/usr/share/sdcc/lib/src/atanf.c is in sdcc-libraries 2.9.0-5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 | /* atanf.c: Computes arctan of a 32-bit float as outlined in [1]
Copyright (C) 2001, 2002 Jesus Calvino-Fraga, jesusc@ieee.org
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* [1] William James Cody and W. M. Waite. _Software manual for the
elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
/* Version 1.0 - Initial release */
#include <math.h>
#include <errno.h>
#define P0 -0.4708325141E+0
#define P1 -0.5090958253E-1
#define Q0 0.1412500740E+1
#define Q1 0.1000000000E+1
#define P(g,f) ((P1*g+P0)*g*f)
#define Q(g) (Q1*g+Q0)
#define K1 0.2679491924 /* 2-sqrt(3) */
#define K2 0.7320508076 /* sqrt(3)-1 */
#define K3 1.7320508076 /* sqrt(3) */
#ifdef SDCC_mcs51
#define myconst __code
#else
#define myconst const
#endif
float atanf(const float x) _FLOAT_FUNC_REENTRANT
{
float f, r, g;
int n=0;
static myconst float a[]={ 0.0, 0.5235987756, 1.5707963268, 1.0471975512 };
f=fabsf(x);
if(f>1.0)
{
f=1.0/f;
n=2;
}
if(f>K1)
{
f=((K2*f-1.0)+f)/(K3+f);
// What it is actually wanted is this more accurate formula,
// but SDCC optimizes it and then it does not work:
// f=(((K2*f-0.5)-0.5)+f)/(K3+f);
n++;
}
if(fabsf(f)<EPS) r=f;
else
{
g=f*f;
r=f+P(g,f)/Q(g);
}
if(n>1) r=-r;
r+=a[n];
if(x<0.0) r=-r;
return r;
}
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