[PATCH v2 3/4] dtc: Add /./

Allow constructing new values for a property using old property values.
Can be used to append, pre-append, duplicate, etc.

In practice, it looks as follows:

dts-v1/;

/ {
	str-prop = "0";
	int-prop = <0>;
};

/ {
	str-prop = /./, "1", /./;
	int-prop = /./, <1>, /./;
};

dts to source output with -T -T also works as expected:

/dts-v1/;

/ { /* base.dts:3:3-5:3, base.dts:7:3-9:3 */
        int-prop = <0x00 0x01>, <0x02 0x03>, <0x00 0x01>; /* base.dts:4:9-4:26, base.dts:8:9-8:36 */
}; /* base.dts:3:3-5:3, base.dts:7:3-9:3 */

Signed-off-by: Ayush Singh <[email protected]>
---
 dtc-lexer.l  |  5 +++++
 dtc-parser.y |  5 +++++
 dtc.h        |  1 +
 livetree.c   | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 4 files changed, 59 insertions(+), 2 deletions(-)

diff --git a/dtc-lexer.l b/dtc-lexer.l
index de60a70b6bdbcb5ae4336ea4171ad6f645e91b36..5efeca10363e0c9c338b6578be9240c3f42249f0 100644
--- a/dtc-lexer.l
+++ b/dtc-lexer.l
@@ -144,6 +144,11 @@ static void PRINTF(1, 2) lexical_error(const char *fmt, ...);
 			return DT_OMIT_NO_REF;
 		}
 
+<*>"/./" {
+			DPRINT("Keyword: /./\n");
+			return DT_PREV_PROP;
+		}
+
 <*>{LABEL}:	{
 			DPRINT("Label: %s\n", yytext);
 			yylval.labelref = xstrdup(yytext);
diff --git a/dtc-parser.y b/dtc-parser.y
index 4d5eece526243460203157464e3cd75f781e50e7..c34eb10a1068b5eb6a0f08e5a1db8066217b16bf 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -57,6 +57,7 @@ static bool is_ref_relative(const char *ref)
 %token DT_LSHIFT DT_RSHIFT DT_LE DT_GE DT_EQ DT_NE DT_AND DT_OR
 %token DT_BITS
 %token DT_DEL_PROP
+%token DT_PREV_PROP
 %token DT_DEL_NODE
 %token DT_OMIT_NO_REF
 %token <propnodename> DT_PROPNODENAME
@@ -308,6 +309,10 @@ propdata:
 		{
 			$$ = data_merge($1, $2);
 		}
+        | propdataprefix DT_PREV_PROP
+                {
+                        $$ = data_add_marker($1, PREV_VALUE, NULL);
+                }
 	| propdataprefix arrayprefix '>'
 		{
 			$$ = data_merge($1, $2.data);
diff --git a/dtc.h b/dtc.h
index 86928e1eea9764fe5d74d6dbb987589d65d54b66..175fe3637a31cc28453dc27980f315a171763b49 100644
--- a/dtc.h
+++ b/dtc.h
@@ -110,6 +110,7 @@ enum markertype {
 	REF_PHANDLE,
 	REF_PATH,
 	LABEL,
+	PREV_VALUE,
 	TYPE_UINT8,
 	TYPE_UINT16,
 	TYPE_UINT32,
diff --git a/livetree.c b/livetree.c
index 93c77d95a320ec05aa355e12920cef9e1c91c26a..22d45ca90bec8971d02231787217deb7caf53310 100644
--- a/livetree.c
+++ b/livetree.c
@@ -139,10 +139,40 @@ struct node *reference_node(struct node *node)
 	return node;
 }
 
+static struct data data_insert_old_value(struct data d, struct marker *m,
+					 struct data old)
+{
+	unsigned int offset = m->offset;
+	struct marker *next = m->next;
+	struct marker *marker;
+	struct data new_data;
+	char *ref;
+
+	new_data = data_insert_at_marker(d, m, old.val, old.len);
+
+	/* Copy all markers from old value */
+	marker = old.markers;
+	for_each_marker(marker) {
+		ref = NULL;
+
+		if (marker->ref)
+			ref = xstrdup(marker->ref);
+
+		m->next = alloc_marker(marker->offset + offset, marker->type,
+				       ref);
+		m = m->next;
+	}
+	m->next = next;
+
+	return new_data;
+}
+
 struct node *merge_nodes(struct node *old_node, struct node *new_node)
 {
 	struct property *new_prop, *old_prop;
 	struct node *new_child, *old_child;
+	bool prev_value_used = false;
+	struct marker *marker;
 	struct label *l;
 
 	old_node->deleted = 0;
@@ -172,10 +202,26 @@ struct node *merge_nodes(struct node *old_node, struct node *new_node)
 				for_each_label_withdel(new_prop->labels, l)
 					add_label(&old_prop->labels, l->label);
 
+				marker = new_prop->val.markers;
+				for_each_marker_of_type(marker, PREV_VALUE) {
+					new_prop->val = data_insert_old_value(
+						new_prop->val, marker,
+						old_prop->val);
+					prev_value_used = true;
+				}
+
 				old_prop->val = new_prop->val;
 				old_prop->deleted = 0;
-				free(old_prop->srcpos);
-				old_prop->srcpos = new_prop->srcpos;
+
+				if (prev_value_used) {
+					old_prop->srcpos =
+						srcpos_extend(old_prop->srcpos,
+							      new_prop->srcpos);
+				} else {
+					srcpos_free(old_prop->srcpos);
+					old_prop->srcpos = new_prop->srcpos;
+				}
+
 				free(new_prop);
 				new_prop = NULL;
 				break;

-- 
2.48.1