Clean up peak calculating code.

Mixer needn't keep peak data around that will never be used. Just
pass pcm_peaks structure to it instead of allocating for every
channel. Plugin API becomes incompatible.

vu_meter digital mode was still using global peak calculation;
switch it to playback channel like the rest.

Remove some accumulated soil peaks inside pcm.c and make it more
generic.

Change-Id: Ib4d268d80b6a9d09915eea1c91eab483c1a2c009

5 files changed, 59 insertions, 70 deletions

diff --git a/firmware/export/pcm-internal.h b/firmware/export/pcm-internal.h
index abe3fe08dc..397cf6832f 100644
--- a/firmware/export/pcm-internal.h
+++ b/firmware/export/pcm-internal.h
@@ -29,13 +29,6 @@
     ({ (start) = (void *)(((uintptr_t)(start) + 3) & ~3); \
        (size) &= ~3; })
 
-struct pcm_peaks
-{
-    long period;
-    long tick;
-    uint16_t val[2];
-};
-
 void pcm_do_peak_calculation(struct pcm_peaks *peaks, bool active,
                              const void *addr, int count);
 
diff --git a/firmware/export/pcm.h b/firmware/export/pcm.h
index df82c6092d..608129c078 100644
--- a/firmware/export/pcm.h
+++ b/firmware/export/pcm.h
@@ -21,7 +21,7 @@
 #ifndef PCM_PLAYBACK_H
 #define PCM_PLAYBACK_H
 
-#include <string.h> /* size_t */
+#include <sys/types.h> /* size_t, uint32_t */
 #include "config.h"
 
 enum pcm_dma_status
@@ -71,6 +71,16 @@ void pcm_play_data(pcm_play_callback_type get_more,
                    pcm_status_callback_type status_cb,
                    const void *start, size_t size);
 
+/* Kept internally for global PCM and used by mixer's verion of peak
+   calculation */
+struct pcm_peaks
+{
+    uint32_t left;  /* Left peak value */
+    uint32_t right; /* Right peak value */
+    long period;    /* For tracking calling period */
+    long tick;      /* Last tick called */
+};
+
 void pcm_calculate_peaks(int *left, int *right);
 const void* pcm_get_peak_buffer(int* count);
 size_t pcm_get_bytes_waiting(void);
diff --git a/firmware/export/pcm_mixer.h b/firmware/export/pcm_mixer.h
index 5d8deb2bbf..f6d212d8e0 100644
--- a/firmware/export/pcm_mixer.h
+++ b/firmware/export/pcm_mixer.h
@@ -111,7 +111,7 @@ const void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count
 
 /* Calculate peak values for channel */
 void mixer_channel_calculate_peaks(enum pcm_mixer_channel channel,
-                                   int *left, int *right);
+                                   struct pcm_peaks *peaks);
 
 /* Adjust channel pointer by a given offset to support movable buffers */
 void mixer_adjust_channel_address(enum pcm_mixer_channel channel,
diff --git a/firmware/pcm.c b/firmware/pcm.c
index 621ed56e0d..94b0d6eefb 100644
--- a/firmware/pcm.c
+++ b/firmware/pcm.c
@@ -102,9 +102,6 @@ unsigned long pcm_sampr SHAREDBSS_ATTR = HW_SAMPR_DEFAULT;
 /* samplerate frequency selection index */
 int pcm_fsel SHAREDBSS_ATTR = HW_FREQ_DEFAULT;
 
-/* peak data for the global peak values - i.e. what the final output is */
-static struct pcm_peaks global_peaks;
-
 /* Called internally by functions to reset the state */
 static void pcm_play_stopped(void)
 {
@@ -125,42 +122,38 @@ static void pcm_wait_for_init(void)
  *
  * Used for recording and playback.
  */
-static void pcm_peak_peeker(const int32_t *addr, int count, uint16_t peaks[2])
+static void pcm_peak_peeker(const int16_t *p, int count,
+                            struct pcm_peaks *peaks)
 {
-    int peak_l = 0, peak_r = 0;
-    const int32_t * const end = addr + count;
+    uint32_t peak_l = 0, peak_r = 0;
+    const int16_t *pend = p + 2 * count;
 
     do
     {
-        int32_t value = *addr;
-        int ch;
-
-#ifdef ROCKBOX_BIG_ENDIAN
-        ch = value >> 16;
-#else
-        ch = (int16_t)value;
-#endif
-        if (ch < 0)
-            ch = -ch;
-        if (ch > peak_l)
-            peak_l = ch;
-
-#ifdef ROCKBOX_BIG_ENDIAN
-        ch = (int16_t)value;
-#else
-        ch = value >> 16;
-#endif
-        if (ch < 0)
-            ch = -ch;
-        if (ch > peak_r)
-            peak_r = ch;
-
-        addr += 4;
+        int32_t s;
+
+        s = p[0];
+
+        if (s < 0)
+            s = -s;
+
+        if ((uint32_t)s > peak_l)
+            peak_l = s;
+
+        s = p[1];
+
+        if (s < 0)
+            s = -s;
+
+        if ((uint32_t)s > peak_r)
+            peak_r = s;
+
+        p += 4 * 2; /* Every 4th sample, interleaved */
     }
-    while (addr < end);
+    while (p < pend);
 
