/**************************************************************************/
/* blink.c                Written by Matt Begg               January '93  */
/**************************************************************************/
/* Sample program for the Analog Devices EZ-Lab board and C compiler 2.0  */
/* or later.                                                              */
/* Demonstrates use of interrupts and 21020 I/O flags without use of      */
/* assmbly level programming.                                             */
/*                                                                        */
/* To compile:                                                            */
/*                                                                        */
/* g21k blink.c -o blink -a ez.ach -Wall -O2 -save-temps -xref            */
/*                                                                        */
/*      blink.c is the file to compile.  If you don't specify ".c" as     */
/*              the extension, it will be assumed to be an object file    */
/*              and passed to the linker, which will probably complain.   */
/*              g21k will also assemble files with ".asm" extensions      */
/*              automatically.                                            */
/*                                                                        */
/*      -o specifies the output file name (.exe automatically added       */
/*         if you don't specify otherwise)                                */
/*      -a specifies the architecture file name.                          */
/*                                                                        */
/*      -Wall turns on the most useful warning messages.  If you get a    */
/*            warning, there is usually something wrong.                  */
/*                                                                        */
/*      -O2 turns on the most optimimiations and will produce the most    */
/*          efficient code.  -O runs only the faster optimizations        */
/*          but still produces much better code than unoptimized, which   */
/*          is the only code the debugger can handle.                     */
/*                                                                        */
/*      -save-temps tells the compiler to keep its temporary files        */
/*          they are:                                                     */
/*              blink.i  Preprocessed file.  Comments are removed, macros */
/*                       are expanded into C code or asm statements       */
/*                                                                        */
/*              blink.s  assembly language file.  Look here to get an     */
/*                       idea of how efficient the compiler is.           */
/*                                                                        */
/*              blink.o  object file.  Ready to link.                     */
/*                                                                        */
/*              blink.ldr  linker file.  This can be treated like an exe. */
/*                         It is probably a bit bigger though.            */
/*                                                                        */
/*              blink.exe  executable file.  Use this one with the        */
/*                         EZ-Lab board or simulator.  Arrays and other   */
/*                         variables have been compressed for faster      */
/*                         loading and smaller ROM requirements.          */
/*                                                                        */
/*      -map   tells linker to generate map file.  Lists varibles and     */
/*             memory requirements.  Does not account for any compression */
/*             after linking.                                             */

/* Note: Flag bits are restored by return from interrupt in rev. 0 21020  */
/* This means led 2 will appear to stay on constantly.  To fix this, get  */
/* a revision 1 part.                                                     */

#include <21020.h>
#include <signal.h>

void timer_isr(int interrupt_number); /* prototypes are very important */

void main(void)
{
  timer_set(6250000, 6250000);  /* period, current count (cycles) */
  /* >6250000/25MHz=4 toggles per sec */
  interrupt(SIG_TMZ0, timer_isr); /* set up timer interrupt routine */
  timer_on();                   /* start timer */
  set_flag(SET_FLAG1, CLR_FLAG); /* turn off led 1 */

  for(;;)                       /* infinite loop */
    {
      poll_flag_in(READ_FLAG0, FLAG_IN_LO_TO_HI); /* wait for switch press  */
      set_flag(SET_FLAG1, SET_FLAG); /* turn on led 1            */
      poll_flag_in(READ_FLAG0, FLAG_IN_HI_TO_LO); /* wait for release       */
      set_flag(SET_FLAG1, CLR_FLAG); /* turn off led 1           */
    }
}

void timer_isr(int interrupt_number) /* The interrupt handler passes the */
{                               /* number of the interrupt to your  */
  /* isr so it can deal with          */
  /* multiple interrupts.  You do not */
  /* have to use this feature; take   */
  /* the parameter then ignore it.    */

  set_flag(SET_FLAG2, TGL_FLAG); /* toggle led 2 on or off */
}