Hi All,
Please ignore my patches for now. I have not run check patch.pl before
sending out
Patches. I will resend with necessary corrections.
Regards,
Prashant
On 01/12/14 2:33 pm, "Prashant Laddha (prladdha)" <prladdha@xxxxxxxxx>
wrote:
>Replaced Taylor series calculation with a look up table based
>calculation of (co)sine values. Also reworked fixed point
>implementation to reduce rounding errors.
>
>Cc: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>Cc: Antti Palosaari <crope@xxxxxx>
>
>Signed-off-by: Prashant Laddha <prladdha@xxxxxxxxx>
>---
> drivers/media/platform/vivid/Makefile | 2 +-
> drivers/media/platform/vivid/vivid-sdr-cap.c | 87 ++++++--------
> drivers/media/platform/vivid/vivid-sin.c | 171
>+++++++++++++++++++++++++++
> drivers/media/platform/vivid/vivid-sin.h | 30 +++++
> 4 files changed, 238 insertions(+), 52 deletions(-)
> create mode 100644 drivers/media/platform/vivid/vivid-sin.c
> create mode 100644 drivers/media/platform/vivid/vivid-sin.h
>
>diff --git a/drivers/media/platform/vivid/Makefile
>b/drivers/media/platform/vivid/Makefile
>index 756fc12..9d5fe1c 100644
>--- a/drivers/media/platform/vivid/Makefile
>+++ b/drivers/media/platform/vivid/Makefile
>@@ -2,5 +2,5 @@ vivid-objs := vivid-core.o vivid-ctrls.o
>vivid-vid-common.o vivid-vbi-gen.o \
> vivid-vid-cap.o vivid-vid-out.o vivid-kthread-cap.o
>vivid-kthread-out.o \
> vivid-radio-rx.o vivid-radio-tx.o vivid-radio-common.o \
> vivid-rds-gen.o vivid-sdr-cap.o vivid-vbi-cap.o vivid-vbi-out.o \
>- vivid-osd.o vivid-tpg.o vivid-tpg-colors.o
>+ vivid-osd.o vivid-tpg.o vivid-tpg-colors.o vivid-sin.o
> obj-$(CONFIG_VIDEO_VIVID) += vivid.o
>diff --git a/drivers/media/platform/vivid/vivid-sdr-cap.c
>b/drivers/media/platform/vivid/vivid-sdr-cap.c
>index 4af55f1..99fc2c7 100644
>--- a/drivers/media/platform/vivid/vivid-sdr-cap.c
>+++ b/drivers/media/platform/vivid/vivid-sdr-cap.c
>@@ -31,6 +31,7 @@
> #include "vivid-core.h"
> #include "vivid-ctrls.h"
> #include "vivid-sdr-cap.h"
>+#include "vivid-sin.h"
>
> static const struct v4l2_frequency_band bands_adc[] = {
> {
>@@ -423,40 +424,17 @@ int vidioc_g_fmt_sdr_cap(struct file *file, void
>*fh, struct v4l2_format *f)
> return 0;
> }
>
>-#define FIXP_FRAC (1 << 15)
>-#define FIXP_PI ((int)(FIXP_FRAC * 3.141592653589))
>-
>-/* cos() from cx88 driver: cx88-dsp.c */
>-static s32 fixp_cos(unsigned int x)
>-{
>- u32 t2, t4, t6, t8;
>- u16 period = x / FIXP_PI;
>-
>- if (period % 2)
>- return -fixp_cos(x - FIXP_PI);
>- x = x % FIXP_PI;
>- if (x > FIXP_PI/2)
>- return -fixp_cos(FIXP_PI/2 - (x % (FIXP_PI/2)));
>- /* Now x is between 0 and FIXP_PI/2.
