static inline int pb_decode_tag(pb_field_t *f)
{
if (pb_decode_varint(f))
{
if(f->left == 0)
f->eom = 1; // signal end-of-message
return -1;
}
if (f->val.i64 == 0)
{
f->eom = 1; // Allow 0-terminated messages.
PB_RETURN_ERROR(f, -2, "0-terminated msg");
}
f->tag = f->val.i64 >> 3;
f->type = (pb_wire_type_t)(f->val.i32 & 7);
DBGOUT("tag %u, type %u\n", f->tag, f->type);
switch (f->type)
{
case PB_WT_VARINT: return pb_decode_varint(f);
case PB_WT_FIXED64: return pb_decode_fixed64(f);
case PB_WT_STRING: return pb_decode_string(f);
case PB_WT_FIXED32: return pb_decode_fixed32(f);
default: PB_RETURN_ERROR(f, -3, "invalid wire_type");
}
return 0;
}
static bool read_fixed32(pb_istream_t *stream, const pb_field_t *field, void **arg)
{
uint32_t value;
if (!pb_decode_fixed32(stream, &value))
return false;
TEST(value == *(uint32_t*)*arg);
return true;
}
static bool read_repeated_fixed32(pb_istream_t *stream, const pb_field_t *field, void **arg)
{
uint32_t** expected = (uint32_t**)arg;
uint32_t value;
if (!pb_decode_fixed32(stream, &value))
return false;
TEST(*(*expected)++ == value);
return true;
}
bool print_container(pb_istream_t *stream)
{
uint64_t type, msgtype;
uint32_t length, tag;
pb_wire_type_t wiretype;
bool eof;
// decode the type tag
if (!pb_decode_tag(stream, &wiretype, &tag, &eof)) {
printf("Parsing tag#1 failed: %s\n", PB_GET_ERROR(stream));
}
if (!pb_decode_varint(stream, &type)) {
printf("Parsing required type field#1 failed: %s\n", PB_GET_ERROR(stream));
}
if (!pb_decode_tag(stream, &wiretype, &tag, &eof)) {
printf("Parsing tag#2 failed: %s\n", PB_GET_ERROR(stream));
}
assert(tag == 1); // tag number of length field
assert(wiretype == 5); // encoding of length field = fixed32
if (!pb_decode_fixed32(stream, &length)) {
printf("Parsing field#1 failed: %s\n", PB_GET_ERROR(stream));
}
printf("wiretype=%d tag=%d fixed32=%d (total message length)\n",
wiretype, tag, length);
if (!pb_decode_tag(stream, &wiretype, &tag, &eof)) {
printf("Parsing tag#2 failed: %s\n", PB_GET_ERROR(stream));
}
assert(tag == 2); // tag number of type field
assert(wiretype == 0); // encoding of length field = varint
if (!pb_decode_varint(stream, &msgtype)) {
printf("Parsing field#2 failed: %s\n", PB_GET_ERROR(stream));
}
printf("wiretype=%d tag=%d varint=%llu (msgtype)\n", wiretype, tag, msgtype);
// the actual message follows.
// It is a submessage encoded in length-delimited format
if (!pb_decode_tag(stream, &wiretype, &tag, &eof)) {
printf("Parsing tag#3 failed: %s\n", PB_GET_ERROR(stream));
}
printf("wiretype=%d tag=%d (submessage type)\n", wiretype, tag);
assert(wiretype == 2); // length-delimited format
printf("submessage: %s NML; %s Motion\n",
is_NML_container(tag) ? "is" : "not",
is_Motion_container(tag) ? "is" : "not");
// decoding the submessage left as exercise
return true;
}
