From c3bc8fda8019c69c1bf9cd74539df07db527eebc Mon Sep 17 00:00:00 2001 From: Maurus Cuelenaere Date: Sat, 4 Jul 2009 13:17:58 +0000 Subject: Revert "Consolidate all fixed point math routines in one library (FS#10400) by Jeffrey Goode" git-svn-id: svn://svn.rockbox.org/rockbox/trunk@21635 a1c6a512-1295-4272-9138-f99709370657 --- apps/plugins/lib/fixedpoint.c | 238 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 238 insertions(+) (limited to 'apps/plugins/lib/fixedpoint.c') diff --git a/apps/plugins/lib/fixedpoint.c b/apps/plugins/lib/fixedpoint.c index e69de29..0ae2cde 100644 --- a/apps/plugins/lib/fixedpoint.c +++ b/apps/plugins/lib/fixedpoint.c @@ -0,0 +1,238 @@ +/*************************************************************************** + * __________ __ ___. + * 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 +#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; +} -- cgit v1.1