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[Core/CPU] improved 68k auto-vectored interrupts acknowledge cycle timing accuracy (fixes Pacman 2 - New Adventures crashes during Pac-Jr minigame levels transitions)

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ekeeke 2024-02-20 18:54:00 +01:00
parent 6b1dfa1cef
commit 405c54555e
5 changed files with 14 additions and 9 deletions
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2
HISTORY.txt
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@ -118,7 +118,7 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
[Core/CPU]
---------------
* added Z80 wait-states on 68k bus access (fixes Remute Red Eyes demo)
* improved 68k auto-vectored interrupts acknowledge cycle timing accuracy (Bubsy background color corruption during cutscenes)
* improved 68k auto-vectored interrupts acknowledge cycle timing accuracy (fixes Bubsy background color corruption during cutscenes & Pacman 2 - New Adventures crashes during Pac-Jr minigame levels transitions)
* improved 68k MOVEM instruction accuracy (implements extra read cycle from memory as verified on real hardware)
* fixed 68k undocumented behaviors for ABCD/SBCD/NBCD instructions (thanks to Flamewing for his test ROM)
* fixed 68k timing of BTST Dn,#Imm instruction (verified by Flamewing in original microcode)

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21
core/m68k/m68kcpu.h
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@ -616,13 +616,13 @@ static const uint16 m68ki_exception_cycle_table[256] =
4*MUL, /* 22: RESERVED */
4*MUL, /* 23: RESERVED */
44*MUL, /* 24: Spurious Interrupt */
54*MUL, /* 25: Level 1 Interrupt Autovector */
54*MUL, /* 26: Level 2 Interrupt Autovector */
54*MUL, /* 27: Level 3 Interrupt Autovector */
54*MUL, /* 28: Level 4 Interrupt Autovector */
54*MUL, /* 29: Level 5 Interrupt Autovector */
54*MUL, /* 30: Level 6 Interrupt Autovector */
54*MUL, /* 31: Level 7 Interrupt Autovector */
44*MUL, /* 25: Level 1 Interrupt Autovector */
44*MUL, /* 26: Level 2 Interrupt Autovector */
44*MUL, /* 27: Level 3 Interrupt Autovector */
44*MUL, /* 28: Level 4 Interrupt Autovector */
44*MUL, /* 29: Level 5 Interrupt Autovector */
44*MUL, /* 30: Level 6 Interrupt Autovector */
44*MUL, /* 31: Level 7 Interrupt Autovector */
34*MUL, /* 32: TRAP #0 -- ASG: chanaged from 38 */
34*MUL, /* 33: TRAP #1 */
34*MUL, /* 34: TRAP #2 */
@ -1374,6 +1374,11 @@ INLINE void m68ki_exception_address_error(void)
}
#endif
/* See MC68000 User Manual appendix B for autovectors interrupts processing time */
/* 44 cycles + N wait-state cycles where N depends on CPU clock alignement with internal E clock (corresponding to CPU clock / 10) when interrupt ack cycle starts */
/* N minimal/maximal values are 6..15 cycles according to manual but real hardware measure apparently indicate 5..14 cycles (cf https://gendev.spritesmind.net/forum/viewtopic.php?f=2&t=2202&p=27485) */
static uint m68ki_cycle_interrupts[10] = {50*MUL, 59*MUL, 58*MUL, 57*MUL, 56*MUL, 55*MUL, 54*MUL, 53*MUL, 52*MUL, 51*MUL};
/* Service an interrupt request and start exception processing */
INLINE void m68ki_exception_interrupt(uint int_level)
{
@ -1416,7 +1421,7 @@ INLINE void m68ki_exception_interrupt(uint int_level)
m68ki_jump(new_pc);
/* Update cycle count now */
USE_CYCLES(CYC_EXCEPTION[vector]);
USE_CYCLES(m68ki_cycle_interrupts[(m68ki_cpu.cycles / MUL) % 10]);
}
/* ASG: Check for interrupts */