ut13_delay.c

小型操作系统,以VC为开发环境,需要boachs调试

/***************************************************************************
**     File name   : ut13_delay.c
**     Author      : x.cheng
**     Create date :
**
**	   Comment:
**        delay defined in this file...
**
**     Revisions:
**     $Log: ut13_delay.c,v $
**
***************************************************************************/
#include "const.h"
#include "type.h"

#define PIT_TICKS_PER_SEC	0x1234ddL
static unsigned long loopsPerSec = 0;

void __delay( unsigned long loops ) {
    int d0;

    __asm__ __volatile__ (
	"\tjmp 1f\n" 
	".align 4 \n"
	"1:\tjmp 2f\n"
	".align 4 \n"
	"2:\tdecl %0\n\tjns 2b":"=&a"(d0):"0"(loops));
}

inline void __const_udelay( unsigned long xloops ) {
    int d0;

    __asm__ ( "mull %0"
	: "=d" ( xloops ), "=&a" ( d0 )
	: "1" ( xloops ), "0" ( loopsPerSec ) );
    __delay( xloops );
}

void UDelay( unsigned long ulLoops ) {
    __const_udelay( ulLoops * 0x000010c6 );
}

void Delay( unsigned long ulLoops ) {
    UDelay( ulLoops * 100 );
}

/*
int ReadPitTimer() {
    int count;

    outb( 0x43, 0x00 );
    count = inb( 0x40 );
    count += inb( 0x40 ) << 8;
    return count;
}

void GetDelay() {
    int loopBit;
    int presicion = 8;

    loopsPerSec = ( 1 << 12 );

    while ( loopsPerSec <<= 1 ) {
	outb( 0x43, 0x30 );
	outb( 0x40, 0xFF );
	outb( 0x40, 0xFF );

	__delay( loopsPerSec );

	if ( ReadPitTimer() < 64000 ) {
	    break;
	}
    }
    loopsPerSec >>= 1;
    loopBit = loopsPerSec;

    while ( presicion-- && ( loopBit >>= 1 ) ) {
	loopsPerSec |= loopBit;

	outb( 0x43, 0x30 );
	outb( 0x40, 0xFF );
	outb( 0x40, 0xFF );
	__delay( loopsPerSec ) ;
	if ( ReadPitTimer() < 64000 ) {
	    break;
	}
    }
    outb( 0x43, 0x34 );
    outb( 0x40, 0x00 );
    outb( 0x40, 0x00 );

    loopsPerSec *= PIT_TICKS_PER_SEC / ( 65535 - 64000 );
    kPrint( "%lu.%02lu BogoMIPS\n", ( loopsPerSec + 2500 ) / 500000,
	( ( loopsPerSec + 2500 ) / 5000 ) % 100 );
}
*/