Repository navigation
Allow rA=0 for 601 integer store-update instructions - #236
Merged
Merged
Conversation
Normally rA (where the effective address is stored) cannot be 0, but the MPC601 user manual explicitly says that it's allowed for POWER compatibility (the update is skipped in that case). Fixes mouse movement in Barrack under on the 6100, which would previously stop executing because of an illegal opcode exeception being raised (and unhandled).
Log a warning whenever an illegal opcode exception is being raised, since it's usually a clue that we have a correctness bug. Just a warning (as opposed to an error) because the guest OS may handle the exception and continue execution.
mihaip
added a commit
to mihaip/infinite-mac
that referenced
this pull request
Oct 10, 2026
Picks up dingusdev/dingusppc#236 which fixes Barrack on the 6100. For #219
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Normally rA (where the effective address is stored) cannot be 0, but the MPC601 user manual explicitly says that it's allowed for POWER compatibility (the update is skipped in that case).
Fixes mouse movement in Barrack under on the 6100, which would previously stop executing because of an illegal opcode exeception being raised (and unhandled).
To make this sort of thing easier to debug, log a warning whenever an illegal opcode exception is being raised,
since it's usually a clue that we have a correctness bug.
Just a warning (as opposed to an error) because the guest OS may handle the exception and continue execution. Also don't log zero opcodes, since the TNT ROM uses them frequently as sentinels.