AmigaDOS Packets

Packet passing handles all communication performed by AmigaDOS between processes. The function diagram below shows how packets fit in with the other components of the Amiga operating system.

   +--------------+
   | User Process +-----------------------+
   +-------+------+                       |
           |                              |
           |                              |
    Function Calls                        |
           |                              |
          \|/                             |
 +---------+--------+                     |
 | AmigaDOS Open(), |                     |
 |   Close(), etc.  |                     |
 +---------+--------+                     |
           |                              |
           |                              |
      +-Packets---+--------+     +-----Packets--------+
      |           |        |     |        |           |
     \|/         \|/      \|/   \|/      \|/         \|/
 +----+----+ +----+----+ +-+--+--+-+ +----+----+ +----+----+
 | FFS/OFS | | FFS/OFS | | FFS/OFS | |   CON:  | |   CON:  |
 |   DH0:  | |   DF0:  | |   DF1:  | | Window1 | | Window2 |
 | Handler | | Handler | | Handler | | Handler | | Handler |
 | Process | | Process | | Process | | Process | | Process |
 +----+----+ +-------+-+ +----+----+ +----+----+ +----+----+
      |              |        |           |           |
     \|/            \|/      \|/         \|/         \|/
 +----+--------+  +--+--------+----+ +----+-----------+----+
 |Hddisk.device|  |Trackdisk.device| |    Console.device   |
 +-------------+  +----------------+ +---------------------+

A StandardPacket (defined in <dos/dosextens.h>) is used to send packet commands to a process's MsgPort. The StandardPacket structure contains an Exec Message structure and an AmigaDOS DOSPacket structure: