Rework "extended value strings":

- Allow direct access when a range of values begins with a value other than 0;
- Provide value_string_ext_new() for creating extended value strings at runtime;
- Do access to value_string_ext members via a macro (all but value_string.c);
- Update documentation.


git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@34514 f5534014-38df-0310-8fa8-9805f1628bb7

6 files changed, 254 insertions, 112 deletions

diff --git a/epan/dfilter/semcheck.c b/epan/dfilter/semcheck.c
index 82cde98243..45b6f7127c 100644
--- a/epan/dfilter/semcheck.c
+++ b/epan/dfilter/semcheck.c
@@ -232,9 +232,8 @@ mk_fvalue_from_val_string(header_field_info *hfinfo, char *s)
 	}
 	else {
 		const value_string *vals = hfinfo->strings;
-
 		if (hfinfo->display & BASE_EXT_STRING)
-			vals = ((value_string_ext *) vals)->vals;
+			vals = VALUE_STRING_EXT_VS_P((value_string_ext *) vals);
 
 		while (vals->strptr != NULL) {
 			if (g_ascii_strcasecmp(s, vals->strptr) == 0) {
diff --git a/epan/dissectors/packet-diameter.c b/epan/dissectors/packet-diameter.c
index 6f55a9d8b1..ee7be3366d 100644
--- a/epan/dissectors/packet-diameter.c
+++ b/epan/dissectors/packet-diameter.c
@@ -130,8 +130,9 @@ struct _diam_avp_t {
 	void* type_data;
 };
 
-#define VND_AVP_VS(v) ((value_string*)(void*)((v)->vs_avps->data))
-#define VND_CMD_VS(v) ((value_string*)(void*)((v)->vs_cmds->data))
+#define VND_AVP_VS(v)      ((value_string*)(void*)((v)->vs_avps->data))
+#define VND_AVP_VS_LEN(v)  ((v)->vs_avps->len)
+#define VND_CMD_VS(v)      ((value_string*)(void*)((v)->vs_cmds->data))
 
 typedef struct _diam_dictionary_t {
 	emem_tree_t* avps;
@@ -182,9 +183,8 @@ typedef struct _proto_avp_t {
 static const char* simple_avp(diam_ctx_t*, diam_avp_t*, tvbuff_t*);
 
 static const value_string no_vs[] = {{0, NULL} };
-static GArray no_garr = { (void*)no_vs, 1 };
-static value_string_ext no_vs_avps_ext = { (value_string_match_t) match_strval_ext_init, 0, (void*)no_vs};
-static diam_vnd_t unknown_vendor = { 0xffffffff, &no_garr, &no_vs_avps_ext,  &no_garr };
+static GArray no_garr = { (void*)no_vs, 0 };
+static diam_vnd_t unknown_vendor = { 0xffffffff, &no_garr, NULL,  &no_garr };
 static diam_vnd_t no_vnd = { 0, NULL, NULL, NULL };
 static diam_avp_t unknown_avp = {0, &unknown_vendor, simple_avp, simple_avp, -1, -1, NULL };
 static GArray* all_cmds;
@@ -344,28 +344,24 @@ dissect_diameter_eap_payload(tvbuff_t *tvb _U_, packet_info *pinfo _U_, proto_tr
 static int
 dissect_diameter_avp(diam_ctx_t* c, tvbuff_t* tvb, int offset)
 {
-	guint32 code = tvb_get_ntohl(tvb,offset);
-	guint32 len = tvb_get_ntohl(tvb,offset+4);
-	guint32 vendor_flag = len & 0x80000000;
+	guint32 code           = tvb_get_ntohl(tvb,offset);
+	guint32 len            = tvb_get_ntohl(tvb,offset+4);
+	guint32 vendor_flag    = len & 0x80000000;
 	guint32 flags_bits_idx = (len & 0xE0000000) >> 29;
-	guint32 flags_bits = (len & 0xFF000000) >> 24;
-	guint32 vendorid = vendor_flag ? tvb_get_ntohl(tvb,offset+8) : 0 ;
-	emem_tree_key_t k[] = {
+	guint32 flags_bits     = (len & 0xFF000000) >> 24;
+	guint32 vendorid       = vendor_flag ? tvb_get_ntohl(tvb,offset+8) : 0 ;
+	emem_tree_key_t k[]    = {
 		{1,&code},
 		{1,&vendorid},
 		{0,NULL}
 	};
-	diam_avp_t* a = emem_tree_lookup32_array(dictionary.avps,k);
+	diam_avp_t* a          = emem_tree_lookup32_array(dictionary.avps,k);
 	proto_item *pi, *avp_item;
 	proto_tree *avp_tree, *save_tree;
 	tvbuff_t* subtvb;
-	const diam_vnd_t* vendor;
-	value_string* vendor_avp_vs;
+	diam_vnd_t* vendor;
 	const char* code_str;
 	const char* avp_str;
-#if 0
-	gint i = 0;
-#endif
 	len &= 0x00ffffff;
 
