Instruction Operands

Instruction Operands

There are some restrictions involving instruction operands. Instruction operands must be of the form:

[HIGH|LOW|UPPER] (<relocatable symbol> + <constant offset>)

where:

• <relocatable symbol> is any label that defines a program or data memory address

<constant offset> is an expression that is resolvable at assembly time to a value between -32768 and 32767

Either <relocatable symbol> or <constant offset> may be omitted.

Operands of the form:

<relocatable symbol> - <relocatable symbol>

will be reduced to a constant value if both symbols are defined in the same code or data section.

If HIGH is used, only bits 8 through15 of the expression will be used. If LOW is used, only bits 0 through 7 of the expression will be used. If UPPER is used, only bits 16 through 21 of the expression will be used.