+void pcm_play_start(void)
+{
+    struct pcmbufdesc *desc = &pcmbuffers[pcmbuf_read_index];
+    int size;
+    char *start;
+    
+    if(!pcm_is_playing())
+    {
+        size = MIN(desc->size, 32768);
+        start = desc->addr;
+        pcm_play_data(start, size, pcm_play_callback);
+        last_chunksize = size;
+        desc->size -= size;
+        desc->addr += size;
+    }
+}
-- 
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