From fe6c36e18042603bb096d3685fe3988e32331ebf Mon Sep 17 00:00:00 2001
From: haturatu <taro@eyes4you.org>
Date: Tue, 10 Dec 2024 21:28:04 +0900
Subject: first commit

---
 DOS-asm/b91enc.asm | 152 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 DOS-asm/b91enc.asm

(limited to 'DOS-asm/b91enc.asm')

diff --git a/DOS-asm/b91enc.asm b/DOS-asm/b91enc.asm
new file mode 100644
index 0000000..c4d00e9
--- /dev/null
+++ b/DOS-asm/b91enc.asm
@@ -0,0 +1,152 @@
+; 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
-- 
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