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#
# Copyright (c) 1999 Global Technology Associates, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# From: btx.s 1.10 1999/02/25 16:27:41 rnordier
# $FreeBSD$
#
# Screen defaults and assumptions.
.set SCR_MAT,0xe1 # Mode/attribute
.set SCR_COL,0x50 # Columns per row
.set SCR_ROW,0x19 # Rows per screen
# BIOS Data Area locations.
.set BDA_POS,0x53e # Cursor position
.globl crt_putchr
# void crt_putchr(int c)
crt_putchr: movb 0x4(%esp,1),%al # Get character
pusha # Save
xorl %ecx,%ecx # Zero for loops
movb $SCR_MAT,%ah # Mode/attribute
movl $BDA_POS,%ebx # BDA pointer
movw (%ebx),%dx # Cursor position
movl $0xa0000,%edi
crt_putchr.1: cmpb $0xa,%al # New line?
je crt_putchr.2 # Yes
movw %dx,%cx
movb %al,(%edi,%ecx,1) # Write char
addl $0x2000,%ecx
movb %ah,(%edi,%ecx,1) # Write attr
addw $0x02,%dx
jmp crt_putchr.3
crt_putchr.2: movw %dx,%ax
movb $SCR_COL*2,%dl
div %dl
incb %al
mul %dl
movw %ax,%dx
crt_putchr.3: cmpw $SCR_ROW*SCR_COL*2,%dx
jb crt_putchr.4 # No
leal 2*SCR_COL(%edi),%esi # New top line
movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
rep # Scroll
movsl # screen
movb $' ',%al # Space
xorb %ah,%ah
movb $SCR_COL,%cl # Columns to clear
rep # Clear
stosw # line
movw $(SCR_ROW-1)*SCR_COL*2,%dx
crt_putchr.4: movw %dx,(%ebx) # Update position
shrw $1,%dx
crt_putchr.5: inb $0x60,%al # Move cursor
testb $0x04,%al
jz crt_putchr.5
movb $0x49,%al
outb %al,$0x62
movb %dl,%al
outb %al,$0x60
movb %dh,%al
outb %al,$0x60
popa # Restore
ret # To caller
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