>- * To calculate cos(x) we use it's Taylor polinom. */
>- t2 = x*x/FIXP_FRAC/2;
>- t4 = t2*x/FIXP_FRAC*x/FIXP_FRAC/3/4;
>- t6 = t4*x/FIXP_FRAC*x/FIXP_FRAC/5/6;
>- t8 = t6*x/FIXP_FRAC*x/FIXP_FRAC/7/8;
>- return FIXP_FRAC-t2+t4-t6+t8;
>-}
>-
>-static inline s32 fixp_sin(unsigned int x)
>-{
>- return -fixp_cos(x + (FIXP_PI / 2));
>-}
>-
> void vivid_sdr_cap_process(struct vivid_dev *dev, struct vivid_buffer
>*buf)
> {
> u8 *vbuf = vb2_plane_vaddr(&buf->vb, 0);
> unsigned long i;
> unsigned long plane_size = vb2_plane_size(&buf->vb, 0);
>- int fixp_src_phase_step, fixp_i, fixp_q;
>+ int fixp_i, fixp_q;
>+
>+ u32 adc_freq;
>+ u32 sig_freq;
>+ u32 src_phase_inc;
>+ u32 mod_phase_inc;
>
> /*
> * TODO: Generated beep tone goes very crackly when sample rate is
>@@ -466,34 +444,41 @@ void vivid_sdr_cap_process(struct vivid_dev *dev,
>struct vivid_buffer *buf)
>
> /* calculate phase step */
> #define BEEP_FREQ 1000 /* 1kHz beep */
>- fixp_src_phase_step = DIV_ROUND_CLOSEST(2 * FIXP_PI * BEEP_FREQ,
>- dev->sdr_adc_freq);
>+
>+ adc_freq = dev->sdr_adc_freq; /* samples per sec*/
>+ sig_freq = BEEP_FREQ; /* cycles per sec */
>+ src_phase_inc = phase_per_sample(sig_freq, adc_freq);
>
> for (i = 0; i < plane_size; i += 2) {
>- dev->sdr_fixp_mod_phase += fixp_cos(dev->sdr_fixp_src_phase);
>- dev->sdr_fixp_src_phase += fixp_src_phase_step;
>
>- /*
>- * Transfer phases 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 < (0 * FIXP_PI))
>- dev->sdr_fixp_mod_phase += (2 * FIXP_PI);
>- while (dev->sdr_fixp_mod_phase > (2 * FIXP_PI))
>- dev->sdr_fixp_mod_phase -= (2 * FIXP_PI);
>+ mod_phase_inc = calc_cos(dev->sdr_fixp_src_phase);
>+ dev->sdr_fixp_src_phase += src_phase_inc;
>+
>+ while(dev->sdr_fixp_src_phase >= ((44 << FIX_PT_PREC)/7))
>+ dev->sdr_fixp_src_phase -= ((44 << FIX_PT_PREC)/7);
>+
>+ mod_phase_inc <<= FIX_PT_PREC;
>+ mod_phase_inc /= 1275;
>+
>+ dev->sdr_fixp_mod_phase += mod_phase_inc;
>+
>+ while(dev->sdr_fixp_mod_phase < 0)
>+ dev->sdr_fixp_mod_phase += ((44 << FIX_PT_PREC)/7);
>
>- while (dev->sdr_fixp_src_phase > (2 * FIXP_PI))
>- dev->sdr_fixp_src_phase -= (2 * FIXP_PI);
>+ while(dev->sdr_fixp_mod_phase >= ((44 << FIX_PT_PREC)/7))
>+ dev->sdr_fixp_mod_phase -= ((44 << FIX_PT_PREC)/7);
>
>- fixp_i = fixp_cos(dev->sdr_fixp_mod_phase);
>- fixp_q = fixp_sin(dev->sdr_fixp_mod_phase);
>+ fixp_i = calc_sin(dev->sdr_fixp_mod_phase);
>+ fixp_q = calc_cos(dev->sdr_fixp_mod_phase);
>
> /* convert 'fixp float' to u8 */
>- /* u8 = X * 127.5f + 127.5f; where X is float [-1.0 / +1.0] */
>- fixp_i = fixp_i * 1275 + FIXP_FRAC * 1275;
>- fixp_q = fixp_q * 1275 + FIXP_FRAC * 1275;
>- *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, FIXP_FRAC * 10);
>- *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, FIXP_FRAC * 10);
>+ /* u8 = X * 127.5f + 127.5f; where X is float [-1.0 / +1.0]
>+ The values stored in sin look table are pre-multipied with 1275.
>+ So, only do addition */
>+
>+ fixp_i += 1275;
>+ fixp_q += 1275;
>+ *vbuf++ = DIV_ROUND_CLOSEST(fixp_i, 10);
>+ *vbuf++ = DIV_ROUND_CLOSEST(fixp_q, 10);
> }
> }
>diff --git a/drivers/media/platform/vivid/vivid-sin.c
>b/drivers/media/platform/vivid/vivid-sin.c
>new file mode 100644
>index 0000000..5bd6677
>--- /dev/null
>+++ b/drivers/media/platform/vivid/vivid-sin.c
>@@ -0,0 +1,171 @@
>+/*
>+ * vivid-sin.c - software defined radio support functions.
>+ *
>+ * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights
>reserved.
>+ *
>+ * This program is free software; you may redistribute it and/or modify
>+ * it under the terms of the GNU General Public License as published by
>+ * the Free Software Foundation; version 2 of the License.
>+ *
>+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
>+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
>+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
>+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
>+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
>+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
>+ * SOFTWARE.
