From e3ae57090f235bd5dc37487b0228c1274d530bd4 Mon Sep 17 00:00:00 2001
From: gwtnz <10123549+gwtnz@users.noreply.github.com>
Date: Tue, 11 Feb 2020 08:55:14 -0600
Subject: [PATCH] runtime/volatile: include ReplaceBits method

---
 src/runtime/volatile/register.go | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/runtime/volatile/register.go b/src/runtime/volatile/register.go
index 57c0e7d2..5be97e7f 100644
--- a/src/runtime/volatile/register.go
+++ b/src/runtime/volatile/register.go
@@ -57,6 +57,16 @@ func (r *Register8) HasBits(value uint8) bool {
 	return (r.Get() & value) > 0
 }
 
+// ReplaceBits is a helper to simplify setting multiple bits high and/or low at
+// once. It is the volatile equivalent of:
+//
+//     r.Reg = (r.Reg & ^(mask << pos)) | value << pos
+//
+// go:inline
+func (r *Register8) ReplaceBits(value uint8, mask uint8, pos uint8) {
+	StoreUint8(&r.Reg, LoadUint8(&r.Reg)&^(mask<<pos)|value<<pos)
+}
+
 type Register16 struct {
 	Reg uint16
 }
@@ -109,6 +119,16 @@ func (r *Register16) HasBits(value uint16) bool {
 	return (r.Get() & value) > 0
 }
 
+// ReplaceBits is a helper to simplify setting multiple bits high and/or low at
+// once. It is the volatile equivalent of:
+//
+//     r.Reg = (r.Reg & ^(mask << pos)) | value << pos
+//
+// go:inline
+func (r *Register16) ReplaceBits(value uint16, mask uint16, pos uint8) {
+	StoreUint16(&r.Reg, LoadUint16(&r.Reg)&^(mask<<pos)|value<<pos)
+}
+
 type Register32 struct {
 	Reg uint32
 }
@@ -160,3 +180,13 @@ func (r *Register32) ClearBits(value uint32) {
 func (r *Register32) HasBits(value uint32) bool {
 	return (r.Get() & value) > 0
 }
+
+// ReplaceBits is a helper to simplify setting multiple bits high and/or low at
+// once. It is the volatile equivalent of:
+//
+//     r.Reg = (r.Reg & ^(mask << pos)) | value << pos
+//
+// go:inline
+func (r *Register32) ReplaceBits(value uint32, mask uint32, pos uint8) {
+	StoreUint32(&r.Reg, LoadUint32(&r.Reg)&^(mask<<pos)|value<<pos)
+}