diff options
Diffstat (limited to 'apps/plugins/lib/fixedpoint.c')
| -rw-r--r-- | apps/plugins/lib/fixedpoint.c | 239 |
1 files changed, 1 insertions, 238 deletions
diff --git a/apps/plugins/lib/fixedpoint.c b/apps/plugins/lib/fixedpoint.c index 0ae2cded69..352e246673 100644 --- a/apps/plugins/lib/fixedpoint.c +++ b/apps/plugins/lib/fixedpoint.c @@ -1,238 +1 @@ -/*************************************************************************** - * __________ __ ___. - * Open \______ \ ____ ____ | | _\_ |__ _______ ___ - * Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ / - * Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < < - * Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \ - * \/ \/ \/ \/ \/ - * $Id$ - * - * Copyright (C) 2006 Jens Arnold - * - * Fixed point library for plugins - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU General Public License - * as published by the Free Software Foundation; either version 2 - * of the License, or (at your option) any later version. - * - * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY - * KIND, either express or implied. - * - ****************************************************************************/ - -#include <inttypes.h> -#include "plugin.h" -#include "fixedpoint.h" - -/* Inverse gain of circular cordic rotation in s0.31 format. */ -static const long cordic_circular_gain = 0xb2458939; /* 0.607252929 */ - -/* Table of values of atan(2^-i) in 0.32 format fractions of pi where pi = 0xffffffff / 2 */ -static const unsigned long atan_table[] = { - 0x1fffffff, /* +0.785398163 (or pi/4) */ - 0x12e4051d, /* +0.463647609 */ - 0x09fb385b, /* +0.244978663 */ - 0x051111d4, /* +0.124354995 */ - 0x028b0d43, /* +0.062418810 */ - 0x0145d7e1, /* +0.031239833 */ - 0x00a2f61e, /* +0.015623729 */ - 0x00517c55, /* +0.007812341 */ - 0x0028be53, /* +0.003906230 */ - 0x00145f2e, /* +0.001953123 */ - 0x000a2f98, /* +0.000976562 */ - 0x000517cc, /* +0.000488281 */ - 0x00028be6, /* +0.000244141 */ - 0x000145f3, /* +0.000122070 */ - 0x0000a2f9, /* +0.000061035 */ - 0x0000517c, /* +0.000030518 */ - 0x000028be, /* +0.000015259 */ - 0x0000145f, /* +0.000007629 */ - 0x00000a2f, /* +0.000003815 */ - 0x00000517, /* +0.000001907 */ - 0x0000028b, /* +0.000000954 */ - 0x00000145, /* +0.000000477 */ - 0x000000a2, /* +0.000000238 */ - 0x00000051, /* +0.000000119 */ - 0x00000028, /* +0.000000060 */ - 0x00000014, /* +0.000000030 */ - 0x0000000a, /* +0.000000015 */ - 0x00000005, /* +0.000000007 */ - 0x00000002, /* +0.000000004 */ - 0x00000001, /* +0.000000002 */ - 0x00000000, /* +0.000000001 */ - 0x00000000, /* +0.000000000 */ -}; - -/* Precalculated sine and cosine * 16384 (2^14) (fixed point 18.14) */ -static const short sin_table[91] = -{ - 0, 285, 571, 857, 1142, 1427, 1712, 1996, 2280, 2563, - 2845, 3126, 3406, 3685, 3963, 4240, 4516, 4790, 5062, 5334, - 5603, 5871, 6137, 6401, 6663, 6924, 7182, 7438, 7691, 7943, - 8191, 8438, 8682, 8923, 9161, 9397, 9630, 9860, 10086, 10310, - 10531, 10748, 10963, 11173, 11381, 11585, 11785, 11982, 12175, 12365, - 12550, 12732, 12910, 13084, 13254, 13420, 13582, 13740, 13894, 14043, - 14188, 14329, 14466, 14598, 14725, 14848, 14967, 15081, 15190, 15295, - 15395, 15491, 15582, 15668, 15749, 15825, 15897, 15964, 16025, 16082, - 16135, 16182, 16224, 16261, 16294, 16321, 16344, 16361, 16374, 16381, - 16384 -}; - -/** - * Implements sin and cos using CORDIC rotation. - * - * @param phase has range from 0 to 0xffffffff, representing 0 and - * 2*pi respectively. - * @param cos return address for cos - * @return sin of phase, value is a signed value from LONG_MIN to LONG_MAX, - * representing -1 and 1 respectively. - */ -long fsincos(unsigned long