/*                              MicrosecondTrapPresent.c                        */

/*

 * MicrosecondTrapPresent.c

 * Copyright © 1992-94 Apple Computer Inc. All Rights Reserved.

 */

#include <OSUtils.h>

#include "MicrosecondTrap.h"

static Boolean              TrapAvailable(

        short                   theTrap

    );

Boolean

MicrosecondTrapPresent(void)

{

        return (TrapAvailable(_Microseconds));

}

/*

 * TrapAvailable (see Inside Mac VI 3-8)

 */

#define NumToolboxTraps() (                             \

        (NGetTrapAddress(_InitGraf, ToolTrap)           \

                == NGetTrapAddress(0xAA6E, ToolTrap))   \

            ? 0x200 : 0x400                             \

    )

#define GetTrapType(theTrap) (                          \

        (((theTrap) & 0x800) != 0) ? ToolTrap : OSTrap  \

    )

static Boolean

TrapAvailable(

        short                   theTrap

    )

{

        TrapType                trapType;

        trapType = GetTrapType(theTrap);

        if (trapType == ToolTrap) {

            theTrap &= 0x07FF;

            if (theTrap >= NumToolboxTraps())

                theTrap = _Unimplemented;

        }

        return (

            NGetTrapAddress(theTrap, trapType)

            != NGetTrapAddress(_Unimplemented, ToolTrap)

        );

}