Odin/core/slice/ptr.odin

package slice

import "core:mem"

ptr_add :: proc(p: $P/^$T, x: int) -> ^T {
	return (^T)(uintptr(p) + size_of(T)*x);
}
ptr_sub :: proc(p: $P/^$T, x: int) -> ^T {
	return #force_inline ptr_add(p, -x);
}

ptr_swap_non_overlapping :: proc(x, y: rawptr, len: int) {
	if len <= 0 {
		return;
	}
	if x == y { // Ignore pointers that are the same
		return;
	}

	Block :: distinct [4]u64;
	BLOCK_SIZE :: size_of(Block);

	i := 0;
	t := &Block{};
	for ; i + BLOCK_SIZE <= len; i += BLOCK_SIZE {
		a := rawptr(uintptr(x) + uintptr(i));
		b := rawptr(uintptr(y) + uintptr(i));

		mem.copy(t, a, BLOCK_SIZE);
		mem.copy(a, b, BLOCK_SIZE);
		mem.copy(b, t, BLOCK_SIZE);
	}

	if i < len {
		rem := len - i;

		a := rawptr(uintptr(x) + uintptr(i));
		b := rawptr(uintptr(y) + uintptr(i));

		mem.copy(t, a, rem);
		mem.copy(a, b, rem);
		mem.copy(b, t, rem);
	}
}


ptr_rotate :: proc(left: int, mid: ^$T, right: int) {
	when size_of(T) != 0 {
		left, mid, right := left, mid, right;

		// TODO(bill): Optimization with a buffer for smaller ranges
		if left >= right {
			for {
				ptr_swap_non_overlapping(ptr_sub(mid, right), mid, right);
				mid = ptr_sub(mid, right);

				left -= right;
				if left < right {
					break;
				}
			}
		} else {
			ptr_swap_non_overlapping(ptr_sub(mid, left), mid, left);
			mid = ptr_add(mid, left);

			right -= left;
			if right < left {
				break;
			}
		}
	}
}