User:Qalle/Algorithms: Difference between revisions
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cmp #$3a ; ASCII("9")+1 | cmp #$3a ; ASCII("9")+1 | ||
bcc + | bcc + | ||
adc # | adc #6 ; ASCII("A")-(ASCII("9")+1)-1 | ||
+ rts | + rts | ||
Latest revision as of 20:42, 21 October 2023
Miscellaneous algorithms that may be useful on the NES.
8-bit unsigned integer to 2 hexadecimal ASCII digits
byte2hex:
; in: A = unsigned integer
; out: X/A = ASCII digits of sixteens/ones in upper case
pha
lsr a
lsr a
lsr a
lsr a
clc
jsr nybble2hex
tax
pla
and #%00001111
jsr nybble2hex
rts
nybble2hex:
adc #$30 ; ASCII("0")
cmp #$3a ; ASCII("9")+1
bcc +
adc #6 ; ASCII("A")-(ASCII("9")+1)-1
+ rts
8-bit unsigned integer to 3 decimal ASCII digits
Source: [1]
byte2dec:
; in: A = unsigned integer
; out: Y/X/A = ASCII digits of hundreds/tens/ones
ldy #$2f ; ASCII("0")-1
ldx #$3a ; ASCII("9")+1
sec
- iny
sbc #100
bcs -
- dex
adc #10
bmi -
adc #$2f ; ASCII("0")
rts
References
- ↑ Tiny .A to ASCII routine, Codebase64
