1 files changed, 95 insertions, 0 deletions
diff --git a/src/runtime/wincallback.go b/src/runtime/wincallback.go
new file mode 100644
index 0000000..fb45222
--- /dev/null
+++ b/src/runtime/wincallback.go
@@ -0,0 +1,95 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+// Generate Windows callback assembly file.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+)
+
+const maxCallback = 2000
+
+func genasm386Amd64() {
+	var buf bytes.Buffer
+
+	buf.WriteString(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
+
+// +build 386 amd64
+// runtime·callbackasm is called by external code to
+// execute Go implemented callback function. It is not
+// called from the start, instead runtime·compilecallback
+// always returns address into runtime·callbackasm offset
+// appropriately so different callbacks start with different
+// CALL instruction in runtime·callbackasm. This determines
+// which Go callback function is executed later on.
+
+TEXT runtime·callbackasm(SB),7,$0
+`)
+	for i := 0; i < maxCallback; i++ {
+		buf.WriteString("\tCALL\truntime·callbackasm1(SB)\n")
+	}
+
+	filename := fmt.Sprintf("zcallback_windows.s")
+	err := os.WriteFile(filename, buf.Bytes(), 0666)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
+		os.Exit(2)
+	}
+}
+
+func genasmArm() {
+	var buf bytes.Buffer
+
+	buf.WriteString(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
+
+// External code calls into callbackasm at an offset corresponding
+// to the callback index. Callbackasm is a table of MOV and B instructions.
+// The MOV instruction loads R12 with the callback index, and the
+// B instruction branches to callbackasm1.
+// callbackasm1 takes the callback index from R12 and
+// indexes into an array that stores information about each callback.
+// It then calls the Go implementation for that callback.
+#include "textflag.h"
+
+TEXT runtime·callbackasm(SB),NOSPLIT|NOFRAME,$0
+`)
+	for i := 0; i < maxCallback; i++ {
+		buf.WriteString(fmt.Sprintf("\tMOVW\t$%d, R12\n", i))
+		buf.WriteString("\tB\truntime·callbackasm1(SB)\n")
+	}
+
+	err := os.WriteFile("zcallback_windows_arm.s", buf.Bytes(), 0666)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
+		os.Exit(2)
+	}
+}
+
+func gengo() {
+	var buf bytes.Buffer
+
+	buf.WriteString(fmt.Sprintf(`// Code generated by wincallback.go using 'go generate'. DO NOT EDIT.
+
+package runtime
+
+const cb_max = %d // maximum number of windows callbacks allowed
+`, maxCallback))
+	err := os.WriteFile("zcallback_windows.go", buf.Bytes(), 0666)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "wincallback: %s\n", err)
+		os.Exit(2)
+	}
+}
+
+func main() {
+	genasm386Amd64()
+	genasmArm()
+	gengo()
+}