pTAL Conversion Guide

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Introduction

pTAL Conversion Guide—527302-002

1-2

TAL FeaturesThat pTAL Does Not Support

•

Optional clauses to optimize program performance by specifying how data is

stored in memory:

FIELDALIGN for structure alignment

REFALIGNED for pointer alignment

•

Compiler directives:

CHECKSHIFTCOUNT

FIELDALIGN

OVERFLOW_TRAPS

REFALIGNED

•

Built-in routines that provide the functionality of some TNS machine instructions

The TAL compiler accepts most of the preceding pTAL features (which means the TAL

and native compilers can usually compile the same source code); however, some of

the new pTAL features do not affect the object code that the TAL compiler generates).

TAL FeaturesThat pTAL Does Not Support

pTAL does not support TAL constructs that are not portable (those that depend on TNS

architecture).

In pTAL program you cannot: In pTAL program you must: (page 1 of 2)

Reference the base-address symbols 'G', 'L',

and 'S'

Change algorithms that depend on

accessing data relative to the G, L, or S

registers

Access the stack marker to obtain

information about the procedure that called

the current procedure

UsepTAL built-in routines that provide

equivalent functionality

Build a parameter mask when you call a

variable or extensible procedure

Use the built-in routine $OPTIONAL for each

optional parameter

Use the TNS instruction CODE(DPCL) to

dynamically select a procedure to call

Use a pTAL procedure pointer (PROCPTR)

instead

Declare equivalenced variables that

reference memory outside of the memory

allocated to the variables they reference

Change algorithms that depend on declaring

equivalenced variables that reference

memory outside of the memory allocated to

the variables they reference.

Assume that separately declared data items

are allocated in contiguous memory

Change algorithms that assume that

separately declared data items are allocated

in contiguous memory.

Depend on how pTAL passes actual

parameters to procedures

Treat each procedure parameter as a unique

data item, unrelated to other parameters or

to the procedure’s local data.