The command processor parameter list (CPPL)

The interface between the TMP and an attached command processor is shown in Figure 1.

Figure 1. Interface between the TMP and a command processor This is an image of the terminal attaching to the command processor through register 1, which point to the CPPL.

This is an image of the terminal attaching to the command processor through register 1, which point to the CPPL.

When the TMP attaches a command processor, register 1 contains a pointer to command processor parameter list (CPPL) containing addresses required by the command processor. The command processor parameter list CPPL is a four-word parameter list that is located in subpool 1. Table 1 describes the contents of the CPPL.

Table 1. The command processor parameter list (CPPL)
Number of Bytes	Field Name	Contents or Meaning
4	CPPLCBUF	The address of the command buffer for the currently attached command processor.
4	CPPLUPT	The address of the user profile table (UPT). Use the IKJUPT mapping macro, which is provided in SYS1.MACLIB, to map the fields in the UPT.
4	CPPLPSCB	The address of the protected step control block (PSCB). Use the IKJPSCB mapping macro, which is provided in SYS1.MACLIB, to map the fields in the PSCB.
4	CPPLECT	The address of the environment control table (ECT). Use the IKJECT mapping macro, which is provided in SYS1.MACLIB, to map the fields in the ECT.

The first word of the CPPL contains the address of the command buffer for the currently attached command processor. As the TMP receives a line of input from the terminal user, the input is placed into the command buffer. After determining that the user has entered a command name, the TMP attaches the appropriate command processor. Figure 2 shows the format of the command buffer.

Figure 2. Format of the Command Buffer Image of the format of the command buffer described below.

When your command buffer receives control, the fields in the command buffer appear as follows:

The two-byte length field contains the length of the command buffer, including the four-byte header.
If the terminal user specified operands, the offset field contains the number of text bytes preceding the first operand. Otherwise, the offset field contains the length of the text portion of the buffer.
The text field contains the command name, in uppercase characters, followed by any operands the user specified.