sample/hello2.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  * 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":"+D" (buf), "+c"(len):"a"(ch):"memory");
  29 }
  30
  31 static void strcpy(char *dst, const char *src)
  32 {
  33     while (*src)
  34         *dst++ = *src++;
  35
  36     *dst = '\0';
  37 }
  38
  39 static void writemsg(const char *msg)
  40 {
  41     com32sys_t inreg;
  42
  43     memset(&inreg, 0, sizeof inreg);
  44
  45     strcpy(__com32.cs_bounce, msg);
  46     inreg.eax.w[0] = 0x0002;    /* Write string */
  47     inreg.ebx.w[0] = OFFS(__com32.cs_bounce);
  48     inreg.es = SEG(__com32.cs_bounce);
  49     __com32.cs_intcall(0x22, &inreg, NULL);
  50 };
  51
  52 int __start(void)
  53 {
  54     writemsg("Hello, World!\r\n" "cmdline = ");
  55     writemsg(__com32.cs_cmdline);
  56     writemsg("\r\n");
  57     return 0;
  58 }