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Introducing fixed point math functions

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This commit is contained in:
Steve Underwood
2011-07-02 22:04:29 +08:00
parent 4a7bbf4ec6
commit 3cee0589e5
6 changed files with 904 additions and 1 deletions
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116
libs/spandsp/src/make_math_fixed_tables.c Normal file
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/*
* SpanDSP - a series of DSP components for telephony
*
* make_fixed_point_math_tables.c - Generate lookup tables for some of the
* fixed point maths functions.
*
* Written by Steve Underwood <steveu@coppice.org>
*
* Copyright (C) 2010 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.
*/
#if defined(HAVE_CONFIG_H)
#include "config.h"
#endif
#include <inttypes.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <memory.h>
#include <math.h>
int main(int argc, char *argv[])
{
int i;
double val;
int ival;
printf("static const uint16_t fixed_reciprocal_table[129] =\n");
printf("{\n");
for (i = 0; i < 129; i++)
{
val = 32768.0*128.0/(128 + i) + 0.5;
ival = val;
if (i < 128)
printf(" %6d,\n", ival);
else
printf(" %6d\n", ival);
}
printf("};\n\n");
printf("static const uint16_t fixed_sqrt_table[193] =\n");
printf("{\n");
for (i = 64; i <= 256; i++)
{
ival = sqrt(i/256.0)*65536.0 + 0.5;
if (ival > 65535)
ival = 65535;
if (i < 256)
printf(" %6d,\n", ival);
else
printf(" %6d\n", ival);
}
printf("};\n\n");
printf("static const int16_t fixed_log10_table[129] =\n");
printf("{\n");
for (i = 128; i <= 256; i++)
{
ival = log10(i/256.0)*32768.0 - 0.5;
if (i <= 255)
printf(" %6d,\n", ival);
else
printf(" %6d\n", ival);
}
printf("};\n\n");
printf("static const int16_t fixed_sine_table[257] =\n");
printf("{\n");
for (i = 0; i <= 256; i++)
{
val = sin(i*3.1415926535/512.0)*32768.0;
ival = val + 0.5;
if (ival > 32767)
ival = 32767;
if (i <= 255)
printf(" %6d,\n", ival);
else
printf(" %6d\n", ival);
}
printf("};\n\n");
printf("static const uint16_t fixed_arctan_table[257] =\n");
printf("{\n");
for (i = 0; i <= 256; i++)
{
val = atan(i/256.0)*65536.0/(2.0*3.1415926535);
ival = val + 0.5;
/* Nudge the result away from zero, so things sit consistently on
the correct side of the axes. */
if (ival == 0)
ival = 1;
if (i <= 255)
printf(" %6d,\n", ival);
else
printf(" %6d\n", ival);
}
printf("};\n\n");
return 0;
}