[RFC PATCH v2 03/74] fdtdump: Introduce get_structured_tag_data()

[Herve Codina]

With structured tag, data len can be encoded in the tag itself (no data,
1 cell data, 2 cells) or with a dedicated cell (varlen) added between
the tag and the data.

In multiple places, getting the data related to the tag will be needed.

In order to avoid code duplication, introduce get_structured_tag_data()
which purpose is to get the tag data part and its length based on the
tag value.

Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
---
 fdtdump.c | 50 ++++++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 20 deletions(-)

diff --git a/fdtdump.c b/fdtdump.c
index 20854752..f26d3a89 100644
--- a/fdtdump.c
+++ b/fdtdump.c
@@ -44,6 +44,33 @@ static const char *tagname(uint32_t tag)
 #define dumpf(fmt, args...) \
 	do { if (debug) printf("// " fmt, ## args); } while (0)
 
+static const char *get_structured_tag_data(uint32_t tag, const char *blob,
+					   const char **data, int *data_size)
+{
+	int sz = 0;
+
+	switch (tag & FDT_TAG_DATA_MASK) {
+	case FDT_TAG_DATA_NONE:
+		break;
+	case FDT_TAG_DATA_1CELL:
+		sz = FDT_CELLSIZE;
+		break;
+	case FDT_TAG_DATA_2CELLS:
+		sz = 2 * FDT_CELLSIZE;
+		break;
+	case FDT_TAG_DATA_VARLEN:
+		/* Get the length */
+		sz = fdt32_to_cpu(GET_CELL(blob));
+		break;
+	}
+
+	*data_size = sz;
+	*data = sz ? blob : NULL;
+
+	/* Skip the data bytes */
+	return PALIGN(blob + sz, 4);
+}
+
 static void dump_blob(void *blob, bool debug, int dump_unknown)
 {
 	uintptr_t blob_off = (uintptr_t)blob;
@@ -58,7 +85,7 @@ static void dump_blob(void *blob, bool debug, int dump_unknown)
 	uint32_t version = fdt32_to_cpu(bph->version);
 	uint32_t totalsize = fdt32_to_cpu(bph->totalsize);
 	uint32_t tag;
-	const char *p, *s, *t;
+	const char *p, *d, *s, *t;
 	int depth, sz, shift;
 	int i;
 	uint64_t addr, size;
@@ -153,21 +180,7 @@ static void dump_blob(void *blob, bool debug, int dump_unknown)
 		}
 
 		if ((tag & FDT_TAG_STRUCTURED) && (tag & FDT_TAG_SKIP_SAFE)) {
-			sz = 0;
-			switch (tag & FDT_TAG_DATA_MASK) {
-			case FDT_TAG_DATA_NONE:
-				break;
-			case FDT_TAG_DATA_1CELL:
-				sz = FDT_CELLSIZE;
-				break;
-			case FDT_TAG_DATA_2CELLS:
-				sz = 2 * FDT_CELLSIZE;
-				break;
-			case FDT_TAG_DATA_VARLEN:
-				/* Get the length */
-				sz = fdt32_to_cpu(GET_CELL(p));
-				break;
-			}
+			p = get_structured_tag_data(tag, p, &d, &sz);
 
 			if (dump_unknown) {
 				printf("%*s// Unknown tag ignored: 0x%08"PRIx32", data len %d",
@@ -175,13 +188,10 @@ static void dump_blob(void *blob, bool debug, int dump_unknown)
 				if (dump_unknown > 1 && sz != 0) {
 					printf(" ");
 					for (i = 0; i < sz; i++)
-						printf("%02hhx", *(p + i));
+						printf("%02hhx", *(d + i));
 				}
 				printf("\n");
 			}
-
-			/* Skip the data bytes */
-			p = PALIGN(p + sz, 4);
 			continue;
 		}
 
-- 
2.55.0