dtc: implement labels on property data

Extend the parser grammer to allow labels before or after any
property data (string, cell list, or byte list), and any
byte or cell within the property data.

Store the labels using the same linked list structure as node
references, but using a parallel list.

When writing assembly output emit global labels as offsets from
the start of the definition of the data.

Note that the alignment for a cell list is done as part of the
opening < delimiter, not the = or , before it.  To label a cell
after a string or byte list put the label inside the cell list.

For example,
	prop = zero: [ aa bb ], two: < four: 1234 > eight: ;
will produce labels with offsets 0, 2, 4, and 8 bytes from
the beginning of the data for property prop.

Signed-off-by: Milton Miller <miltonm@bga.com>

4 files changed, 60 insertions, 12 deletions

diff --git a/data.c b/data.c
index 3d68792..3e96d11 100644
--- a/data.c
+++ b/data.c
@@ -29,12 +29,17 @@ void fixup_free(struct fixup *f)
 
 void data_free(struct data d)
 {
-	struct fixup *f;
+	struct fixup *f, *nf;
 
 	f = d.refs;
 	while (f) {
-		struct fixup *nf;
+		nf = f->next;
+		fixup_free(f);
+		f = nf;
+	}
 
+	f = d.labels;
+	while (f) {
 		nf = f->next;
 		fixup_free(f);
 		f = nf;
@@ -198,27 +203,36 @@ struct data data_append_data(struct data d, void *p, int len)
 	return d;
 }
 
-struct data data_merge(struct data d1, struct data d2)
+void fixup_merge(struct fixup **fd, struct fixup **fd2, int d1_len)
 {
-	struct data d;
 	struct fixup **ff;
 	struct fixup *f, *f2;
 
-	d = data_append_data(d1, d2.val, d2.len);
-
 	/* Extract d2's fixups */
-	f2 = d2.refs;
-	d2.refs = NULL;
+	f2 = *fd2;
+	*fd2 = NULL;
 
 	/* Tack them onto d's list of fixups */
-	ff = &d.refs;
+	ff = fd;
 	while (*ff)
 		ff = &((*ff)->next);
 	*ff = f2;
 
 	/* And correct them for their new position */
 	for (f = f2; f; f = f->next)
-		f->offset += d1.len;
+		f->offset += d1_len;
+
+
+}
+
+struct data data_merge(struct data d1, struct data d2)
+{
+	struct data d;
+
+	d = data_append_data(d1, d2.val, d2.len);
+
+	fixup_merge(&d.refs, &d2.refs, d1.len);
+	fixup_merge(&d.labels, &d2.labels, d1.len);
 
 	data_free(d2);
 
@@ -285,6 +299,22 @@ struct data data_add_fixup(struct data d, char *ref)
 	return nd;
 }
 
+struct data data_add_label(struct data d, char *label)
+{
+	struct fixup *f;
+	struct data nd;
+
+	f = xmalloc(sizeof(*f));
+	f->offset = d.len;
+	f->ref = label;
+	f->next = d.labels;
+
+	nd = d;
+	nd.labels = f;
+
+	return nd;
+}
+
 int data_is_one_string(struct data d)
 {
 	int i;
diff --git a/dtc-parser.y b/dtc-parser.y
index d88cbf1..19bc58e 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -131,9 +131,11 @@ propdata:	propdataprefix DT_STRING { $$ = data_merge($1, $2); }
 			$$ = data_merge(data_append_align($1, sizeof(cell_t)), $3);
 		}
 	|	propdataprefix '[' bytestring ']' { $$ = data_merge($1, $3); }
+	|	propdata DT_LABEL { $$ = data_add_label($1, $2); }
 	;
 
 propdataprefix:	propdata ',' { $$ = $1; }
+	|	propdataprefix DT_LABEL { $$ = data_add_label($1, $2); }
 	|	/* empty */ { $$ = empty_data; }
 	;
 
@@ -150,10 +152,12 @@ celllist:	celllist opt_cell_base DT_CELL {
 	|	celllist DT_REF	{
 			$$ = data_append_cell(data_add_fixup($1, $2), -1);
 		}
+	|	celllist DT_LABEL { $$ = data_add_label($1, $2); }
 	|	/* empty */ { $$ = empty_data; }
 	;
 
 bytestring:	bytestring DT_BYTE { $$ = data_append_byte($1, $2); }
+	|	bytestring DT_LABEL { $$ = data_add_label($1, $2); }
 	|	/* empty */ { $$ = empty_data; }
 	;
 
diff --git a/dtc.h b/dtc.h
index 8cfe1a1..0a1f960 100644
--- a/dtc.h
+++ b/dtc.h
@@ -111,10 +111,10 @@ struct data {
 	char *val;
 	int asize;
 	struct fixup *refs;
+	struct fixup *labels;
 };
 
-#define empty_data \
-	((struct data){.len = 0, .val = NULL, .asize = 0, .refs = NULL})
+#define empty_data ((struct data){ /* all .members = 0 or NULL */ })
 
 void fixup_free(struct fixup *f);
 void data_free(struct data d);
@@ -135,6 +135,7 @@ struct data data_append_zeroes(struct data d, int len);
 struct data data_append_align(struct data d, int align);
 
 struct data data_add_fixup(struct data d, char *ref);
+struct data data_add_label(struct data d, char *label);
 
 int data_is_one_string(struct data d);
 
diff --git a/flattree.c b/flattree.c
index 31609d6..c7817c6 100644
--- a/flattree.c
+++ b/flattree.c
@@ -121,6 +121,12 @@ static void emit_label(FILE *f, char *prefix, char *label)
 	fprintf(f, "_%s_%s:\n", prefix, label);
 }
 
+static void emit_offset_label(FILE *f, char *label, int offset)
+{
+	fprintf(f, "\t.globl\t%s\n", label);
+	fprintf(f, "%s\t= . + %d\n", label, offset);
+}
+
 static void asm_emit_cell(void *e, cell_t val)
 {
 	FILE *f = e;
@@ -157,6 +163,13 @@ static void asm_emit_data(void *e, struct data d)
 {
 	FILE *f = e;
 	int off = 0;
+	struct fixup *l;
+
+	l = d.labels;
+	while (l) {
+		emit_offset_label(f, l->ref, l->offset);
+		l = l->next;
+	}
 
 	while ((d.len - off) >= sizeof(u32)) {
 		fprintf(f, "\t.long\t0x%x\n",