www.pudn.com > SJF2443.zip > TSTIO.C

/********************************************************************* 
 
Author:     Dale Roberts 
Date:       8/30/95 
Program:    TSTIO.EXE 
Compile:    cl -DWIN32 tstio.c 
 
Purpose:    Test the GIVEIO device driver by doing some direct 
            port I/O.  We access the PC's internal speaker. 
 
*********************************************************************/ 
#include  
#include  
#include  
#include  
 
typedef struct { 
	short int pitch; 
	short int duration; 
} NOTE; 
 
/* 
 *  Table of notes.  Given in half steps.  It's a communication from 
 * the "other side." 
 */ 
NOTE notes[] = {{14, 500}, {16, 500}, {12, 500}, {0, 500}, {7, 1000}}; 
 
/********************************************************************* 
  Set PC's speaker frequency in Hz.  The speaker is controlled by an 
Intel 8253/8254 timer at I/O port addresses 0x40-0x43. 
*********************************************************************/ 
void setfreq(int hz) 
{ 
	hz = 1193180 / hz;						// clocked at 1.19MHz 
	_outp(0x43, 0xb6);						// timer 2, square wave 
	_outp(0x42, hz); 
	_outp(0x42, hz >> 8); 
} 
 
/********************************************************************* 
  Pass a note, in half steps relative to 400 Hz.  The 12 step scale 
is an exponential thing.  The speaker control is at port 0x61. 
Setting the lowest two bits enables timer 2 of the 8253/8254 timer 
and turns on the speaker. 
*********************************************************************/ 
void playnote(NOTE note) 
{ 
	_outp(0x61, _inp(0x61) | 0x03);			// start speaker going 
	setfreq((int)(400 * pow(2, note.pitch / 12.0))); 
	Sleep(note.duration); 
	_outp(0x61, _inp(0x61) & ~0x03);		// stop that racket! 
} 
 
/********************************************************************* 
  Open and close the GIVEIO device.  This should give us direct I/O 
access.  Then try it out by playin' our tune. 
*********************************************************************/ 
int main() 
{ 
	int i; 
	HANDLE h; 
 
    h = CreateFile("\\\\.\\giveio", GENERIC_READ, 0, NULL, 
					OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); 
    if(h == INVALID_HANDLE_VALUE) { 
        printf("Couldn't access giveio device\n"); 
        return -1; 
    } 
	CloseHandle(h); 
 
	for(i=0; i < sizeof(notes)/sizeof(int); ++i) 
		playnote(notes[i]); 
 
	return 0; 
}