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380 lines
8.4 KiB
C
380 lines
8.4 KiB
C
/* Copyright (C) 2005 Jean-Marc Valin */
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/**
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@file pseudofloat.h
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@brief Pseudo-floating point
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* This header file provides a lightweight floating point type for
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* use on fixed-point platforms when a large dynamic range is
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* required. The new type is not compatible with the 32-bit IEEE format,
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* it is not even remotely as accurate as 32-bit floats, and is not
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* even guaranteed to produce even remotely correct results for code
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* other than Speex. It makes all kinds of shortcuts that are acceptable
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* for Speex, but may not be acceptable for your application. You're
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* quite welcome to reuse this code and improve it, but don't assume
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* it works out of the box. Most likely, it doesn't.
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the Xiph.org Foundation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef PSEUDOFLOAT_H
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#define PSEUDOFLOAT_H
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#include "arch.h"
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#include "os_support.h"
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#include "math_approx.h"
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#include <math.h>
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#ifdef FIXED_POINT
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typedef struct {
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spx_int16_t m;
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spx_int16_t e;
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} spx_float_t;
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static const spx_float_t FLOAT_ZERO = {0,0};
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static const spx_float_t FLOAT_ONE = {16384,-14};
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static const spx_float_t FLOAT_HALF = {16384,-15};
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#define MIN(a,b) ((a)<(b)?(a):(b))
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static inline spx_float_t PSEUDOFLOAT(spx_int32_t x)
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{
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int e=0;
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int sign=0;
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if (x<0)
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{
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sign = 1;
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x = -x;
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}
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if (x==0)
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{
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spx_float_t r = {0,0};
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return r;
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}
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e = spx_ilog2(ABS32(x))-14;
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x = VSHR32(x, e);
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if (sign)
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{
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spx_float_t r;
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r.m = -x;
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r.e = e;
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return r;
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}
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else
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{
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spx_float_t r;
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r.m = x;
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r.e = e;
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return r;
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}
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}
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static inline spx_float_t FLOAT_ADD(spx_float_t a, spx_float_t b)
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{
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spx_float_t r;
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if (a.m==0)
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return b;
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else if (b.m==0)
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return a;
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if ((a).e > (b).e)
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{
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r.m = ((a).m>>1) + ((b).m>>MIN(15,(a).e-(b).e+1));
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r.e = (a).e+1;
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}
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else
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{
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r.m = ((b).m>>1) + ((a).m>>MIN(15,(b).e-(a).e+1));
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r.e = (b).e+1;
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}
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if (r.m>0)
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{
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if (r.m<16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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} else {
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if (r.m>-16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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}
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/*printf ("%f + %f = %f\n", REALFLOAT(a), REALFLOAT(b), REALFLOAT(r));*/
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return r;
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}
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static inline spx_float_t FLOAT_SUB(spx_float_t a, spx_float_t b)
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{
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spx_float_t r;
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if (a.m==0)
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return b;
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else if (b.m==0)
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return a;
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if ((a).e > (b).e)
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{
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r.m = ((a).m>>1) - ((b).m>>MIN(15,(a).e-(b).e+1));
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r.e = (a).e+1;
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}
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else
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{
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r.m = ((a).m>>MIN(15,(b).e-(a).e+1)) - ((b).m>>1);
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r.e = (b).e+1;
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}
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if (r.m>0)
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{
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if (r.m<16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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} else {
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if (r.m>-16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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}
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/*printf ("%f + %f = %f\n", REALFLOAT(a), REALFLOAT(b), REALFLOAT(r));*/
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return r;
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}
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static inline int FLOAT_LT(spx_float_t a, spx_float_t b)
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{
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if (a.m==0)
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return b.m>0;
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else if (b.m==0)
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return a.m<0;
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if ((a).e > (b).e)
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return ((a).m>>1) < ((b).m>>MIN(15,(a).e-(b).e+1));
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else
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return ((b).m>>1) > ((a).m>>MIN(15,(b).e-(a).e+1));
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}
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static inline int FLOAT_GT(spx_float_t a, spx_float_t b)
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{
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return FLOAT_LT(b,a);
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}
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static inline spx_float_t FLOAT_MULT(spx_float_t a, spx_float_t b)
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{
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spx_float_t r;
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r.m = (spx_int16_t)((spx_int32_t)(a).m*(b).m>>15);
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r.e = (a).e+(b).e+15;
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if (r.m>0)
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{
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if (r.m<16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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} else {
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if (r.m>-16384)
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{
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r.m<<=1;
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r.e-=1;
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}
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}
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/*printf ("%f * %f = %f\n", REALFLOAT(a), REALFLOAT(b), REALFLOAT(r));*/
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return r;
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}
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static inline spx_float_t FLOAT_AMULT(spx_float_t a, spx_float_t b)
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{
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spx_float_t r;
