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| author | Bryan Bishop <kanzure@gmail.com> | 2013-09-09 15:59:08 -0500 |
|---|---|---|
| committer | Bryan Bishop <kanzure@gmail.com> | 2013-09-09 15:59:08 -0500 |
| commit | 3a2dbb5289e745dfb5f26844148c0981f14e8fcf (patch) | |
| tree | dfb418aa41502c67ae3f75bab4d3df91b5cfd6c1 /common/double_speed.asm | |
| parent | 37e1aa4e8ec2400ba97db4c767bd3a9fcd43a1ac (diff) | |
| parent | abb7f2fa20e49cf56a55c81d4ec86431e3009098 (diff) | |
Merge branch 'yenatch/split-predefs-specials-stds' into fix-split-predefs-specials-stds
https://github.com/kanzure/pokecrystal/pull/198
Diffstat (limited to 'common/double_speed.asm')
| -rw-r--r-- | common/double_speed.asm | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/common/double_speed.asm b/common/double_speed.asm new file mode 100644 index 000000000..fc1234215 --- /dev/null +++ b/common/double_speed.asm @@ -0,0 +1,31 @@ +; 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: ; 2fef + ld hl, rKEY1 + bit 7, [hl] + jr z, SwitchSpeed + ret +; 2ff7 + +NormalSpeed: ; 2ff7 + ld hl, rKEY1 + bit 7, [hl] + ret z +; 2ffd + +SwitchSpeed: ; 2ffd + set 0, [hl] + xor a + ld [rIF], a + ld [rIE], a + ld a, $30 + ld [rJOYP], a + stop ; rgbasm adds a nop after this instruction by default + ret +; 300b + |