Major update of chunk system for 1.16.2

bot/world/bitarray.go

@@ -0,0 +1,38 @@
+package world
+
+// bitArray implements a bitfield array where values are packed into uint64
+// values. If the next value does not fit into remaining space, the remaining
+// space of a uint64 is unused.
+type bitArray struct {
+	width          uint // bit width of each value
+	valsPerElement uint // number of values which fit into a single uint64.
+
+	data []uint64
+}
+
+// Size returns the number of elements that can fit into the bit array.
+func (b *bitArray) Size() int {
+	return int(b.valsPerElement) * len(b.data)
+}
+
+func (b *bitArray) Set(idx, val uint) {
+	var (
+		arrayIdx = idx / b.valsPerElement
+		startBit = (idx % b.valsPerElement) * b.width
+		mask     = ^uint64((1<<b.width - 1) << startBit) // set for all bits except target
+	)
+	b.data[arrayIdx] = (b.data[arrayIdx] & mask) | uint64(val<<startBit)
+}
+
+func (b *bitArray) Get(idx uint) uint {
+	var (
+		arrayIdx = idx / b.valsPerElement
+		offset   = (idx % b.valsPerElement) * b.width
+		mask     = uint64((1<<b.width - 1) << offset) // set for just the target
+	)
+	return uint(b.data[arrayIdx]&mask) >> offset
+}
+
+func valsPerBitArrayElement(bitsPerValue uint) uint {
+	return uint(64 / bitsPerValue)
+}