pTAL Guidelines for TAL Programmers

Coding Guidelines

pTAL Guidelines for TAL Programmers—527256-002

2-15

Addresses and Integer Expressions

Guideline: Include only constant operands in an integer expression whose value is

assigned to a 16-bit pointer.

In TAL, the expression you store into a 16-bit pointer can include both constant and

nonconstant integer values.

In pTAL, you can store an integer into a 16-bit pointer only if the integer is a constant

expression.

This guideline does not apply to 32-bit pointers. You can store 32-bit constants, literal

values, or variable values into a 32-bit pointer.

Address Conversions

Guideline: Restrict address conversions to the rules described in this guideline.

You can convert addresses from one address type to another. Table 2-2 on page 2-15

shows the low-level conversions that pTAL supports.

Example 2-10. Valid Assignments

DEFINE offset = 14;

LITERAL distance = 20;

INT .p;

BADDR b;

@p := 0;

@p := -1 + (offset * 100) / distance;

b := @177777;

Table 2-2. Address Conversions (page1of2)

Conversion Expression Result Type Example

WADDR ‘<<‘ 1 BADDR INT .p;

STRING .s := @p ‘<<‘ 1;

SGWADDR ‘<<‘ 1 SGBADDR INT .SG p;

STRING .SG s := @p ‘<<‘ 1;

SGXWADDR ‘<<‘ 1 SGBADDR INT .SGX p;

STRING .SG s := @p ‘<<‘ 1;

BADDR ‘>>‘ 1 WADDR STRING .p;

INT .s := @p ‘>>’ 1;

SGBADDR ‘>>‘ 1 SGWADDR STRING .SG p;

INT .SG s := @p ‘>>’ 1;

SGXBADDR ‘>>‘ 1 SGWADDR STRING .SGX p;

INT .SG s := @p ‘>>’ 1;

$UDBL(BADDR ) EXTADDR STRING .p;

STRING .EXT s := $UDBL(@p);