Enable setting of global output samplerate on certain targets.

Replaces the NATIVE_FREQUENCY constant with a configurable frequency.

The user may select 48000Hz if the hardware supports it. The default is
still 44100Hz and the minimum is 44100Hz. The setting is located in the
playback settings, under "Frequency".

"Frequency" was duplicated in english.lang for now to avoid having to
fix every .lang file for the moment and throwing everything out of sync
because of the new play_frequency feature in features.txt. The next
cleanup should combine it with the one included for recording and
generalize the ID label.

If the hardware doesn't support 48000Hz, no setting will be available.

On particular hardware where very high rates are practical and desireable,
the upper bound can be extended by patching.

The PCM mixer can be configured to play at the full hardware frequency
range. The DSP core can configure to the hardware minimum up to the
maximum playback setting (some buffers must be reserved according to
the maximum rate).

If only 44100Hz is supported or possible on a given target for playback,
using the DSP and mixer at other samperates is possible if the hardware
offers them.

Change-Id: I6023cf0c0baa8bc6292b6919b4dd3618a6a25622
Reviewed-on: http://gerrit.rockbox.org/479
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>

1 files changed, 8 insertions, 5 deletions

diff --git a/apps/beep.c b/apps/beep.c
index 8ac7ccf224..25b5e0e391 100644
--- a/apps/beep.c
+++ b/apps/beep.c
@@ -21,10 +21,10 @@
 #include "config.h"
 #include "system.h"
 #include "settings.h"
-#include "dsp_core.h" /* for NATIVE_FREQUENCY */
 #include "pcm.h"
 #include "pcm_mixer.h"
 #include "misc.h"
+#include "fixedpoint.h"
 
 /** Beep generation, CPU optimized **/
 #include "asm/beep.c"
@@ -39,8 +39,10 @@ static uint32_t beep_amplitude; /* Amplitude of square wave generator */
 #endif
 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)
+#define BEEP_COUNT(fs, duration) ((fs) / 1000 * (duration))
+
+/* Reserve enough static space for keyclick to fit in worst case */
+#define BEEP_BUF_COUNT  BEEP_COUNT(PLAY_SAMPR_MAX, KEYCLICK_DURATION)
 static int16_t beep_buf[BEEP_BUF_COUNT*2] IBSS_ATTR __attribute__((aligned(4)));
 
 /* Callback to generate the beep frames - also don't want inlining of
@@ -75,9 +77,10 @@ void beep_play(unsigned int frequency, unsigned int duration,
         amplitude = INT16_MAX;
 
     /* Setup the parameters for the square wave generator */
+    uint32_t fout = mixer_get_frequency();
     beep_phase = 0;
-    beep_step = 0xffffffffu / NATIVE_FREQUENCY * frequency;
-    beep_count = NATIVE_FREQUENCY / 1000 * duration;
+    beep_step = fp_div(frequency, fout, 32);
+    beep_count = BEEP_COUNT(fout, duration);
 
 #ifdef BEEP_GENERIC
     beep_amplitude = amplitude;