User:Qalle/Algorithms: Difference between revisions
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Miscellaneous algorithms that may be useful on the NES. | 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 == | == 8-bit unsigned integer to 3 decimal ASCII digits == | ||
Source: <ref>[https://codebase64.org/doku.php?id=base:tiny_.a_to_ascii_routine Tiny .A to ASCII routine], Codebase64</ref> | Source: <ref>[https://codebase64.org/doku.php?id=base:tiny_.a_to_ascii_routine Tiny .A to ASCII routine], Codebase64</ref> | ||
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 | |||
- iny | sec | ||
- iny | |||
sbc #100 | |||
- dex | bcs - | ||
- dex | |||
adc #10 | |||
bmi - | |||
adc #$2f ; ASCII("0") | |||
rts | |||
== References == | == References == | ||
<references/> | <references/> | ||
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