-    peaks[0] = peak_l;
-    peaks[1] = peak_r;
+    peaks->left = peak_l;
+    peaks->right = peak_r;
 }
 
 void pcm_do_peak_calculation(struct pcm_peaks *peaks, bool active,
@@ -177,7 +170,7 @@ void pcm_do_peak_calculation(struct pcm_peaks *peaks, bool active,
     else if (period > HZ/5)
         period = HZ/5;
 
-    peaks->period = (3*peaks->period + period) >> 2;
+    peaks->period = (3*peaks->period + period) / 4;
     peaks->tick = tick;
 
     if (active)
@@ -186,29 +179,32 @@ void pcm_do_peak_calculation(struct pcm_peaks *peaks, bool active,
         count = MIN(framecount, count);
 
         if (count > 0)
-            pcm_peak_peeker((int32_t *)addr, count, peaks->val);
+            pcm_peak_peeker(addr, count, peaks);
         /* else keep previous peak values */
     }
     else
     {
         /* peaks are zero */
-        peaks->val[0] = peaks->val[1] = 0;
+        peaks->left = peaks->right = 0;
     }
 }
 
 void pcm_calculate_peaks(int *left, int *right)
 {
+    /* peak data for the global peak values - i.e. what the final output is */
+    static struct pcm_peaks peaks;
+
     int count;
     const void *addr = pcm_play_dma_get_peak_buffer(&count);
 
-    pcm_do_peak_calculation(&global_peaks, pcm_playing && !pcm_paused,
+    pcm_do_peak_calculation(&peaks, pcm_playing && !pcm_paused,
                             addr, count);
 
     if (left)
-        *left = global_peaks.val[0];
+        *left = peaks.left;
 
     if (right)
-        *right = global_peaks.val[1];
+        *right = peaks.right;
 }
 
 const void* pcm_get_peak_buffer(int * count)
@@ -471,20 +467,20 @@ static void pcm_recording_stopped(void)
  */
 void pcm_calculate_rec_peaks(int *left, int *right)
 {
-    static uint16_t peaks[2];
+    static struct pcm_peaks peaks;
 
     if (pcm_recording)
     {
-        const void *peak_addr = pcm_rec_peak_addr;
-        const void *addr = pcm_rec_dma_get_peak_buffer();
+        const int16_t *peak_addr = pcm_rec_peak_addr;
+        const int16_t *addr = pcm_rec_dma_get_peak_buffer();
 
         if (addr != NULL)
         {
-            int count = (int)(((intptr_t)addr - (intptr_t)peak_addr) >> 2);
+            int count = (addr - peak_addr) / 2; /* Interleaved L+R */
 
             if (count > 0)
             {
-                pcm_peak_peeker((int32_t *)peak_addr, count, peaks);
+                pcm_peak_peeker(peak_addr, count, &peaks);
 
                 if (peak_addr == pcm_rec_peak_addr)
                     pcm_rec_peak_addr = addr;
@@ -494,15 +490,15 @@ void pcm_calculate_rec_peaks(int *left, int *right)
     }
     else
     {
-        peaks[0] = peaks[1] = 0;
+        peaks.left = peaks.right = 0;
     }
 
     if (left)
-        *left = peaks[0];
+        *left = peaks.left;
 
     if (right)
-        *right = peaks[1];
-} /* pcm_calculate_rec_peaks */
+        *right = peaks.right;
+}
 
 bool pcm_is_recording(void)
 {
diff --git a/firmware/pcm_mixer.c b/firmware/pcm_mixer.c
index 85d31ade70..cddff431ec 100644
--- a/firmware/pcm_mixer.c
+++ b/firmware/pcm_mixer.c
@@ -60,9 +60,6 @@ static size_t next_size = 0;    /* Size of buffer to play next time */
 /* Descriptors for all available channels */
 static struct mixer_channel channels[PCM_MIXER_NUM_CHANNELS] IBSS_ATTR;
 
-/* History for channel peaks */
-static struct pcm_peaks channel_peaks[PCM_MIXER_NUM_CHANNELS];
-
 /* Packed pointer array of all playing (active) channels in "channels" array */
 static struct mixer_channel * active_channels[PCM_MIXER_NUM_CHANNELS+1] IBSS_ATTR;
 
@@ -389,21 +386,14 @@ const void * mixer_channel_get_buffer(enum pcm_mixer_channel channel, int *count
 
 /* Calculate peak values for channel */
 void mixer_channel_calculate_peaks(enum pcm_mixer_channel channel,
-                                   int *left, int *right)
+                                   struct pcm_peaks *peaks)
 {
-    struct mixer_channel *chan = &channels[channel];
-    struct pcm_peaks *peaks = &channel_peaks[channel];
     int count;
     const void *addr = mixer_channel_get_buffer(channel, &count);
 
-    pcm_do_peak_calculation(peaks, chan->status == CHANNEL_PLAYING,
+    pcm_do_peak_calculation(peaks,
+                            channels[channel].status == CHANNEL_PLAYING,
                             addr, count);
-
-    if (left)
-        *left = peaks->val[0];
-
-    if (right)
-        *right = peaks->val[1];
 }
 
 /* Adjust channel pointer by a given offset to support movable buffers */