delay.c

用ATmega8 做的MP3播放器

/*
 * Copyright (c) 2003-2004 K. John '2B|!2B' Crispin
 * Copyright (c) 2005      Stephan Dobretsberger
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA02111-1307USA
 *
 * Feedback, Bugs, ... mail [e-mail]
 *
 */

 // TODO:
 //   add preprocessors for different cpu speeds currently 8mhz is support

#include <avr/io.h>
#include <avr/signal.h>
#include <avr/interrupt.h>
#include "types.h"
#include "config.h"
// delays n microseconds
// for 8MHZ 8 ticks
// assuming a for loop is 3 commands in asm -->  inc, tst, jmp
// if a loop takes more or less then 3 let me know. this is sort of a guess
void delay_us(u16 n)
{ for(;n>0;n--)
  { NOP; NOP; NOP; NOP; NOP;
  };
};

void delay_ms(u16 m)
{ for(;m>0;m--)
  { for(global_tmp = 1000 ;global_tmp>0;global_tmp--)
    { NOP; NOP; NOP; NOP; NOP;
    };
  };
};