Implement universal in-PCM-driver software volume control.

Implements double-buffered volume, balance and prescaling control in
the main PCM driver when HAVE_SW_VOLUME_CONTROL is defined ensuring
that all PCM is volume controlled and level changes are low in latency.

Supports -73 to +6 dB using a 15-bit factor so that no large-integer
math is needed.

Low-level hardware drivers do not have to implement it themselves but
parameters can be changed (currently defined in pcm-internal.h) to work
best with a particular SoC or to provide different volume ranges.

Volume and prescale calls should be made in the codec driver. It should
appear as a normal hardware interface. PCM volume calls expect .1 dB
units.

Change-Id: Idf6316a64ef4fb8abcede10707e1e6c6d01d57db
Reviewed-on: http://gerrit.rockbox.org/423
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>

1 files changed, 0 insertions, 18 deletions

diff --git a/lib/rbcodec/dsp/dsp_misc.c b/lib/rbcodec/dsp/dsp_misc.c
index 1083215c17..a8c9423cfb 100644
--- a/lib/rbcodec/dsp/dsp_misc.c
+++ b/lib/rbcodec/dsp/dsp_misc.c
@@ -35,11 +35,6 @@
 #endif
 #include <string.h>
 
-#if defined(HAVE_SW_TONE_CONTROLS) && defined(HAVE_SW_VOLUME_CONTROL)
-/* Still need this for volume control */
-#include "settings.h"
-#endif
-
 /** Firmware callback interface **/
 
 /* Hook back from firmware/ part of audio, which can't/shouldn't call apps/
@@ -58,19 +53,6 @@ int dsp_callback(int msg, intptr_t param)
     case DSP_CALLBACK_SET_TREBLE:
         tone_set_treble(param);
         break;
-    /* FIXME: This must be done by bottom-level PCM driver so it works with
-              all PCM, not here and not in mixer. I won't fully support it
-              here with all streams. -- jethead71 */
-#ifdef HAVE_SW_VOLUME_CONTROL
-    case DSP_CALLBACK_SET_SW_VOLUME:
-        if (global_settings.volume < SW_VOLUME_MAX ||
-            global_settings.volume > SW_VOLUME_MIN)
-        {
-            int vol_gain = get_replaygain_int(global_settings.volume * 100);
-            pga_set_gain(PGA_VOLUME, vol_gain);
-        }
-        break;
-#endif /* HAVE_SW_VOLUME_CONTROL */
 #endif /* HAVE_SW_TONE_CONTROLS */
     case DSP_CALLBACK_SET_CHANNEL_CONFIG:
         channel_mode_set_config(param);