Add flag to indicate data length field.

Also, don't overwrite length argument in decode_link_packet()
which breaks decoding negative offset fields.

1 files changed, 12 insertions, 14 deletions

diff --git a/nosy-dump.c b/nosy-dump.c
index d139578..03fe664 100644
--- a/nosy-dump.c
+++ b/nosy-dump.c
@@ -495,7 +495,8 @@ struct packet_info {
 };
 
 enum {
-  PACKET_FIELD_DETAIL	= 0x01,
+  PACKET_FIELD_DETAIL		= 0x01,
+  PACKET_FIELD_DATA_LENGTH	= 0x02
 };
 
 struct packet_field {
@@ -548,7 +549,7 @@ struct packet_field read_block_request_fields[] = {
 
 struct packet_field block_response_fields[] = {
   COMMON_RESPONSE_FIELDS,
-  { "data_length", 96, 16 },
+  { "data_length", 96, 16, PACKET_FIELD_DATA_LENGTH },
   { "extended_tcode", 112, 16 },
   { "crc", 128, 32, PACKET_FIELD_DETAIL },
   { "data", 160, 0 },
@@ -564,7 +565,7 @@ struct packet_field write_quadlet_request_fields[] = {
 
 struct packet_field block_request_fields[] = {
   COMMON_REQUEST_FIELDS,
-  { "data_length", 96, 16 },
+  { "data_length", 96, 16, PACKET_FIELD_DATA_LENGTH },
   { "extended_tcode", 112, 16 },
   { "crc", 128, 32, PACKET_FIELD_DETAIL },
   { "data", 160, 0 },
@@ -583,7 +584,7 @@ struct packet_field cycle_start_fields[] = {
 };
 
 struct packet_field iso_data_fields[] = {
-  { "data_length", 0, 16 },
+  { "data_length", 0, 16, PACKET_FIELD_DATA_LENGTH },
   { "tag", 16, 2 },
   { "channel", 18, 6 },
   { "tcode", 24, 4, 0, tcode_names },
@@ -835,6 +836,7 @@ void dump_data(unsigned char *data, int length)
 void decode_link_packet(struct link_packet *packet, size_t length)
 {
   struct packet_info *pi;
+  int data_length = 0;
   int i;
 
   pi = &packet_info[packet->common.tcode];
@@ -858,16 +860,9 @@ void decode_link_packet(struct link_packet *packet, size_t length)
       printf("%s", f->value_names[bits]);
     }
     else if (f->width == 0) {
-      /* The way I'd like to do this instead is to have a way to
-       * specify which of the other fields designate the length of the
-       * data field. */
-      if (packet->common.tcode == TCODE_ISO_DATA)
-	length = packet->iso_data.data_length;
-      else
-	length = packet->write_block.data_length;
       printf("%s=[", f->name);
-      dump_data((unsigned char *) packet + (offset / 8 + 4), length);
-      printf("] ");
+      dump_data((unsigned char *) packet + (offset / 8 + 4), data_length);
+      printf("]");
     }
     else {
       unsigned long long bits;
@@ -879,13 +874,16 @@ void decode_link_packet(struct link_packet *packet, size_t length)
 	low_width = f->width - high_width;
 
 	bits = get_bits(packet, offset, high_width);
-	bits = (bits << low_width) | 
+	bits = (bits << low_width) |
 	  get_bits(packet, offset + high_width, low_width);
       }
       else
 	bits = get_bits(packet, offset, f->width);
 
       printf("%s=0x%0*llx", f->name, (f->width + 3) / 4, bits);
+
+      if (f->flags & PACKET_FIELD_DATA_LENGTH)
+	data_length = bits;
     }
 
     if (i < pi->field_count - 1)