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GB: Backport STAT register behavior 

http://www.devrs.com/gb/files/faqs.html#GBBugs
This commit is contained in:
retro-wertz 2018-07-26 13:45:06 +08:00
parent d9e0d0f88d
commit faf01db2cf
1 changed files with 17 additions and 1 deletions
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18
src/gb/GB.cpp
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@ -1268,7 +1268,23 @@ void gbWriteMemory(register uint16_t address, register uint8_t value)
// (value & 0x7c);
gbMemory[0xff41] = register_STAT = (value & 0xf8) | (register_STAT & 0x07); // fix ?
// GB bug from Devrs FAQ
// proper fix
// http://www.devrs.com/gb/files/faqs.html#GBBugs
// 2018-7-26 Backported STAT register bug behavior
// Corrected : it happens if Lcd Mode < 2, but also if LY == LYC whatever
// Lcd Mode is, and if !gbInt48Signal in all cases. The screen being off
// doesn't matter (the bug will still happen).
// That fixes 'Satoru Nakajima - F-1 Hero' crash bug.
// Games below relies on this bug, , and are incompatible with the GBC.
// - Road Rash: crash after player screen
// - Zerg no Densetsu: crash right after showing a small portion of intro
if ((gbHardware & 5)
&& (((!gbInt48Signal) && (gbLcdMode < 2) && (register_LCDC & 0x80))
|| (register_LY == register_LYC))) {
gbMemory[0xff0f] = register_IF |=2;
}
gbInt48Signal &= ((register_STAT >> 3) & 0xF);
if ((register_LCDC & 0x80)) {