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Add doc on pattern detector for overflow

This commit is contained in:
Eddie Hung 2019-09-18 12:35:24 -07:00
parent fd3b033903
commit 44bf4ac35c
1 changed files with 5 additions and 0 deletions
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5
passes/pmgen/xilinx_dsp.cc
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@ -2,6 +2,7 @@
* yosys -- Yosys Open SYnthesis Suite
*
* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
* 2019 Eddie Hung <eddie@fpgeh.com>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@ -519,6 +520,10 @@ struct XilinxDspPass : public Pass {
log("the add/subtract operator will cause those operations to be implemented using\n");
log("the 'SIMD' feature of DSPs.\n");
log("\n");
log("Experimental feature: the presence of a `$ge' cell attached to the registered\n");
log("P output implementing the operation \"(P >= <power-of-2>)\" will be transformed\n");
log("into using the DSP48E1's pattern detector feature for overflow detection.\n");
log("\n");
}
void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
{