3 * Copyright 2004 Free Software Foundation, Inc.
5 * This file is part of GNU Radio
7 * GNU Radio is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 3, or (at your option)
12 * GNU Radio is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with GNU Radio; see the file COPYING. If not, write to
19 * the Free Software Foundation, Inc., 51 Franklin Street,
20 * Boston, MA 02110-1301, USA.
22 #ifndef INCLUDED_GR_FXPT_H
23 #define INCLUDED_GR_FXPT_H
28 * \brief fixed point sine and cosine and friends.
35 * 2**31-1 pi - epsilon
40 static const int WORDBITS = 32;
41 static const int NBITS = 10;
42 static const float s_sine_table[1 << NBITS][2];
43 static const float PI = 3.14159265358979323846;
44 static const float TWO_TO_THE_31 = 2147483648.0;
48 float_to_fixed (float x)
50 return (gr_int32) ((float) x * TWO_TO_THE_31 / PI);
54 fixed_to_float (gr_int32 x)
56 return x * (PI / TWO_TO_THE_31);
60 * \brief Given a fixed point angle x, return float sine (x)
66 int index = ux >> (WORDBITS - NBITS);
67 return s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
71 * \brief Given a fixed point angle x, return float cosine (x)
76 gr_uint32 ux = x + 0x40000000;
77 int index = ux >> (WORDBITS - NBITS);
78 return s_sine_table[index][0] * (ux >> 1) + s_sine_table[index][1];
83 #endif /* INCLUDED_GR_FXPT_H */