 	if (!a) {
@@ -378,24 +374,23 @@ dissect_diameter_avp(diam_ctx_t* c, tvbuff_t* tvb, int offset)
 			vendor = &no_vnd;
 		}
 	} else {
-		vendor = a->vendor;
+		vendor = (diam_vnd_t *)a->vendor;
 	}
 
-	if(vendor->vs_avps_ext->vals == NULL){
+	if(vendor->vs_avps_ext == NULL) {
 		g_array_sort(vendor->vs_avps, compare_avps);
-		/* Get dictionary of AVPs matching found vendor */
-		vendor_avp_vs = VND_AVP_VS(vendor);
-		vendor->vs_avps_ext->vals = vendor_avp_vs;
+		vendor->vs_avps_ext = value_string_ext_new(VND_AVP_VS(vendor), VND_AVP_VS_LEN(vendor)+1, 
+                                                           "diameter_vendor");
 #if 0
-		Debug code
-		while(vendor_avp_vs[i].strptr!=NULL){
-			g_warning("%u %s",vendor_avp_vs[i].value,vendor_avp_vs[i].strptr);
-			i++;
+		{ /* Debug code */
+			value_string* vendor_avp_vs=VALUE_STRING_EXT_VS_P(vendor->vs_avps_ext);
+			gint i = 0;
+			while(vendor_avp_vs[i].strptr!=NULL){
+				g_warning("%u %s",vendor_avp_vs[i].value,vendor_avp_vs[i].strptr);
+				i++;
+			}
 		}
 #endif
-	}else{
-		/* Get dictionary of AVPs matching found vendor */
-		vendor_avp_vs = VND_AVP_VS(vendor);
 	}
 
 	/* Add root of tree for this AVP */
@@ -403,7 +398,7 @@ dissect_diameter_avp(diam_ctx_t* c, tvbuff_t* tvb, int offset)
 	avp_tree = proto_item_add_subtree(avp_item,a->ett);
 
 	pi = proto_tree_add_item(avp_tree,hf_diameter_avp_code,tvb,offset,4,FALSE);
-	code_str = val_to_str_ext(code, vendor->vs_avps_ext, "Unknown");
+	code_str = val_to_str_ext_const(code, vendor->vs_avps_ext, "Unknown");
 	proto_item_append_text(pi," %s", code_str);
 
 	/* Code */
@@ -1230,9 +1225,6 @@ dictionary_load(void)
 
 	no_vnd.vs_cmds = g_array_new(TRUE,TRUE,sizeof(value_string));
 	no_vnd.vs_avps = g_array_new(TRUE,TRUE,sizeof(value_string));
-	no_vnd.vs_avps_ext = g_malloc0(sizeof(value_string_ext));
-	no_vnd.vs_avps_ext->match = (value_string_match_t) match_strval_ext_init;
-	no_vnd.vs_avps_ext->length = 0;
 
 	all_cmds = g_array_new(TRUE,TRUE,sizeof(value_string));
 
