0xrsydn/gameboy-rust
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fix(video): read BG maps and tiles through the 128 KiB VRAM mirror window

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0xrsydn 2026-10-07 10:06:48 +07:00
commit d7de5f7121
6 changed files with 60 additions and 50 deletions
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22
crates/gba-core/tests/affine_backgrounds.rs
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@ -252,7 +252,7 @@ fn transformed_backgrounds_composite_with_regular_and_affine_sprites() {
}
#[test]
fn diagnostics_leave_output_unchanged_and_disabled_layers_skip_validation() {
fn unsupported_layers_leave_output_unchanged_and_disabled_layers_skip_validation() {
let mut m = setup(2, 3, false);
let mut f = Framebuffer::default();
f.clear(0x001f);
@ -262,15 +262,8 @@ fn diagnostics_leave_output_unchanged_and_disabled_layers_skip_validation() {
m.render_frame(&mut f),
Err(VideoError::UnsupportedLayers(control))
);
assert!(f.pixels().iter().all(|&p| p == 0xff0000));
}
m.write16(DISPCNT, 0x402).unwrap();
m.write16(BG2CNT, 0xdf00).unwrap(); // Map31, 1024 pixels.
m.write32(BG2Y, 128 * 256).unwrap(); // Flat row starts outside first64K.
assert_eq!(
m.render_frame(&mut f),
Err(VideoError::UnsupportedMapAddress(0x10000))
);
assert!(f.pixels().iter().all(|&p| p == 0xff0000));
m.write16(DISPCNT, 2).unwrap();
m.render_frame(&mut f).unwrap();
assert!(f.pixels().iter().all(|&p| p == rgb555_to_rgb888(0x4000)));
@ -279,6 +272,17 @@ fn diagnostics_leave_output_unchanged_and_disabled_layers_skip_validation() {
assert!(f.pixels().iter().all(|&p| p == 0xffffff));
}
#[test]
fn affine_map_at_map_base_31_reads_high_vram_through_the_bus_mirror() {
let mut m = setup(2, 3, false);
m.write16(BG2CNT, 0xdf00).unwrap(); // Map31, 1024 pixels.
m.write32(BG2Y, 128 * 256).unwrap(); // Map row16 starts at offset0x10000.
m.write16(VRAM + 0x18000, 1).unwrap(); // Halfword bus mirror of the selected map byte.
let mut f = Framebuffer::default();
m.render_frame(&mut f).unwrap();
assert_eq!(f.pixels()[0], rgb555_to_rgb888(31));
}
#[test]
fn cpu_demo_pans_rotates_zooms_clips_cancels_opposites_and_resets() {
use gba_core::input::{Button, Buttons};