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[media] vivid: sdr cap: few enhancements 

* Constify struct

* Fix comments

* Fix alignment

* Use modulus to transfer phase angles

* Correct float [-1.0, +1.0] to s8 [-128, 127] conversion

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Antti Palosaari 2015-09-01 20:04:51 -03:00 committed by Mauro Carvalho Chehab
parent f335c3f229
commit 60f6873544
1 changed files with 12 additions and 19 deletions
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31
drivers/media/platform/vivid/vivid-sdr-cap.c
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@ -41,7 +41,7 @@ struct vivid_format {
};
/* format descriptions for capture and preview */
static struct vivid_format formats[] = {
static const struct vivid_format formats[] = {
{
.pixelformat = V4L2_SDR_FMT_CU8,
.buffersize = SDR_CAP_SAMPLES_PER_BUF * 2,
@ -502,16 +502,10 @@ void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
s32 fixp_i;
s32 fixp_q;
/*
* TODO: Generated beep tone goes very crackly when sample rate is
* increased to ~1Msps or more. That is because of huge rounding error
* of phase angle caused by used cosine implementation.
*/
/* calculate phase step */
#define BEEP_FREQ 1000 /* 1kHz beep */
src_phase_step = DIV_ROUND_CLOSEST(FIXP_2PI * BEEP_FREQ,
dev->sdr_adc_freq);
dev->sdr_adc_freq);
for (i = 0; i < plane_size; i += 2) {
mod_phase_step = fixp_cos32_rad(dev->sdr_fixp_src_phase,
@ -522,17 +516,15 @@ void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
dev->sdr_fixp_mod_phase += div_s64(s64tmp, M_100000PI);
/*
* Transfer phases to [0 / 2xPI] in order to avoid variable
* Transfer phase angle to [0, 2xPI] in order to avoid variable
* overflow and make it suitable for cosine implementation
* used, which does not support negative angles.
*/
while (dev->sdr_fixp_mod_phase < FIXP_2PI)
dev->sdr_fixp_mod_phase += FIXP_2PI;
while (dev->sdr_fixp_mod_phase > FIXP_2PI)
dev->sdr_fixp_mod_phase -= FIXP_2PI;
dev->sdr_fixp_src_phase %= FIXP_2PI;
dev->sdr_fixp_mod_phase %= FIXP_2PI;
while (dev->sdr_fixp_src_phase > FIXP_2PI)
dev->sdr_fixp_src_phase -= FIXP_2PI;
if (dev->sdr_fixp_mod_phase < 0)
dev->sdr_fixp_mod_phase += FIXP_2PI;
fixp_i = fixp_cos32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
fixp_q = fixp_sin32_rad(dev->sdr_fixp_mod_phase, FIXP_2PI);
@ -544,7 +536,7 @@ void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
switch (dev->sdr_pixelformat) {
case V4L2_SDR_FMT_CU8:
/* convert 'fixp float' to u8 */
/* convert 'fixp float' to u8 [0, +255] */
/* u8 = X * 127.5 + 127.5; X is float [-1.0, +1.0] */
fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
@ -552,9 +544,10 @@ void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
break;
case V4L2_SDR_FMT_CS8:
/* convert 'fixp float' to s8 */
fixp_i = fixp_i * 1275;
fixp_q = fixp_q * 1275;
/* convert 'fixp float' to s8 [-128, +127] */
/* s8 = X * 127.5 - 0.5; X is float [-1.0, +1.0] */
fixp_i = fixp_i * 1275 - FIXP_FRAC * 5;
fixp_q = fixp_q * 1275 - FIXP_FRAC * 5;
*vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
*vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
break;