@@ -1296,9 +1288,13 @@ dictionary_load(void)
 			vnd->code = v->code;
 			vnd->vs_cmds = g_array_new(TRUE,TRUE,sizeof(value_string));
 			vnd->vs_avps = g_array_new(TRUE,TRUE,sizeof(value_string));
+#if 0
 			vnd->vs_avps_ext = g_malloc0(sizeof(value_string_ext));
 			vnd->vs_avps_ext->match = (value_string_match_t) match_strval_ext_init;
+			vnd->vs_avps_ext->offset= 0;
 			vnd->vs_avps_ext->length= 0;
+#endif
+			vnd->vs_avps_ext = NULL;
 			pe_tree_insert32(dictionary.vnds,vnd->code,vnd);
 			g_hash_table_insert(vendors,v->name,vnd);
 		}
@@ -1331,7 +1327,6 @@ dictionary_load(void)
 		if ((vnd = g_hash_table_lookup(vendors,vend))) {
 			value_string vndvs = {a->code,a->name};
 			g_array_append_val(vnd->vs_avps,vndvs);
-			vnd->vs_avps_ext->length++;
 		} else {
 			fprintf(stderr,"Diameter Dictionary: No Vendor: %s",vend);
 			vnd = &unknown_vendor;
diff --git a/epan/libwireshark.def b/epan/libwireshark.def
index a8f3a0d3e4..2ac377fa31 100644
--- a/epan/libwireshark.def
+++ b/epan/libwireshark.def
@@ -631,7 +631,7 @@ match_strrval
 match_strrval_idx
 match_strval
 match_strval_ext
-match_strval_ext_init
+_match_strval_ext_init
 match_strval_idx
 md5_append
 md5_finish
diff --git a/epan/proto.c b/epan/proto.c
index 7a2a690254..d04ee42a15 100644
--- a/epan/proto.c
+++ b/epan/proto.c
@@ -6007,7 +6007,7 @@ proto_registrar_dump_values(void)
 				hfinfo->type == FT_INT64)) {
 
 				if ((hfinfo->display & BASE_EXT_STRING)) {
-					vals = ((value_string_ext *) hfinfo->strings)->vals;
+					vals = VALUE_STRING_EXT_VS_P((value_string_ext *) hfinfo->strings);
 				} else if ((hfinfo->display & BASE_RANGE_STRING) == 0) {
 					vals = hfinfo->strings;
 				} else {
diff --git a/epan/value_string.c b/epan/value_string.c
index 91c22bbda7..53bdb10436 100644
--- a/epan/value_string.c
+++ b/epan/value_string.c
@@ -33,6 +33,7 @@
 #include "value_string.h"
 #include <string.h>
 
+/* --------------------------------------------------------------------*/
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr on a match.
    Formats val with fmt, and returns the resulting string, on failure. */
@@ -49,19 +50,7 @@ val_to_str(const guint32 val, const value_string *vs, const char *fmt) {
   return ep_strdup_printf(fmt, val);
 }
 
-const gchar*
-val_to_str_ext(const guint32 val, const value_string_ext *vs, const char *fmt) {
-  const gchar *ret;
-
-  g_assert(fmt != NULL);
-
-  ret = match_strval_ext(val, vs);
-  if (ret != NULL)
-    return ret;
-
-  return ep_strdup_printf(fmt, val);
-}
-
+/* --------------------------------------------------------------------*/
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr on a match.
    Returns 'unknown_str', on failure. */
@@ -78,19 +67,7 @@ val_to_str_const(const guint32 val, const value_string *vs, const char *unknown_
   return unknown_str;
 }
 
