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add monobound binary search

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Brendan Hansknecht 2024-07-24 21:39:30 -07:00
parent b8f488edcf
commit 9e7619ef2a
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1 changed files with 55 additions and 0 deletions
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55
crates/compiler/builtins/bitcode/src/sort.zig
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@ -122,6 +122,34 @@ fn quadsort_stack_swap(
// These are used as backup if the swap size is not large enough.
// Also can be used for the final merge to reduce memory footprint.
/// Binary search, but more cache friendly!
fn monobound_binary_first(
array: [*]u8,
initial_top: usize,
value_ptr: [*]u8,
cmp: CompareFn,
cmp_data: Opaque,
element_width: usize,
) usize {
var top = initial_top;
var end_ptr = array + top * element_width;
while (top > 1) {
const mid = top / 2;
if (compare(cmp, cmp_data, value_ptr, end_ptr - mid * element_width) != GT) {
end_ptr -= mid * element_width;
}
top -= mid;
}
if (compare(cmp, cmp_data, value_ptr, end_ptr - element_width) != GT) {
end_ptr -= element_width;
}
return (@intFromPtr(end_ptr) - @intFromPtr(array)) / element_width;
}
/// Swap two neighboring chunks of an array quickly with limited memory.
fn trinity_rotation(
array: [*]u8,
len: usize,
@ -281,6 +309,33 @@ fn trinity_rotation(
}
}
test "monobound_binary_first" {
var arr = [25]i64{ 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49 };
var arr_ptr = @as([*]u8, @ptrCast(&arr[0]));
var value: i64 = undefined;
var value_ptr = @as([*]u8, @ptrCast(&value));
value = 7;
var res = monobound_binary_first(arr_ptr, 25, value_ptr, &test_i64_compare, null, @sizeOf(i64));
try testing.expectEqual(res, 3);
value = 39;
res = monobound_binary_first(arr_ptr, 25, value_ptr, &test_i64_compare, null, @sizeOf(i64));
try testing.expectEqual(res, 19);
value = 40;
res = monobound_binary_first(arr_ptr, 25, value_ptr, &test_i64_compare, null, @sizeOf(i64));
try testing.expectEqual(res, 20);
value = -10;
res = monobound_binary_first(arr_ptr, 25, value_ptr, &test_i64_compare, null, @sizeOf(i64));
try testing.expectEqual(res, 0);
value = 10000;
res = monobound_binary_first(arr_ptr, 25, value_ptr, &test_i64_compare, null, @sizeOf(i64));
try testing.expectEqual(res, 25);
}
test "trinity_rotation" {
{
var arr: [10]i64 = undefined;