Small change to PCM recording API for low latency effects. Latency can be as low as 14 samples from input to output including the FIFOs (ColdFire) but 16 is more reasonable an expectation if only tranferring one sample per interrupt (\!). May convert PCM playback to use the same method as it can still be used in the old manner with some slight mods but has the potential to enable new features since it is more flexible.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@11668 a1c6a512-1295-4272-9138-f99709370657

apps/plugin.c

@@ -482,6 +482,7 @@ static const struct plugin_api rockbox_api = {
 
 #if CONFIG_CODEC == SWCODEC && defined(HAVE_RECORDING) && !defined(SIMULATOR)
     sound_default,
+    pcm_record_more,
 #endif
 };
 

apps/plugin.h

@@ -580,8 +580,8 @@ struct plugin_api {
 #ifndef SIMULATOR
     void (*pcm_init_recording)(void);
     void (*pcm_close_recording)(void);
-    void (*pcm_record_data)(pcm_more_callback_type more_ready,
+    void (*pcm_record_data)(pcm_more_callback_type2 more_ready,
-                            unsigned char *start, size_t size);
+                            void *start, size_t size);
     void (*pcm_stop_recording)(void);
     void (*pcm_calculate_rec_peaks)(int *left, int *right);
     void (*audio_set_recording_gain)(int left, int right, int type);
@@ -598,6 +598,7 @@ struct plugin_api {
 
 #if CONFIG_CODEC == SWCODEC && defined(HAVE_RECORDING) && !defined(SIMULATOR)
     int (*sound_default)(int setting);
+    void (*pcm_record_more)(void *start, size_t size);
 #endif
 };
 

firmware/export/pcm_playback.h

@@ -24,6 +24,7 @@
 /* Typedef for registered callback (play and record) */
 typedef void (*pcm_more_callback_type)(unsigned char **start,
                                        size_t *size);
+typedef int (*pcm_more_callback_type2)(int status);
 
 void pcm_init(void);
 

firmware/export/pcm_record.h

@@ -20,9 +20,9 @@
 #ifndef PCM_RECORD_H
 #define PCM_RECORD_H
 
-#define DMA_REC_ERROR_DMA       ((size_t)-1)
+#define DMA_REC_ERROR_DMA       (-1)
 #ifdef HAVE_SPDIF_IN
-#define DMA_REC_ERROR_SPDIF     ((size_t)-2)
+#define DMA_REC_ERROR_SPDIF     (-2)
 #endif
 
 /**
@@ -36,12 +36,15 @@ void pcm_init_recording(void);
 void pcm_close_recording(void);
 
 /* Start recording "raw" PCM data */
-void pcm_record_data(pcm_more_callback_type more_ready,
+void pcm_record_data(pcm_more_callback_type2 more_ready,
-                     unsigned char *start, size_t size);
+                     void *start, size_t size);
 
 /* Stop tranferring data into supplied buffer */
 void pcm_stop_recording(void);
 
+/* Continue transferring data in - call during interrupt handler */
+void pcm_record_more(void *start, size_t size);
+
 void pcm_calculate_rec_peaks(int *left, int *right);
 
 /** General functions for high level codec recording **/
@@ -64,12 +67,12 @@ int  pcm_get_num_unprocessed(void);
 /** The following are for internal use between pcm_record.c and target-
     specific portion **/
 /* the registered callback function for when more data is available */
-extern volatile pcm_more_callback_type pcm_callback_more_ready;
+extern volatile pcm_more_callback_type2 pcm_callback_more_ready;
 /* DMA transfer in is currently active */
 extern volatile bool                    pcm_recording;
 
 /* APIs implemented in the target-specific portion */
-extern void pcm_rec_dma_start(const void *addr, size_t size);
+extern void pcm_rec_dma_start(void *addr, size_t size);
 extern void pcm_rec_dma_stop(void);
 
