microchip_dsp - MICROCHIP: pack resources into DSPs

yosys> help microchip_dsp

microchip_dsp [options] [selection]

Pack input registers 'A', 'B', 'C', and 'D' (with optional enable/reset),
output register 'P' (with optional enable/reset), pre-adder and/or post-adder into
Microchip DSP resources.

Multiply-accumulate operations using the post-adder with feedback on the 'C'
input will be folded into the DSP. In this scenario only, the 'C' input can be
used to override the current accumulation result with a new value. This will
be added to the multiplier result to form the next accumulation result.

Use of the dedicated 'PCOUT' -> 'PCIN' cascade path is detected for 'P' -> 'C'
connections (optionally, where 'P' is right-shifted by 17-bits and used as an
input to the post-adder. This pattern is common for summing partial products to
implement wide multipliers). Cascade chains are limited to a mazimum length
of 24 cells, corresponding to PolarFire (pf) devices.

This pass is a no-op if the scratchpad variable 'microchip_dsp.multonly' is set
to 1.

-family {polarfire}

select the family to target
default: polarfire