Fix: Correct cycle counts for branch taken and branch page crossing#130
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schmelze wants to merge 2 commits intomre:masterfrom
Open
Fix: Correct cycle counts for branch taken and branch page crossing#130schmelze wants to merge 2 commits intomre:masterfrom
schmelze wants to merge 2 commits intomre:masterfrom
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mre
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Feb 8, 2026
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mre
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Thanks for the fix. This all sounds reasonable to me. @omarandlorraine, any thoughts before merging?
Owner
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Oh, and can you run |
Collaborator
Don't think so; it's definitely a positive change and feels DRYer than what we had as well |
Author
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Ran fmt and updated PR |
Owner
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Thanks. Can you fix the lint error as well? You can test locally with |
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This PR fixes an issue where CPU cycles were not being incremented correctly during conditional branch instructions. According to the MOS 6502 specification:
This patch refactors all of the branch_if_* functions to call a new branch() function. This function centralizes the check to calculate page crossings and adjust cycle count as needed. This does remove the const qualifier on all branch functions, as they now mutate the cycle count.
A new test has been added to check this count: test_branch_cycle_timing()