sample/hello2.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2002 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  * hello2.c
  15  *
  16  * Simple COM32 image
  17  *
  18  * This version shows how to use the bounce buffer for data transfer
  19  * to the BIOS or COMBOOT system calls.
  20  */
  21
  22 #include <com32.h>
  23
  24 #define NULL ((void *)0)
  25
  26 static inline void memset(void *buf, int ch, unsigned int len)
  27 {
  28   asm volatile("cld; rep; stosb"
  29                : "+D" (buf), "+c" (len) : "a" (ch) : "memory");
  30 }
  31
  32 static void strcpy(char *dst, const char *src)
  33 {
  34   while ( *src )
  35     *dst++ = *src++;
  36
  37   *dst = '\0';
  38 }
  39
  40 static void writemsg(const char *msg)
  41 {
  42   com32sys_t inreg;
  43
  44   memset(&inreg, 0, sizeof inreg);
  45
  46   strcpy(__com32.cs_bounce, msg);
  47   inreg.eax.w[0] = 0x0002;      /* Write string */
  48   inreg.ebx.w[0] = OFFS(__com32.cs_bounce);
  49   inreg.es       = SEG(__com32.cs_bounce);
  50   __com32.cs_intcall(0x22, &inreg, NULL);
  51 };
  52
  53 int __start(void)
  54 {
  55   writemsg("Hello, World!\r\n"
  56            "cmdline = ");
  57   writemsg(__com32.cs_cmdline);
  58   writemsg("\r\n");
  59   return 0;
  60 }