The Graphics-Orders Header File (PMORD.H)

A set of helper constants, macros, and structures has been provided to help you decode and encode graphics orders. These items are defined in the header file PMORD.H.

There are four types of graphics orders. The first byte of each order, regardless of the graphics-order type, is the order code itself, which either partially or completely describes what follows. Depending on the order type, the graphics order can contain further information.

The four types of graphics order are:

• Byte Order
  The 1-byte order comprises a single byte:

  BYTE 1 : order code.
  

  2-Byte Order
  The 2-byte order consists of two bytes:

  BYTE 1 : order code
  BYTE 2 : associated value.
  

  Long Order
  The long order can comprise up to 257 bytes of information:

  BYTE 1     : order code
  BYTE 2     : length of order (0 to 255)
  BYTE 3-257 : associated value bytes
               depending on the order code.
  

  There is a special long order (Escape) where:

  BYTE 3     : escape type
  BYTE 4     : escape identifier
  BYTE 5-257 : associated value bytes
               depending on the escape
               identifier.
  

  Very Long Order
  The very long order can comprise up to 65537 bytes of information:

  BYTE 1       : order code
  BYTE 2       : order qualifier
  BYTE 3       : length of order
                 (most significant byte)
  BYTE 4       : length of order
                 (least significant byte -
                  length of order is 0 to 65535)
  BYTE 5-65537 : associated value bytes
                 depending on the order
                 qualifier.
  

  There is a special very long order (Escape) where :

  BYTE 5       : escape type
  BYTE 6       : escape identifier
  BYTE 7-65537 : associated value bytes
                 depending on the escape
                 identifier.
  

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  [Back: Introduction to Graphics Orders]
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