 #endif /* PCM_RECORD_H */

firmware/pcm_record.c

@@ -55,14 +55,10 @@
     be shared semi-privately **/
 
 /* the registered callback function for when more data is available */
-volatile pcm_more_callback_type pcm_callback_more_ready = NULL;
+volatile pcm_more_callback_type2 pcm_callback_more_ready = NULL;
 /* DMA transfer in is currently active */
 volatile bool                    pcm_recording           = false;
 
-/* APIs implemented in the target-specific portion */
-void pcm_rec_dma_start(const void *addr, size_t size);
-void pcm_rec_dma_stop(void);
-
 /** General recording state **/
 static bool is_recording;              /* We are recording */
 static bool is_paused;                 /* We have paused   */
@@ -225,16 +221,16 @@ static void pcm_thread_wait_for_stop(void)
 /*******************************************************************/
     
 /* Callback for when more data is ready */
-static void pcm_rec_have_more(unsigned char **data, size_t *size)
+static int pcm_rec_have_more(int status)
 {
-    if (*size != 0)
+    if (status < 0)
     {
         /* some error condition */
-        if (*size == DMA_REC_ERROR_DMA)
+        if (status == DMA_REC_ERROR_DMA)
         {
             /* Flush recorded data to disk and stop recording */
             queue_post(&pcmrec_queue, PCMREC_STOP, NULL);
-            return;
+            return -1;
         }
         /* else try again next transmission */
     }
@@ -244,8 +240,8 @@ static void pcm_rec_have_more(unsigned char **data, size_t *size)
         dma_wr_pos = (dma_wr_pos + PCM_CHUNK_SIZE) & PCM_CHUNK_MASK;
     }
 
-    *data = (unsigned char *)GET_PCM_CHUNK(dma_wr_pos);
+    pcm_record_more(GET_PCM_CHUNK(dma_wr_pos), PCM_CHUNK_SIZE);
-    *size = PCM_CHUNK_SIZE;
+    return 0;
 } /* pcm_rec_have_more */
 
 /** pcm_rec_* group **/
@@ -423,9 +419,9 @@ void audio_set_recording_options(struct audio_recording_options *options)
     if (audio_load_encoder(enc_config.afmt))
     {
         /* start DMA transfer */
-        pcm_record_data(pcm_rec_have_more, NULL, 0);
-        /* do unlock after starting to prevent preincrement of dma_wr_pos */
         dma_lock = pre_record_ticks == 0;
+        pcm_record_data(pcm_rec_have_more, GET_PCM_CHUNK(dma_wr_pos),
+                        PCM_CHUNK_SIZE);
     }
     else
     {
@@ -1621,19 +1617,13 @@ size_t enc_unget_pcm_data(size_t size)
  * Functions that do not require targeted implementation but only a targeted
  * interface
  */
-void pcm_record_data(pcm_more_callback_type more_ready,
+void pcm_record_data(pcm_more_callback_type2 more_ready,
-                     unsigned char *start, size_t size)
+                     void *start, size_t size)
 {
-    pcm_callback_more_ready = more_ready;
-
     if (!(start && size))
-    {
+        return;
-        size = 0;
-        if (more_ready)
-            more_ready(&start, &size);
-    }
 
-    if (start && size)
+    pcm_callback_more_ready = more_ready;
     pcm_rec_dma_start(start, size);
 } /* pcm_record_data */
 

firmware/target/coldfire/pcm-coldfire.c

@@ -287,7 +287,7 @@ void DMA0(void)
 /****************************************************************************
  ** Recording DMA transfer
  **/
-void pcm_rec_dma_start(const void *addr, size_t size)
+void pcm_rec_dma_start(void *addr, size_t size)
 {
     logf("pcm_rec_dma_start");
 
@@ -296,12 +296,6 @@ void pcm_rec_dma_start(const void *addr, size_t size)
 
     pcm_recording = true;
 
-    DAR1 = (unsigned long)addr;   /* Destination address */
-    SAR1 = (unsigned long)&PDIR2; /* Source address      */
-    BCR1 = size;                  /* Bytes to transfer   */
-
-    rec_peak_addr = (unsigned long *)addr;
-
     pcm_apply_settings(false);
 
