这段程序好象有错请哪位大侠纠正一下!!k/***
*dos.h - definitions for MS-DOS interface routines
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the structs and unions used for the direct DOS interface
* routines; includes macros to access the segment and offset
* values of far pointers, so that they may be used by the routines; and
* provides function prototypes for direct DOS interface functions.
*
* [Public]
*
****/#if _MSC_VER > 1000
#pragma once
#endif#ifndef _INC_DOS
#define _INC_DOS#if !defined(_WIN32) && !defined(_MAC)
#error ERROR: Only Mac or Win32 targets supported!
#endif
#ifdef _MSC_VER
/*
* Currently, all MS C compilers for Win32 platforms default to 8 byte
* alignment.
*/
#pragma pack(push,8)
#endif /* _MSC_VER */#ifdef __cplusplus
extern "C"{
#endif/* Define _CRTIMP */#ifndef _CRTIMP
#ifdef _DLL
#define _CRTIMP __declspec(dllimport)
#else /* ndef _DLL */
#define _CRTIMP
#endif /* _DLL */
#endif /* _CRTIMP */
/* Define __cdecl for non-Microsoft compilers */#if ( !defined(_MSC_VER) && !defined(__cdecl) )
#define __cdecl
#endif/* Define _CRTAPI1 (for compatibility with the NT SDK) */#ifndef _CRTAPI1
#if _MSC_VER >= 800 && _M_IX86 >= 300
#define _CRTAPI1 __cdecl
#else
#define _CRTAPI1
#endif
#endif#ifndef _MAC
#ifndef _WCHAR_T_DEFINED
typedef unsigned short wchar_t;
#define _WCHAR_T_DEFINED
#endif
#endif /* ndef _MAC */#ifndef _MAC
#ifndef _DISKFREE_T_DEFINED
/* _getdiskfree structure (duplicated in DIRECT.H) */
struct _diskfree_t {
unsigned total_clusters;
unsigned avail_clusters;
unsigned sectors_per_cluster;
unsigned bytes_per_sector;
};#define _DISKFREE_T_DEFINED
#endif
#endif /* ndef _MAC *//* File attribute constants */#define _A_NORMAL 0x00 /* Normal file - No read/write restrictions */
#define _A_RDONLY 0x01 /* Read only file */
#define _A_HIDDEN 0x02 /* Hidden file */
#define _A_SYSTEM 0x04 /* System file */
#define _A_SUBDIR 0x10 /* Subdirectory */
#define _A_ARCH 0x20 /* Archive file */#ifndef _MAC
/* Function prototypes */
_CRTIMP unsigned __cdecl _getdiskfree(unsigned, struct _diskfree_t *);
#endif /* ndef _MAC */#ifdef _M_IX86
void __cdecl _disable(void);
void __cdecl _enable(void);
#endif /* _M_IX86 */#ifndef _MAC
#if !__STDC__
/* Non-ANSI name for compatibility */
#define diskfree_t _diskfree_t
#endif /* __STDC__ */
#endif /* ndef _MAC */#ifdef __cplusplus
}
#endif#ifdef _MSC_VER
#pragma pack(pop)
#endif /* _MSC_VER */#endif /* _INC_DOS */
*dos.h - definitions for MS-DOS interface routines
*
* Copyright (c) 1985-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Defines the structs and unions used for the direct DOS interface
* routines; includes macros to access the segment and offset
* values of far pointers, so that they may be used by the routines; and
* provides function prototypes for direct DOS interface functions.
*
* [Public]
*
****/#if _MSC_VER > 1000
#pragma once
#endif#ifndef _INC_DOS
#define _INC_DOS#if !defined(_WIN32) && !defined(_MAC)
#error ERROR: Only Mac or Win32 targets supported!
#endif
#ifdef _MSC_VER
/*
* Currently, all MS C compilers for Win32 platforms default to 8 byte
* alignment.
*/
#pragma pack(push,8)
#endif /* _MSC_VER */#ifdef __cplusplus
extern "C"{
#endif/* Define _CRTIMP */#ifndef _CRTIMP
#ifdef _DLL
#define _CRTIMP __declspec(dllimport)
#else /* ndef _DLL */
#define _CRTIMP
#endif /* _DLL */
#endif /* _CRTIMP */
/* Define __cdecl for non-Microsoft compilers */#if ( !defined(_MSC_VER) && !defined(__cdecl) )
#define __cdecl
#endif/* Define _CRTAPI1 (for compatibility with the NT SDK) */#ifndef _CRTAPI1
#if _MSC_VER >= 800 && _M_IX86 >= 300
#define _CRTAPI1 __cdecl
#else
#define _CRTAPI1
#endif
#endif#ifndef _MAC
#ifndef _WCHAR_T_DEFINED
typedef unsigned short wchar_t;
#define _WCHAR_T_DEFINED
#endif
#endif /* ndef _MAC */#ifndef _MAC
#ifndef _DISKFREE_T_DEFINED
/* _getdiskfree structure (duplicated in DIRECT.H) */
struct _diskfree_t {
unsigned total_clusters;
unsigned avail_clusters;
unsigned sectors_per_cluster;
unsigned bytes_per_sector;
};#define _DISKFREE_T_DEFINED
#endif
#endif /* ndef _MAC *//* File attribute constants */#define _A_NORMAL 0x00 /* Normal file - No read/write restrictions */
#define _A_RDONLY 0x01 /* Read only file */
#define _A_HIDDEN 0x02 /* Hidden file */
#define _A_SYSTEM 0x04 /* System file */
#define _A_SUBDIR 0x10 /* Subdirectory */
#define _A_ARCH 0x20 /* Archive file */#ifndef _MAC
/* Function prototypes */
_CRTIMP unsigned __cdecl _getdiskfree(unsigned, struct _diskfree_t *);
#endif /* ndef _MAC */#ifdef _M_IX86
void __cdecl _disable(void);
void __cdecl _enable(void);
#endif /* _M_IX86 */#ifndef _MAC
#if !__STDC__
/* Non-ANSI name for compatibility */
#define diskfree_t _diskfree_t
#endif /* __STDC__ */
#endif /* ndef _MAC */#ifdef __cplusplus
}
#endif#ifdef _MSC_VER
#pragma pack(pop)
#endif /* _MSC_VER */#endif /* _INC_DOS */
#include <iostream.h>
#include <dos.h>void main()
{
unsigned int t_a,t_b,in,inl=0,n,i=0; //定义变量,令inl, i初值为零
float T,F; //定义变量为单精度实数
outportb(0x43,0x34); //写8253方式字
outportb(0x40,0); //低位置零
outportb(0x40,0); //高位置零
t_a=peek(0,0x46c)+peek(0,0x46e)*65536; //读BIOS时间计数器 while(i<=2000) //循环2000次,跳出
{
in=inportb(0x3fe) & 0x20; //读D5位
if(in!=inl) //in=inl则跳过i+1
i++; // in≠inl,则i+1
inl=in; //令inl=in
}
outportb(0x43,4); //锁存8253计数器0
t_b=inportb(0x40); //读8253计数器0
t_b=t_b+inportb(0x40)*256;
t_b=65536-t_b; //求8253计数器
t_a=peek(0,0x46c)+peek(0,0x46e)*65536-t_a; //读时间计数器,求改变量
T=((t_a+1)*65536-t_b)*1/1.193186;
F=1000/T; //计算时间和频率 cout<<"F="<<F<<"HZ"<<endl; // 打印F值
}