-const gchar*
-val_to_str_ext_const(const guint32 val, const value_string_ext *vs, const char *unknown_str) {
-  const gchar *ret;
-
-  g_assert(unknown_str != NULL);
-
-  ret = match_strval_ext(val, vs);
-  if (ret != NULL)
-    return ret;
-
-  return unknown_str;
-}
-
+/* --------------------------------------------------------------------*/
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr, and sets "*idx" to the index in
    that table, on a match, and returns NULL, and sets "*idx" to -1,
@@ -120,89 +97,205 @@ match_strval(const guint32 val, const value_string *vs) {
     return match_strval_idx(val, vs, &ignore_me);
 }
 
+/* --------------------------------------------------------------------*/
+/* value_string_ext functions
+ *
+ *   Extended value strings allow fast(er) value_string array lookups by
+ *    using (if possible) direct access or a binary search of the array.
+ *
+ *    If the values in the value_string array are a contiguous range of values
+ *    from min to max, the value will be used as as a direct index into the array.
+ *
+ *    If the values in the array are not contiguous (ie: there are "gaps"),
+ *    but are in assending order a binary search will be used.
+ *
+ *    If direct access or binary search cannot be used, then a linear search
+ *    is used.
+ *
+ *    Note that the value_string array used with VALUE_STRING_EXT_INIT
+ *     *must* be terminated with {0, NULL}).
+ *
+ *    Extended value strings are defined at compile time as follows:
+ *      static const value_string vs[] = { {value1, "string1"}, {value2, "string2"}, ..., {0, NULL}};
+ *      static value_string_ext vse = VALUE_STRING_EXT_INIT(vs);
+ *
+ *    Extended value strings can be created at runtime by calling
+ *      value_string_ext_new(<ptr to value_string array>,
+ *                           <total number of entries in the value_string_array>,
+ *                           <value_string_name>);
+ *      Note: <total number of entries in the value_string_array> should include the {0, NULL} entry
+ *
+ */
+
+/* --------------------------------------------------------------------*/
+
+/* Create a value_string_ext given a ptr to a value_string array and the total number of entries.           */
+/* Note:  The total number of entries should include the required {0, NULL} terminating entry of the array. */
+/* Return: a pointer to a gmalloc'd and initialized value_string_ext struct.                                */
+value_string_ext *
+value_string_ext_new(value_string *vs, guint vs_tot_num_entries, gchar *vs_name) {
+    value_string_ext *vse;
+    g_assert (vs_name != NULL);
+    g_assert (vs_tot_num_entries > 0);
+    g_assert (vs[vs_tot_num_entries-1].strptr == NULL); /* Null-terminated value-string ? */
+    vse                  = g_malloc(sizeof (value_string_ext));
+    vse->_vs_p           = vs;
+    vse->_vs_num_entries = vs_tot_num_entries - 1; /* remember the actual number of entries */
+    vse->_vs_first_value = 0;                      /* initialized in _match_strval_ext_init */
+    vse->_vs_match       = (_value_string_match_t) _match_strval_ext_init;
+    vse->_vs_name        = vs_name;
+    return vse;
+}
+
+/* Looks up val in a value_string array using access method (direct, binary search
+ *  or linear) determined at rutime during the initial access); (see _match_strval_ext_init)
+ * Returns the associated string ptr on a match, and returns NULL on failure.
+ */
+const gchar*
+match_strval_ext(const guint32 val, const value_string_ext *vse) {
+    if (vse)
+      return vse->_vs_match(val, vse);
+    return NULL;
+}
+
+/* Similar to match_strval_ext except that on failure
+ * Formats val with fmt, and returns the resulting string
+ */
+const gchar*
+val_to_str_ext(const guint32 val, const value_string_ext *vse, const char *fmt) {
+  const gchar *ret;
+
+  g_assert(fmt != NULL);
+
+  ret = match_strval_ext(val, vse);
+  if (ret != NULL)
+    return ret;
+
+  return ep_strdup_printf(fmt, val);
+}
+
+/* Similar to match_strval_ext except that on failure
+ *  Returns 'unknown_str'
+ */
+const gchar*
+val_to_str_ext_const(const guint32 val, const value_string_ext *vse, const char *unknown_str) {
+  const gchar *ret;
+
+  g_assert(unknown_str != NULL);
+
+  ret = match_strval_ext(val, vse);
+  if (ret != NULL)
+    return ret;
+
+  return unknown_str;
+}
+
 static const gchar *
-_match_strval_linear(const guint32 val, const value_string_ext *vs)
+_match_strval_linear(const guint32 val, const value_string_ext *vse)
 {
-  return match_strval(val, vs->vals);
+  const value_string *vs_p = vse->_vs_p;
+  guint i;
+  for (i=0; i<vse->_vs_num_entries; i++) {
+    if (vs_p[i].value == val) {
+      return vs_p[i].strptr;
+    }
+  }
+  return NULL;
 }
 
