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fix: preserve indexed Boolean CopyBits semantics #601

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Merged
benletchford merged 1 commit into from
Aug 17, 2026
Merged

fix: preserve indexed Boolean CopyBits semantics #601

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175 changes: 172 additions & 3 deletions src/trap/quickdraw.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3363,6 +3363,14 @@ impl super::TrapDispatcher {
let src_clut = src_clut.as_ref();
let dst_clut = dst_clut.as_ref();
let palette_translation = palette_translation.as_ref();
let shared_indexed_pixel_mask = Self::shared_indexed_pixel_mask(
src_info.pixel_size,
dst_info.pixel_size,
src_info.ctab_handle,
dst_ctab_handle,
src_clut,
dst_clut,
);
let transformed_blit = !no_scaling
|| palette_translation.is_some()
|| src_info.pixel_size != dst_info.pixel_size
Expand Down Expand Up @@ -3773,6 +3781,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
shared_indexed_pixel_mask,
mode_base,
src_pixel,
dst_pixel,
Expand Down Expand Up @@ -3817,6 +3826,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
None,
mode_base,
src_pixel,
bus.read_byte(dst_addr),
Expand Down Expand Up @@ -3873,6 +3883,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
shared_indexed_pixel_mask,
mode_base,
src_pixel,
bus.read_byte(dst_addr),
Expand Down Expand Up @@ -19104,6 +19115,14 @@ impl super::TrapDispatcher {
let src_clut = src_clut.as_ref();
let dst_clut = dst_clut.as_ref();
let palette_translation = palette_translation.as_ref();
let shared_indexed_pixel_mask = Self::shared_indexed_pixel_mask(
src_info.pixel_size,
dst_info.pixel_size,
src_info.ctab_handle,
dst_ctab_handle,
src_clut,
dst_clut,
);
let (copy_fg_rgb, copy_bg_rgb) = self.copy_bits_port_draw_colors(bus, port);
if trace_copybits_enabled()
&& (mask_rgn != 0
Expand Down Expand Up @@ -19375,6 +19394,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
shared_indexed_pixel_mask,
mode_base,
src_pixel,
dst_pixel,
Expand Down Expand Up @@ -19411,6 +19431,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
None,
mode_base,
src_pixel,
bus.read_byte(dst_addr),
Expand Down Expand Up @@ -19438,6 +19459,7 @@ impl super::TrapDispatcher {
src_clut,
dst_clut,
palette_translation,
shared_indexed_pixel_mask,
mode_base,
src_pixel,
bus.read_byte(dst_addr),
Expand Down Expand Up @@ -21385,15 +21407,25 @@ impl super::TrapDispatcher {
src_clut: Option<&[[u16; 3]; 256]>,
dst_clut: Option<&[[u16; 3]; 256]>,
palette_translation: Option<&[u8; 256]>,
shared_indexed_pixel_mask: Option<u8>,
mode_base: u16,
src_pixel: u8,
dst_pixel: u8,
fg_rgb: [u16; 3],
bg_rgb: [u16; 3],
) -> Option<u8> {
// Color QuickDraw applies current foreground/background colors for
// Boolean source modes on colored pixels, and leaves destination
// pixels untouched for the table's white/black preserve cases.
if let Some(pixel_mask) = shared_indexed_pixel_mask {
if let Some(pixel) =
Self::indexed_boolean_transfer(src_pixel, dst_pixel, mode_base, pixel_mask)
{
return Some(pixel);
}
}

// Across different indexed color spaces, Color QuickDraw applies
// current foreground/background colors for Boolean source modes and
// leaves destination pixels untouched for the table's white/black
// preserve cases.
// Imaging With QuickDraw 1994, p. 4-33.
let raw_source = || {
palette_translation
Expand Down Expand Up @@ -21426,6 +21458,58 @@ impl super::TrapDispatcher {
}
}

fn indexed_boolean_transfer(
src_pixel: u8,
dst_pixel: u8,
mode_base: u16,
pixel_mask: u8,
) -> Option<u8> {
// A shared indexed color space makes the pixel value itself the
// Boolean operand. Mask complemented results to the active depth.
// Imaging With QuickDraw (1994), pp. 4-32--4-34.
let src_pixel = src_pixel & pixel_mask;
let dst_pixel = dst_pixel & pixel_mask;
let result = match mode_base {
0 => src_pixel,
1 => src_pixel | dst_pixel,
2 => src_pixel ^ dst_pixel,
3 => !src_pixel & dst_pixel,
4 => !src_pixel,
5 => !src_pixel | dst_pixel,
6 => !src_pixel ^ dst_pixel,
7 => src_pixel & dst_pixel,
_ => return None,
};
Some(result & pixel_mask)
}

