emailler/client/ip65/dottedquad.s

78 lines
1.4 KiB
ArmAsm

.include "../inc/common.i"
.export parse_dotted_quad
.export dotted_quad_value
.bss
dotted_quad_value: .res 4 ;set to 32 bit ip address on a succesful call to parse_dotted_quad
dotted_quad_ptr: .res 4
.code
; convert a string representing a dotted quad (IP address, netmask) into 4 octets
; inputs:
; AX= pointer to null-terminated string containing dotted quad
; e.g. "192.168.1.0",0
; outputs:
; carry flag is set if there was an error, clear otherwise
; dotted_quad_value: will be set to (32 bit) ip address (if no error)
parse_dotted_quad:
stax dotted_quad_ptr+1
lda #$AD ; $AD='LDA immediate'
sta dotted_quad_ptr
lda #$60 ; $60='RTS
sta dotted_quad_ptr+3
ldx #0
txa
sta dotted_quad_value
@each_byte:
jsr get_next_byte
cmp #0
beq @done
and #$7F ;turn off bit 7
cmp #'.'
beq @got_dot
sec
sbc #'0'
bcc @error
cmp #10
bcs @error
clc
ldy #10
@mul_by_y:
adc dotted_quad_value,x
bcs @error
dey
bne @mul_by_y
sta dotted_quad_value,x
jmp @each_byte
@got_dot:
inx
lda #0
sta dotted_quad_value,x
jmp @each_byte
@done:
cpx #3
bne @error
clc
rts
@error:
sec
rts
get_next_byte:
jsr dotted_quad_ptr
inc dotted_quad_ptr+1
bne :+
inc dotted_quad_ptr+2
:
rts