

/* BEEBS newlib ef_log implementation

   ====================================================
   Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.

   Developed at SunPro, a Sun Microsystems, Inc. business.
   Permission to use, copy, modify, and distribute this
   software is freely granted, provided that this notice
   is preserved.
   ====================================================

   Copyright (C) 2014 Embecosm Limited and University of Bristol

   Contributor Pierre Langlois <pierre.langlois@embecosm.com>

   This file is part of the Bristol/Embecosm Embedded Benchmark Suite.

   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 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program. If not, see <http://www.gnu.org/licenses/>. */

#include "support.h"
#include <stdint.h>

typedef union
{
  float value;
  uint32_t word;
} ieee_float_shape_type;

#define GET_FLOAT_WORD(i,d)					\
  ieee_float_shape_type gf_u;					\
  gf_u.value = (d);						\
  (i) = gf_u.word;

#define SET_FLOAT_WORD(d,i)					\
  ieee_float_shape_type sf_u;					\
  sf_u.word = (i);						\
  (d) = sf_u.value;

#define FLT_UWORD_IS_FINITE(x) ((x)<0x7f800000L)
#define FLT_UWORD_IS_NAN(x) ((x)>0x7f800000L)
#define FLT_UWORD_IS_INFINITE(x) ((x)==0x7f800000L)
#define FLT_UWORD_IS_ZERO(x) ((x)==0)
#define FLT_UWORD_IS_SUBNORMAL(x) ((x)<0x00800000L)

static const float
ln2_hi =   6.9313812256e-01,	/* 0x3f317180 */
ln2_lo =   9.0580006145e-06,	/* 0x3717f7d1 */
two25 =    3.355443200e+07,	/* 0x4c000000 */
Lg1 = 6.6666668653e-01,	/* 3F2AAAAB */
Lg2 = 4.0000000596e-01,	/* 3ECCCCCD */
Lg3 = 2.8571429849e-01, /* 3E924925 */
Lg4 = 2.2222198546e-01, /* 3E638E29 */
Lg5 = 1.8183572590e-01, /* 3E3A3325 */
Lg6 = 1.5313838422e-01, /* 3E1CD04F */
Lg7 = 1.4798198640e-01; /* 3E178897 */

static const float zero   =  0.0;

	float __ieee754_logf(float x)
{
	float hfsq,f,s,z,R,w,t1,t2,dk;
	int32_t k,ix,i,j;

	GET_FLOAT_WORD(ix,x);

	k=0;
	if (FLT_UWORD_IS_ZERO(ix&0x7fffffff))
	    return -two25/zero;		/* log(+-0)=-inf */
        if (ix<0) return (x-x)/zero;	/* log(-#) = NaN */
	if (!FLT_UWORD_IS_FINITE(ix)) return x+x;
	if (FLT_UWORD_IS_SUBNORMAL(ix)) {
	    k -= 25; x *= two25; /* subnormal number, scale up x */
	    GET_FLOAT_WORD(ix,x);
	}
	k += (ix>>23)-127;
	ix &= 0x007fffff;
	i = (ix+(0x95f64<<3))&0x800000;
	SET_FLOAT_WORD(x,ix|(i^0x3f800000));	/* normalize x or x/2 */
	k += (i>>23);
	f = x-(float)1.0;
	if((0x007fffff&(15+ix))<16) {	/* |f| < 2**-20 */
           if(f==zero) { if(k==0) return zero;  else {dk=(float)k;
                                return dk*ln2_hi+dk*ln2_lo;}}
	    R = f*f*((float)0.5-(float)0.33333333333333333*f);
	    if(k==0) return f-R; else {dk=(float)k;
	    	     return dk*ln2_hi-((R-dk*ln2_lo)-f);}
	}
 	s = f/((float)2.0+f);
	dk = (float)k;
	z = s*s;
	i = ix-(0x6147a<<3);
	w = z*z;
	j = (0x6b851<<3)-ix;
	t1= w*(Lg2+w*(Lg4+w*Lg6));
	t2= z*(Lg1+w*(Lg3+w*(Lg5+w*Lg7)));
	i |= j;
	R = t2+t1;
	if(i>0) {
	    hfsq=(float)0.5*f*f;
	    if(k==0) return f-(hfsq-s*(hfsq+R)); else
		     return dk*ln2_hi-((hfsq-(s*(hfsq+R)+dk*ln2_lo))-f);
	} else {
	    if(k==0) return f-s*(f-R); else
		     return dk*ln2_hi-((s*(f-R)-dk*ln2_lo)-f);
	}
}


/* This scale factor will be changed to equalise the runtime of the
   benchmarks. */
#define SCALE_FACTOR    (REPEAT_FACTOR >> 0)

/* Tell the compiler not to optimize out calls in BENCHMARK. */
volatile float result = 0;



/* This benchmark does not support verification */

int
verify_benchmark (int res __attribute ((unused)) )
{
  return -1;
}


void
initialise_benchmark (void)
{
}


int
benchmark (void)
{
  result = __ieee754_logf(2);
  result = __ieee754_logf(3);
  result = __ieee754_logf(4);
  result = __ieee754_logf(5);
  result = __ieee754_logf(6);
  return 0;
}


