Category : Network Files
Archive   : PKTD11A.ZIP
Filename : GETNUM.ASM

;put into the public domain by Russell Nelson, [email protected]

public get_number
get_number:
mov bp,10 ;we default to 10.
jmp short get_number_0

public get_hex
get_hex:
mov bp,16
;get a hex number, skipping leading blanks.
;enter with si->string of digits,
; di -> dword to store the number in. [di] is not modified if no
; digits are given, so it acts as the default.
;return cy if there are no digits at all.
;return nc, bx:cx = number, and store bx:cx at [di].
get_number_0:
call skip_blanks
call get_digit ;is there really a number here?
jc get_number_3
xor ah,ah
cmp ax,bp ;larger than our base?
jae get_number_3 ;yes.
or al,al ;Does the number begin with zero?
jne get_number_4 ;no.
mov bp,8 ;yes - they want octal.
get_number_4:

xor cx,cx ;get a hex number.
xor bx,bx
get_number_1:
lodsb
cmp al,'x' ;did they really want hex?
je get_number_5 ;yes.
cmp al,'X' ;did they really want hex?
je get_number_5 ;yes.
call get_digit ;convert a character into an int.
jc get_number_2 ;not a digit (neither hex nor dec).
xor ah,ah
cmp ax,bp ;larger than our base?
jae get_number_2 ;yes.

push ax ;save the new digit.

mov ax,bp ;multiply the low word by ten.
mul cx
mov cx,ax ;keep the low word.
push dx ;save the high word for later.
mov ax,bp
mul bx
mov bx,ax ;we keep only the low word (which is our high word)
pop dx
add bx,dx ;add the high result from earlier.

pop ax ;get the new digit back.
add cx,ax ;add the new digit in.
adc bx,0
jmp get_number_1
get_number_5:
mov bp,16 ;change the base to hex.
jmp get_number_1
get_number_2:
dec si
mov [di],cx ;store the parsed number.
mov [di+2],bx
clc
jmp short get_number_6
get_number_3:
cmp al,'?' ;did they ask for the default?
stc
jne get_number_6 ;no, return cy.
add si,2 ;skip past the question mark.
mov cx,-1
mov bx,-1
jmp get_number_2 ;and return the -1.
get_number_6:
ret