TAL Programmer's Guide

Parameter Masks

Using Procedures

096254 Tandem Computers Incorporated 11–47

Procedure Entry Sequence

When an EXTENSIBLE procedure is activated, the procedure’s entry code loads

certain values onto the register stack. Table 11-7 shows:

The values that the entry code loads onto the register stack

The RP setting that results

Table 11-7. Entry Values Loaded Onto Register Stack

Kind of Procedure

Stack Value Loaded

Setting

EXTENSIBLE R[0] Number of parameter words expected 0

EXTENSIBLE, converted R[0] Number of parameters when procedure was

VARIABLE

R[1] Number of parameter words when procedure

was VARIABLE

R[2] Number of parameter words now expected 2

The procedure’s entry code then executes an ESE instruction, which uses the RP

setting to tell the cases apart. ESE sets RP to 7 but does not save the values in R0

through R7.

For a converted VARIABLE procedure, ESE converts the mask format to the

EXTENSIBLE format. ESE adds the needed bits and words and initializes them to 0. It

does not initialize any extra words on the register stack caused by the stack movement.

For information on the RP setting and ESE instruction, see the System Description

Manual for your system.