84 lines
2.9 KiB
ArmAsm
84 lines
2.9 KiB
ArmAsm
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# Copyright (c) 1999 Global Technology Associates, Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS
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# BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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# OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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# BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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# WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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# OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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# EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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# From: btx.s 1.10 1999/02/25 16:27:41 rnordier
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# $Id:$
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#
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# Screen defaults and assumptions.
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.set SCR_MAT,0x7 # Mode/attribute
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.set SCR_COL,0x50 # Columns per row
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.set SCR_ROW,0x19 # Rows per screen
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# BIOS Data Area locations.
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.set BDA_SCR,0x449 # Video mode
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.set BDA_POS,0x450 # Cursor position
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.globl crt_putchr
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# void crt_putchr(int c)
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crt_putchr: movb 0x4(%esp,1),%al # Get character
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pusha # Save
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xorl %ecx,%ecx # Zero for loops
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movb $SCR_MAT,%ah # Mode/attribute
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movl $BDA_POS,%ebx # BDA pointer
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movw (%ebx),%dx # Cursor position
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movl $0xb8000,%edi # Regen buffer (color)
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cmpb %ah,BDA_SCR-BDA_POS(%ebx) # Mono mode?
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jne crt_putchr.1 # No
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xorw %di,%di # Regen buffer (mono)
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crt_putchr.1: cmpb $0xa,%al # New line?
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je crt_putchr.2 # Yes
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xchgl %eax,%ecx # Save char
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movb $SCR_COL,%al # Columns per row
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mulb %dh # * row position
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addb %dl,%al # + column
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adcb $0x0,%ah # position
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shll %eax # * 2
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xchgl %eax,%ecx # Swap char, offset
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movw %ax,(%edi,%ecx,1) # Write attr:char
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incl %edx # Bump cursor
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cmpb $SCR_COL,%dl # Beyond row?
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jb crt_putchr.3 # No
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crt_putchr.2: xorb %dl,%dl # Zero column
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incb %dh # Bump row
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crt_putchr.3: cmpb $SCR_ROW,%dh # Beyond screen?
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jb crt_putchr.4 # No
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leal 2*SCR_COL(%edi),%esi # New top line
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movw $(SCR_ROW-1)*SCR_COL/2,%cx # Words to move
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rep # Scroll
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movsl # screen
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movb $' ',%al # Space
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movb $SCR_COL,%cl # Columns to clear
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rep # Clear
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stosw # line
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movb $SCR_ROW-1,%dh # Bottom line
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crt_putchr.4: movw %dx,(%ebx) # Update position
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popa # Restore
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ret # To caller
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