sample/hello.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2002-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   This program is free software; you can redistribute it and/or modify
   6  *   it under the terms of the GNU General Public License as published by
   7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
   8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
   9  *   (at your option) any later version; incorporated herein by reference.
  10  *
  11  * ----------------------------------------------------------------------- */
  12
  13 /*
  14  * hello.c
  15  *
  16  * Simple COM32 image
  17  */
  18
  19 #include <com32.h>
  20
  21 #define NULL ((void *)0)
  22
  23 static inline void memset(void *buf, int ch, unsigned int len)
  24 {
  25   asm volatile("cld; rep; stosb"
  26                : "+D" (buf), "+c" (len) : "a" (ch) : "memory");
  27 }
  28
  29 int __start(void)
  30 {
  31   const char *msg = "Hello, World!\r\n";
  32   com32sys_t inreg;
  33   const char *p;
  34
  35   memset(&inreg, 0, sizeof inreg);
  36
  37   for ( p = msg ; *p ; p++ ) {
  38     inreg.edx.b[0] = *p;
  39     inreg.eax.b[1] = 0x02;      /* Write Character */
  40     __com32.cs_intcall(0x21, &inreg, NULL);
  41   }
  42
  43   return 0;
  44 }