HAVE_SW_VOLUME_CONTROL is required and at this time only affects the
SDL targets using pcm-sdl.c.

Enables balance control in SDL targets, unless mono volume is in use.

Compiles software volume control as unbuffered when
PCM_SW_VOLUME_UNBUFFERED is defined. This avoids the overhead and
extra latency introduced by the double buffer when it is not needed.
Use this config when the target's PCM driver is buffered and sufficient
latency exists to perform safely the volume scaling.

Simulated targets that are double-buffered when made as native targets
remain so in the sim in order to run the same code.

Change-Id: Ifa77d2d3ae7376c65afecdfc785a084478cb5ffb
Reviewed-on: http://gerrit.rockbox.org/457
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested-by: Michael Sevakis <jethead71@rockbox.org>

Change-Id: I082411145a411ca7d41b359dea419ef8190d70ce

* SOUND_x enum can be generated by audiohw_settings.h along with settings
entries and sound_val2phys.

* VOLUME_MIN and VOLUME_MAX are no longer necessary within sound.c. If
you need them, they are for target-defined purposes.

* Fix up SDL volume implementation in sdl.c. Move sim volume calculation
code to pcm-sdl.c.

* Min trigger tresholds were based upon VOLUME_MIN for some reason.
These setting have nothing to do with playback volume. Since it is no
longer present, set these at -89dB which is the minimum peak meter
sensitivity setting.

* Fix an oversight in wm8758.c. I forgot to add the dB->register
conversion to audiohw_set_volume.

Change-Id: Ie1df33f1793eee75e6793f16bc7bddd16edb7f75

Change-Id: Ifeebed8f594fc56acbbd2439fb8186566cc04de8

Change-Id: I0678d3307fbcad32156f9f4e0f8b90eed5a20d92

This is going right in since it's long overdue. If anything is goofed,
drop me a line or just tweak it yourself if you know what's wrong. :-)

Make HW/SW codec interface more uniform when emulating HW functionality
on SWCODEC for functions such as "audiohw_set_pitch". The firmware-to-
DSP plumbing is in firmware/drivers/audiohw-swcodec.c. "sound_XXX"
APIs are all in sound.c with none in DSP code any longer.

Reduce number of settings definitions needed by each codec by providing
defaults for common ones like balance, channels and SW tone controls.

Remove need for separate SIM code and tables and add virtual codec header
for hosted targets.

Change-Id: I3f23702bca054fc9bda40f49824ce681bb7f777b

Onda VX747 sim was missing a limits #define; #include limits.h in
pcm_sw_volume.h.

Simply use the software volume control for the SIM volume control
rather than the SDL volume control when the target would have it
natively.

Change-Id: I8e924a2ff1b410f602452d2ea9b691efb82c931e

* Introduce CONFIG_BATTERY_MEASURE define, to allow targets (application)
to break powermgmt.c's assumption about the ability to read battery voltage.
There's now additionally percentage (android) and remaining time measure
(maemo). No measure at all also works (sdl app). If voltage can't be measured,
then battery_level() is king and it'll be used for power_history and runtime
estimation.

* Implement target's API in the simulator, i.e. _battery_voltage(), so it
doesn't need to implement it's own powermgmt.c and other stubs. Now
the sim behaves much more like a native target, although it still
changes the simulated battery voltage quickly,

* Other changes include include renaming battery_adc_voltage() to
_battery_voltage(), for consistency with the new target functions and
making some of the apps code aware that voltage and runtime estimation
is not always available.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31548 a1c6a512-1295-4272-9138-f99709370657

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31181 a1c6a512-1295-4272-9138-f99709370657

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@29452 a1c6a512-1295-4272-9138-f99709370657