hardware protocol v2.1: device log, diagnostic routines, manual links

Three additions, all driven from the simulator debug panel.

DEVICE_LOG lets a controller send text lines; they reach the simulator log
and a per connection view in the panel which keeps the last 64 of them.

Diagnostic routines: a controller lists the procedures it offers, the
operator picks one from a drop down and starts it, and the controller
reports progress and the result. While a routine runs the controller can
ask the simulator to show a message box with its own text and buttons and
gets back which one was pressed, which is what a valve or gauge
calibration needs. The message box appears whether the debug panel is
open or not.

Links can now be disconnected and reconnected by hand: disconnecting
closes the serial port so the controller can be reprogrammed, and the
session is rebuilt from scratch on reconnect. Ports which appear while
the simulation runs can be picked from a refreshed list, given a baud
rate and added as a new controller, so the manager now starts even with
no uart2 entries in eu07.ini.

hardware/protocol/protocol_defs.h

@@ -20,7 +20,7 @@ namespace hardware
 
 // protocol version implemented by this build
 constexpr std::uint8_t protocol_version_major = 2;
-constexpr std::uint8_t protocol_version_minor = 0;
+constexpr std::uint8_t protocol_version_minor = 1;
 
 // 'M2', stored little-endian in the frame header
 constexpr std::uint16_t protocol_magic = 0x324D;
@@ -36,6 +36,10 @@ constexpr std::size_t protocol_frame_size_max = 4096;
 constexpr std::size_t protocol_symbol_name_max = 128;
 constexpr std::size_t protocol_string_max = 128;
 constexpr std::size_t protocol_symbols_per_message_max = 64;
+constexpr std::size_t protocol_diagnostic_functions_max = 32;
+constexpr std::size_t protocol_prompt_options_max = 4;
+// device log lines kept per connection for the debug panel
+constexpr std::size_t protocol_log_history = 64;
 
 // message identifiers; the numbering is part of the public protocol and must not be reordered
 enum class message_type : std::uint16_t
@@ -56,6 +60,7 @@ enum class message_type : std::uint16_t
 
 	device_info = 0x0010,
 	device_diagnostics = 0x0011,
+	device_log = 0x0012,
 
 	resolve_symbols = 0x0020,
 	symbols_resolved = 0x0021,
@@ -77,7 +82,14 @@ enum class message_type : std::uint16_t
 
 	property_read = 0x0050,
 	property_value = 0x0051,
-	property_write = 0x0052
+	property_write = 0x0052,
+
+	diagnostic_functions = 0x0060,
+	diagnostic_run = 0x0061,
+	diagnostic_cancel = 0x0062,
+	diagnostic_status = 0x0063,
+	diagnostic_prompt = 0x0064,
+	diagnostic_prompt_result = 0x0065
 };
 
 // header flag bits
@@ -189,9 +201,32 @@ enum capability_flag : std::uint32_t
 	capability_send_controls = 0x00000004,
 	capability_diagnostics = 0x00000008,
 	capability_soft_takeover = 0x00000010,
-	capability_control_leases = 0x00000020
+	capability_control_leases = 0x00000020,
+	// the device offers diagnostic routines which can be started from the debug panel
+	capability_diagnostic_functions = 0x00000040
 };
 
+// severity of a text line sent by the device
+enum class log_severity : std::uint8_t
+{
+	debug = 0,
+	info = 1,
+	warning = 2,
+	error = 3
+};
+
+// progress of a diagnostic routine running on the device
+enum class diagnostic_state : std::uint8_t
+{
+	idle = 0,
+	running = 1,
+	succeeded = 2,
+	failed = 3
+};
+
+// answer index reported when the user closes a prompt without choosing
+constexpr std::uint8_t prompt_dismissed = 0xFF;
+
 // session progress, mirrors the connection lifecycle of the specification
 enum class session_state : std::uint8_t
 {
@@ -216,6 +251,8 @@ char const *to_string( error_code const Code );
 char const *to_string( value_quality const Quality );
 char const *to_string( session_state const State );
 char const *to_string( link_state const State );
+char const *to_string( log_severity const Severity );
+char const *to_string( diagnostic_state const State );
 
 // size of a fixed-width type on the wire, 0 for variable-length ones
 std::size_t value_type_size( value_type const Type );