px4_autopilot/Tools/px_generate_uorb_topic_helper.py

# helper methods & common code for the uorb message templates msg.{cpp,h}.template

# Another positive effect of having the code here, is that this file will get
# precompiled and thus message generation will be much faster


import genmsg.msgs
import gencpp

type_map = {
    'int8': 'int8_t',
    'int16': 'int16_t',
    'int32': 'int32_t',
    'int64': 'int64_t',
    'uint8': 'uint8_t',
    'uint16': 'uint16_t',
    'uint32': 'uint32_t',
    'uint64': 'uint64_t',
    'float32': 'float',
    'float64': 'double',
    'bool': 'bool',
    'char': 'char',
}

msgtype_size_map = {
    'int8': 1,
    'int16': 2,
    'int32': 4,
    'int64': 8,
    'uint8': 1,
    'uint16': 2,
    'uint32': 4,
    'uint64': 8,
    'float32': 4,
    'float64': 8,
    'bool': 1,
    'char': 1,
}


def bare_name(msg_type):
    """
    Get bare_name from <dir>/<bare_name>[x] format
    """
    bare = msg_type
    if '/' in msg_type:
        # removing prefix
        bare = (msg_type.split('/'))[1]
    # removing suffix
    return bare.split('[')[0]


def sizeof_field_type(field):
    """
    Get size of a field, used for sorting
    """
    bare_name_str = bare_name(field.type)
    if bare_name_str in msgtype_size_map:
        return msgtype_size_map[bare_name_str]
    return 0 # this is for non-builtin types: sort them at the end

def get_children_fields(base_type, search_path):
    (package, name) = genmsg.names.package_resource_name(base_type)
    tmp_msg_context = genmsg.msg_loader.MsgContext.create_default()
    spec_temp = genmsg.msg_loader.load_msg_by_type(tmp_msg_context, '%s/%s' %(package, name), search_path)  
    sorted_fields = sorted(spec_temp.parsed_fields(), key=sizeof_field_type, reverse=True)
    return sorted_fields

def add_padding_bytes(fields, search_path):
    """
    Add padding fields before the embedded types, at the end and calculate the
    struct size
    returns a tuple with the struct size and padding at the end
    """
    struct_size = 8 # account for the timestamp
    align_to = 8 # this is always 8, because of the 64bit timestamp
    i = 0
    padding_idx = 0
    while i < len(fields):
        field = fields[i]
        if not field.is_header:
            a_pos = field.type.find('[')
            array_size = 1
            if field.is_array:
                array_size = field.array_len
            if field.is_builtin:
                field.sizeof_field_type = sizeof_field_type(field)
            else:
                # embedded type: may need to add padding
                num_padding_bytes = align_to - (struct_size % align_to)
                if num_padding_bytes != align_to:
                    padding_field = genmsg.Field('_padding'+str(padding_idx),
                        'uint8['+str(num_padding_bytes)+']')
                    padding_idx += 1
                    padding_field.sizeof_field_type = 1
                    struct_size += num_padding_bytes
                    fields.insert(i, padding_field)
                    i += 1
                children_fields = get_children_fields(field.base_type, search_path)
                field.sizeof_field_type, unused = add_padding_bytes(children_fields,
                        search_path)
            struct_size += field.sizeof_field_type * array_size
        i += 1

    # add padding at the end (necessary for embedded types)
    num_padding_bytes = align_to - (struct_size % align_to)
    if num_padding_bytes == align_to:
        num_padding_bytes = 0
    else:
        padding_field = genmsg.Field('_padding'+str(padding_idx),
                'uint8['+str(num_padding_bytes)+']')
        padding_idx += 1
        padding_field.sizeof_field_type = 1
        struct_size += num_padding_bytes
        fields.append(padding_field)
    return (struct_size, num_padding_bytes)


def convert_type(spec_type):
    """
    Convert from msg type to C type
    """
    bare_type = spec_type
    if '/' in spec_type:
        # removing prefix
        bare_type = (spec_type.split('/'))[1]

    msg_type, is_array, array_length = genmsg.msgs.parse_type(bare_type)
    c_type = msg_type
    if msg_type in type_map:
        c_type = type_map[msg_type]
    if is_array:
        return c_type + "[" + str(array_length) + "]"
    return c_type


def print_field_def(field):
    """
    Print the C type from a field
    """
    type_name = field.type
    # detect embedded types
    sl_pos = type_name.find('/')
    type_appendix = ''
    type_prefix = ''
    if (sl_pos >= 0):
        type_name = type_name[sl_pos + 1:]
        type_prefix = 'struct '
        type_appendix = '_s'

    # detect arrays
    a_pos = type_name.find('[')
    array_size = ''
    if (a_pos >= 0):
        # field is array
        array_size = type_name[a_pos:]
        type_name = type_name[:a_pos]

    if type_name in type_map:
        # need to add _t: int8 --> int8_t
        type_px4 = type_map[type_name]
    else:
        type_px4 = type_name

    comment = ''
    if field.name.startswith('_padding'):
        comment = ' // required for logger'

    print('\t%s%s%s %s%s;%s'%(type_prefix, type_px4, type_appendix, field.name,
                array_size, comment))