4.6.3 Unit Specifier Field

The unit specifier field is an optional field that follows the mnemonic field for machine-instruction mnemonics. The unit specifier field begins with a period (.) followed by a functional unit specifier. In general, one instruction can be assigned to each functional unit in a single instruction cycle. There are eight functional units, two of each functional type:

There are several ways to use the unit specifier field:

• You can specify the particular functional unit (for example, .D1).
• You can specify only the functional type (for example, .M), and the assembler assigns the specific unit (for example, .M2).
• If you do not specify the functional unit, the assembler assigns the functional unit based on the mnemonic field, operand fields, and other instructions in the same execute packet.

For more information on functional units, including which assembly instructions require which functional type, see the TMS320C64x/C64x+ DSP CPU and Instruction Set Reference Guide, or TMS320C66x DSP CPU and Instruction Set Reference Guide, or TMS320C674x CPU and Instruction Set Reference Guide.