fn shared_indexed_pixel_mask(
src_pixel_size: u32,
dst_pixel_size: u32,
src_ctab_handle: u32,
dst_ctab_handle: u32,
src_clut: Option<&[[u16; 3]; 256]>,
dst_clut: Option<&[[u16; 3]; 256]>,
) -> Option<u8> {
// Equal explicit ColorTables describe the same indexed color space;
// null tables instead inherit a device context and cannot establish
// that relationship by themselves.
if src_pixel_size != dst_pixel_size
|| !matches!(src_pixel_size, 2 | 4 | 8)
|| src_ctab_handle == 0
|| dst_ctab_handle == 0
|| (src_ctab_handle != dst_ctab_handle && src_clut != dst_clut)
{
return None;
}

Some(if src_pixel_size == 8 {
u8::MAX
} else {
(1u8 << src_pixel_size) - 1
})
}

fn copy_bits_direct_source_mode_rgb(
src_rgb: [u16; 3],
dst_rgb: [u16; 3],
Expand Down Expand Up @@ -32506,6 +32590,91 @@ mod tests {
);
}

#[test]
fn indexed_boolean_transfer_masks_all_eight_source_modes() {
let results = (0..=7)
.map(|mode| {
TrapDispatcher::indexed_boolean_transfer(0b1010, 0b1100, mode, 0x0F)
.expect("Boolean source mode")
})
.collect::<Vec<_>>();

assert_eq!(results, vec![0xA, 0xE, 0x6, 0x4, 0x5, 0xD, 0x9, 0x8]);
assert_eq!(
TrapDispatcher::indexed_boolean_transfer(0, 0, 4, 0x03),
Some(0x03),
"complemented two-bit pixels must not leak high bits"
);
}

#[test]
fn copy_bits_shared_palette_srcxor_restores_packed_indexed_pixels() {
// When indexed PixMaps use the same depth and ColorTable, Boolean
// source modes operate directly on their pixel values. Applying
// srcXor twice must therefore restore every packed destination byte.
// Imaging With QuickDraw (1994), pp. 4-32--4-34.
let (mut d, mut cpu, mut bus) = setup_with_port();

for (case, pixel_size) in [2u16, 4, 8].into_iter().enumerate() {
let root = 0x340000 + case as u32 * 0x10000;
let src_pixmap = root + 0x100;
let dst_pixmap = root + 0x200;
let src_base = root + 0x1000;
let dst_base = root + 0x2000;
let shared_ctab = root + 0x3000;
let src_rect = root + 0x4000;
let dst_rect = root + 0x4010;
let width = 8 / pixel_size;
let source = 0b1011_0001u8;
let original = 0b0110_1100u8;

write_color_table(
&mut bus,
shared_ctab,
0x1234_5678 + case as u32,
&[(0, 0xFFFF, 0xFFFF, 0xFFFF)],
);
write_pixmap_indexed(
&mut bus,
src_pixmap,
src_base,
1,
width,
1,
pixel_size,
shared_ctab,
);
write_pixmap_indexed(
&mut bus,
dst_pixmap,
dst_base,
1,
width,
1,
pixel_size,
shared_ctab,
);
bus.write_byte(src_base, source);
bus.write_byte(dst_base, original);
write_rect(&mut bus, src_rect, 0, 0, 1, width as i16);
write_rect(&mut bus, dst_rect, 0, 0, 1, width as i16);

for expected in [source ^ original, original] {
cpu.write_reg(Register::A7, TEST_SP);
bus.write_long(TEST_SP, 0);
bus.write_word(TEST_SP + 4, 2u16); // srcXor
bus.write_long(TEST_SP + 6, dst_rect);
bus.write_long(TEST_SP + 10, src_rect);
bus.write_long(TEST_SP + 14, dst_pixmap);
bus.write_long(TEST_SP + 18, src_pixmap);

let result = d.dispatch_quickdraw(true, 0x0EC, &mut cpu, &mut bus);
assert!(result.unwrap().is_ok());
assert_eq!(bus.read_byte(dst_base), expected, "{pixel_size}bpp srcXor");
}
}
}

fn write_pixmap_8(
bus: &mut crate::memory::MacMemoryBus,
pixmap_ptr: u32,
Expand Down