 static const gchar *
-_match_strval_index(const guint32 val, const value_string_ext *vs)
+_match_strval_index(const guint32 val, const value_string_ext *vse)
 {
-  return (val < vs->length) ? vs->vals[val].strptr : NULL;
+  if ((val - vse->_vs_first_value) < vse->_vs_num_entries) {
+    g_assert (val == vse->_vs_p[val - vse->_vs_first_value].value);
+    return vse->_vs_p[val - vse->_vs_first_value].strptr;
+  }
+  return NULL;
 }
 
 static const gchar *
-_match_strval_bsearch(const guint32 val, const value_string_ext *vs)
+_match_strval_bsearch(const guint32 val, const value_string_ext *vse)
 {
   guint low, idx, max;
   guint32 item;
 
-  for (low = 0, max = vs->length; low < max; ) {
+  for (low = 0, max = vse->_vs_num_entries; low < max; ) {
     idx = (low + max) / 2;
-    item = vs->vals[idx].value;
+    item = vse->_vs_p[idx].value;
 
     if (val < item)
       max = idx;
     else if (val > item)
       low = idx + 1;
     else
-      return vs->vals[idx].strptr;
+      return vse->_vs_p[idx].strptr;
   }
   return NULL;
 }
 
+/* Init value_string_ext struct
+   - Go thru the value_string array to determine whether indexed access
+      or binary search access is possible;
+   - Verify that the value_string array does not contain any
+      NULL string pointers;
+   - Verify that the value_string array is terminated
+      by {0, NULL};
+*/
 const gchar *
-match_strval_ext_init(const guint32 val, value_string_ext *vse)
+_match_strval_ext_init(const guint32 val, value_string_ext *vse)
 {
-  const value_string *vals = vse->vals;
+  const value_string *vs_p           = vse->_vs_p;
+  const guint         vs_num_entries = vse->_vs_num_entries;
 
 /* The way matching of value is done in a value_string:
  * 0 Sequential search (as in a normal value string)
  * 1 Binary search, the values MUST be in numerical order.
- * 2 The value used as an index(the value string MUST have all values 0-max defined)
+ * 2 The value used as an index(the value string MUST have all values between first and last defined in numerical order)
  */
   enum { VS_SEARCH = 0, VS_BIN_TREE, VS_INDEX } type = VS_INDEX;
 
-  guint32 prev = 0;
-  guint i;
+  guint32 prev_value;
+  guint   first_value;
+  guint   i;
 
-  for (i = 0; i < vse->length; i++) {
-    if (type == VS_INDEX && vals[i].value != i)
-      type = VS_BIN_TREE;
+  g_assert((vs_p[vs_num_entries].value==0) && (vs_p[vs_num_entries].strptr==NULL));
 
-    if (type == VS_BIN_TREE && prev > vals[i].value) {
+  vse->_vs_first_value = vs_p[0].value;
+  first_value          = vs_p[0].value;
+  prev_value           = first_value;
+
+  for (i = 0; i < vs_num_entries; i++) {
+    g_assert(vs_p[i].strptr != NULL);
+    if ((type == VS_INDEX) && (vs_p[i].value != (i + first_value))) {
+      type = VS_BIN_TREE;
+    }
+    if ((type == VS_BIN_TREE) && (prev_value > vs_p[i].value)) {
       type = VS_SEARCH;
       break;
     }
 
