riscv/dummy-rocc.h

   1 #ifndef _RISCV_DUMMY_ROCC_H
   2 #define _RISCV_DUMMY_ROCC_H
   3
   4 #include "rocc.h"
   5 #include "mmu.h"
   6
   7 class dummy_rocc_t : public rocc_t
   8 {
   9  public:
  10   const char* name() { return "dummy"; }
  11
  12   reg_t custom0(rocc_insn_t insn, reg_t xs1, reg_t xs2)
  13   {
  14     reg_t prev_acc = acc[insn.rs2];
  15
  16     if (insn.rs2 > num_acc)
  17       illegal_instruction();
  18
  19     switch (insn.funct)
  20     {
  21       case 0: // acc <- xs1
  22         acc[insn.rs2] = xs1;
  23         break;
  24       case 1: // xd <- acc (the only real work is the return statement below)
  25         break;
  26       case 2: // acc[rs2] <- Mem[xs1]
  27         acc[insn.rs2] = p->get_mmu()->load_uint64(xs1);
  28         break;
  29       case 3: // acc[rs2] <- accX + xs1
  30         acc[insn.rs2] += xs1;
  31         break;
  32       default:
  33         illegal_instruction();
  34     }
  35
  36     return prev_acc; // in all cases, xd <- previous value of acc[rs2]
  37   }
  38
  39  private:
  40   static const int num_acc = 4;
  41   reg_t acc[num_acc];
  42 };
  43
  44 REGISTER_EXTENSION(dummy, []() { return new dummy_rocc_t; })
  45
  46 #endif