Merge pull request #1231 from slingamn/buffer.2

more memory-efficient implementation of line reading

irc/utils/math.go

@@ -0,0 +1,16 @@
+// Copyright (c) 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
+// released under the MIT license
+
+package utils
+
+// return n such that v <= n and n == 2**i for some i
+func RoundUpToPowerOfTwo(v int) int {
+	// http://graphics.stanford.edu/~seander/bithacks.html
+	v -= 1
+	v |= v >> 1
+	v |= v >> 2
+	v |= v >> 4
+	v |= v >> 8
+	v |= v >> 16
+	return v + 1
+}

irc/utils/math_test.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2020 Shivaram Lingamneni <slingamn@cs.stanford.edu>
+// released under the MIT license
+
+package utils
+
+import (
+	"testing"
+)
+
+func TestRoundUp(t *testing.T) {
+	assertEqual(RoundUpToPowerOfTwo(2), 2, t)
+	assertEqual(RoundUpToPowerOfTwo(3), 4, t)
+	assertEqual(RoundUpToPowerOfTwo(64), 64, t)
+	assertEqual(RoundUpToPowerOfTwo(65), 128, t)
+	assertEqual(RoundUpToPowerOfTwo(100), 128, t)
+	assertEqual(RoundUpToPowerOfTwo(1000), 1024, t)
+	assertEqual(RoundUpToPowerOfTwo(1025), 2048, t)
+	assertEqual(RoundUpToPowerOfTwo(269435457), 536870912, t)
+}