From 51d62d1a3cd965f23af48a20886cf0c916e3977e Mon Sep 17 00:00:00 2001
From: Michael Brown
Date: Wed, 28 Jun 2006 18:59:54 +0000
Subject: Provide a mechanism for returning the encapsulator as well as the
 encapsulated option; this will be needed for modifications to the options
 block.

---
 src/include/gpxe/dhcp.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

(limited to 'src/include')

diff --git a/src/include/gpxe/dhcp.h b/src/include/gpxe/dhcp.h
index 26016cf81..cc9b94eb9 100644
--- a/src/include/gpxe/dhcp.h
+++ b/src/include/gpxe/dhcp.h
@@ -88,6 +88,20 @@ extern unsigned long dhcp_num_option ( struct dhcp_option *option );
 extern struct dhcp_option * find_dhcp_option ( unsigned int tag,
 					   struct dhcp_option_block *options );
 
+/**
+ * Find DHCP numerical option, and return its value
+ *
+ * @v tag		DHCP option tag to search for
+ * @v options		DHCP options block
+ * @ret value		Numerical value of the option, or 0 if not found
+ *
+ * This function exists merely as a notational shorthand for a call to
+ * find_dhcp_option() followed by a call to dhcp_num_option().  It is
+ * not possible to distinguish between the cases "option not found"
+ * and "option has a value of zero" using this function; if this
+ * matters to you then issue the two constituent calls directly and
+ * check that find_dhcp_option() returns a non-NULL value.
+ */
 static inline unsigned long
 find_dhcp_num_option ( unsigned int tag, struct dhcp_option_block *options ) {
 	return dhcp_num_option ( find_dhcp_option ( tag, options ) );
-- 
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