From 00b1c62fe8dc671584841c916040f2effb901552 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@nicira.com>
Date: Tue, 23 Nov 2010 13:33:48 -0800
Subject: [PATCH] ofp-parse: Add support for registers.

This updates the ovs-ofctl manpage even though ovs-ofctl doesn't really
support registers yet.
---
 lib/ofp-parse.c          | 25 +++++++++++++++++++++++++
 utilities/ovs-ofctl.8.in | 17 +++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/lib/ofp-parse.c b/lib/ofp-parse.c
index 49408454..e800edbc 100644
--- a/lib/ofp-parse.c
+++ b/lib/ofp-parse.c
@@ -18,6 +18,7 @@
 
 #include "ofp-parse.h"
 
+#include <ctype.h>
 #include <errno.h>
 #include <stdlib.h>
 
@@ -515,6 +516,24 @@ parse_field_value(struct cls_rule *rule, enum field_index index,
     }
 }
 
+static void
+parse_reg_value(struct cls_rule *rule, int reg_idx, const char *value)
+{
+    uint32_t reg_value, reg_mask;
+
+    if (!strcmp(value, "ANY") || !strcmp(value, "*")) {
+        cls_rule_set_reg_masked(rule, reg_idx, 0, 0);
+    } else if (sscanf(value, "%"SCNi32"/%"SCNi32,
+                      &reg_value, &reg_mask) == 2) {
+        cls_rule_set_reg_masked(rule, reg_idx, reg_value, reg_mask);
+    } else if (sscanf(value, "%"SCNi32, &reg_value)) {
+        cls_rule_set_reg(rule, reg_idx, reg_value);
+    } else {
+        ovs_fatal(0, "register fields must take the form <value> "
+                  "or <value>/<mask>");
+    }
+}
+
 /* Convert 'string' (as described in the Flow Syntax section of the ovs-ofctl
  * man page) into 'pf'.  If 'actions' is specified, an action must be in
  * 'string' and may be expanded or reallocated. */
@@ -595,6 +614,12 @@ parse_ofp_str(struct parsed_flow *pf, struct ofpbuf *actions, char *string)
                 } else {
                     parse_field_value(&pf->rule, f->index, value);
                 }
+            } else if (!strncmp(name, "reg", 3) && isdigit(name[3])) {
+                unsigned int reg_idx = atoi(name + 3);
+                if (reg_idx >= FLOW_N_REGS) {
+                    ovs_fatal(0, "only %d registers supported", FLOW_N_REGS);
+                }
+                parse_reg_value(&pf->rule, reg_idx, value);
             } else {
                 ovs_fatal(0, "unknown keyword %s", name);
             }
diff --git a/utilities/ovs-ofctl.8.in b/utilities/ovs-ofctl.8.in
index 8cd5ef00..eb20fa76 100644
--- a/utilities/ovs-ofctl.8.in
+++ b/utilities/ovs-ofctl.8.in
@@ -357,6 +357,23 @@ When \fBtun_id\fR is specified, \fBovs\-ofctl\fR will automatically
 attempt to negotiate use of one of these extensions, preferring NXM.
 If the switch does not support either extension, then \fBovs\-ofctl\fR
 will report a fatal error.
+.IP "\fBreg\fIidx\fB=\fIvalue\fR[\fB/\fImask\fR]"
+Matches \fIvalue\fR either exactly or with optional \fImask\fR in
+register number \fIidx\fR.  The valid range of \fIidx\fR depends on
+the switch.  \fIvalue\fR and \fImask\fR are 32-bit integers, by
+default in decimal (use a \fB0x\fR prefix to specify hexadecimal).
+Arbitrary \fImask\fR values are allowed: a 1-bit in \fImask\fR
+indicates that the corresponding bit in \fIvalue\fR must match
+exactly, and a 0-bit wildcards that bit.
+.IP
+When a packet enters an OpenFlow switch, all of the registers are set
+to 0.  Only explicit Nicira extension actions change register values.
+.IP
+Register matches require support for the NXM (Nicira Extended Match)
+extension to OpenFlow.  When a register match is specified,
+\fBovs\-ofctl\fR will automatically attempt to negotiate use of this
+extension.  If the switch does not support NXM, then \fBovs\-ofctl\fR
+will report a fatal error.
 .
 .PP
 The following shorthand notations are also available:
-- 
2.30.2