audiostuff: spandsp-0.0.3/spandsp-0.0.3/src/dds.c comparison

comparison spandsp-0.0.3/spandsp-0.0.3/src/dds.c @ 5:f762bf195c4b

import spandsp-0.0.3

author	Peter Meerwald <pmeerw@cosy.sbg.ac.at>
date	Fri, 25 Jun 2010 16:00:21 +0200
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children

comparison

equal deleted inserted replaced

-:26cd8f1ef0b1
+:f762bf195c4b
+/*
+* SpanDSP - a series of DSP components for telephony
+*
+* dds.c
+*
+* Written by Steve Underwood <steveu@coppice.org>
+*
+* Copyright (C) 2003 Steve Underwood
+*
+* All rights reserved.
+*
+* This program is free software; you can redistribute it and/or modify
+* it under the terms of the GNU General Public License version 2, as
+* published by the Free Software Foundation.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License
+* along with this program; if not, write to the Free Software
+* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*
+* $Id: dds.c,v 1.17 2006/11/19 14:07:24 steveu Exp $
+*/
+/*! \file */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <inttypes.h>
+#if defined(HAVE_TGMATH_H)
+#include <tgmath.h>
+#endif
+#if defined(HAVE_MATH_H)
+#include <math.h>
+#endif
+#include "spandsp/telephony.h"
+#include "spandsp/dds.h"
+#if !defined(M_PI)
+# define M_PI           3.14159265358979323846  /* pi */
+#endif
+/* In a A-law or u-law channel, and 128 step sine table is adequate to keep the spectral
+mess due to the DDS at a similar level to the spectral mess due to the A-law or u-law
+compression. */
+#define SLENK       7
+#define DDS_STEPS   (1 << SLENK)
+#define DDS_SHIFT   (32 - 2 - SLENK)
+/* This is a simple set of direct digital synthesis (DDS) functions to generate sine
+waves. This version uses a 128 entry sin/cos table to cover one quadrant. */
+static const int16_t sine_table[DDS_STEPS] =
+{
+201,
+603,
+1005,
+1407,
+1809,
+2210,
+2611,
+3012,
+3412,
+3812,
+4211,
+4609,
+5007,
+5404,
+5800,
+6195,
+6590,
+6983,
+7376,
+7767,
+8157,
+8546,
+8933,
+9319,
+9704,
+10088,
+10469,
+10850,
+11228,
+11605,
+11980,
+12354,
+12725,
+13095,
+13463,
+13828,
+14192,
+14553,
+14912,
+15269,
+15624,
+15976,
+16326,
+16673,
+17018,
+17361,
+17700,
+18037,
+18372,
+18703,
+19032,
+19358,
+19681,
+20001,
+20318,
+20632,
+20943,
+21251,
+21555,
+21856,
+22154,
+22449,
+22740,
+23028,
+23312,
+23593,
+23870,
+24144,
+24414,
+24680,
+24943,
+25202,
+25457,
+25708,
+25956,
+26199,
+26439,
+26674,
+26906,
+27133,
+27357,
+27576,
+27791,
+28002,
+28209,
+28411,
+28610,
+28803,
+28993,
+29178,
+29359,
+29535,
+29707,
+29875,
+30038,
+30196,
+30350,
+30499,
+30644,
+30784,
+30920,
+31050,
+31177,
+31298,
+31415,
+31527,
+31634,
+31737,
+31834,
+31927,
+32015,
+32099,
+32177,
+32251,
+32319,
+32383,
+32442,
+32496,
+32546,
+32590,
+32629,
+32664,
+32693,
+32718,
+32738,
+32753,
+32762,
+32767,
+};
+int32_t dds_phase_rate(float frequency)
+{
+return (int32_t) (frequency*65536.0f*65536.0f/SAMPLE_RATE);
+}
+/*- End of function --------------------------------------------------------*/
+float dds_frequency(int32_t phase_rate)
+{
+return (float) phase_rate*(float) SAMPLE_RATE/(65536.0f*65536.0f);
+}
+/*- End of function --------------------------------------------------------*/
+int dds_scaling_dbm0(float level)
+{
+return (int) (powf(10.0f, (level - DBM0_MAX_POWER)/20.0f)*(32767.0f*1.414214f));
+}
+/*- End of function --------------------------------------------------------*/
+int dds_scaling_dbov(float level)
+{
+return (int) (powf(10.0f, (level + 3.02f)/20.0f)*(32767.0f*1.414214f));
+}
+/*- End of function --------------------------------------------------------*/
+int16_t dds_lookup(uint32_t phase)
+{
+uint32_t step;
+uint32_t fred;
+int16_t amp;
+phase >>= DDS_SHIFT;
+step = phase & (DDS_STEPS - 1);
+fred = step;
+if ((phase & DDS_STEPS))
+step = (DDS_STEPS - 1) - step;
+amp = sine_table[step];
+if ((phase & (2*DDS_STEPS)))
+	amp = -amp;
+return amp;
+}
+/*- End of function --------------------------------------------------------*/
+int16_t dds_offset(uint32_t phase_acc, int32_t phase_offset)
+{
+return dds_lookup(phase_acc + phase_offset);
+}
+/*- End of function --------------------------------------------------------*/
+int16_t dds(uint32_t *phase_acc, int32_t phase_rate)
+{
+int16_t amp;
+amp = dds_lookup(*phase_acc);
+*phase_acc += phase_rate;
+return amp;
+}
+/*- End of function --------------------------------------------------------*/
+int16_t dds_mod(uint32_t *phase_acc, int32_t phase_rate, int scale, int32_t phase)
+{
+int16_t amp;
+amp = (int16_t) ((dds_lookup(*phase_acc + phase)*scale) >> 15);
+*phase_acc += phase_rate;
+return amp;
+}
+/*- End of function --------------------------------------------------------*/
+icomplex_t dds_complex(uint32_t *phase_acc, int32_t phase_rate)
+{
+icomplex_t amp;
+amp.re = dds_lookup(*phase_acc + (1 << 30));
+amp.im = dds_lookup(*phase_acc);
+*phase_acc += phase_rate;
+return amp;
+}
+/*- End of function --------------------------------------------------------*/
+icomplex_t dds_complex_mod(uint32_t *phase_acc, int32_t phase_rate, int scale, int32_t phase)
+{
+icomplex_t amp;
+amp.re = (dds_lookup(*phase_acc + phase + (1 << 30))*scale) >> 15;
+amp.im = (dds_lookup(*phase_acc + phase)*scale) >> 15;
+*phase_acc += phase_rate;
+return amp;
+}
+/*- End of function --------------------------------------------------------*/
+/*- End of file ------------------------------------------------------------*/

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comparison spandsp-0.0.3/spandsp-0.0.3/src/dds.c @ 5:f762bf195c4b