A2osX/SYS/KERNEL.S.CNV.txt

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PR#3
PREFIX /A2OSX.BUILD
LOMEM $A00
INC 1
AUTO 6
*--------------------------------------
* Convert HEXBUF to ASCBUF decimal padded with 0
*--------------------------------------
HEX2DEC ldx #4
.1 stz BCDBUF,x Clear all 5 bytes
dex
bpl .1
sed switch to BCD mode
ldx #32 let's roll 32 bits
.2 jsr HEXBUF.ROL
ldy #4
.3 lda BCDBUF,y
adc BCDBUF,y
sta BCDBUF,y
dey
bpl .3
dex
bne .2
cld
ldy #4
ldx #9
.4 lda BCDBUF,y
pha
and #$0F
ora #$30
sta ASCBUF,x
dex
pla
lsr
lsr
lsr
lsr
ora #$30
sta ASCBUF,x
dey
dex
bpl .4
rts
*--------------------------------------
* Convert ASCBUF decimal to HEXBUF
*--------------------------------------
DEC2HEX stz HEXBUF
stz HEXBUF+1
stz HEXBUF+2
stz HEXBUF+3
lda ASCBUF
beq .8
ldx #0
.1 lda HEXBUF+3 save HEXBUF for 4+1
pha
lda HEXBUF+2
pha
lda HEXBUF+1
pha
lda HEXBUF
pha
jsr HEXBUF.ROL HEXBUF * 2 -> HEXBUF
* bcs .9 overflow!!!
jsr HEXBUF.ROL HEXBUF * 4 -> HEXBUF
* bcs .9 overflow!!!
pla HEXBUF * 4 + HEXBUF -> HEXBUF
adc HEXBUF
sta HEXBUF
pla
adc HEXBUF+1
sta HEXBUF+1
pla
adc HEXBUF+2
sta HEXBUF+2
pla
adc HEXBUF+3
sta HEXBUF+3
* bcs .99 overflow!!!
jsr HEXBUF.ROL HEXBUF * 10 -> HEXBUF
* bcs .99 overflow!!!
inx
lda ASCBUF,x
and #$0F
adc HEXBUF
sta HEXBUF
bcc .2
inc HEXBUF+1
bne .2
inc HEXBUF+2
bne .2
inc HEXBUF+3
.2 cpx ASCBUF
bne .1
.8 rts
*.9 pla discard saved HEXBUF
* pla
* pla
* pla
*.99 rts
*--------------------------------------
HEXBUF.ROL asl HEXBUF
rol HEXBUF+1
rol HEXBUF+2
rol HEXBUF+3
rts
*--------------------------------------
HEXBUF .BS 4 32 bits max
BCDBUF .BS 5 5, enough to handle 10 digits (32bits)
ASCBUF .BS 12 LEN + sign + 10 digits ($FFFFFFFF=4.294.967.295)
*--------------------------------------
MAN
SAVE /A2OSX.SRC/SYS/KERNEL.S.CNV
LOAD /A2OSX.SRC/SYS/KERNEL.S
ASM