Created
October 12, 2012 20:32
-
-
Save ysangkok/3881337 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
; basE91 encoder for DOS | |
; | |
; Copyright (c) 2005-2006 Joachim Henke | |
; All rights reserved. | |
; | |
; Redistribution and use in source and binary forms, with or without | |
; modification, are permitted provided that the following conditions are met: | |
; | |
; - Redistributions of source code must retain the above copyright notice, | |
; this list of conditions and the following disclaimer. | |
; - 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. | |
; - Neither the name of Joachim Henke nor the names of his contributors may | |
; be used to endorse or promote products derived from this software without | |
; specific prior written permission. | |
; | |
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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. | |
bits 16 | |
cpu 8086 | |
org 256 | |
xor sp, sp | |
mov si, ld_0 ; create lookup table | |
mov bp, 90 | |
lc_0: | |
mov bx, 90 | |
mov ah, [bp + si] | |
lc_1: | |
mov al, [bx + si] | |
push ax | |
dec bx | |
jns lc_1 | |
dec bp | |
jns lc_0 | |
inc bx | |
mov sp, a_stck | |
lc_2: | |
push bx | |
push bx | |
jmp short lc_5 | |
lc_3: | |
mov ax, [si] | |
cmp cl, 6 ; bits in queue + 8 < 14? | |
sbb dx, dx | |
inc si | |
mov ch, ah | |
add bp, dx | |
sbb dx, dx | |
xor ch, al | |
and ah, dl | |
and ch, dl | |
sub si, dx | |
xor ch, al | |
shl ax, cl | |
add cl, 8 | |
or bx, ax | |
test bp, bp | |
js lc_4 | |
and bh, 0x1F ; keep 13 bits | |
and dl, 8 | |
and ah, 0x3F | |
cmp bx, byte 89 ; value in bit queue < 89? | |
sbb al, al | |
add dl, cl | |
and ah, al | |
mov cl, 13 | |
or bh, ah ; take 13 or 14 bits | |
sub cl, al | |
add bx, bx | |
mov ax, [bx + a_ltab] | |
mov bx, cx | |
add cl, 16 | |
sub cl, dl | |
sub dl, bl | |
shr bx, cl ; restore bit queue | |
mov cl, dl | |
stosw | |
dec bp | |
jns lc_3 | |
lc_4: | |
push bx | |
mov ah, 0x40 | |
push cx | |
mov bx, 1 | |
lea cx, [di - a_obuf] | |
mov dx, a_obuf | |
int 0x21 ; write to standard output | |
dec bx | |
lc_5: | |
mov ah, 0x3F | |
mov cx, s_ibuf | |
mov dx, a_ibuf | |
int 0x21 ; read from standard input | |
cld | |
pop cx | |
mov si, dx | |
mov di, a_obuf | |
pop bx | |
add bp, ax ; ax = 0 -> EOF | |
jc lc_3 | |
push ax | |
test cl, cl | |
jz lc_6 | |
cmp bx, byte 91 ; value in bit queue < 91? | |
sbb dx, dx | |
cmp cl, 8 ; less than 8 bits in queue? | |
sbb cx, cx | |
add bx, bx | |
and cx, dx | |
mov dx, a_obuf | |
mov ax, [bx + a_ltab] | |
inc cx | |
mov bx, 1 | |
inc cx | |
stosw | |
mov ah, 0x40 | |
int 0x21 ; write out 1 or 2 bytes | |
lc_6: | |
retn ; exit program | |
ld_0: | |
db 'ABCDEFGHIJKLM' | |
db 'NOPQRSTUVWXYZ' | |
db 'abcdefghijklm' | |
db 'nopqrstuvwxyz' | |
db '0123456789!#$' | |
db '%&()*+,./:;<=' | |
db '>?@[]^_`{|}~"' | |
a_stck equ ((lc_2 - $$) + 256) & 510 | |
a_ltab equ 48974 | |
a_obuf equ ((ld_0 - $$) + 257) & 510 | |
s_ibuf equ ((a_ltab - a_obuf - 2) << 4) / 29 | |
a_ibuf equ a_ltab - s_ibuf |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment