Vector35 / Vector35/Z80

Assorted flag-lifting inaccuracies

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Dominant language
Python
Stars
12
Forks
5
PR merge metrics
No merged PRs in 30d

Description

Smaller flag issues found while reviewing the lifter, grouped since each is a line or two:

  • CPL uses flags="*", but it only sets H and N.
  • SCF / CCF do not touch H or N.
  • LD A,I / LD A,R set no flags; they should set S and Z, clear H and N, and copy IFF2 into P/V.
  • RETI / RETN do not model IFF1 <- IFF2.
  • CPI / CPD write only Z.
  • pv is mapped to OverflowFlagRole, so parity after logic ops is modelled as signed overflow (there is already a TODO about this in the source).

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by locating the Z80 lifter handlers for CPL, SCF, CCF, LD A,I, LD A,R, RETI, RETN, CPI and CPD, then read the existing TODO about the pv mapping. Compare each handler's flag effects with the issue, including IFF1/IFF2 behavior, and consider the work done when all listed inaccuracies are modeled correctly.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
reverse-engineering
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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