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add quad merge
This commit is contained in:
Brendan Hansknecht
parent
5bc97b58c8
commit
8726c05339
1 changed files with 90 additions and 19 deletions
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@ -73,6 +73,10 @@ fn quadsort_direct(
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roc_panic("todo: quadsort", 0);
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}
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// ================ Inplace Rotate Merge ======================================
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// These are used as backup if the swap size is not large enough.
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// Also used for the final merge to reduce copying of data.
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// ================ Unbalanced Merges =========================================
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/// Merges the remaining blocks at the tail of the array.
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@ -89,7 +93,7 @@ fn tail_merge(
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) void {
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const end_ptr = array + len * element_width;
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var current_block_len = block_len;
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while (current_block_len < len and current_block_len <= swap_len) {
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while (current_block_len < len and current_block_len <= swap_len) : (current_block_len *= 2) {
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var arr_ptr = array;
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while (@intFromPtr(arr_ptr) + current_block_len * element_width < @intFromPtr(end_ptr)) : (arr_ptr += 2 * current_block_len * element_width) {
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if (@intFromPtr(arr_ptr) + 2 * current_block_len * element_width < @intFromPtr(end_ptr)) {
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@ -100,7 +104,6 @@ fn tail_merge(
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partial_backwards_merge(arr_ptr, rem_len, swap, swap_len, current_block_len, cmp_data, cmp, element_width, copy);
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break;
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}
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current_block_len *= 2;
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}
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}
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@ -455,26 +458,24 @@ fn partial_forward_merge_left_head_2(
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}
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test "tail_merge" {
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{
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const expected = [10]i64{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
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const expected = [10]i64{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
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var arr: [10]i64 = undefined;
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var arr_ptr = @as([*]u8, @ptrCast(&arr[0]));
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var swap: [10]i64 = undefined;
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var swap_ptr = @as([*]u8, @ptrCast(&swap[0]));
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var arr: [10]i64 = undefined;
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var arr_ptr = @as([*]u8, @ptrCast(&arr[0]));
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var swap: [10]i64 = undefined;
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var swap_ptr = @as([*]u8, @ptrCast(&swap[0]));
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 2, 9, 10 };
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tail_merge(arr_ptr, 10, swap_ptr, 10, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 2, 9, 10 };
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tail_merge(arr_ptr, 10, swap_ptr, 10, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 2, 9, 10 };
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tail_merge(arr_ptr, 9, swap_ptr, 9, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 2, 9, 10 };
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tail_merge(arr_ptr, 9, swap_ptr, 9, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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arr = [10]i64{ 3, 4, 6, 9, 1, 2, 5, 10, 7, 8 };
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tail_merge(arr_ptr, 10, swap_ptr, 10, 4, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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}
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arr = [10]i64{ 3, 4, 6, 9, 1, 2, 5, 10, 7, 8 };
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tail_merge(arr_ptr, 10, swap_ptr, 10, 4, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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}
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test "partial_backwards_merge" {
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@ -578,7 +579,41 @@ test "partial_forward_merge" {
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// ================ Quad Merge Support ========================================
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// TODO: quad_merge, requires tail merge first.
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/// Merges an array of of sized blocks of sorted elements with a tail.
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/// Returns the block length of sorted runs after the call.
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/// This is needed if the merge ran out of swap space.
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fn quad_merge(
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array: [*]u8,
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len: usize,
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swap: [*]u8,
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swap_len: usize,
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block_len: usize,
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cmp_data: Opaque,
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cmp: CompareFn,
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element_width: usize,
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copy: CopyFn,
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) usize {
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const end_ptr = array + len * element_width;
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var current_block_len = block_len * 4;
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while (current_block_len <= len and current_block_len <= swap_len) : (current_block_len *= 4) {
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var arr_ptr = array;
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while (true) {
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quad_merge_block(arr_ptr, swap, current_block_len / 4, cmp_data, cmp, element_width, copy);
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arr_ptr += current_block_len * element_width;
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if (@intFromPtr(arr_ptr) + current_block_len * element_width > @intFromPtr(end_ptr))
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break;
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}
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const rem_len = (@intFromPtr(end_ptr) - @intFromPtr(arr_ptr)) / element_width;
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tail_merge(arr_ptr, rem_len, swap, swap_len, current_block_len / 4, cmp_data, cmp, element_width, copy);
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}
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tail_merge(array, len, swap, swap_len, current_block_len / 4, cmp_data, cmp, element_width, copy);
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return current_block_len / 2;
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}
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/// Merges 4 even sized blocks of sorted elements.
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fn quad_merge_block(
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@ -743,6 +778,42 @@ fn cross_merge(
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}
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}
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test "quad_merge" {
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const expected = [10]i64{ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
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var arr: [10]i64 = undefined;
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var arr_ptr = @as([*]u8, @ptrCast(&arr[0]));
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var swap: [10]i64 = undefined;
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var swap_ptr = @as([*]u8, @ptrCast(&swap[0]));
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var size: usize = undefined;
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 2, 9, 10 };
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size = quad_merge(arr_ptr, 10, swap_ptr, 10, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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try testing.expectEqual(size, 16);
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 9, 2, 10 };
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size = quad_merge(arr_ptr, 9, swap_ptr, 9, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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try testing.expectEqual(size, 16);
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arr = [10]i64{ 3, 4, 6, 9, 1, 2, 5, 10, 7, 8 };
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size = quad_merge(arr_ptr, 10, swap_ptr, 10, 4, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, expected);
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try testing.expectEqual(size, 8);
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// Limited swap, can't finish merge
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 9, 2, 10 };
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size = quad_merge(arr_ptr, 10, swap_ptr, 4, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, [10]i64{ 1, 3, 4, 5, 6, 7, 8, 9, 2, 10 });
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try testing.expectEqual(size, 4);
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arr = [10]i64{ 7, 8, 5, 6, 3, 4, 1, 9, 2, 10 };
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size = quad_merge(arr_ptr, 10, swap_ptr, 3, 2, null, &test_i64_compare, @sizeOf(i64), &test_i64_copy);
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try testing.expectEqual(arr, [10]i64{ 5, 6, 7, 8, 1, 3, 4, 9, 2, 10 });
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try testing.expectEqual(size, 4);
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}
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test "quad_merge_block" {
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const expected = [8]i64{ 1, 2, 3, 4, 5, 6, 7, 8 };
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