1#
2# Copyright (c) 1999 Global Technology Associates, Inc.
3# All rights reserved.
4#
5# Redistribution and use in source and binary forms, with or without
6# modification, are permitted provided that the following conditions
7# are met:
8# 1. Redistributions of source code must retain the above copyright
9#    notice, this list of conditions and the following disclaimer.
10# 2. Redistributions in binary form must reproduce the above copyright
11#    notice, this list of conditions and the following disclaimer in the
12#    documentation and/or other materials provided with the distribution.
13#
14# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
15# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
17# PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
18# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
19# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
20# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
21# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
23# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
24# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25#
26#	From: btx.s 1.10 1999/02/25 16:27:41 rnordier
27# $FreeBSD$
28#
29
30# Screen defaults and assumptions.
31
32		.set SCR_MAT,0x7		# Mode/attribute
33		.set SCR_COL,0x50		# Columns per row
34		.set SCR_ROW,0x19		# Rows per screen
35
36# BIOS Data Area locations.
37
38		.set BDA_SCR,0x449		# Video mode
39		.set BDA_POS,0x450		# Cursor position
40
41		.globl crt_putchr
42
43# void crt_putchr(int c)
44
45crt_putchr: 	movb 0x4(%esp,1),%al		# Get character
46		pusha				# Save
47		xorl %ecx,%ecx			# Zero for loops
48		movb $SCR_MAT,%ah		# Mode/attribute
49		movl $BDA_POS,%ebx		# BDA pointer
50		movw (%ebx),%dx 		# Cursor position
51		movl $0xb8000,%edi		# Regen buffer (color)
52		cmpb %ah,BDA_SCR-BDA_POS(%ebx)	# Mono mode?
53		jne crt_putchr.1		# No
54		xorw %di,%di			# Regen buffer (mono)
55crt_putchr.1:	cmpb $0xa,%al			# New line?
56		je crt_putchr.2			# Yes
57		xchgl %eax,%ecx 		# Save char
58		movb $SCR_COL,%al		# Columns per row
59		mulb %dh			#  * row position
60		addb %dl,%al			#  + column
61		adcb $0x0,%ah			#  position
62		shll %eax			#  * 2
63		xchgl %eax,%ecx 		# Swap char, offset
64		movw %ax,(%edi,%ecx,1)		# Write attr:char
65		incl %edx			# Bump cursor
66		cmpb $SCR_COL,%dl		# Beyond row?
67		jb crt_putchr.3			# No
68crt_putchr.2:	xorb %dl,%dl			# Zero column
69		incb %dh			# Bump row
70crt_putchr.3:	cmpb $SCR_ROW,%dh		# Beyond screen?
71		jb crt_putchr.4			# No
72		leal 2*SCR_COL(%edi),%esi	# New top line
73		movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
74		rep				# Scroll
75		movsl				#  screen
76		movb $' ',%al			# Space
77		movb $SCR_COL,%cl		# Columns to clear
78		rep				# Clear
79		stosw				#  line
80		movb $SCR_ROW-1,%dh		# Bottom line
81crt_putchr.4:	movw %dx,(%ebx) 		# Update position
82		popa				# Restore
83		ret				# To caller
84