gusucode.com > vnt工具箱matlab源码程序 > vnt/vnt/+vnt/+internal/+mixin/+message/SignalAccess.m
classdef (Abstract) SignalAccess < handle
% SignalAccess Implements common message signal operations.
%
% This class is provided as a mixin that implements signal access operations
% for message and message-like data items, such as J1939 parameter
% groups. It provides:
%
% - Unpack/get signals using CANdbLib API
% - Pack/set signals using CANdbLib API
%
% See also VNT.
% Authors: Jaremy Pyle
% Copyright 2015 The MathWorks, Inc.
properties (Abstract, Hidden, SetAccess = protected)
% PrivateData - Array of data bytes for the item.
PrivateData
% PrivateDatabase - A can.Database object defining the item.
PrivateDatabase
% PrivateName - The name of the item per the database definition.
PrivateName
end
methods (Abstract, Access = protected)
validity = isSignalValid(obj, signalIndex)
% isSignalValid Verifies signal integrity.
%
% This method is used to perform any required signal integrity
% checking needed when reading or writing signals values.
end
methods (Access = protected)
function result = getSignalValues(obj)
% getSignalValues Unpacks all signals for an item using the database.
%
% This method implements a full unpack of all signal values from the
% provided item. It works for CAN messages and J1939 parameter
% groups. It returns a structure with a field for each signal or
% empty in the event of an issue. It uses the underlying database
% object to perform the operation.
% Verify the message is of physical type. When the message is
% configured as a raw message, there are no signal values
% to reference, so the Signals property is irrelevant.
if strcmpi(obj.PrivateName, '')
result = [];
return;
end
% Call to the database interface to unpack the signal values
% for this item and return the resulting structure containing
% named fields for each signal.
[status, statusText, result] = obj.PrivateDatabase.getSignalValueAll( ...
obj.PrivateName, ...
obj.PrivateData);
% Check the returned status.
obj.checkStatus(status, statusText);
% Get the field names of the signals in the item.
signalNames = fieldnames(result);
% If the structure is received back from the database interface
% with no fields, it means no signals are defined for this
% message in the database file. In that case, return the
% property value as empty instead of the blank structure.
if isempty(signalNames)
result = [];
end
% Loop through and check the integrity of each signal.
for ii = 1:numel(signalNames)
% Perform any required signal integrity verification.
if ~obj.isSignalValid(ii)
% Negate the value of this specific signal.
result.(signalNames{ii}) = [];
end
end
end
function setSignalValues(obj, value)
% setSignalValues Packs signals for an item using the database.
%
% This method implements a pack of all changed signal values from the
% provided item. It works for CAN messages and J1939 parameter
% groups. It uses the underlying database object to perform the
% operation.
% Verify the item is of physical type. The Signals property
% is only relevant when item has a database definition.
if strcmpi(obj.PrivateName, '')
error(message('vnt:SignalAccess:NoDatabaseAttached'));
end
% Verify that the value to set is a structure. Changing the
% type or definition of the property away from a structure is
% not allowed.
if ~isstruct(value)
error(message('vnt:SignalAccess:StructureInputRequired'));
end
% OPTIMIZATION: Read the signal names for this item from the
% database object.
msgInfo = obj.PrivateDatabase.messageInfo(obj.PrivateName);
signalNames = msgInfo.Signals;
% Verify that the fields of the input structure match the
% signal names defined in the database. A mismatch means the
% user is trying to set a field that doesn't exist for the item.
if ~isequal(sort(fields(value)), signalNames)
error(message('vnt:SignalAccess:SignalDoesNotExist'));
end
% Read the current value of all the signals. This is used to
% compare against the new value in order to determine which
% signals have changed.
[~, ~, currentValue] = obj.PrivateDatabase.getSignalValueAll( ...
obj.PrivateName, ...
obj.PrivateData);
% Process each signal of the item.
for ii = 1:numel(signalNames)
% Only set the signal when the new value differs from the current.
if value.(signalNames{ii}) == currentValue.(signalNames{ii})
continue;
end
% Validate the values of each field of the structure. Only
% numeric values are accepted as all data is fundamentally
% numeric. We do not know specifically which field of the
% structure is being changed, so we validate them all.
if ~isnumeric(value.(signalNames{ii}))
error(message('vnt:SignalAccess:InvalidSignalValue'));
end
% Perform any required signal integrity verification.
if ~obj.isSignalValid(ii)
error(message('vnt:SignalAccess:InvalidSignal'));
end
% Call to the database interface to pack the new signal values
% for this item and set the resulting data array.
[status, statusText, obj.PrivateData] = obj.PrivateDatabase.setSignalPhysicalValue( ...
obj.PrivateName, ...
signalNames{ii}, ...
obj.PrivateData, ...
value.(signalNames{ii}));
% Check the returned status.
obj.checkStatus(status, statusText);
end
end
end
methods (Access = private)
function checkStatus(obj, status, statusText) %#ok<INUSL>
% Validate that the signal operation was correct.
% - Note a value of 0 is success.
% - A value of 4 means out of range; however, this does not
% indicate an error. It indicates that the raw signal
% value scaled to value defined as out of range for the
% signal. We apply min/max capping in the MEX function,
% so a range error is not an error.
% - A value of 5 indicates a mode error. This is generally
% because the current mode signal for a multiplexed signal
% is not currently for this signal. We do no treat this as
% an error. We leave it to the user to determine
% appropriate mode and usage.
if status ~= 0 && status ~= 4 && status ~= 5
% Error if the signal operation failed.
error(message('vnt:SignalAccess:CANdbLibError', status, statusText));
end
end
end
end