07091: sgunner2, sgunner2j: Player 1 and Player 2 Coin buttons missing

ID	Category [?]	Severity [?]	Reproducibility	Date Submitted	Last Update
07091	DIP/Input	Major	Always	Sep 4, 2018, 09:04	Sep 6, 2018, 13:56

Tester	MetalGod	View Status	Public	Platform	MAME (Official Binary)
Assigned To	AJR	Resolution	Fixed	OS	Windows Vista/7/8 (64-bit)
Status [?]	Resolved			Driver	namco/namcos2.cpp
Version	0.201	Fixed in Version	0.202	Build	64-bit
		Fixed in Git Commit		Github Pull Request #

Summary	07091: sgunner2, sgunner2j: Player 1 and Player 2 Coin buttons missing
Description	Coin buttons for player 1 and 2 don't work ingame. They are both recognized inside the service menu but don't work ingame. This incidence started in Mame 0.193 and it's still happening in Mame 0.201 It looks similar to ticket 05287
Steps To Reproduce	Just try to insert a credit ingame (5 or 6 keys by default)
Additional Information
Github Commit

Flags
Regression Version	0.193
Affected Sets / Systems	sgunner2, sgunner2j

Attached Files

No.15411 AJR Developer Sep 6, 2018, 13:56	This was the result of a M740 bug introduced as a subtle and unnecessary change during the great disassembler refactoring. To make a long story short, variable shadowing made the SET and CLT instructions not actually affect execution, even though they could affect the disassembly. If you want to see the exact point where sgunner2's coin inputs were getting lost, run the debugger, focus on the c68 MCU and then enter 'bpset 83b9, a & 3'. This breakpoint will trigger when a coin input is received. Examine the surrounding code, and you can tell that the coin inputs will be obliterated if LDT #$00 (the instruction at 83B9) is executed as LDA #$00 (which the instruction would be interpreted as without SET). Stepping over the instruction will confirm whether or not that happens.

No.15411

AJR

Developer

Sep 6, 2018, 13:56

This was the result of a M740 bug introduced as a subtle and unnecessary change during the great disassembler refactoring. To make a long story short, variable shadowing made the SET and CLT instructions not actually affect execution, even though they could affect the disassembly.

If you want to see the exact point where sgunner2's coin inputs were getting lost, run the debugger, focus on the c68 MCU and then enter 'bpset 83b9, a & 3'. This breakpoint will trigger when a coin input is received. Examine the surrounding code, and you can tell that the coin inputs will be obliterated if LDT #$00 (the instruction at 83B9) is executed as LDA #$00 (which the instruction would be interpreted as without SET). Stepping over the instruction will confirm whether or not that happens.