     /* Start the DMA transfer.. */
@@ -309,18 +303,22 @@ void pcm_rec_dma_start(const void *addr, size_t size)
     INTERRUPTCLEAR = 0x03c00000;
 #endif
 
-    DCR1 = DMA_INT | DMA_EEXT | DMA_CS | DMA_AA | DMA_DINC |
+    SAR1 = (unsigned long)&PDIR2; /* Source address        */
-           DMA_DSIZE(3) | DMA_START;
+    DCR1 = DMA_INT | DMA_CS | DMA_AA | DMA_DINC | DMA_DSIZE(3);
+
+    pcm_record_more(addr, size);
+
+    DCR1 |= DMA_START;
 } /* pcm_dma_start */
 
 void pcm_rec_dma_stop(void)
 {
     logf("pcm_rec_dma_stop");
 
-    pcm_recording = false;
-
-    DCR1 = 0;
     DSR1 = 1;         /* Clear interrupt */
+    DCR1 = 0;
+
+    pcm_recording = false;
 } /* pcm_dma_stop */
 
 void pcm_init_recording(void)
@@ -338,7 +336,7 @@ void pcm_init_recording(void)
 
     pcm_rec_dma_stop();
 
-    ICR7 = (7 << 2);        /* Enable interrupt at level 7, priority 0      */
+    ICR7 = (6 << 2);        /* Enable interrupt at level 6, priority 0      */
     IMR &= ~(1 << 15);      /* bit 15 is DMA1                               */
 } /* pcm_init_recording */
 
@@ -359,17 +357,15 @@ void DMA1(void) __attribute__ ((interrupt_handler, section(".icode")));
 void DMA1(void)
 {
     int res = DSR1;
-    pcm_more_callback_type more_ready;
+    int status = 0;
-    unsigned char         *next_start;
+    pcm_more_callback_type2 more_ready;
-    ssize_t                next_size = 0; /* passing <> 0 is indicates
-                                             an error condition */
 
     DSR1  = 1;          /* Clear interrupt */
-    DCR1 &= ~DMA_EEXT;
+    DCR1 &= ~DMA_EEXT;  /* Disable peripheral request */
 
     if (res & 0x70)
     {
-        next_size = DMA_REC_ERROR_DMA;
+        status = DMA_REC_ERROR_DMA;
         logf("DMA1 err: 0x%x", res);
     }
 #ifdef HAVE_SPDIF_IN
@@ -377,37 +373,33 @@ void DMA1(void)
         (INTERRUPTSTAT & 0x01c00000)) /* valnogood, symbolerr, parityerr */
     {
         INTERRUPTCLEAR = 0x03c00000;
-        next_size = DMA_REC_ERROR_SPDIF;
+        status = DMA_REC_ERROR_SPDIF;
         logf("spdif err");
     }
 #endif
 
     more_ready = pcm_callback_more_ready;
 
-    if (more_ready)
+    if (more_ready != NULL && more_ready(status) >= 0)
-        more_ready(&next_start, &next_size);
-
-    if (next_size > 0)
-    {
-        /* Start peaking at dest */
-        rec_peak_addr = (unsigned long *)next_start;
-        DAR1  = (unsigned long)next_start; /* Destination address */
-        BCR1  = (unsigned long)next_size;  /* Bytes to transfer   */
-        DCR1 |= DMA_EEXT;
         return;
-    }
+
-    else
-    {
 #if 0
     /* int. logfs can trash the display */
-        logf("DMA1 No Data:0x%04x", res);
+    logf("DMA1 done:%04x %d", res, status);
 #endif
-    }
-
     /* Finished recording */
     pcm_rec_dma_stop();
 } /* DMA1 */
 
+/* Continue transferring data in */
+void pcm_record_more(void *start, size_t size)
+{
+    rec_peak_addr = (unsigned long *)start; /* Start peaking at dest */
+    DAR1          = (unsigned long)start;   /* Destination address */
+    BCR1          = (unsigned long)size;    /* Bytes to transfer   */
+    DCR1         |= DMA_EEXT;
+}
+
 void pcm_mute(bool mute)
 {
     ac_mute(mute);