synth_greenpak4 - synthesis for GreenPAK4 FPGAs

    synth_greenpak4 [options]

This command runs synthesis for GreenPAK4 FPGAs. This work is experimental.
It is intended to be used with https://github.com/azonenberg/openfpga as the
place-and-route.

    -top <module>
        use the specified module as top module (default='top')

    -part <part>
        synthesize for the specified part. Valid values are SLG46140V,
        SLG46620V, and SLG46621V (default).

    -json <file>
        write the design to the specified JSON file. writing of an output file
        is omitted if this parameter is not specified.

    -run <from_label>:<to_label>
        only run the commands between the labels (see below). an empty
        from label is synonymous to 'begin', and empty to label is
        synonymous to the end of the command list.

    -noflatten
        do not flatten design before synthesis

    -retime
        run 'abc' with -dff option


The following commands are executed by this synthesis command:

    begin:
        read_verilog -lib +/greenpak4/cells_sim.v
        hierarchy -check -top <top>

    flatten:    (unless -noflatten)
        proc
        flatten
        tribuf -logic

    coarse:
        synth -run coarse

    fine:
        extract_counter -pout GP_DCMP,GP_DAC -maxwidth 14
        clean
        opt -fast -mux_undef -undriven -fine
        memory_map
        opt -undriven -fine
        techmap
        techmap -map +/greenpak4/cells_latch.v
        dfflibmap -prepare -liberty +/greenpak4/gp_dff.lib
        opt -fast
        abc -dff    (only if -retime)

    map_luts:
        nlutmap -assert -luts 0,6,8,2     (for -part SLG46140V)
        nlutmap -assert -luts 2,8,16,2    (for -part SLG46620V)
        nlutmap -assert -luts 2,8,16,2    (for -part SLG46621V)
        clean

    map_cells:
        shregmap -tech greenpak4
        dfflibmap -liberty +/greenpak4/gp_dff.lib
        dffinit -ff GP_DFF Q INIT
        dffinit -ff GP_DFFR Q INIT
        dffinit -ff GP_DFFS Q INIT
        dffinit -ff GP_DFFSR Q INIT
        iopadmap -bits -inpad GP_IBUF OUT:IN -outpad GP_OBUF IN:OUT -inoutpad GP_OBUF OUT:IN -toutpad GP_OBUFT OE:IN:OUT -tinoutpad GP_IOBUF OE:OUT:IN:IO
        attrmvcp -attr src -attr LOC t:GP_OBUF t:GP_OBUFT t:GP_IOBUF n:*
        attrmvcp -attr src -attr LOC -driven t:GP_IBUF n:*
        techmap -map +/greenpak4/cells_map.v
        greenpak4_dffinv
        clean

    check:
        hierarchy -check
        stat
        check -noinit

    json:
        write_json <file-name>