From 4c28f1b87500adfe44228270d795df86dfea77f6 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Wed, 2 Mar 2022 18:14:17 +0100
Subject: [PATCH] runtime: add fastrand

This is needed for hash/maphash support.
---
 src/runtime/algorithm.go | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 src/runtime/algorithm.go

diff --git a/src/runtime/algorithm.go b/src/runtime/algorithm.go
new file mode 100644
index 00000000..8b443d48
--- /dev/null
+++ b/src/runtime/algorithm.go
@@ -0,0 +1,22 @@
+package runtime
+
+// This file implements various core algorithms used in the runtime package and
+// standard library.
+
+// This function is used by hash/maphash.
+func fastrand() uint32 {
+	xorshift32State = xorshift32(xorshift32State)
+	return xorshift32State
+}
+
+var xorshift32State uint32 = 1
+
+func xorshift32(x uint32) uint32 {
+	// Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs".
+	// Improved sequence based on
+	// http://www.iro.umontreal.ca/~lecuyer/myftp/papers/xorshift.pdf
+	x ^= x << 7
+	x ^= x >> 1
+	x ^= x << 9
+	return x
+}