timer.h

计算时间间隔的程序

/***************************************************************************\
** TIMING CODE MODULE                                                      **
**=========================================================================**
**  Written by Ethan Rohrer, (c) Nuthing Software, December 4, 1994        **
**                                                                         **
**  Revision History                                                       **
**  ----------------                                                       **
**  Date        Description                                                **
**  ---------   ---------------------------------------------------------  **
**  13 May 94   Initial Release                                            **
**  04 Dec 94   Updated code to conform to current coding standards/style  **
**              Allowed appl. to specify # of timers as param. to TM_Init  **
**              Standardized error handling with function _TM_Error   	   **
**=========================================================================**
**  This file contains the declarations for publicly available types and   **
**  functions.                                                             **
**=========================================================================**
**  USING THIS MODULE                                                      **
**      Before calling any other timing routine, you must call TM_Init(n), **
**      where  n  specifies the number of timers your application needs.   **
**      It may be a good idea to call TM_Init() in the initialization      **
**      portion of your application.                                       **
**                                                                         **
**      To begin timing an event, make a call to TM_StartTimer(tid),       **
**      where tid is an integer in the range [0..(n-1)] which specifies    **
**      which of the n timers you are starting.                            **
**                                                                         **
**      To compute the duration of the event, just call                    **
**      TM_ElapsedTime(tid), where tid is the same integer used in the     **
**      call to TM_StartTimer().                                           **
**                                                                         **
**      When you are finished with the timing routines, call TM_Close().   **
**      This should fit in nicely with the cleanup section of your         **
**      application.                                                       **
**                                                                         **
**      If your application NEEDS to handle the time computations itself,  **
**      the function TM_ReadTimer(tid) is also available.  This function   **
**      will return the current time (MOD 1 hour, approximately).  I       **
**      discourage use of this function, but discovered that I need it     **
**      for another module/library...                                      **
**                                                                         **
**      EXAMPLES                                                           **
**          A simple delaying routine:                                     **
**          (TM_Init() must be called before this routine!)                **
**              void delay( tTIME duration )                               **
**              {                                                          **
**                  TM_StartTimer(0);                                      **
**                  while (TM_ElapsedTime(0) < duration)                   **
**                      ;                                                  **
**              }                                                          **
**                                                                         **
**          A fixed frame-rate game:                                       **
**              TM_Init(1);                                                **
**              while (player_not_dead)                                    **
**              {                                                          **
**                  TM_StartTimer(0);                                      **
**                  MoveMonsters();                                        **
**                  MovePlayers();                                         **
**                  UpdateDisplay();                                       **
**                  while (TM_ElapsedTime(0) < frame_duration)             **
**                      ;                                                  **
**              }                                                          **
**              TM_Close();                                                **
\***************************************************************************/

#ifndef __TIMER_H__
#define __TIMER_H__

/*------------------------------ Types ------------------------------------*/

/* type used to store time: should be 32-bits */

typedef  unsigned long int  tTIME;

/*----------------------------- Defines -----------------------------------*/

/* maximum number of timers to allow */

#define  TM_MAX_TIMERS  1

/* just a handy constant */

#define  ONE_SECOND  1193200    /* 65536(ticks/cycle) * 18.207(cycles/sec) */

/*------------------------- Public Prototypes -----------------------------*/

extern  void   TM_Close( );
extern  tTIME  TM_ElapsedTime( );
extern  int    TM_Init( );
extern  tTIME  TM_ReadTime( );
extern  void   TM_StartTimer( );

#endif /* __TIMER_H__ */