-    prev = vals[i].value;
+    prev_value = vs_p[i].value;
   }
-  
+
   switch (type) {
   case VS_SEARCH:
-    vse->match = _match_strval_linear;
-    break;
-  case VS_INDEX:
-    vse->match = _match_strval_index;
+    vse->_vs_match = _match_strval_linear;
+    g_warning("Extended value string: %s not sorted; accessing linearly", vse->_vs_name);
     break;
   case VS_BIN_TREE:
-    vse->match = _match_strval_bsearch;
+    vse->_vs_match = _match_strval_bsearch;
+    break;
+  case VS_INDEX:
+    vse->_vs_match = _match_strval_index;
     break;
   default:
     g_assert_not_reached();
     break;
   }
 
-  return vse->match(val, vse);
-}
-
-const gchar*
-match_strval_ext(const guint32 val, const value_string_ext *vs) {
-    if (vs)
-      return vs->match(val, vs);
-    return NULL;
+  return vse->_vs_match(val, vse);
 }
+/* ----------- */
 
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr on a match.
diff --git a/epan/value_string.h b/epan/value_string.h
index cd30e9eb69..35c64b3507 100644
--- a/epan/value_string.h
+++ b/epan/value_string.h
@@ -34,18 +34,6 @@ typedef struct _value_string {
   const gchar   *strptr;
 } value_string;
 
-struct _value_string_ext;
-typedef const char *(*value_string_match_t)(const guint32, const struct _value_string_ext *);
-
-typedef struct _value_string_ext {
-  value_string_match_t match;
-  guint length;                 /* length of the array */
-  const value_string *vals;     /* the value string */
-} value_string_ext;
-
-const gchar *match_strval_ext_init(const guint32 val, value_string_ext *vse);
-#define VALUE_STRING_EXT_INIT(x) { (value_string_match_t) match_strval_ext_init, array_length(x)-1, x }
-
 /* Struct for the str_to_str, match_strstr_idx, and match_strstr functions */
 
 typedef struct _string_string {
@@ -71,19 +59,17 @@ extern const gchar* match_strval_idx(const guint32 val, const value_string *vs,
 
 /* Like match_strval_idx(), but doesn't return the index. */
 extern const gchar* match_strval(const guint32 val, const value_string *vs);
-extern const gchar* match_strval_ext(const guint32 val, const value_string_ext *vs);
 
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr on a match.
    Formats val with fmt, and returns the resulting string, on failure. */
 extern const gchar* val_to_str(const guint32 val, const value_string *vs, const char *fmt);
-extern const gchar* val_to_str_ext(const guint32 val, const value_string_ext *vs, const char *fmt);
+
 
 /* Tries to match val against each element in the value_string array vs.
    Returns the associated string ptr on a match.
    Returns 'unknown_str', on failure. */
 extern const gchar* val_to_str_const(const guint32 val, const value_string *vs, const char *unknown_str);
-extern const gchar* val_to_str_ext_const(const guint32 val, const value_string_ext *vs, const char *unknown_str);
 
 /* Tries to match val against each element in the string_string array vs.
    Returns the associated string ptr, and sets "*idx" to the index in
@@ -91,7 +77,7 @@ extern const gchar* val_to_str_ext_const(const guint32 val, const value_string_e
    on failure. */
 extern const gchar* match_strstr_idx(const gchar *val, const string_string *vs, gint *idx);
 
-/* Like match_strval_idx(), but doesn't return the index. */
+/* Like match_strstr_idx(), but doesn't return the index. */
 extern const gchar* match_strstr(const gchar *val, const string_string *vs);
 
