thread.h

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#ifndef NSBACI_SERVICES_RUNTIME_THREAD_H
#define NSBACI_SERVICES_RUNTIME_THREAD_H
 
#include <cstdint>
#include <queue>
#include <vector>
 
#include "runtimeTypes.h"

namespace nsbaci::services::runtime {

class Thread {
 public:
  Thread()
      : id(nextThreadId++),
        state(nsbaci::types::ThreadState::Ready),
        priority(0),
        pc(0),
        bp(0),
        sp(0) {}
  ~Thread() = default;

  nsbaci::types::ThreadID getId() const;

  nsbaci::types::ThreadState getState() const;

  void setState(nsbaci::types::ThreadState newState);

  nsbaci::types::Priority getPriority() const;

  void setPriority(nsbaci::types::Priority newPriority);
 
  // ============== Stack Operations ==============

  void push(int32_t value);

  int32_t pop();

  int32_t top() const;
 
  // ============== Program Counter ==============

  uint32_t getPC() const { return pc; }

  void setPC(uint32_t addr) { pc = addr; }

  void advancePC() { ++pc; }
 
  // ============== Base/Stack Pointers ==============
 
  uint32_t getBP() const { return bp; }
  void setBP(uint32_t addr) { bp = addr; }
 
  uint32_t getSP() const { return sp; }
  void setSP(uint32_t addr) { sp = addr; }
 
  // ============== Call Stack ==============

  void pushReturnAddress(uint32_t addr) { callStack.push_back(addr); }

  uint32_t popReturnAddress() {
    if (callStack.empty()) return 0;
    uint32_t addr = callStack.back();
    callStack.pop_back();
    return addr;
  }

  bool callStackEmpty() const { return callStack.empty(); }

  void pushFrame(const std::vector<int32_t>& savedLocals) {
    frameStack.push_back(savedLocals);
  }

  std::vector<int32_t> popFrame() {
    if (frameStack.empty()) return {};
    auto frame = frameStack.back();
    frameStack.pop_back();
    return frame;
  }

  bool frameStackEmpty() const { return frameStack.empty(); }
 
 private:
  nsbaci::types::ThreadID id;
  nsbaci::types::ThreadState state;
  nsbaci::types::Priority priority;
 
  // Program counter - index into instruction stream
  uint32_t pc;
  // Base pointer - for stack frames
  uint32_t bp;
  // Stack pointer
  uint32_t sp;
 
  // