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Add #defines for the maximum encoded message size.

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Update issue 89
Status: FixedInGit
This commit is contained in:
Petteri Aimonen
2013-09-26 10:23:37 +03:00
parent 2363af29a2
commit 388d4de833
5 changed files with 111 additions and 19 deletions
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111
generator/nanopb_generator.py
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@@ -38,22 +38,22 @@ except:
import time
import os.path
# Values are tuple (c type, pb type)
# Values are tuple (c type, pb type, encoded size)
FieldD = descriptor.FieldDescriptorProto
datatypes = {
FieldD.TYPE_BOOL: ('bool', 'BOOL'),
FieldD.TYPE_DOUBLE: ('double', 'DOUBLE'),
FieldD.TYPE_FIXED32: ('uint32_t', 'FIXED32'),
FieldD.TYPE_FIXED64: ('uint64_t', 'FIXED64'),
FieldD.TYPE_FLOAT: ('float', 'FLOAT'),
FieldD.TYPE_INT32: ('int32_t', 'INT32'),
FieldD.TYPE_INT64: ('int64_t', 'INT64'),
FieldD.TYPE_SFIXED32: ('int32_t', 'SFIXED32'),
FieldD.TYPE_SFIXED64: ('int64_t', 'SFIXED64'),
FieldD.TYPE_SINT32: ('int32_t', 'SINT32'),
FieldD.TYPE_SINT64: ('int64_t', 'SINT64'),
FieldD.TYPE_UINT32: ('uint32_t', 'UINT32'),
FieldD.TYPE_UINT64: ('uint64_t', 'UINT64')
FieldD.TYPE_BOOL: ('bool', 'BOOL', 1),
FieldD.TYPE_DOUBLE: ('double', 'DOUBLE', 8),
FieldD.TYPE_FIXED32: ('uint32_t', 'FIXED32', 4),
FieldD.TYPE_FIXED64: ('uint64_t', 'FIXED64', 8),
FieldD.TYPE_FLOAT: ('float', 'FLOAT', 4),
FieldD.TYPE_INT32: ('int32_t', 'INT32', 5),
FieldD.TYPE_INT64: ('int64_t', 'INT64', 10),
FieldD.TYPE_SFIXED32: ('int32_t', 'SFIXED32', 4),
FieldD.TYPE_SFIXED64: ('int64_t', 'SFIXED64', 8),
FieldD.TYPE_SINT32: ('int32_t', 'SINT32', 5),
FieldD.TYPE_SINT64: ('int64_t', 'SINT64', 10),
FieldD.TYPE_UINT32: ('uint32_t', 'UINT32', 5),
FieldD.TYPE_UINT64: ('uint64_t', 'UINT64', 10)
}
class Names:
@@ -83,6 +83,17 @@ def names_from_type_name(type_name):
raise NotImplementedError("Lookup of non-absolute type names is not supported")
return Names(type_name[1:].split('.'))
def varint_max_size(max_value):
'''Returns the maximum number of bytes a varint can take when encoded.'''
for i in range(1, 11):
if (max_value >> (i * 7)) == 0:
return i
raise ValueError("Value too large for varint: " + str(max_value))
assert varint_max_size(0) == 1
assert varint_max_size(127) == 1
assert varint_max_size(128) == 2
class Enum:
def __init__(self, names, desc, enum_options):
'''desc is EnumDescriptorProto'''
@@ -113,6 +124,7 @@ class Field:
self.max_size = None
self.max_count = None
self.array_decl = ""
self.enc_size = None
# Parse field options
if field_options.HasField("max_size"):
@@ -141,12 +153,13 @@ class Field:
# Decide the C data type to use in the struct.
if datatypes.has_key(desc.type):
self.ctype, self.pbtype = datatypes[desc.type]
self.ctype, self.pbtype, self.enc_size = datatypes[desc.type]
elif desc.type == FieldD.TYPE_ENUM:
self.pbtype = 'ENUM'
self.ctype = names_from_type_name(desc.type_name)
if self.default is not None:
self.default = self.ctype + self.default
self.enc_size = 5 # protoc rejects enum values > 32 bits
elif desc.type == FieldD.TYPE_STRING:
self.pbtype = 'STRING'
if self.max_size is None:
@@ -154,15 +167,18 @@ class Field:
else:
self.ctype = 'char'
self.array_decl += '[%d]' % self.max_size
self.enc_size = varint_max_size(self.max_size) + self.max_size
elif desc.type == FieldD.TYPE_BYTES:
self.pbtype = 'BYTES'
if self.max_size is None:
can_be_static = False
else:
self.ctype = self.struct_name + self.name + 't'
self.enc_size = varint_max_size(self.max_size) + self.max_size
elif desc.type == FieldD.TYPE_MESSAGE:
self.pbtype = 'MESSAGE'
self.ctype = self.submsgname = names_from_type_name(desc.type_name)
self.enc_size = None # Needs to be filled in after the message type is available
else:
raise NotImplementedError(desc.type)
@@ -277,6 +293,42 @@ class Field:
return max(self.tag, self.max_size, self.max_count)
def encoded_size(self, allmsgs):
'''Return the maximum size that this field can take when encoded,
including the field tag. If the size cannot be determined, returns
None.'''
if self.allocation != 'STATIC':
return None
encsize = self.enc_size
if self.pbtype == 'MESSAGE':
for msg in allmsgs:
if msg.name == self.submsgname:
encsize = msg.encoded_size(allmsgs)
if encsize is None:
return None # Submessage size is indeterminate
encsize += varint_max_size(encsize) # submsg length is encoded also
break
else:
# Submessage cannot be found, this currently occurs when
# the submessage type is defined in a different file.
return None
if encsize is None:
raise RuntimeError("Could not determine encoded size for %s.%s"
% (self.struct_name, self.name))
encsize += varint_max_size(self.tag << 3) # Tag + wire type
if self.rules == 'REPEATED':
# Decoders must be always able to handle unpacked arrays.
# Therefore we have to reserve space for it, even though
# we emit packed arrays ourselves.
encsize *= self.max_count
return encsize
class ExtensionRange(Field):
def __init__(self, struct_name, range_start, field_options):
@@ -305,6 +357,12 @@ class ExtensionRange(Field):
def tags(self):
return ''
def encoded_size(self, allmsgs):
# We exclude extensions from the count, because they cannot be known
# until runtime. Other option would be to return None here, but this
# way the value remains useful if extensions are not used.
return 0
class ExtensionField(Field):
def __init__(self, struct_name, desc, field_options):
@@ -429,6 +487,18 @@ class Message:
result += ' PB_LAST_FIELD\n};'
return result
def encoded_size(self, allmsgs):
'''Return the maximum size that this message can take when encoded.
If the size cannot be determined, returns None.
'''
size = 0
for field in self.fields:
fsize = field.encoded_size(allmsgs)
if fsize is None:
return None
size += fsize
return size
# ---------------------------------------------------------------------------
@@ -597,8 +667,17 @@ def generate_header(dependencies, headername, enums, messages, extensions, optio
yield '/* Struct field encoding specification for nanopb */\n'
for msg in messages:
yield msg.fields_declaration() + '\n'
yield '\n'
yield '\n#ifdef __cplusplus\n'
yield '/* Maximum encoded size of messages (where known) */\n'
for msg in messages:
msize = msg.encoded_size(messages)
if msize is not None:
identifier = '%s_size' % msg.name
yield '#define %-40s %d\n' % (identifier, msize)
yield '\n'
yield '#ifdef __cplusplus\n'
yield '} /* extern "C" */\n'
yield '#endif\n'