 /* Tries to match val against each element in the string_string array vs.
@@ -99,6 +85,75 @@ extern const gchar* match_strstr(const gchar *val, const string_string *vs);
    Formats val with fmt, and returns the resulting string, on failure. */
 extern const gchar* str_to_str(const gchar *val, const string_string *vs, const char *fmt);
 
+/* --------------------------------------------------------------------*/
+/* value_string_ext functions
+ *
+ *   Extended value strings allow fast(er) value_string array lookups by
+ *    using (if possible) direct access or a binary search of the array.
+ *
+ *    If the values in the value_string array are a contiguous range of values
+ *    from min to max, the value will be used as as a direct index into the array.
+ *
+ *    If the values in the array are not contiguous (ie: there are "gaps"),
+ *    but are in assending order a binary search will be used.
+ *
+ *    If direct access or binary search cannot be used, then a linear search
+ *    is used.
+ *
+ *    Note that the value_string array used with VALUE_STRING_EXT_INIT
+ *     *must* be terminated with {0, NULL}).
+ *
+ *    Extended value strings are defined at compile time as follows:
+ *      static const value_string vs[] = { {value1, "string1"}, {value2, "string2"}, ..., {0, NULL}};
+ *      static value_string_ext vse = VALUE_STRING_EXT_INIT(vs);
+ *
+ *    Extended value strings can be created at runtime by calling
+ *      value_string_ext_new(<ptr to value_string array>,
+ *                           <total number of entries in the value_string_array>, 
+ *                           <value_string_name>);
+ *      Note: <total number of entries in the value_string_array> should include the {0, NULL} entry
+ */
+/* --------------------------------------------------------------------*/
+struct _value_string_ext;
+typedef const char *(*_value_string_match_t)(const guint32, const struct _value_string_ext *);
+
+typedef struct _value_string_ext {
+  _value_string_match_t _vs_match;
+  guint32 _vs_first_value;    /* first value of the value_string array       */
+  guint   _vs_num_entries;    /* number of entries in the value_string array */
+                              /*  (excluding final {0, NULL})                */
+  const value_string *_vs_p;  /* the value string array address              */
+  const gchar *_vs_name;      /* vse "Name" (for error messages)             */
+} value_string_ext;
+
+#define VALUE_STRING_EXT_VS_P(x) (x)->_vs_p
+
+extern const gchar *_match_strval_ext_init(const guint32 val, value_string_ext *vse);
+#define VALUE_STRING_EXT_INIT(x) { (_value_string_match_t) _match_strval_ext_init, 0, array_length(x)-1, x, #x }
+
+/* Create a value_string_ext given a ptr to a value_string array and the total number of entries. */
+/* Note: vs_tot_num_entries should include the required {0, NULL} terminating entry of the array. */
+/* Return: a pointer to a gmalloc'd and initialized value_string_ext struct.                      */
+extern value_string_ext *value_string_ext_new(value_string *vs, guint vs_tot_num_entries, gchar *vs_name);
+
+/* Looks up val in a value_string array using access method (direct, binary search
+ *  or linear) determined at rutime during the initial access); (see _match_strval_ext_init)
+ * Returns the associated string ptr on a match or NULL on failure.
+ */
+extern const gchar* match_strval_ext(const guint32 val, const value_string_ext *vse);
+
+/* Similar to match_strval_ext except that on failure
+ * Formats val with fmt, and returns the resulting string
+ */
+extern const gchar* val_to_str_ext(const guint32 val, const value_string_ext *vs, const char *fmt);
+
+/* Similar to match_strval_ext except that on failure
+ *  Returns 'unknown_str'
+ */
+extern const gchar* val_to_str_ext_const(const guint32 val, const value_string_ext *vs, const char *unknown_str);
+
+/* ---- ---- */
+
 /* Generate a string describing an enumerated bitfield (an N-bit field
    with various specific values having particular names). */
 extern const char *decode_enumerated_bitfield(const guint32 val, const guint32 mask,