pTAL Conversion Guide

Pointers

pTAL Conversion Guide—527302-002

10-24

Pointer Arithmetic

TAL

All addresses are INT or INT(32) values, which you can use as operands in

expressions anywhere an INT or INT(32) value is valid. For example, the following

code rounds an address up to the next address that is an integral multiple of 32 if the

address is not already an integral multiple of 32:

INT .x; ! Declare a pointer

@x := (@x '+' 3) / 4 * 4; ! Round @x up to next 4-byte address

pTAL

The preceding assignment statement is invalid in pTAL because the data type of @x is

WADDR. Although you can add or subtract a constant value to a WADDR—3 in the

preceding statement—you cannot perform division or multiplication on a WADDR.

In pTAL, arithmetic on addresses is restricted to the operations shown in Table 10-8 on

page 10-25.

Example 10-7. Address Shifts (pTAL)

Invalid:

INT a;

STRING .b;

INT(32) .SG c;

STRING .SGX d;

@c := @b '>>' 1; ! ERROR: Cannot convert BADDR to SGWADDR

Valid:

INT a;

STRING .b;

INT(32) .SG c;

STRING .SGX d;

@b := @a '<<' 1; ! Convert WADDR to BADDR

@c := @d '>>' 1; ! Convert SGXBADDR to SGWADDR