/*                                  MicrosecondDelta.c                              */

/*

 * MicrosecondDelta.c

 * Copyright © 1994 Apple Computer Inc. All rights reserved.

 */

#include "MicrosecondTrap.h"

/*

 * Convert an epoch to microseconds (use floating-point operations).

 * Note that 4294967296.0 is 2^32, which is represented accurately

 * in double-precision floating point. Note that this can loose

 * low-order bits.

 */

#define kTwoPower32 (4294967296.0)

double

MicrosecondToDouble(

        register const UnsignedWide *epochPtr

    )

{

        register double         result;

        result = (((double) epochPtr->hi) * kTwoPower32) + epochPtr->lo;

        return (result);

}

/*

 * Return the difference between two Microsecond Trap values.

 * Integer subtraction is used to preserve accuracy.

 */

void

MicrosecondDelta(

        register const UnsignedWide *startPtr,

        register const UnsignedWide *endPtr,

        register UnsignedWide       *result

    )

{

        if (endPtr->lo >= startPtr->lo)

            result->hi = endPtr->hi - startPtr->hi;

        else {

            result->hi = (endPtr->hi - 1) - startPtr->hi;

        }

        result->lo = endPtr->lo - startPtr->lo;

}