>+ */
>+
>+#include <linux/errno.h>
>+#include <linux/kernel.h>
>+
>+#include "vivid-sin.h"
>+
>+#define SIN_TAB_SIZE 256
>+
>+ /*TODO- Reduce the size of the table */
>+/* Since sinewave is symmetric, it can be represented using only quarter
>+ of the samples compared to the number of samples used below */
>+
>+static s32 sin[257] = {
>+ 0, 31, 63, 94, 125, 156, 187, 218, 249, 279, 310, 340,
>+ 370, 400, 430, 459, 488, 517, 545, 573, 601, 628, 655,
>682,
>+ 708, 734, 760, 784, 809, 833, 856, 879, 902, 923, 945,
>965,
>+ 986, 1005, 1024, 1042, 1060, 1077, 1094, 1109, 1124, 1139, 1153,
>1166,
>+ 1178, 1190, 1200, 1211, 1220, 1229, 1237, 1244, 1251, 1256, 1261,
>1265,
>+ 1269, 1272, 1273, 1275, 1275, 1275, 1273, 1272, 1269, 1265, 1261,
>1256,
>+ 1251, 1244, 1237, 1229, 1220, 1211, 1200, 1190, 1178, 1166, 1153,
>1139,
>+ 1124, 1109, 1094, 1077, 1060, 1042, 1024, 1005, 986, 965, 945,
>923,
>+ 902, 879, 856, 833, 809, 784, 760, 734, 708, 682, 655,
>628,
>+ 601, 573, 545, 517, 488, 459, 430, 400, 370, 340, 310,
>279,
>+ 249, 218, 187, 156, 125, 94, 63, 31, 0, -31, -63,
>-94,
>+ -125, -156, -187, -218, -249, -279, -310, -340, -370, -400, -430,
>-459,
>+ -488, -517, -545, -573, -601, -628, -655, -682, -708, -734, -760,
>-784,
>+ -809, -833, -856, -879, -902, -923, -945, -965,
>-986,-1005,-1024,-1042,
>+
>-1060,-1077,-1094,-1109,-1124,-1139,-1153,-1166,-1178,-1190,-1200,-1211,
>+
>-1220,-1229,-1237,-1244,-1251,-1256,-1261,-1265,-1269,-1272,-1273,-1275,
>+
>-1275,-1275,-1273,-1272,-1269,-1265,-1261,-1256,-1251,-1244,-1237,-1229,
>+
>-1220,-1211,-1200,-1190,-1178,-1166,-1153,-1139,-1124,-1109,-1094,-1077,
>+ -1060,-1042,-1024,-1005, -986, -965, -945, -923, -902, -879, -856,
>-833,
>+ -809, -784, -760, -734, -708, -682, -655, -628, -601, -573, -545,
>-517,
>+ -488, -459, -430, -400, -370, -340, -310, -279, -249, -218, -187,
>-156,
>+ -125, -94, -63, -31, 0
>+ };
>+
>+/*
>+ * Calculation of sine is implemented using a look up table for range of
>+ * phase values from 0 to 2*pi. Look table contains finite entries, say
>N.
>+ *
>+ * Since sinusoid are periodic with period 2*pi, look table stores
>entries
>+ * for phase values from 0 to 2*pi.
>+ *
>+ * The interval [0,2*pi] is divided into N equal intervals, each
>representing
>+ * a phase increment of (2*pi/N)
>+ *
>+ * The index 'n' in look up table stores sine value for phase (2*pi*n/N)
>as -
>+ * sin_tab[N] = {sin(0), sin(1*(2*pi/N)),sin(2*(2*pi/N)), ...,
>sin(N*(2*pi/N))}
>+ *
>+ |---------|---------|---------|---- . . . .|---------| . . . .
>|---------|
>+ 0 (2*pi/N) (2*2*pi/N) (3*2*pi/N) (n*2*pi/N)
> 2*pi
>+ *
>+ * Generation of sine waveform with different frequencies -
>+ *
>+ * Consider a sine tone with frequency 'f', so,
>+ * num_cycles_per_sec = f
>+ * Let sampling frequency be 'Fs' so,
>+ * num_samples_per_sec = Fs
>+ * So, num_samples_per_cycle = Fs/f
>+ * Let Nc = Fs/f
>+ *
>+ * That is, number of samples during one interval of 0 tp 2*pi = Nc, each
>+ * sample represents a phase increment of (2*pi/Nc = 2*pi*f/Fs).
