99 lines
1.7 KiB
ArmAsm
99 lines
1.7 KiB
ArmAsm
.include "../inc/common.inc"
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.export _dotted_quad
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.export _parse_dotted_quad
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.import parse_dotted_quad
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.import dotted_quad_value
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.importzp sreg, tmp1, tmp2, tmp3
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.bss
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dotted_quad: .res 4*4 ; "xxx.xxx.xxx.xxx\0"
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.code
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_dotted_quad:
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stax dotted_quad_value
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ldax sreg
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stax dotted_quad_value+2
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ldx #$00
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ldy #$00
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: jsr convert_byte
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inx
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cpx #4
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bcc :-
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dey
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lda #$00
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sta dotted_quad,y ; replace last dot with '\0'
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ldax #dotted_quad
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rts
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convert_byte:
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; hex to bcd routine taken from Andrew Jacob's code at
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; http://www.6502.org/source/integers/hex2dec-more.htm
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sed ; switch to decimal mode
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lda #$00 ; ensure the result is clear
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sta tmp1 ; BCD low
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sta tmp2 ; BCD high
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lda #8 ; the number of source bits
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sta tmp3
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: asl dotted_quad_value,x ; shift out one bit
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lda tmp1 ; and add into result
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adc tmp1
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sta tmp1
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lda tmp2 ; propagating any carry
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adc tmp2
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sta tmp2
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dec tmp3 ; and repeat for next bit
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bne :-
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cld ; back to binary
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lda tmp1
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lsr
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lsr
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lsr
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lsr
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pha
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lda tmp2
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beq :+
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ora #'0'
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sta dotted_quad,y ; write x00
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pla
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iny
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bne :++ ; always
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: pla
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beq :++
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: ora #'0'
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sta dotted_quad,y ; write 0x0
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iny
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: lda tmp1
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and #$0F
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ora #'0'
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sta dotted_quad,y ; write 00x
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iny
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lda #'.'
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sta dotted_quad,y ; write dot
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iny
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rts
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_parse_dotted_quad:
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jsr parse_dotted_quad
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bcs error
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ldax dotted_quad_value+2
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stax sreg
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ldax dotted_quad_value
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rts
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error:
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ldx #$00
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txa
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stax sreg
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rts
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