Texas Instruments TMS320C67X/C67X+ DSP - Manual (Page 87)

Resource Constraints
3-27 Instruction Set SPRU733
MPYDP No other instruction on the same side can use the cross
path on cycles i, i + 1, i + 2, and i + 3.
MPYSPDP No other instruction on the same side can use the cross
path on cycles i and i + 1.
Other hazards exist because instructions have varying numbers of delay slots,
and need the functional unit read and write ports of varying numbers of cycles.
A read or write hazard exists when two instructions on the same functional unit
attempt to read or write, respectively, to the register file on the same cycle.
An instruction of the following types scheduled on cycle i has the following
constraints:
2-cycle DP A single-cycle instruction cannot be scheduled on that
functional unit on cycle i + 1 due to a write hazard on cycle
i + 1.
Another 2-cycle DP instruction cannot be scheduled on
that functional unit on cycle i + 1 due to a write hazard on
cycle i + 1.
4-cycle A single-cycle instruction cannot be scheduled on that
functional unit on cycle i + 3 due to a write hazard on cycle
i + 3.
A multiply (16 × 16-bit) instruction cannot be scheduled
on that functional unit on cycle i + 2 due to a write hazard
on cycle i + 3.
ADDDP/SUBDP A single-cycle instruction cannot be scheduled on that
functional unit on cycle i + 5 or i + 6 due to a write hazard
on cycle i + 5 or i + 6, respectively.
A 4-cycle instruction cannot be scheduled on that func-
tional unit on cycle i + 2 or i + 3 due to a write hazard on
cycle i + 5 or i + 6, respectively.
An INTDP instruction cannot be scheduled on that func-
tional unit on cycle i + 2 or i + 3 due to a write hazard on
cycle i + 5 or i + 6, respectively.
INTDP A single-cycle instruction cannot be scheduled on that
functional unit on cycle i + 3 or i + 4 due to a write hazard
on cycle i + 3 or i + 4, respectively.
An INTDP instruction cannot be scheduled on that func-
tional unit on cycle i + 1 due to a write hazard on cycle
i + 1.
A 4-cycle instruction cannot be scheduled on that func-
tional unit on cycle i + 1 due to a write hazard on cycle
i + 1.