sim/decoder.h

/*
 * Copyright 2023 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SIM_DECODER_H_
#define SIM_DECODER_H_

#include <memory>

#include "sim/kelvin_decoder.h"
#include "sim/kelvin_encoding.h"
#include "sim/kelvin_enums.h"
#include "sim/kelvin_state.h"
#include "mpact/sim/generic/arch_state.h"
#include "mpact/sim/generic/data_buffer.h"
#include "mpact/sim/generic/decoder_interface.h"
#include "mpact/sim/generic/instruction.h"
#include "mpact/sim/generic/program_error.h"
#include "mpact/sim/util/memory/memory_interface.h"

namespace kelvin::sim {

// This is the factory class needed by the generated decoder. It is responsible
// for creating the decoder for each slot instance. Since the RISC-V
// architecture only has a single slot, it's a pretty simple class.
class KelvinIsaFactory : public isa32::KelvinInstructionSetFactory {
 public:
  std::unique_ptr<isa32::KelvinSlot> CreateKelvinSlot(
      mpact::sim::generic::ArchState *state) override {
    return std::make_unique<isa32::KelvinSlot>(state);
  }
};

// This class implements the generic DecoderInterface and provides a bridge
// to the (isa specific) generated decoder classes.
class KelvinDecoder : public mpact::sim::generic::DecoderInterface {
 public:
  using SlotEnum = isa32::SlotEnum;
  using OpcodeEnum = isa32::OpcodeEnum;

  KelvinDecoder(KelvinState *state, mpact::sim::util::MemoryInterface *memory);
  KelvinDecoder() = delete;
  ~KelvinDecoder() override;

  // This will always return a valid instruction that can be executed. In the
  // case of a decode error, the semantic function in the instruction object
  // instance will raise an internal simulator error when executed.
  mpact::sim::generic::Instruction *DecodeInstruction(
      uint64_t address) override;

  // Getter.
  isa32::KelvinEncoding *kelvin_encoding() const { return kelvin_encoding_; }

 private:
  KelvinState *state_;
  mpact::sim::util::MemoryInterface *memory_;
  std::unique_ptr<mpact::sim::generic::ProgramError> decode_error_;
  mpact::sim::generic::DataBuffer *inst_db_;
  isa32::KelvinEncoding *kelvin_encoding_;
  KelvinIsaFactory *kelvin_isa_factory_;
  isa32::KelvinInstructionSet *kelvin_isa_;
};

}  // namespace kelvin::sim

#endif  // SIM_DECODER_H_