1 files changed, 104 insertions, 0 deletions
diff --git a/src/pkg/runtime/386/closure.c b/src/pkg/runtime/386/closure.c
new file mode 100644
index 000000000..6ccbe3b8b
--- /dev/null
+++ b/src/pkg/runtime/386/closure.c
@@ -0,0 +1,104 @@
+// Copyright 2009 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.
+
+#include "runtime.h"
+
+#pragma textflag 7
+// func closure(siz int32,
+//	fn func(arg0, arg1, arg2 *ptr, callerpc uintptr, xxx) yyy,
+//	arg0, arg1, arg2 *ptr) (func(xxx) yyy)
+void
+sys·closure(int32 siz, byte *fn, byte *arg0)
+{
+	byte *p, *q, **ret;
+	int32 i, n;
+	int32 pcrel;
+
+	if(siz < 0 || siz%4 != 0)
+		throw("bad closure size");
+
+	ret = (byte**)((byte*)&arg0 + siz);
+
+	if(siz > 100) {
+		// TODO(rsc): implement stack growth preamble?
+		throw("closure too big");
+	}
+
+	// compute size of new fn.
+	// must match code laid out below.
+	n = 6+5+2+1;	// SUBL MOVL MOVL CLD
+	if(siz <= 4*4)
+		n += 1*siz/4;	// MOVSL MOVSL...
+	else
+		n += 6+2;	// MOVL REP MOVSL
+	n += 5;	// CALL
+	n += 6+1;	// ADDL RET
+
+	// store args aligned after code, so gc can find them.
+	n += siz;
+	if(n%4)
+		n += 4 - n%4;
+
+	p = mal(n);
+	*ret = p;
+	q = p + n - siz;
+	mcpy(q, (byte*)&arg0, siz);
+
+	// SUBL $siz, SP
+	*p++ = 0x81;
+	*p++ = 0xec;
+	*(uint32*)p = siz;
+	p += 4;
+
+	// MOVL $q, SI
+	*p++ = 0xbe;
+	*(byte**)p = q;
+	p += 4;
+
+	// MOVL SP, DI
+	*p++ = 0x89;
+	*p++ = 0xe7;
+
+	// CLD
+	*p++ = 0xfc;
+
+	if(siz <= 4*4) {
+		for(i=0; i<siz; i+=4) {
+			// MOVSL
+			*p++ = 0xa5;
+		}
+	} else {
+		// MOVL $(siz/4), CX  [32-bit immediate siz/4]
+		*p++ = 0xc7;
+		*p++ = 0xc1;
+		*(uint32*)p = siz/4;
+		p += 4;
+
+		// REP; MOVSL
+		*p++ = 0xf3;
+		*p++ = 0xa5;
+	}
+
+	// call fn
+	pcrel = fn - (p+5);
+	// direct call with pc-relative offset
+	// CALL fn
+	*p++ = 0xe8;
+	*(int32*)p = pcrel;
+	p += 4;
+
+	// ADDL $siz, SP
+	*p++ = 0x81;
+	*p++ = 0xc4;
+	*(uint32*)p = siz;
+	p += 4;
+
+	// RET
+	*p++ = 0xc3;
+
+	if(p > q)
+		throw("bad math in sys.closure");
+}
+
+