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fix(timers): retain shared free-running prescaler phase

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0xrsydn 2026-10-06 22:04:59 +07:00
commit 27806ccf9e
13 changed files with 459 additions and 32 deletions
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@ -35,6 +35,7 @@ Update this file when a feature lands or a limit is removed.
- CPU interrupt entry, interrupt masks, and FIQ priority.
- GBA interrupt enable (`IE`), request flags (`IF`), and master enable (`IME`) registers.
- Four 16-bit timers, with reloads, prescalers, count-up cascading, and timer-generated IRQs.
- A shared free-running timer divider survives enable and clock-source changes; HALT advances it and STOP freezes it.
- A 228-line display clock, VCOUNT/DISPSTAT, and VBlank/HBlank/VCount-match interrupts.
- Four direct memory access (DMA) channels, with immediate, VBlank, and visible-line HBlank triggers.
- Halfword/word DMA, address controls, repeat, channel priority, CPU pausing, and completion IRQs.
@ -175,7 +176,8 @@ Writes to cartridge addresses return errors instead of modeling cartridge hardwa
The desktop runner still uses only the original BIOS. Keep protected reads image-derived for all supplied images.
2. Validate the active nominal Game Pak prefetch queue against independent timing tests.
The [cancellation probe](research/prefetch-cancellation.md) now matches after [ordered timer accesses](research/ordered-timer-access.md).
Validate absolute timer startup/control edges and extend ordered observations to other devices without duplicate clocks or lost rollback.
The [shared timer prescaler](research/timer-prescaler.md) now retains a common clock origin across enable and clock-source changes.
Validate delayed timer startup/control edges and extend ordered observations to other devices without duplicate clocks or lost rollback.
Validate full-buffer restart, page boundaries, live WAITCNT transitions, and cold-start costs.
See [prefetch behavior and evidence](research/gamepak-prefetch.md); exact bus arbitration and timer/IRQ delays remain separate work.
3. Validate keypad retrigger behavior with hardware tests and add remaining device registers; extend BIOS reset coverage as sound/serial support becomes available.