---

/fixedpt.c

Go to the documentation of this file.

/*! \file fixedpt.c \brief Fixed-point math function library. */
//*****************************************************************************
//
// File Name    : 'fixedpt.c'
// Title        : Fixed-point math function library
// Author       : Pascal Stang - Copyright (C) 2003
// Created      : 2003.01.26
// Revised      : 2003.02.02
// Version      : 0.1
// Target MCU   : Atmel AVR Series
// Editor Tabs  : 4
//
// NOTE: This code is currently below version 1.0, and therefore is considered
// to be lacking in some functionality or documentation, or may not be fully
// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************


#include "fixedpt.h"

// Program ROM constants

// Global variables
u08 FixedPtBits;

// Functions

// fixedptInit() initializes fixed-point math function library
void fixedptInit(u08 fixedPtBits)
{
    // set the number of bits to use behind the point
    FixedPtBits = fixedPtBits;
}

s32 fixedptConvertFromInt(s32 int_number)
{
    // convert integer to fixed-point number
    return (int_number<<FixedPtBits);
}

s32 fixedptConvertToInt(s32 fp_number)
{
    // convert fixed-point number to integer
    // do rounding
    if( fp_number & 1<<(FixedPtBits-1) )
    {
        // bit behind the point was a '1'
        // round up to next higher integer
        return (fp_number>>FixedPtBits)+1;
    }
    else
    {
        // bit behind the point was a '0'
        // round down (truncate) to next lower integer
        return (fp_number>>FixedPtBits);
    }
}

s32 fixedptAdd(s32 a, s32 b)
{
    // add a and b (a+b) with fixed-point math
    return a+b;
}

s32 fixedptSubtract(s32 a, s32 b)
{
    // subtract a and b (a-b) with fixed-point math
    return a-b;
}

s32 fixedptMultiply(s32 a, s32 b)
{
    // multiply a and b (a*b) with fixed-point math
    return (a*b)>>FixedPtBits;
}

s32 fixedptDivide(s32 numer, s32 denom)
{
    // divide numer by denom (numer/denom) with fixed-point math
    return (numer<<FixedPtBits)/denom;
}

---