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consolidate prev_board from 4 arrays to 1 #20

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Merged
andy-k merged 1 commit into from
Mar 28, 2026
Merged

consolidate prev_board from 4 arrays to 1 #20

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116 changes: 48 additions & 68 deletions src/movegen.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,10 +58,7 @@ struct WorkingBuffer {
cached_cross_set_for_down_plays: Box<[CachedCrossSet]>, // r*c
cross_set_buffer_for_across_plays: Box<[CrossSetComputation]>, // c*r (perpendicular strips)
cross_set_buffer_for_down_plays: Box<[CrossSetComputation]>, // r*c (perpendicular strips)
prev_board_for_across_cross_sets: Box<[u8]>, // c*r (previous transposed tiles)
prev_board_for_down_cross_sets: Box<[u8]>, // r*c (previous board tiles)
prev_board_for_across_ext_sets: Box<[u8]>, // r*c (previous board tiles for ext sets)
prev_board_for_down_ext_sets: Box<[u8]>, // c*r (previous transposed tiles for ext sets)
prev_board_tiles: Box<[u8]>, // r*c (previous board tiles for dirty tracking)
remaining_word_multipliers_for_across_plays: Box<[i8]>, // r*c (1 if tile placed)
remaining_word_multipliers_for_down_plays: Box<[i8]>, // c*r
remaining_tile_multipliers_for_across_plays: Box<[i8]>, // r*c (1 if tile placed)
Expand Down Expand Up @@ -112,10 +109,7 @@ impl Clone for WorkingBuffer {
cached_cross_set_for_down_plays: self.cached_cross_set_for_down_plays.clone(),
cross_set_buffer_for_across_plays: self.cross_set_buffer_for_across_plays.clone(),
cross_set_buffer_for_down_plays: self.cross_set_buffer_for_down_plays.clone(),
prev_board_for_across_cross_sets: self.prev_board_for_across_cross_sets.clone(),
prev_board_for_down_cross_sets: self.prev_board_for_down_cross_sets.clone(),
prev_board_for_across_ext_sets: self.prev_board_for_across_ext_sets.clone(),
prev_board_for_down_ext_sets: self.prev_board_for_down_ext_sets.clone(),
prev_board_tiles: self.prev_board_tiles.clone(),
remaining_word_multipliers_for_across_plays: self
.remaining_word_multipliers_for_across_plays
.clone(),
Expand Down Expand Up @@ -189,14 +183,7 @@ impl Clone for WorkingBuffer {
.clone_from(&source.cross_set_buffer_for_across_plays);
self.cross_set_buffer_for_down_plays
.clone_from(&source.cross_set_buffer_for_down_plays);
self.prev_board_for_across_cross_sets
.clone_from(&source.prev_board_for_across_cross_sets);
self.prev_board_for_down_cross_sets
.clone_from(&source.prev_board_for_down_cross_sets);
self.prev_board_for_across_ext_sets
.clone_from(&source.prev_board_for_across_ext_sets);
self.prev_board_for_down_ext_sets
.clone_from(&source.prev_board_for_down_ext_sets);
self.prev_board_tiles.clone_from(&source.prev_board_tiles);
self.remaining_word_multipliers_for_across_plays
.clone_from(&source.remaining_word_multipliers_for_across_plays);
self.remaining_word_multipliers_for_down_plays
Expand Down Expand Up @@ -311,10 +298,7 @@ impl WorkingBuffer {
rows_times_cols
]
.into_boxed_slice(),
prev_board_for_across_cross_sets: vec![0xFFu8; rows_times_cols].into_boxed_slice(),
prev_board_for_down_cross_sets: vec![0xFFu8; rows_times_cols].into_boxed_slice(),
prev_board_for_across_ext_sets: vec![0xFFu8; rows_times_cols].into_boxed_slice(),
prev_board_for_down_ext_sets: vec![0xFFu8; rows_times_cols].into_boxed_slice(),
prev_board_tiles: vec![0xffu8; rows_times_cols].into_boxed_slice(),
remaining_word_multipliers_for_across_plays: vec![0i8; rows_times_cols]
.into_boxed_slice(),
remaining_word_multipliers_for_down_plays: vec![0i8; rows_times_cols]
Expand Down Expand Up @@ -395,10 +379,9 @@ impl WorkingBuffer {
let dim = board_layout.dim();
let area = (dim.rows as isize * dim.cols as isize) as usize;
// Skip board-dependent work if board tiles haven't changed.
// prev_board_for_down_cross_sets stores the most recent board_tiles
// (row-major), updated by the cross set strip caching.
// On first call it's 0xFF so this always runs initially.
if self.prev_board_for_down_cross_sets[..area] != board_snapshot.board_tiles[..area] {
// prev_board_tiles stores the most recent board_tiles (row-major).
// On first call it's 0xff so this always runs initially.
if self.prev_board_tiles[..area] != board_snapshot.board_tiles[..area] {
let premiums = board_layout.premiums();
let transposed_premiums = board_layout.transposed_premiums();
// row * dim.cols + col
Expand Down Expand Up @@ -594,10 +577,7 @@ impl WorkingBuffer {
p_right: 0,
bits: 0,
});
self.prev_board_for_across_cross_sets.fill(0xFF);
self.prev_board_for_down_cross_sets.fill(0xFF);
self.prev_board_for_across_ext_sets.fill(0xFF);
self.prev_board_for_down_ext_sets.fill(0xFF);
self.prev_board_tiles.fill(0xff);
self.left_extension_set_for_across_plays.fill(!0u64);
self.right_extension_set_for_across_plays.fill(!0u64);
self.left_extension_set_for_down_plays.fill(!0u64);
Expand Down Expand Up @@ -3014,14 +2994,30 @@ fn kurnia_gen_place_moves_iter<
let max_rack_size = game_config.rack_size();
let num_max_played = max_rack_size.min(working_buffer.num_tiles_on_rack);