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r.m = (spx_int16_t)((spx_int32_t)(a).m*(b).m>>15);
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r.e = (a).e+(b).e+15;
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return r;
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}
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static inline spx_float_t FLOAT_SHL(spx_float_t a, int b)
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{
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spx_float_t r;
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r.m = a.m;
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r.e = a.e+b;
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return r;
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}
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static inline spx_int16_t FLOAT_EXTRACT16(spx_float_t a)
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{
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if (a.e<0)
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return EXTRACT16((EXTEND32(a.m)+(EXTEND32(1)<<(-a.e-1)))>>-a.e);
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else
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return a.m<<a.e;
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}
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static inline spx_int32_t FLOAT_EXTRACT32(spx_float_t a)
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{
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if (a.e<0)
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return (EXTEND32(a.m)+(EXTEND32(1)<<(-a.e-1)))>>-a.e;
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else
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return EXTEND32(a.m)<<a.e;
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}
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static inline spx_int32_t FLOAT_MUL32(spx_float_t a, spx_word32_t b)
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{
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return VSHR32(MULT16_32_Q15(a.m, b),-a.e-15);
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}
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static inline spx_float_t FLOAT_MUL32U(spx_word32_t a, spx_word32_t b)
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{
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int e1, e2;
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spx_float_t r;
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if (a==0 || b==0)
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{
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return FLOAT_ZERO;
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}
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e1 = spx_ilog2(ABS32(a));
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a = VSHR32(a, e1-14);
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e2 = spx_ilog2(ABS32(b));
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b = VSHR32(b, e2-14);
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r.m = MULT16_16_Q15(a,b);
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r.e = e1+e2-13;
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return r;
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}
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/* Do NOT attempt to divide by a negative number */
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static inline spx_float_t FLOAT_DIV32_FLOAT(spx_word32_t a, spx_float_t b)
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{
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int e=0;
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spx_float_t r;
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if (a==0)
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{
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return FLOAT_ZERO;
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}
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e = spx_ilog2(ABS32(a))-spx_ilog2(b.m-1)-15;
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a = VSHR32(a, e);
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if (ABS32(a)>=SHL32(EXTEND32(b.m-1),15))
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{
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a >>= 1;
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e++;
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}
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r.m = DIV32_16(a,b.m);
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r.e = e-b.e;
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return r;
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}
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/* Do NOT attempt to divide by a negative number */
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static inline spx_float_t FLOAT_DIV32(spx_word32_t a, spx_word32_t b)
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{
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int e0=0,e=0;
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spx_float_t r;
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if (a==0)
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{
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return FLOAT_ZERO;
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}
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if (b>32767)
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{
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e0 = spx_ilog2(b)-14;
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b = VSHR32(b, e0);
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e0 = -e0;
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}
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e = spx_ilog2(ABS32(a))-spx_ilog2(b-1)-15;
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a = VSHR32(a, e);
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if (ABS32(a)>=SHL32(EXTEND32(b-1),15))
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{
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a >>= 1;
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e++;
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}
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e += e0;
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r.m = DIV32_16(a,b);
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r.e = e;
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return r;
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}
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/* Do NOT attempt to divide by a negative number */
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static inline spx_float_t FLOAT_DIVU(spx_float_t a, spx_float_t b)
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{
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int e=0;
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spx_int32_t num;
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spx_float_t r;
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if (b.m<=0)
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{
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speex_warning_int("Attempted to divide by", b.m);
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return FLOAT_ONE;
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}
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num = a.m;
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a.m = ABS16(a.m);
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while (a.m >= b.m)
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{
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e++;
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a.m >>= 1;
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}
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num = num << (15-e);
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r.m = DIV32_16(num,b.m);
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r.e = a.e-b.e-15+e;
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return r;
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}
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static inline spx_float_t FLOAT_SQRT(spx_float_t a)
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{
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spx_float_t r;
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spx_int32_t m;
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m = SHL32(EXTEND32(a.m), 14);
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r.e = a.e - 14;
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if (r.e & 1)
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{
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r.e -= 1;
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m <<= 1;
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}
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r.e >>= 1;
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r.m = spx_sqrt(m);
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return r;
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}
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#else
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#define spx_float_t float
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#define FLOAT_ZERO 0.f
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#define FLOAT_ONE 1.f
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#define FLOAT_HALF 0.5f
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#define PSEUDOFLOAT(x) (x)
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#define FLOAT_MULT(a,b) ((a)*(b))
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#define FLOAT_AMULT(a,b) ((a)*(b))
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#define FLOAT_MUL32(a,b) ((a)*(b))
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#define FLOAT_DIV32(a,b) ((a)/(b))
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#define FLOAT_EXTRACT16(a) (a)
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#define FLOAT_EXTRACT32(a) (a)
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#define FLOAT_ADD(a,b) ((a)+(b))
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#define FLOAT_SUB(a,b) ((a)-(b))
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#define REALFLOAT(x) (x)
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#define FLOAT_DIV32_FLOAT(a,b) ((a)/(b))
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#define FLOAT_MUL32U(a,b) ((a)*(b))
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#define FLOAT_SHL(a,b) (a)
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#define FLOAT_LT(a,b) ((a)<(b))
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#define FLOAT_GT(a,b) ((a)>(b))
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#define FLOAT_DIVU(a,b) ((a)/(b))
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#define FLOAT_SQRT(a) (spx_sqrt(a))
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#endif
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#endif
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