src/arch/i386/firmware/pcbios/bios_console.c

   1 /* Etherboot routines for PCBIOS firmware.
   2  *
   3  * Body of routines taken from old pcbios.S
   4  */
   5
   6 #include "realmode.h"
   7 #include "console.h"
   8
   9 #define ZF ( 1 << 6 )
  10
  11 /**************************************************************************
  12 bios_putchar - Print a character on console
  13 **************************************************************************/
  14 static void bios_putchar ( int character ) {
  15         REAL_EXEC ( rm_console_putc,
  16                     "sti\n\t"
  17                     "movb $0x0e, %%ah\n\t"
  18                     "movl $1, %%ebx\n\t"
  19                     "int $0x10\n\t"
  20                     "cli\n\t",
  21                     1,
  22                     OUT_CONSTRAINTS ( "=a" ( character ) ),
  23                     IN_CONSTRAINTS ( "a" ( character ) ),
  24                     CLOBBER ( "ebx", "ecx", "edx", "ebp", "esi", "edi" ) );
  25
  26         /* NOTE: %eax may be clobbered, so must be specified as an output
  27          * parameter, even though we don't then do anything with it.
  28          */
  29 }
  30
  31 /**************************************************************************
  32 bios_getchar - Get a character from console
  33 **************************************************************************/
  34 static int bios_getchar ( void ) {
  35         uint16_t character;
  36
  37         REAL_EXEC ( rm_console_getc,
  38                     "sti\n\t"
  39                     "xorw %%ax, %%ax\n\t"
  40                     "int $0x16\n\t"
  41                     "cli\n\t",
  42                     1,
  43                     OUT_CONSTRAINTS ( "=a" ( character ) ),
  44                     IN_CONSTRAINTS (),
  45                     CLOBBER ( "ebx", "ecx", "edx", "ebp", "esi", "edi" ) );
  46
  47         return ( character & 0xff );
  48 }
  49
  50 /**************************************************************************
  51 bios_iskey - Check for keyboard interrupt
  52 **************************************************************************/
  53 static int bios_iskey ( void ) {
  54         uint16_t flags;
  55
  56         REAL_EXEC ( rm_console_ischar,
  57                     "sti\n\t"
  58                     "movb $1, %%ah\n\t"
  59                     "int $0x16\n\t"
  60                     "pushfw\n\t"
  61                     "popw %%ax\n\t"
  62                     "cli\n\t",
  63                     1,
  64                     OUT_CONSTRAINTS ( "=a" ( flags ) ),
  65                     IN_CONSTRAINTS (),
  66                     CLOBBER ( "ebx", "ecx", "edx", "ebp", "esi", "edi" ) );
  67
  68         return ( ( flags & ZF ) == 0 );
  69 }
  70
  71 static struct console_driver bios_console __console_driver = {
  72         .putchar = bios_putchar,
  73         .getchar = bios_getchar,
  74         .iskey = bios_iskey,
  75 };