>+ *
>+ * So, for "k" th sample the phase, phi = k*(2*pi/Nc)
>+ *
>+ * The sine value at phase increments of (2*pi/Nc) is calculated by
>interpolating
>+ * two adjecent samples from sine look table
>+ *
>+ * As an example, sine value for phase (phi) is calculated below
>+ *
>+ * 1. Find the interval [(n*2*pi/N), ((n+1)*2*pi/N)] to which phi belongs
>+
>+ 0 (2*pi/N) (n*2*pi/N) ((n+1)*2*pi/N) 2*pi
>+ |---------| . . . . . |---------|---------| . . . . . |---------|
>+ ^
>+ d0---->|<--d1
>+ |
>+ phi = k*(2*pi/Nc)
>+
>+ * For phase (phi) the index n in sine table is given by (phi)/(2*pi/N)
>+ * n = integer part of ( phi / (2*pi/N) )
>+ *
>+ * 2. Find distance d0 and d1 using fractional arithmatic.
>+ * d0 = phi - n*(2*pi/N),
>+ * d1 = 2*pi/N - d0
>+ *
>+ * 3. The calculations of fractions are done using fixed point
>implementation
>+ *
>+ * 4. To improve the precision of fixed point implementations, divisions
>+ * in different calculations are delayed till last operations. Say,
>+ * d0 = phi - n*(2*pi/N)
>+ * d0 = phi - n * (2 * (22/7)/N) , substitute pi = 22/7
>+ * d0 = phi - (n * 44 * N)/7
>+ */
>+s32 calc_sin(u32 phase)
>+{
>+ u32 index;
>+ u32 d0;
>+ u32 d1;
>+ s32 result;
>+ u64 temp0;
>+ u64 temp1;
>+
>+ temp0 = phase * SIN_TAB_SIZE;
>+ index = (temp0 * 7) /(44 << FIX_PT_PREC);
>+
>+ temp0 = (temp0 * 7) /44;
>+ temp1 = index << FIX_PT_PREC;
>+
>+ d1 = temp0 - temp1;
>+ d0 = (1 << FIX_PT_PREC) - d1;
>+
>+ result = (d0 * sin[index % 256] + d1 * sin[(index+1)%256]);
>+
>+ return result >> FIX_PT_PREC;
>+}
>+
>+s32 calc_cos(u32 phase)
>+{
>+ u32 index;
>+ u32 d0;
>+ u32 d1;
>+ s32 result;
>+ u64 temp0;
>+ u64 temp1;
>+
>+ temp0 = phase * SIN_TAB_SIZE;
>+ index = (temp0 * 7) /(44 << FIX_PT_PREC);
>+
>+ temp0 = (temp0 * 7) /44;
>+ temp1 = index << FIX_PT_PREC;
>+
>+ d1 = temp0 - temp1;
>+ d0 = (1 << FIX_PT_PREC) - d1;
>+
>+ index += 64;
>+ result = (d0 * sin[index % 256] + d1 * sin[(index+1)%256]);
>+
>+ return result >> FIX_PT_PREC;
>+}
>+
>+u32 phase_per_sample(u32 signal_freq, u32 sampling_freq)
>+{
>+ /* phase increment or decrement with each sample is given by
>+ * (2 x Pi x signal frequency)/sampling frequency
>+ * To get a better accuracy with fixed point implementation we use
>+ * Pi = 22/7
>+ * */
>+ u64 temp = 44 * ((u64)signal_freq << FIX_PT_PREC);
>+ return temp / (7*sampling_freq);
>+}
>diff --git a/drivers/media/platform/vivid/vivid-sin.h
>b/drivers/media/platform/vivid/vivid-sin.h
>new file mode 100644
>index 0000000..2f77d64
>--- /dev/null
>+++ b/drivers/media/platform/vivid/vivid-sin.h
>@@ -0,0 +1,30 @@
>+/*
>+ * vivid-sin.h - support functions used to generate (co)sine waveforms
>for
>+ * software defined radio.
>+ *
>+ * Copyright 2014 Cisco Systems, Inc. and/or its affiliates. All rights
>reserved.
>+ *
>+ * This program is free software; you may redistribute it and/or modify
>+ * it under the terms of the GNU General Public License as published by
>+ * the Free Software Foundation; version 2 of the License.
>+ *
>+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
>+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
>+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
>+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
>+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
>+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
>+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
>+ * SOFTWARE.
>+ */
>+
>+#ifndef _VIVID_SIN_H_
>+#define _VIVID_SIN_H_
>+
>+#define FIX_PT_PREC 16
>+
>+s32 calc_sin(u32 phase);
>+s32 calc_cos(u32 phase);
>+u32 phase_per_sample(u32 signal_freq, u32 sampling_freq);
>+
>+#endif
>--
>1.9.1
>
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