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/*

 * Mon2000 Trap handler (syscall interface).

 *

 * This trap handler is linked into the mon2000 libgloss (libmon).

 */

#include <reent.h>

#include "syscall.h"

int __trap0 (int function, int p1, int p2, int p3, struct _reent *r)

{

  int rc = 0;

  switch (function) {

  case SYS_exit:

    /* loop so GDB can't go past system exit call */

    while (1) {

      asm volatile (

          "ldi    r0, #0                                                \n"

          "trap    #15        ; return control to Mon2000");

    }

    break;

  case SYS_write:

  {

    int i;

    for( i=0; i<p3; i++ ) {

      asm volatile (

          "ldi   r0, #2                                                 \n"

          "ldi   r1, #15      ; load Ctrl-O (ASCII 15)                  \n"

          "trap  #15          ; write Ctrl-O for quoting purposes" );

      asm volatile (

          "ldi   r0, #2                                                 \n"

          "ldb   r1, %0                                                 \n"

          "trap  #15          ; write character to console"

          : /* no outputs */

          : "m" (((char*)p2)[i]));

    }

    rc = p3;                 /* return number of chars written */

    break;

  }

  default:

    rc = 0;

    break;

  }

  return rc;

}