/*      $NetBSD: comio.S,v 1.4 2003/04/16 14:23:11 dsl Exp $    */

/* serial console handling
  modelled after code in FreeBSD:sys/i386/boot/netboot/start2.S
 */

#include <machine/asm.h>

        .text

/**************************************************************************
INIT - Initialization (com number)
**************************************************************************/
ENTRY(cominit)
        push    %ebp
        mov     %esp,%ebp
        push    %ebx
        push    %edx
        push    %esi
        push    %edi

        movl    8(%ebp), %edx

        call    _C_LABEL(prot_to_real)  # enter real mode
        .code16

        # Initialize the serial port (dl) to 9600 baud, 8N1.
        movb    $0xe3, %al
        movb    $0, %ah
        int     $0x14
        mov     %ax,%bx

        calll   _C_LABEL(real_to_prot) # back to protected mode
        .code32

        xor     %eax,%eax
        mov     %bx,%ax

        pop     %edi
        pop     %esi
        pop     %edx
        pop     %ebx
        pop     %ebp
        ret

/**************************************************************************
PUTC - Print a character (char, com number)
**************************************************************************/
ENTRY(computc)
        push    %ebp
        mov     %esp,%ebp
        push    %ecx
        push    %ebx
        push    %edx
        push    %esi
        push    %edi

        movb    8(%ebp),%cl
        movl    12(%ebp),%edx

        call    _C_LABEL(prot_to_real)  # enter real mode
        .code16

        movb    %cl,%al
        movb    $0x01, %ah
        int     $0x14

        movb    %ah,%bl

        calll   _C_LABEL(real_to_prot) # back to protected mode
        .code32

        xor     %eax,%eax
        movb    %bl,%al

        pop     %edi
        pop     %esi
        pop     %edx
        pop     %ebx
        pop     %ecx
        pop     %ebp
        ret

/**************************************************************************
GETC - Get a character (com number)
**************************************************************************/
ENTRY(comgetc)
        push    %ebp
        mov     %esp,%ebp
        push    %ebx
        push    %edx
        push    %esi
        push    %edi

        movl    8(%ebp),%edx

        call    _C_LABEL(prot_to_real)  # enter real mode
        .code16

        movb    $0x02, %ah
        int     $0x14
        mov     %ax, %bx

        calll   _C_LABEL(real_to_prot) # back to protected mode
        .code32

        xor     %eax,%eax
        mov     %bx,%ax

        pop     %edi
        pop     %esi
        pop     %edx
        pop     %ebx
        pop     %ebp
        ret

/**************************************************************************
ISKEY - Check for keyboard interrupt (com number)
**************************************************************************/
ENTRY(comstatus)
        push    %ebp
        mov     %esp,%ebp
        push    %ebx
        push    %edx
        push    %esi
        push    %edi

        movl    8(%ebp),%edx

        call    _C_LABEL(prot_to_real)  # enter real mode
        .code16

        movb    $0x03, %ah
        int     $0x14
        mov     %ax,%bx

        calll   _C_LABEL(real_to_prot) # back to protected mode
        .code32

        xor     %eax,%eax
        mov     %bx,%ax

        pop     %edi
        pop     %esi
        pop     %edx
        pop     %ebx
        pop     %ebp
        ret