mirror of
https://gitlab.com/xCrystal/pokecrystal-board.git
synced 2024-09-09 09:51:34 -07:00
28 lines
489 B
NASM
28 lines
489 B
NASM
; The CGB hardware introduces Double Speed Mode.
|
|
; While active, the clock speed is doubled.
|
|
|
|
; The hardware can switch between normal speed
|
|
; and double speed at any time, but LCD output
|
|
; collapses during the switch.
|
|
|
|
DoubleSpeed::
|
|
ld hl, rKEY1
|
|
bit 7, [hl]
|
|
jr z, SwitchSpeed
|
|
ret
|
|
|
|
NormalSpeed::
|
|
ld hl, rKEY1
|
|
bit 7, [hl]
|
|
ret z
|
|
|
|
SwitchSpeed::
|
|
set 0, [hl]
|
|
xor a
|
|
ldh [rIF], a
|
|
ldh [rIE], a
|
|
ld a, $30
|
|
ldh [rJOYP], a
|
|
stop ; rgbasm adds a nop after this instruction by default
|
|
ret
|