0xrsydn/gameboy-rust
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feat(input): implement KEYCNT keypad interrupt control

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Add a dependency-free keypad state machine in gba-core, map KEYCNT, latch IF bit 12, and wake HALT through the existing interrupt gates. Sample complete CPU/DMA control writes once so transient byte values cannot create false requests.

Document the mGBA-style polling policy and its unverified hardware retrigger limits. Cover every button-state/selection pair, register masks, repeated requests, byte/word writes, failed-store isolation, DMA priority, ARM/Thumb IRQ return, BIOS IntrWait, and retained BIOS reset state.

Follow the restructured workspace and modular documentation. Validated on Darwin arm64: workspace and core/demo tests pass in debug and release, with Clippy, rustdoc, ten native window smoke tests, and terminal demos passing.
This commit is contained in:
0xrsydn 2026-10-05 18:00:46 +07:00
commit 597b02881b
14 changed files with 710 additions and 21 deletions
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9
crates/gba-core/src/memory.rs
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@ -4,7 +4,7 @@ use crate::{
display::{DisplayPosition, CYCLES_PER_LINE, HBLANK_START, VISIBLE_LINES},
dma::{DmaError, DMA_BASE, DMA_END},
input::Buttons,
io::{Io, HALTCNT, POSTFLG},
io::{Io, HALTCNT, KEYINPUT, POSTFLG},
timing::{bus_cycles, AccessKind, AccessWidth, DataTiming, StepTiming},
video::{self, sprites::pipeline, Framebuffer, VideoError},
};
@ -325,7 +325,8 @@ impl Memory {
}
/// Replace the current pressed-button state. This does not advance time.
/// KEYCNT and keypad interrupts are not implemented yet.
/// Sample KEYCNT and latch a matching keypad IRQ immediately, without cycles.
/// This can wake HALT; CPU IRQ delivery occurs on a later Machine::step.
pub fn set_buttons(&mut self, buttons: Buttons) {
self.io.set_buttons(buttons);
}
@ -424,6 +425,10 @@ impl Memory {
},
);
if address >> 24 == 0x04 {
if address & !3 == KEYINPUT {
self.io.write_keypad(address, &bytes);
return Ok(());
}
for (offset, byte) in bytes.into_iter().enumerate() {
let byte_address = address + offset as u32;
if matches!(byte_address, POSTFLG | HALTCNT) && !self.can_write_power_control() {