emailler/ip65/dottedquad_c.s
2018-07-20 13:59:06 +02:00

94 lines
1.7 KiB
ArmAsm

.include "../inc/common.inc"
.export _dotted_quad
.export _parse_dotted_quad
.import parse_dotted_quad
.import dotted_quad_value
.importzp sreg, tmp1, tmp2, tmp3
.bss
dotted_quad: .res 4*4 ; "xxx.xxx.xxx.xxx\0"
.code
_dotted_quad:
stax dotted_quad_value
ldax sreg
stax dotted_quad_value+2
ldx #$00
ldy #$00
: jsr convert_byte
inx
cpx #4
bcc :-
dey
lda #$00
sta dotted_quad,y ; replace last dot with '\0'
ldax #dotted_quad
rts
convert_byte:
; hex to bcd routine taken from Andrew Jacob's code at http://www.6502.org/source/integers/hex2dec-more.htm
sed ; switch to decimal mode
lda #$00 ; ensure the result is clear
sta tmp1 ; BCD low
sta tmp2 ; BCD high
lda #8 ; the number of source bits
sta tmp3
: asl dotted_quad_value,x ; shift out one bit
lda tmp1 ; and add into result
adc tmp1
sta tmp1
lda tmp2 ; propagating any carry
adc tmp2
sta tmp2
dec tmp3 ; and repeat for next bit
bne :-
cld ; back to binary
lda tmp2
beq :+
ora #'0'
sta dotted_quad,y ; write x00 if not 0
iny
: lda tmp1
lsr
lsr
lsr
lsr
beq :+
ora #'0'
sta dotted_quad,y ; write 0x0 if not 0
iny
: lda tmp1
and #$0F
ora #'0'
sta dotted_quad,y ; write 00x
iny
lda #'.'
sta dotted_quad,y ; write dot
iny
rts
_parse_dotted_quad:
jsr parse_dotted_quad
bcs error
ldax dotted_quad_value+2
stax sreg
ldax dotted_quad_value
rts
error:
ldx #$00
txa
stax sreg
rts