fixedpt.h

00001 /* Copyright (c) 2011 Bob Cousins bobcousins42@googlemail.com       */
00002 /* All rights reserved.
00003 
00004    Redistribution and use in source and binary forms, with or without
00005    modification, are permitted provided that the following conditions are met:
00006 
00007    * Redistributions of source code must retain the above copyright
00008      notice, this list of conditions and the following disclaimer.
00009    * Redistributions in binary form must reproduce the above copyright
00010      notice, this list of conditions and the following disclaimer in
00011      the documentation and/or other materials provided with the
00012      distribution.
00013    * Neither the name of the copyright holders nor the names of
00014      contributors may be used to endorse or promote products derived
00015      from this software without specific prior written permission.
00016 
00017   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
00018   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
00021   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
00022   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
00023   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00024   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00025   CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
00026   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00027   POSSIBILITY OF SUCH DAMAGE.
00028 */
00029 #ifndef _FIXEDPT_H
00030 #define _FIXEDPT_H
00031 
00032 #include "stdint.h"
00033 
00034 typedef unsigned short uint16_t;
00035 
00036 // some fixed point functions
00037 
00038 // choose int type and scale for best range/accuracy/speed
00039 
00040 // int64 (52.12) --> best accuracy
00041 // int32 (22.10) --> best performance
00042 
00043 typedef int32_t tFixedPt;
00044 
00045 #define scale  10 // nr of decimals (bits)
00046 
00047 
00048 // Convert number to fixed point
00049 #define to_fixed(n) ((n) << scale)
00050 
00051 // Divide fixed by n
00052 #define div_f(a,b) (((a)<<scale) / (b))
00053 
00054 // Fixed to integer
00055 #define to_int(n) ((n)>>scale)
00056 
00057 // Fixed to double
00058 float to_double (tFixedPt n);
00059 
00060 //Multiply two fixed point numbers
00061 tFixedPt mul_f (tFixedPt a, tFixedPt b);
00062 
00063 #endif
00064