Livt.Base

src/Array.lvt

namespace Livt.Array

/**
 * Fixed-size array operations that fit Livt's synthesis model.
 *
 * Arrays must have a statically known size. All functions are synthesizable.
 *
 * The byte[] unsized parameter form is supported: any byte[N] can be passed
 * to a function that declares a byte[] parameter. Element reads inside the
 * function generate correct VHDL. The size must be supplied as a separate
 * int parameter; the caller is responsible for providing the correct value.
 */
component Array
{
	/**
	 * Returns true if index is within the valid range [0, size-1].
	 * Use this before accessing an array at a dynamically computed index.
	 */
	public fn IsIndexInRange(index: int, size: int) bool
	{
		if (index < 0) {
			return false
		}

		if (index >= size) {
			return false
		}

		return true
	}

	/**
	 * Returns true if the first size bytes of a and b are equal.
	 * Both a and b must contain at least size bytes. The caller is
	 * responsible for providing a correct size value.
	 */
	public fn Equals(a: byte[], b: byte[], size: int) bool
	{
		for (var i = 0; i < size; i++) {
			var ai: byte = a[i]
			var bi: byte = b[i]

			if (ai != bi) {
				return false
			}
		}

		return true
	}

	/**
	 * Returns the first index at which value appears in the first size bytes
	 * of arr. Returns -1 if value is not found.
	 * arr must contain at least size bytes. The caller is responsible for
	 * providing a correct size value.
	 */
	public fn IndexOf(arr: byte[], size: int, value: byte) int
	{
		for (var i = 0; i < size; i++) {
			var ai: byte = arr[i]

			if (ai == value) {
				return i
			}
		}

		return -1
	}

	/**
	 * Returns the number of times value appears in the first size bytes of arr.
	 * arr must contain at least size bytes. The caller is responsible for
	 * providing a correct size value.
	 */
	public fn CountOf(arr: byte[], size: int, value: byte) int
	{
		var count: int = 0

		for (var i = 0; i < size; i++) {
			var ai: byte = arr[i]

			if (ai == value) {
				count = count + 1
			}
		}

		return count
	}
}