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/****************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
*
* Copyright (C) 2007 Michael Giacomelli
*
* 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 "wmadec.h"
#include "wmafixed.h"
fixed64 IntTo64(int x){
fixed64 res = 0;
unsigned char *p = (unsigned char *)&res;
#ifdef ROCKBOX_BIG_ENDIAN
p[5] = x & 0xff;
p[4] = (x & 0xff00)>>8;
p[3] = (x & 0xff0000)>>16;
p[2] = (x & 0xff000000)>>24;
#else
p[2] = x & 0xff;
p[3] = (x & 0xff00)>>8;
p[4] = (x & 0xff0000)>>16;
p[5] = (x & 0xff000000)>>24;
#endif
return res;
}
int IntFrom64(fixed64 x)
{
int res = 0;
unsigned char *p = (unsigned char *)&x;
#ifdef ROCKBOX_BIG_ENDIAN
res = p[5] | (p[4]<<8) | (p[3]<<16) | (p[2]<<24);
#else
res = p[2] | (p[3]<<8) | (p[4]<<16) | (p[5]<<24);
#endif
return res;
}
fixed32 Fixed32From64(fixed64 x)
{
return x & 0xFFFFFFFF;
}
fixed64 Fixed32To64(fixed32 x)
{
return (fixed64)x;
}
/*
Not performance senstitive code here
*/
fixed32 fixdiv32(fixed32 x, fixed32 y)
{
fixed64 temp;
if(x == 0)
return 0;
if(y == 0)
return 0x7fffffff;
temp = x;
temp <<= PRECISION;
return (fixed32)(temp / y);
}
fixed64 fixdiv64(fixed64 x, fixed64 y)
{
fixed64 temp;
if(x == 0)
return 0;
if(y == 0)
return 0x07ffffffffffffffLL;
temp = x;
temp <<= PRECISION64;
return (fixed64)(temp / y);
}
fixed32 fixsqrt32(fixed32 x)
{
unsigned long r = 0, s, v = (unsigned long)x;
#define STEP(k) s = r + (1 << k * 2); r >>= 1; \
if (s <= v) { v -= s; r |= (1 << k * 2); }
STEP(15);
STEP(14);
STEP(13);
STEP(12);
STEP(11);
STEP(10);
STEP(9);
STEP(8);
STEP(7);
STEP(6);
STEP(5);
STEP(4);
STEP(3);
STEP(2);
STEP(1);
STEP(0);
return (fixed32)(r << (PRECISION / 2));
}
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 */
};
/**
* 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.
*
* Gives at least 24 bits precision (last 2-8 bits or so are probably off)
*/
long fsincos(unsigned long phase, fixed32 *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;
}
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