From 4ee7bf00e1fc5003699d3d04aaa5ee6e327446b2 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Fri, 17 Jan 2020 21:40:09 +0100
Subject: [PATCH] machine: avoid bytes package in USB logic

This greatly cuts down on compile time (by about 5x for small programs)
and also makes the program a whole lot smaller. Overall it cuts down
`make smoke-test` in the drivers repository by half (from 160s to 80s).

This will probably also fix the timeout issue in the Playground:
https://github.com/tinygo-org/playground/issues/7
---
 src/machine/usb.go | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/machine/usb.go b/src/machine/usb.go
index ffc95f90..106693a0 100644
--- a/src/machine/usb.go
+++ b/src/machine/usb.go
@@ -3,7 +3,6 @@
 package machine
 
 import (
-	"bytes"
 	"errors"
 	"runtime/volatile"
 )
@@ -348,18 +347,18 @@ const cdcSize = iadDescriptorSize +
 
 // Bytes returns CDCDescriptor data.
 func (d CDCDescriptor) Bytes() []byte {
-	buf := bytes.NewBuffer(make([]byte, 0))
-	buf.Write(d.iad.Bytes())
-	buf.Write(d.cif.Bytes())
-	buf.Write(d.header.Bytes())
-	buf.Write(d.controlManagement.Bytes())
-	buf.Write(d.functionalDescriptor.Bytes())
-	buf.Write(d.callManagement.Bytes())
-	buf.Write(d.cifin.Bytes())
-	buf.Write(d.dif.Bytes())
-	buf.Write(d.out.Bytes())
-	buf.Write(d.in.Bytes())
-	return buf.Bytes()
+	var buf []byte
+	buf = append(buf, d.iad.Bytes()...)
+	buf = append(buf, d.cif.Bytes()...)
+	buf = append(buf, d.header.Bytes()...)
+	buf = append(buf, d.controlManagement.Bytes()...)
+	buf = append(buf, d.functionalDescriptor.Bytes()...)
+	buf = append(buf, d.callManagement.Bytes()...)
+	buf = append(buf, d.cifin.Bytes()...)
+	buf = append(buf, d.dif.Bytes()...)
+	buf = append(buf, d.out.Bytes()...)
+	buf = append(buf, d.in.Bytes()...)
+	return buf
 }
 
 // MSCDescriptor is not used yet.