Texas Instruments TMS320C67X/C67X+ DSP manual Resource Constraints

Resource Constraints

3.7 Resource Constraints

No two instructions within the same execute packet can use the same resources. Also, no two instructions can write to the same register during the same cycle. The following sections describe how an instruction can use each of the resources.

3.7.1Constraints on Instructions Using the Same Functional Unit

Two instructions using the same functional unit cannot be issued in the same execute packet.

The following execute packet is invalid:

ADD .S1 A0, A1, A2 ;.S1 is used for

SHR .S1 A3, 15, A4 ;...both instructions

The following execute packet is valid:

ADD .L1 A0, A1, A2 ;Two different functional

SHR .S1 A3, 15, A4 ;...units are used

3.7.2Constraints on the Same Functional Unit Writing in the Same Instruction Cycle

Two instructions using the same functional unit cannot write their results in the same instruction cycle.

3-20 Instruction Set SPRU733