// striped by row
let mut any_across_strip_changed = false;
// Compute dirty rows and columns in one pass over board_tiles.
let area = (dim.rows as isize * dim.cols as isize) as usize;
let mut dirty_rows = 0u32;
let mut dirty_cols = 0u32;
for (idx, (&cur, &prev)) in board_snapshot.board_tiles[..area]
.iter()
.zip(working_buffer.prev_board_tiles[..area].iter())
.enumerate()
{
if cur != prev {
let row = idx / dim.cols as usize;
let col = idx % dim.cols as usize;
dirty_rows |= 1 << row;
dirty_cols |= 1 << col;
}
}
let any_across_strip_changed = dirty_cols != 0;
let any_down_strip_changed = dirty_rows != 0;

// Cross sets for across plays: recompute dirty columns.
for col in 0..dim.cols {
let strip_range_start = (col as isize * dim.rows as isize) as usize;
let strip_range_end = strip_range_start + dim.rows as usize;
if working_buffer.prev_board_for_across_cross_sets[strip_range_start..strip_range_end]
!= working_buffer.transposed_board_tiles[strip_range_start..strip_range_end]
{
if dirty_cols & (1 << col) != 0 {
let strip_range_start = (col as isize * dim.rows as isize) as usize;
let strip_range_end = strip_range_start + dim.rows as usize;
gen_cross_set(
board_snapshot,
&working_buffer.transposed_board_tiles[strip_range_start..strip_range_end],
Expand All @@ -3033,25 +3029,17 @@ fn kurnia_gen_place_moves_iter<
[strip_range_start..strip_range_end],
&mut working_buffer.used_letters_tally,
);
working_buffer.prev_board_for_across_cross_sets[strip_range_start..strip_range_end]
.copy_from_slice(
&working_buffer.transposed_board_tiles[strip_range_start..strip_range_end],
);
any_across_strip_changed = true;
}
}
let transposed_dim = matrix::Dim {
rows: dim.cols,
cols: dim.rows,
};
// striped by columns for better cache locality
let mut any_down_strip_changed = false;
// Cross sets for down plays: recompute dirty rows.
for row in 0..dim.rows {
let strip_range_start = (row as isize * dim.cols as isize) as usize;
let strip_range_end = strip_range_start + dim.cols as usize;
if working_buffer.prev_board_for_down_cross_sets[strip_range_start..strip_range_end]
!= board_snapshot.board_tiles[strip_range_start..strip_range_end]
{
if dirty_rows & (1 << row) != 0 {
let strip_range_start = (row as isize * dim.cols as isize) as usize;
let strip_range_end = strip_range_start + dim.cols as usize;
gen_cross_set(
board_snapshot,
&board_snapshot.board_tiles[strip_range_start..strip_range_end],
Expand All @@ -3063,9 +3051,6 @@ fn kurnia_gen_place_moves_iter<
[strip_range_start..strip_range_end],
&mut working_buffer.used_letters_tally,
);
working_buffer.prev_board_for_down_cross_sets[strip_range_start..strip_range_end]
