pTAL Conversion Guide

Pointers

pTAL Conversion Guide—527302-002

10-34

Using Addresses in Expressions

Using pointer arithmetic described in the preceding topics, you can rewrite the

expression in Figure 10-4 on page 10-33 so that it is valid in pTAL. Figure 10-5 on

page 10-34 shows how you can create an expression with valid operations on

addresses. BASE0 is a WADDR value equal to zero. Subtracting BASE0 from @x

produces a 16-bit INT for which addition, multiplication, and division are defined.

Adding the result of the expression inside the parentheses to BASE0 produces a

WADDR value, which you can assign to @x.

Using Addresses in Expressions

TAL

•

You can use an address in an expression wherever an operand of the address

type—INT or INT(32)—is valid.

•

You can use built-in routines such as $INT and $UDBL to convert an address to

the required length.

•

You can assign the value of an arithmetic expression to a pointer.

The value you assign must be a 32-bit integer for an extended pointer and a 16-bit

integer for any other pointer.

Example 10-15 on page 10-35 declares pointer p, uses p’s value in an expression, and

assigns the resultant 16-bit value to p.

Figure 10-5. A Valid Arithmetic Expression in pTAL

INT .x;

WADDR base0 := 0;

@x := base0 ‘+’ (((@x + base0) + 3) / 4 * 4;

WADDR

INT

WADDR

INT

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