mame/src/emu/attotime.c

/***************************************************************************

    attotime.c

    Support functions for working with attotime data.

****************************************************************************

    Copyright Aaron Giles
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions are
    met:

        * Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.
        * Redistributions in binary form must reproduce the above copyright
          notice, this list of conditions and the following disclaimer in
          the documentation and/or other materials provided with the
          distribution.
        * Neither the name 'MAME' nor the names of its contributors may be
          used to endorse or promote products derived from this software
          without specific prior written permission.

    THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR
    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT,
    INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
    STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
    IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.

***************************************************************************/

#include "emucore.h"
#include "eminline.h"
#include "attotime.h"


//**************************************************************************
//  GLOBAL VARIABLES
//**************************************************************************

const attotime attotime::zero(0, 0);
const attotime attotime::never(ATTOTIME_MAX_SECONDS, 0);



//**************************************************************************
//  CORE MATH FUNCTIONS
//**************************************************************************

//-------------------------------------------------
//  operator*= - multiply an attotime by a
//  constant
//-------------------------------------------------

attotime &attotime::operator*=(UINT32 factor)
{
	// if one of the items is attotime::never, return attotime::never
	if (seconds >= ATTOTIME_MAX_SECONDS)
		return *this = never;

	// 0 times anything is zero
	if (factor == 0)
		return *this = zero;

	// split attoseconds into upper and lower halves which fit into 32 bits
	UINT32 attolo;
	UINT32 attohi = divu_64x32_rem(attoseconds, ATTOSECONDS_PER_SECOND_SQRT, &attolo);

	// scale the lower half, then split into high/low parts
	UINT64 temp = mulu_32x32(attolo, factor);
	UINT32 reslo;
	temp = divu_64x32_rem(temp, ATTOSECONDS_PER_SECOND_SQRT, &reslo);

	// scale the upper half, then split into high/low parts
	temp += mulu_32x32(attohi, factor);
	UINT32 reshi;
	temp = divu_64x32_rem(temp, ATTOSECONDS_PER_SECOND_SQRT, &reshi);

	// scale the seconds
	temp += mulu_32x32(seconds, factor);
	if (temp >= ATTOTIME_MAX_SECONDS)
		return *this = never;

	// build the result
	seconds = temp;
	attoseconds = (attoseconds_t)reslo + mul_32x32(reshi, ATTOSECONDS_PER_SECOND_SQRT);
	return *this;
}


//-------------------------------------------------
//  operator/= - divide an attotime by a constant
//-------------------------------------------------

attotime &attotime::operator/=(UINT32 factor)
{
	// if one of the items is attotime::never, return attotime::never
	if (seconds >= ATTOTIME_MAX_SECONDS)
		return *this = never;

	// ignore divide by zero
	if (factor == 0)
		return *this;

	// split attoseconds into upper and lower halves which fit into 32 bits
	UINT32 attolo;
	UINT32 attohi = divu_64x32_rem(attoseconds, ATTOSECONDS_PER_SECOND_SQRT, &attolo);

	// divide the seconds and get the remainder
	UINT32 remainder;
	seconds = divu_64x32_rem(seconds, factor, &remainder);

	// combine the upper half of attoseconds with the remainder and divide that
	UINT64 temp = (INT64)attohi + mulu_32x32(remainder, ATTOSECONDS_PER_SECOND_SQRT);
	UINT32 reshi = divu_64x32_rem(temp, factor, &remainder);

	// combine the lower half of attoseconds with the remainder and divide that
	temp = attolo + mulu_32x32(remainder, ATTOSECONDS_PER_SECOND_SQRT);
	UINT32 reslo = divu_64x32_rem(temp, factor, &remainder);

	// round based on the remainder
	attoseconds = (attoseconds_t)reslo + mulu_32x32(reshi, ATTOSECONDS_PER_SECOND_SQRT);
	if (remainder >= factor / 2)
		if (++attoseconds >= ATTOSECONDS_PER_SECOND)
		{
			attoseconds = 0;
			seconds++;
		}
	return *this;
}


//-------------------------------------------------
//  as_string - return a temporary printable
//  string describing an attotime
//-------------------------------------------------

const char *attotime::as_string(int precision) const
{
	static char buffers[8][30];
	static int nextbuf;
	char *buffer = &buffers[nextbuf++ % 8][0];

	// special case: never
	if (*this == never)
		sprintf(buffer, "%-*s", precision, "(never)");

	// case 1: we want no precision; seconds only
	else if (precision == 0)
		sprintf(buffer, "%d", seconds);

	// case 2: we want 9 or fewer digits of precision
	else if (precision <= 9)
	{
		UINT32 upper = attoseconds / ATTOSECONDS_PER_SECOND_SQRT;
		int temp = precision;
		while (temp < 9)
		{
			upper /= 10;
			temp++;
		}
		sprintf(buffer, "%d.%0*d", seconds, precision, upper);
	}

	// case 3: more than 9 digits of precision
	else
	{
		UINT32 lower;
		UINT32 upper = divu_64x32_rem(attoseconds, ATTOSECONDS_PER_SECOND_SQRT, &lower);
		int temp = precision;
		while (temp < 18)
		{
			lower /= 10;
			temp++;
		}
		sprintf(buffer, "%d.%09d%0*d", seconds, upper, precision - 9, lower);
	}
	return buffer;
}