yosys4gal/techmaps/README.md

Techmaps

All the yosys techmapping libraries/Verilog files used for mapping to the GAL structure. See the synth_gal.tcl file for details on how they're used. A summary is below (in the order they're used):

• gal_dff.lib Liberty library for supported FFs (only positive edge-triggered DFFs). Used to prevent yosys from using fancy flip-flops
• pla.v splits SOPs into a chain of SOPs with a specified size
• trivial_sop.v replaces SOPs which are just buffers/NOT gates with buffer/NOT cells
• olmc_seq.v converts all existing sequential elements into GAL_OLMCs this includes special merged types from other techmap passes/extractions
• one_sop.v converts GAL_SOPs with only one product into GAL_1SOPs. Used on enabled (tristate) lines
• pla_olmc_int.v adds a combinational GAL_OLMC after a GAL_SOP. Used to insert GAL_OLMC between GAL_SOPs or enable lines
• olmc_comb.v creates GAL_OLMCs for combinational/tristate output pads
• trivial_sop_olmc.v adds a buffer GAL_SOP before a GAL_OLMC. Used to add GAL_SOPs between directly connect GAL_OLMCs/GAL_INPUTs
• trivial_1sop_olmc.v same as above but for enable lines