XPost: comp.os.msdos.programmer, alt.lang.asm
From: admin@nospicedham.127.0.0.1
On Mon, 2 Jan 2023 11:53:55 +0100
wolfgang kern wrote:
> On 31/12/2022 21:52, Kerr-Mudd, John wrote:
>
> >>>> example text to unrot:
> >>>>
> >>>> Onebarff Znetnerg Gungpure!
>
> >>> Now allows >1 space between the strings! (but no error checking)
> >> Now 90 bytes, assumes that at start ax=0,bh=0 and that cx > lth of
> >> parameters.
> >> I think that's as small as I can manage.
[I've found a problem and a few small gains; now 87]
>
> >> Wolfgang, would you like it in asm? here it is -
>
> :) Happy New Year!
>
And to you!
> I actually had no idea what this is supposed to do...
> if it is something like ROT13 I dunno the required algo. but
Sorry I dropped that part; it's an implementation of unix's
'tr' utility that unix users use to do rot13.
rot13:
tr '[A-Za-z]' '[N-ZA-Mn-za-m]'
or
tr 'A-Za-z' 'N-ZA-Mn-za-m'
(luckily both work as the square brackets are translated to themselves!)
> code parts look suspicious as if compiled by good old BASIC.
Er, I'm that good? - the 'clever' bits are:
1) using 'dl' as a toggle to alterately get a 'from' char and then a 'to'
char.
2) dealing with the range by keeping 'si' at the 'dash'
once the table is setup it's just a matter of fileio and using 'xlat' on
each input byte.
>
> >> -> u 100 l5A
> >> 1637:0100 99 cwd
> >> 1637:0101 BF 5A 01 mov di,015A ; Xlat Table after code
> >> 1637:0104 AA stosb
> >> 1637:0105 FE C0 inc al ; full range 0-255
> >> 1637:0107 75 FB jnz 0104
> >> 1637:0109 B3 83 mov bl,83 ; pt to PSP parms, after 1st
string's initial quote
> >> 1637:010B B0 20 mov al,20
> >> 1637:010D 89 DF mov di,bx
> >> 1637:010F F2 AE repnz scasb ; find gap
> >> 1637:0111 F3 AE repz scasb ;;; skip intermediate spaces
> >> 1637:0113 89 FE mov si,di ; after 1st quote of 2nd
string
> >> 1637:0115 80 F2 01 xor dl,01
> >> 1637:0118 74 04 jz 011E
> >
> > 1637:011A 88 85 5A 01 mov [di+015A],al
this is the 'problem'; on 1st run it hits a table entry; I hadn't noticed
unitl now as it's a non-ASCII 8x posn. It can be lived with, but I find it
unsatisfactory; I want the smallest, but fully functional code!
> > 1637:011E 97 xchg ax,di
> >
> >> 1637:011F 87 DE xchg bx,si
> >> 1637:0121 80 3C 2D cmp byte [si],2D ; processing a range?
> >> 1637:0124 75 08 jnz 012E
> >> 1637:0126 40 inc ax
> >> 1637:0127 3A 44 01 cmp al,[si+01]
> >> 1637:012A 76 E9 jbe 0115
> >> 1637:012C 46 inc si
> >> 1637:012D 46 inc si
> >> 1637:012E AC lodsb
> >> 1637:012F 3C 27 cmp al,27 ; end of string
> >> 1637:0131 75 E2 jnz 0115
> >> 1637:0133 BA 5A 02 mov dx,025A ; IO area
> >> 1637:0136 31 DB xor bx,bx
> >> 1637:0138 89 D6 mov si,dx
> >> 1637:013A 89 F7 mov di,si
> >> 1637:013C B9 A5 FD mov cx,FDA5 ; remainder of seg as IO
area
> >> 1637:013F B4 3F mov ah,3F ; read from STDIN
> >> 1637:0141 CD 21 int 21
> >> 1637:0143 91 xchg ax,cx
> >> 1637:0144 E3 13 jcxzw 0159 ; no more input
> >> 1637:0146 BB 5A 01 mov bx,015A
> >> 1637:0149 51 push cx
> >> 1637:014A AC lodsb
> >> 1637:014B D7 xlat [bx]
> >> 1637:014C AA stosb
> >> 1637:014D E2 FB loopw 014A
> >> 1637:014F 59 pop cx
> >> 1637:0150 BB 01 00 mov bx,0001
> >> 1637:0153 B4 40 mov ah,40 ; write to STDOUT
> >> 1637:0155 CD 21 int 21
> >> 1637:0157 EB DD jmp 0136
> >> 1637:0159 C3 ret
--
Bah, and indeed Humbug.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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