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