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/* dparam.s */
/* Written 1992 by Werner Almesberger */
.text
.globl _main
.org 0x100
_main: mov bl,0x80 ! NUL-terminate the command line
xor bh,bh
mov 0x81(bx),bh
mov bx,#0x81
aloop: mov al,(bx) ! get the next character
inc bx
cmp al,#32 ! space ?
je aloop ! yes -> skip it
cmp al,#48 ! '0' ?
jne error ! no -> invalid
cmpb (bx),#120 ! 'x' ?
je okay ! yes -> okay
cmpb (bx),#88 ! 'X' ?
jne error ! no -> invalid
okay: cmpb 1(bx),#56 ! '8' ?
jne error ! no -> invalid
cmpb 3(bx),#0 ! one more digit ?
jne error ! no -> invalid
mov dl,2(bx) ! get the digit
sub dl,#48 ! convert to a number
cmp dl,#1 ! valid ?
ja error ! no -> error
add dl,#0x80 ! adjust the number
mov ah,#8 ! get the drive parameters
int 0x13
or ah,ah ! error ?
jnz derror ! yes -> display a message
push cx ! save the parameters
push dx
mov al,cl ! number of sectors
and al,#0x3f
xor ah,ah
call decout
call space
pop dx ! number of heads
mov al,dh
inc al
xor ah,ah
call decout
call space
pop ax ! number of cylinders
xchg ah,al
mov cl,#6
shr ah,cl
inc ax
call decout
mov dx,#crlf ! crlf
mov ah,#9
int 0x21
ret ! done
error: mov dx,#errmsg ! display the error message
jmp dispit
derror: mov dx,#invdrv ! display the error message
jmp dispit
space: mov dx,#spc ! display two blanks
jmp dispit
decout: mov bx,#decend ! set the pointer to the end
declp: xor dx,dx ! divide by 10
mov cx,#10
div cx
add dl,#48 ! make a digit
dec bx ! store digit
mov (bx),dl
or ax,ax ! zero ?
jnz declp ! no -> go on
mov dx,bx ! display the string
dispit: mov ah,#9
int 0x21
ret ! done
errmsg: .ascii "usage: dparam 0x80"
.byte 13,10
.ascii " or dparam 0x81"
crlf: .byte 13,10
.ascii "$"
invdrv: .ascii "Invalid drive"
.byte 13,10
.ascii "$"
spc: .ascii " $"
decbuf: .byte 0,0,0,0,0
decend: .ascii "$"
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