From: admin@nospicedham.127.0.0.1
On Fri, 14 May 2021 21:53:32 +0200
Terje Mathisen wrote:
> Robert Prins wrote:
> > Is it possible to fit the conversion of a 16 bit signed integer to
> > left-aligned ASCII without leading zeroes in just 65 bytes?
>
> Naively I would say yes: I assume you don't care about speed here?
>
> ;; AX has the value to be converted to ascii
[code elided]
I took the liberty of moving the "mov bx,10" out of the loop!
NASM .lst file:
1 org 0x100
2 cpu 8086
3
4 ;; AX has the value to be converted to
ascii
5 ;; Store the string to the buffer
pointed to by DI
6 00000000 B80180 mov ax,0x8001
7 00000003 BF[3000] mov di,Ostr
8
9 putnum:
10 00000006 31C9 xor cx,cx ; Count how many digits
we find
11 00000008 85C0 test ax,ax ; Positive?
12 0000000A 7D09 jge next
13
14 ;; Negative input value, so print a
'-' sign
15 0000000C C6052D mov byte [di],'-'
16 0000000F F7D8 neg ax
17 00000011 47 inc di
18
19 00000012 BB0A00 mov bx,10
20
21 next:
22 00000015 31D2 xor dx,dx
23 00000017 F7F3 div bx
24 00000019 52 push dx ; Remainder is the digit
25 0000001A 41 inc cx
26 0000001B 85C0 test ax,ax ; Is it zero yet?
27 0000001D 75F6 jnz next
28
29 dump_digits:
30 0000001F 58 pop ax
31 00000020 0430 add al,'0'
32 00000022 AA stosb
33 00000023 E2FA loop dump_digits
34
35 convlth equ $-putnum
36
37 00000025 B82409 mov ax,0x100*9+'$'
38 00000028 AA stosb
39 00000029 BA[3000] mov dx,Ostr
40 0000002C CD21 int 0x21
41 0000002E C3 ret
42 0000002F 1F db convlth
43 Ostr equ $
> That looks like 17 instructions, most of them two-byte, 5 one-byte and a
> couple that are longer, so 32-35 bytes?
1F=31 bytes
--
Bah, and indeed Humbug.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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