.copy_from_slice(&board_snapshot.board_tiles[strip_range_start..strip_range_end]);
any_down_strip_changed = true;
}
}
if working_buffer.num_tiles_on_board == 0 {
Expand All @@ -3085,12 +3070,11 @@ fn kurnia_gen_place_moves_iter<
board_snapshot.game_config.game_rules(),
game_config::GameRules::Classic
) {
// Across extension sets: recompute dirty rows.
for row in 0..dim.rows {
let strip_range_start = (row as isize * dim.cols as isize) as usize;
let strip_range_end = strip_range_start + dim.cols as usize;
if working_buffer.prev_board_for_across_ext_sets[strip_range_start..strip_range_end]
!= board_snapshot.board_tiles[strip_range_start..strip_range_end]
{
if dirty_rows & (1 << row) != 0 {
let strip_range_start = (row as isize * dim.cols as isize) as usize;
let strip_range_end = strip_range_start + dim.cols as usize;
working_buffer.left_extension_set_for_across_plays
[strip_range_start..strip_range_end]
.fill(!0u64);
Expand All @@ -3106,18 +3090,13 @@ fn kurnia_gen_place_moves_iter<
&mut working_buffer.right_extension_set_for_across_plays
[strip_range_start..strip_range_end],
);
working_buffer.prev_board_for_across_ext_sets[strip_range_start..strip_range_end]
.copy_from_slice(
&board_snapshot.board_tiles[strip_range_start..strip_range_end],
);
}
}
// Down extension sets: recompute dirty columns.
for col in 0..dim.cols {
let strip_range_start = (col as isize * dim.rows as isize) as usize;
let strip_range_end = strip_range_start + dim.rows as usize;
if working_buffer.prev_board_for_down_ext_sets[strip_range_start..strip_range_end]
!= working_buffer.transposed_board_tiles[strip_range_start..strip_range_end]
{
if dirty_cols & (1 << col) != 0 {
let strip_range_start = (col as isize * dim.rows as isize) as usize;
let strip_range_end = strip_range_start + dim.rows as usize;
working_buffer.left_extension_set_for_down_plays
[strip_range_start..strip_range_end]
.fill(!0u64);
Expand All @@ -3133,13 +3112,14 @@ fn kurnia_gen_place_moves_iter<
&mut working_buffer.right_extension_set_for_down_plays
[strip_range_start..strip_range_end],
);
working_buffer.prev_board_for_down_ext_sets[strip_range_start..strip_range_end]
.copy_from_slice(
&working_buffer.transposed_board_tiles[strip_range_start..strip_range_end],
);
}
}
}
// Update prev_board after all dirty processing is done.
if dirty_rows != 0 || dirty_cols != 0 {
working_buffer.prev_board_tiles[..area]
.copy_from_slice(&board_snapshot.board_tiles[..area]);
}
working_buffer.init_after_cross_sets(
board_snapshot,
any_across_strip_changed,
Expand Down
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