[Sound-open-firmware] [PATCH 2/4] Tone: Add channel specific volume plus other fixes

[Takashi Iwai]

On Thu, 22 Jun 2017 10:47:54 +0200,
Seppo Ingalsuo wrote:
> 
> 
> 
> On 22.06.2017 11:28, Takashi Iwai wrote:
> > On Thu, 22 Jun 2017 10:04:27 +0200,
> > Seppo Ingalsuo wrote:
> >>
> >> On 22.06.2017 04:31, Keyon Jie wrote:
> >>> On 2017年06月22日 01:12, Seppo Ingalsuo wrote:
> >>>> The mono tone level can be controlled per channel. A similar channel map
> >>>> feature as in the volume component was added into volume command of
> >>>> tone.
> >>>>
> >>>> The default tone frequency of 997 Hz was updated to a proper Q16.16
> >>>> value.
> >>>>
> >>>> Moved tone function pointer set to tone_new() since it is not modified
> >>>> later.
> >>>>
> >>>> Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo at linux.intel.com>
> >>>> ---
> >>>>    src/audio/tone.c | 56
> >>>> ++++++++++++++++++++++++++++++++++++++++++--------------
> >>>>    1 file changed, 42 insertions(+), 14 deletions(-)
> >>>>
> >>>> diff --git a/src/audio/tone.c b/src/audio/tone.c
> >>>> index f45d8be..d1c7468 100644
> >>>> --- a/src/audio/tone.c
> >>>> +++ b/src/audio/tone.c
> >>>> @@ -56,7 +56,8 @@
> >>>>      #define TONE_NUM_FS            13       /* Table size for 8-192
> >>>> kHz range */
> >>>>    #define TONE_AMPLITUDE_DEFAULT 2147484  /* -60 dB from full scale */
> >>>> -#define TONE_FREQUENCY_DEFAULT 16334848 /* 997 in Q18.14 */
> >>>> +#define TONE_FREQUENCY_DEFAULT 65339392 /* 997 Hz in Q16.16 */
> >>>> +#define TONE_VOLUME_DEFAULT 65536       /* 1.0 in Q16.16 */
> >>> will they be more readable in hexadecimal?
> >> Unfortunately the C preprocessor doesn't process float to fixed math
> >> so I can't use any nice macro to create these. In hex it would look
> >> like this and in my opinion it's not any better. The Q notation is
> >> only sometimes by chance such that integer and decimal bits are not
> >> mixed into same hex digit. For frequency Qx.y notation the used x is
> >> sufficient to get to ultrasound frequencies and y to make precise
> >> enough sweeps.
> >>
> >> #define TONE_AMPLITUDE_DEFAULT 0x20C49C  /* -60 dB from full scale */
> >> #define TONE_FREQUENCY_DEFAULT 0xF940000 /* 997 Hz in Q18.14 */
> >> #define TONE_FREQUENCY_DEFAULT 0x3E50000 /* 997 Hz in Q16.16 */
> >> #define TONE_VOLUME_DEFAULT 0x10000       /* 1.0 in Q16.16 */
> >>
> >> To convert these with any calculator to floats when debugging code
> >> (these are fractional numbers) there's extra effort needed with hex so
> >> I definitely prefer decimal. Hex is good for bit masks but these are
> >> not such.
> > It's a fixed-point, so you can introduce a simple macro like
> >
> > #define TONE_FREQ_SHIFT		16
> > #define TONE_FREQ(x, y)		((x) << TONE_FREQ_SHIFT | (y))
> >
> > then TONE_FREQUENCY_DEFAULT will be TONE_FREQ(997, 0), and so on.
> > If you need to change the base shift, just change the TONE_FREQ_SHIFT
> > and the rest remains as is.
> 
> Yes, that works for integers and it is readable but the needed
> frequencies are often decimal numbers in Hz. E.g. C5 note is 523.251
> Hz or if a sweep is started from 4th third octave band the frequency
> would be 31.5 Hz.

Yeah, the decimal point is tricky.

> So I myself do with Octave that I use as pocket calculator
> >> printf('%d\n',round(523.251*2^16))
> 34291778
> >> printf('%d\n',round(31.5*2^16))
> 2064384
> >> printf('%d\n',round(10^(-60/20)*2^31))
> 2147484

I thought C compiler (not preprocessor) should optimize the conversion 
and handle as an integer constant.

#define TONE_FREQ(f)	(int)((f) * (2 << 16))	/* f = float */

and
	int x = TONE_FREQ(523.251);

should be converted to

	int x = 34291778;


Takashi