* 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@xxxxxx>
---
drivers/media/platform/vivid/vivid-sdr-cap.c | 31 +++++++++++-----------------
1 file changed, 12 insertions(+), 19 deletions(-)
diff --git a/drivers/media/platform/vivid/vivid-sdr-cap.c b/drivers/media/platform/vivid/vivid-sdr-cap.c
index c36b3f5..fcbf498 100644
--- a/drivers/media/platform/vivid/vivid-sdr-cap.c
+++ b/drivers/media/platform/vivid/vivid-sdr-cap.c
@@ -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 agle 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;
--
http://palosaari.fi/
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