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improved HINT accuracy in Master System Compatibility mode.

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ekeeke31 2011-04-28 00:13:23 +00:00
parent ea8228be66
commit 7cd0eb4a4b
1 changed files with 8 additions and 0 deletions
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8
source/system.c
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@ -757,6 +757,14 @@ static void system_frame_sms(int do_skip)
hint_pending = 0x10; hint_pending = 0x10;
if (reg[0] & 0x10) if (reg[0] & 0x10)
{ {
/* IRQ line is latched between instructions, on instruction last cycle */
/* This means that if Z80 cycle count is exactly a multiple of MCYCLES_PER_LINE, */
/* interrupt should be triggered AFTER the next instruction. */
if ((mcycles_z80 % MCYCLES_PER_LINE) == 0)
{
z80_run(mcycles_z80 + 1);
}
Z80.irq_state = ASSERT_LINE; Z80.irq_state = ASSERT_LINE;
} }
} }