From 8a45917f3d8011b231c4524f42a34732717e0027 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 20 Aug 2009 11:12:04 -0700
Subject: [PATCH] len and cap on chans

R=ken
OCL=33599
CL=33599
---
 doc/go_spec.html       |  4 ----
 src/cmd/6g/cgen.c      | 26 ++++++++++++++++++++++++--
 src/cmd/8g/cgen.c      | 24 +++++++++++++++++++++++-
 src/cmd/gc/align.c     |  5 ++---
 src/pkg/runtime/chan.c |  4 ++--
 test/chancap.go        | 27 +++++++++++++++++++++++++++
 6 files changed, 78 insertions(+), 12 deletions(-)
 create mode 100644 test/chancap.go

diff --git a/doc/go_spec.html b/doc/go_spec.html
index 789232c6a00..2190dca3fc8 100644
--- a/doc/go_spec.html
+++ b/doc/go_spec.html
@@ -4345,10 +4345,6 @@ The following minimal alignment properties are guaranteed:
 <p>
 <font color=red>
 Implementation does not honor the restriction on goto statements and targets (no intervening declarations).
-<br/>
-cap() does not work on chans.
-<br/>
-len() does not work on chans.
 </font>
 </p>
 
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 97af9349bb5..d36c0e15da2 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -242,8 +242,8 @@ cgen(Node *n, Node *res)
 		break;
 
 	case OLEN:
-		if(istype(nl->type, TMAP)) {
-			// map has len in the first 32-bit word.
+		if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
+			// map and chan have len in the first 32-bit word.
 			// a zero pointer means zero length
 			regalloc(&n1, types[tptr], res);
 			cgen(nl, &n1);
@@ -279,6 +279,28 @@ cgen(Node *n, Node *res)
 		break;
 
 	case OCAP:
+		if(istype(nl->type, TCHAN)) {
+			// chan has cap in the second 32-bit word.
+			// a zero pointer means zero length
+			regalloc(&n1, types[tptr], res);
+			cgen(nl, &n1);
+
+			nodconst(&n2, types[tptr], 0);
+			gins(optoas(OCMP, types[tptr]), &n1, &n2);
+			p1 = gbranch(optoas(OEQ, types[tptr]), T);
+
+			n2 = n1;
+			n2.op = OINDREG;
+			n2.xoffset = 4;
+			n2.type = types[TINT32];
+			gmove(&n2, &n1);
+
+			patch(p1, pc);
+
+			gmove(&n1, res);
+			regfree(&n1);
+			break;
+		}
 		if(isslice(nl->type)) {
 			regalloc(&n1, types[tptr], res);
 			agen(nl, &n1);
diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c
index 25f700ae9f5..db1986df985 100644
--- a/src/cmd/8g/cgen.c
+++ b/src/cmd/8g/cgen.c
@@ -237,7 +237,7 @@ cgen(Node *n, Node *res)
 		break;
 
 	case OLEN:
-		if(istype(nl->type, TMAP)) {
+		if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
 			// map has len in the first 32-bit word.
 			// a zero pointer means zero length
 			tempalloc(&n1, types[tptr]);
@@ -280,6 +280,28 @@ cgen(Node *n, Node *res)
 		break;
 
 	case OCAP:
+		if(istype(nl->type, TCHAN)) {
+			// chan has cap in the second 32-bit word.
+			// a zero pointer means zero length
+			regalloc(&n1, types[tptr], res);
+			cgen(nl, &n1);
+
+			nodconst(&n2, types[tptr], 0);
+			gins(optoas(OCMP, types[tptr]), &n1, &n2);
+			p1 = gbranch(optoas(OEQ, types[tptr]), T);
+
+			n2 = n1;
+			n2.op = OINDREG;
+			n2.xoffset = 4;
+			n2.type = types[TINT32];
+			gmove(&n2, &n1);
+
+			patch(p1, pc);
+
+			gmove(&n1, res);
+			regfree(&n1);
+			break;
+		}
 		if(isslice(nl->type)) {
 			igen(nl, &n1, res);
 			n1.op = OINDREG;
diff --git a/src/cmd/gc/align.c b/src/cmd/gc/align.c
index 81ea9a7fe83..bd8b690471a 100644
--- a/src/cmd/gc/align.c
+++ b/src/cmd/gc/align.c
@@ -303,11 +303,10 @@ typeinit(void)
 	okforbool[TBOOL] = 1;
 
 	okforcap[TARRAY] = 1;
-	//okforcap[TCHAN] = 1;
-	//okforcap[TMAP] = 1;
+	okforcap[TCHAN] = 1;
 
 	okforlen[TARRAY] = 1;
-	//okforlen[TCHAN] = 1;
+	okforlen[TCHAN] = 1;
 	okforlen[TMAP] = 1;
 	okforlen[TSTRING] = 1;
 
diff --git a/src/pkg/runtime/chan.c b/src/pkg/runtime/chan.c
index 64a52d48a93..c72ea1dff9e 100644
--- a/src/pkg/runtime/chan.c
+++ b/src/pkg/runtime/chan.c
@@ -39,10 +39,10 @@ struct	WaitQ
 
 struct	Hchan
 {
+	uint32	qcount;			// total data in the q
+	uint32	dataqsiz;		// size of the circular q
 	uint16	elemsize;
 	uint16	closed;			// Wclosed Rclosed errorcount
-	uint32	dataqsiz;		// size of the circular q
-	uint32	qcount;			// total data in the q
 	Alg*	elemalg;		// interface for element type
 	Link*	senddataq;		// pointer for sender
 	Link*	recvdataq;		// pointer for receiver
diff --git a/test/chancap.go b/test/chancap.go
new file mode 100644
index 00000000000..15256f731d3
--- /dev/null
+++ b/test/chancap.go
@@ -0,0 +1,27 @@
+// $G $D/$F.go && $L $F.$A && ./$A.out
+
+// 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.
+
+package main
+
+func main() {
+	c := make(chan int, 10);
+	if len(c) != 0 || cap(c) != 10 {
+		panicln("chan len/cap ", len(c), cap(c), " want 0 10");
+	}
+
+	for i := 0; i < 3; i++ {
+		c <- i;
+	}
+	if len(c) != 3 || cap(c) != 10 {
+		panicln("chan len/cap ", len(c), cap(c), " want 3 10");
+	}
+	
+	c = make(chan int);
+	if len(c) != 0 || cap(c) != 0 {
+		panicln("chan len/cap ", len(c), cap(c), " want 0 0");
+	}
+}
+