HLASM Language Reference

Examples of Coded Machine Instructions
always one less than the effective length. If you want an assembled length value
of 0, an explicit length of 0 or 1 can be specified.
In the SS-format instructions requiring one length value, the allowable range for
explicit lengths is 0 through 256. In the SS-format instructions requiring two length
values, the allowable range for explicit lengths is 0 through 16.
Immediate Data
In addition to registers, numeric values, relative addresses, and lengths, some
machine instruction operands require immediate data. Such data is assembled
directly into the object code of the machine instructions. Use immediate data to
specify the bit patterns for masks or other absolute values you need.
Specify immediate data only where it is required. Do not confuse it with address
references to constants and areas, or with any literals you specify as the operands
of machine instructions.
Immediate data must be specified as absolute expressions whose range of values
depends on the machine instruction for which the data is required. The immediate
data is assembled into its binary representation.
Examples of Coded Machine Instructions
The examples that follow are grouped according to machine instruction format, and
the groups are shown in order of the instruction length. They show the various
ways in which you can code the operands of machine instructions. Both symbolic
and numeric representation of fields and subfields are shown in the examples.
Therefore, assume that all symbols used are defined elsewhere in the same source
module.
The object code assembled from at least one coded statement per group is also
included. A complete summary of machine instruction formats with the coded
assembler language variants can be found in the applicable Principles of Operation
manual.
The examples that follow show the various instruction formats, and are not meant
to show how the machine instructions should be used.
RI Format
The operand fields of RI-format instructions designate a register and an immediate
operand, with the following exception:
In BRC branching instructions, a 4-bit branching mask with a value between 0
and 15 inclusive replaces the register designation.
Symbols used to represent registers (such as REG1 in the example) are assumed
to be equated to absolute values between 0 and 15. The 16-bit immediate operand
has two different interpretations, depending on whether the instruction is a
branching instruction or not.
There are two types of non-branching RI-format instructions.
Chapter 4. Machine Instruction Statements 91