Extension IPC Caller

IPC Caller

• Structure
  • Length
  • Metadata
  • Name
  • Arguments
  • Checksum
• Example
  • FooBar
  • OnStartUp

Structure

Length

|Len        |
+--+--+--+--+
|01|00|00|00|
+--+--+--+--+
0     2     4

It specifies the length of the data, including itself.
It's a 4 bytes little-endian unsigned integer.
In this example, the length is 1.

Metadata

Metadata is fixed with 6 items but only 4 used.
For reserved items please set them to 0x00. The length of each item is 2 bytes.

|Ver  |Seq  |Flg  |Arg  |X    |X    |
+--+--+--+--+--+--+--+--+--+--+--+--+
|01|00|E9|00|00|00|01|00|--|--|--|--|
+--+--+--+--+--+--+--+--+--+--+--+--+
0     2     4     6     8     A     C

1. The protocol version, which contains an unsigned short in little-endian.
   In this example, the version is 1.

2. The event sequence, which contains an unsigned short in little endian.
   While the sequence comes up to the max value(65535), will be turned to 0 in the next event.
   In this example, the sequence is 233.

3. The event flag.

4. The argument count, which contains an unsigned short in little endian.
   In this example, the total argument is 1.

The event flag can be a combination of the following constants

Name	Value
Need Result	1

Name

The event name has 1 byte for length ahead and without '\0' cut off.

|L.|Name    |
+--+--+--+--+
|03|46|6F|6F|
+--+--+--+--+
0     2     4

In this example, the event name is Foo.

Arguments

Every argument is a <string, raw> key value pair.
The arguments are stored one by one.

|L.|Key     |Len        |Val     |
+--+--+--+--+--+--+--+--+--+--+--+
|03|46|6F|6F|03|00|00|00|42|61|72|
+--+--+--+--+--+--+--+--+--+--+--+
0     2     4     6     8        A

A valid argument has 4 parts.

• The first is the length of the key name, not including itself, unsigned short.
• The second is the key name string without the '\0' cut off.
• The third is the length of the value name, not including itself, unsigned short.
• The last is the raw value data.

In this example, the argument name is Foo which value is Bar.

Checksum

|S.|
+--+
|FE|
+--+
0  1

The checksum is very simple only 1 byte.
Calculate the sum with every single byte and placed it at the end of the data. including the length.

In this example, the original data is FF FF, so finally the checksum is FE.

Example

FooBar

27 00 00 00 01 00 E9 00    #.....é.
00 00 02 00 00 00 00 00    ........
03 46 6F 6F 01 78 03 00    .Foo.x..
00 00 46 6F 6F 01 79 03    ..Foo.y.
00 00 00 42 61 72 6C       ...Barl

The pseudo code in C

void Foo("Foo", "Bar");

OnStartUp

17 00 00 00 01 00 E9 00    ......é.
01 00 00 00 00 00 00 00    ........
09 4F 6E 53 74 61 72 74    .OnStart
55 70 9B                   Up›

The pseudo code in C

bool OnStartUp();