[Nextor 3] Fix key scanning for disk change on floppy emulation mode

[Konamiman]

"Backport" of #161

Part of #164

[coderabbitai]

📝 Walkthrough

Walkthrough

The CHGLOOP rotation and shift sequence in source/kernel/drv.mac was reordered, changing from sra c; rr e; rr d; ...; rr h to srl h; rr l; rr d; rr e; rr c. This alters the sequence and timing of register operations within the loop iteration while maintaining the subsequent bit test logic.

Changes

Cohort / File(s)	Summary
Register Rotation Sequence source/kernel/drv.mac	Reordered the rotation/shift instructions in CHGLOOP from sra c; rr e; rr d; ...; rr h to srl h; rr l; rr d; rr e; rr c, changing the progression of register updates and key index advancement per loop iteration.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• v2.1.4 #163: Modifies the same CHGLOOP rotation/shift sequence in source/kernel/drv.mac, reordering which registers are rotated.
• Fix key scanning for disk change on floppy emulation mode #161: Directly alters the CHGLOOP bit-rotation sequence in source/kernel/drv.mac, reordering register shift operations (H/L vs C/E/D) before the bit test.

Poem

🐰 With whiskers twitching, I rearrange,
The register dance in loops most strange,
From C to E, now H leads the way,
Each rotation spins a different day! 🔄

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically identifies the main change: a fix to key scanning for disk change in floppy emulation mode, directly matching the file modification in CHGLOOP.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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