phase, long *cos) -{ - int32_t x, x1, y, y1; - unsigned long z, z1; - int i; - - /* Setup initial vector */ - x = cordic_circular_gain; - y = 0; - z = phase; - - /* The phase has to be somewhere between 0..pi for this to work right */ - if (z < 0xffffffff / 4) { - /* z in first quadrant, z += pi/2 to correct */ - x = -x; - z += 0xffffffff / 4; - } else if (z < 3 * (0xffffffff / 4)) { - /* z in third quadrant, z -= pi/2 to correct */ - z -= 0xffffffff / 4; - } else { - /* z in fourth quadrant, z -= 3pi/2 to correct */ - x = -x; - z -= 3 * (0xffffffff / 4); - } - - /* Each iteration adds roughly 1-bit of extra precision */ - for (i = 0; i < 31; i++) { - x1 = x >> i; - y1 = y >> i; - z1 = atan_table[i]; - - /* Decided which direction to rotate vector. Pivot point is pi/2 */ - if (z >= 0xffffffff / 4) { - x -= y1; - y += x1; - z -= z1; - } else { - x += y1; - y -= x1; - z += z1; - } - } - - if (cos) - *cos = x; - - return y; -} - -/** - * Fixed point square root via Newton-Raphson. - * @param a square root argument. - * @param fracbits specifies number of fractional bits in argument. - * @return Square root of argument in same fixed point format as input. - */ -long fsqrt(long a, unsigned int fracbits) -{ - long b = a/2 + BIT_N(fracbits); /* initial approximation */ - unsigned n; - const unsigned iterations = 4; - - for (n = 0; n < iterations; ++n) - b = (b + (long)(((long long)(a) << fracbits)/b))/2; - - return b; -} - -/** - * Fixed point sinus using a lookup table - * don't forget to divide the result by 16384 to get the actual sinus value - * @param val sinus argument in degree - * @return sin(val)*16384 - */ -long sin_int(int val) -{ - val = (val+360)%360; - if (val < 181) - { - if (val < 91)/* phase 0-90 degree */ - return (long)sin_table[val]; - else/* phase 91-180 degree */ - return (long)sin_table[180-val]; - } - else - { - if (val < 271)/* phase 181-270 degree */ - return -(long)sin_table[val-180]; - else/* phase 270-359 degree */ - return -(long)sin_table[360-val]; - } - return 0; -} - -/** - * Fixed point cosinus using a lookup table - * don't forget to divide the result by 16384 to get the actual cosinus value - * @param val sinus argument in degree - * @return cos(val)*16384 - */ -long cos_int(int val) -{ - val = (val+360)%360; - if (val < 181) - { - if (val < 91)/* phase 0-90 degree */ - return (long)sin_table[90-val]; - else/* phase 91-180 degree */ - return -(long)sin_table[val-90]; - } - else - { - if (val < 271)/* phase 181-270 degree */ - return -(long)sin_table[270-val]; - else/* phase 270-359 degree */ - return (long)sin_table[val-270]; - } - return 0; -} - -/** - * Fixed-point natural log - * taken from http://www.quinapalus.com/efunc.html - * "The code assumes integers are at least 32 bits long. The (positive) - * argument and the result of the function are both expressed as fixed-point - * values with 16 fractional bits, although intermediates are kept with 28 - * bits of precision to avoid loss of accuracy during shifts." - */ - -long flog(int x) { - long t,y; - - y=0xa65af; - if(x<0x00008000) x<<=16, y-=0xb1721; - if(x<0x00800000) x<<= 8, y-=0x58b91; - if(x<0x08000000) x<<= 4, y-=0x2c5c8; - if(x<0x20000000) x<<= 2, y-=0x162e4; - if(x<0x40000000) x<<= 1, y-=0x0b172; - t=x+(x>>1); if((t&0x80000000)==0) x=t,y-=0x067cd; - t=x+(x>>2); if((t&0x80000000)==0) x=t,y-=0x03920; - t=x+(x>>3); if((t&0x80000000)==0) x=t,y-=0x01e27; - t=x+(x>>4); if((t&0x80000000)==0) x=t,y-=0x00f85; - t=x+(x>>5); if((t&0x80000000)==0) x=t,y-=0x007e1; - t=x+(x>>6); if((t&0x80000000)==0) x=t,y-=0x003f8; - t=x+(x>>7); if((t&0x80000000)==0) x=t,y-=0x001fe; - x=0x80000000-x; - y-=x>>15; - return y; -} +#include "../../fixedpoint.c" |