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PicoRV32 - A Size-Optimized RISC-V CPU
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Equivalent Gate Count PicoRV32I #119

Closed apdn closed 5 years ago

apdn commented 5 years ago

Hello,

I tried synthesizing the PicoRV32I core in design compiler using 250 nm LEDA library and got a gate equivalent of 5437 (number of cells in DC area report). I am just wondering if the gate count is right as the number seemed quite low. Any help/suggestion/comment would be much appreciated.

Thanks!

cliffordwolf commented 5 years ago

gate equivalent of 5437 (number of cells in DC area report)

What configuration is that? What cell library? I don't have DC, but yosys -p 'synth -top picorv32; abc -g cmos2; stat' picorv32.v gives me ~16k gates for the default configuration (that's a cell library with just NAND, NOR, NOT, and FFs). For a pretty minimal RV32E configuration I get ~10k gates. Mapping that minimal config to a cell lib that also includes AOI and OAI gates further reduces the gate count I see to ~7k. Also adding MUX gates further reduces the gate count I see to 5838.

as the number seemed quite low.

Since I can not reproduce what you are seeing as I neither have your cell library, nor DC, nor know which config you are using, I can only suggest that you run a post-synthesis simulation and see if it behaves as intended.

That being said, the whole point of PicoRV32 is that it's quite small (and easy to integrate). ;)

apdn commented 5 years ago

Thanks much for the elaborate reply. It is really helpful. :)