TAL Reference Manual

Statements
TAL Reference Manual—526371-001
12-16
Usage Considerations
mnemonic
is either an instruction code or a pseudocode.
. (period)
is the dereferencing operator, which converts the value of identifier into the
standard word address of another data item.
@
removes indirection. If identifier is a pointer, @ accesses the address contained in
the pointer. Otherwise, @ accesses the address of
identifier.
identifier
is the identifier of a procedure or label:
•
For a PCAL or XCAL instruction, it is a procedure. The procedure identifier
must be resolvable by the time the executable object file is created.
•
For a branch instruction, it is a label.
An indirect
identifier specified without @ generates instructions for an indirect
reference through
identifier.
constant
is an INT constant of the same size as the instruction field.
register
is either:
•
An INT constant that specifies a register number in the range 0 through 7
•
An identifier associated with an index register by a USE statement
If you omit
register, no indexing occurs.
Usage Considerations
Because CODE statements are not portable to future software platforms, modularize
their use as much as possible to simplify future modification of your program.
Instruction Codes
You can use instruction codes and pseudocodes as CODE statement mnemonics. The
six instruction forms shown in the syntax diagram correlate to instruction codes
described in the
System Description Manual for your system. You must include all
required operands for each instruction. The compiler inserts indirect branches around
data or instructions emitted in a CODE statement, if needed. Normally, the compiler
emits these values after the first unconditional branch instruction occurs.