examples/cxx-api/evaldemo.cc

   1 /* A simple Yosys plugin. (Copy&paste from http://stackoverflow.com/questions/32093541/how-does-the-yosys-consteval-api-work)
   2
   3 Usage example:
   4
   5 $ cat > evaldemo.v <<EOT
   6 module main(input [1:0] A, input [7:0] B, C, D, output [7:0] Y);
   7   assign Y = A == 0 ? B : A == 1 ? C : A == 2 ? D : 42;
   8 endmodule
   9 EOT
  10
  11 $ yosys-config --build evaldemo.so evaldemo.cc
  12 $ yosys -m evaldemo.so -p evaldemo evaldemo.v
  13 */
  14
  15 #include "kernel/yosys.h"
  16 #include "kernel/consteval.h"
  17
  18 USING_YOSYS_NAMESPACE
  19 PRIVATE_NAMESPACE_BEGIN
  20
  21 struct EvalDemoPass : public Pass
  22 {
  23         EvalDemoPass() : Pass("evaldemo") { }
  24
  25         void execute(vector<string>, Design *design) YS_OVERRIDE
  26         {
  27                 Module *module = design->top_module();
  28
  29                 if (module == nullptr)
  30                         log_error("No top module found!\n");
  31
  32                 Wire *wire_a = module->wire(ID::A);
  33                 Wire *wire_y = module->wire(ID::Y);
  34
  35                 if (wire_a == nullptr)
  36                         log_error("No wire A found!\n");
  37
  38                 if (wire_y == nullptr)
  39                         log_error("No wire Y found!\n");
  40
  41                 ConstEval ce(module);
  42                 for (int v = 0; v < 4; v++) {
  43                         ce.push();
  44                         ce.set(wire_a, Const(v, GetSize(wire_a)));
  45                         SigSpec sig_y = wire_y, sig_undef;
  46                         if (ce.eval(sig_y, sig_undef))
  47                                 log("Eval results for A=%d: Y=%s\n", v, log_signal(sig_y));
  48                         else
  49                                 log("Eval failed for A=%d: Missing value for %s\n", v, log_signal(sig_undef));
  50                         ce.pop();
  51                 }
  52         }
  53 } EvalDemoPass;
  54
  55 PRIVATE_NAMESPACE_END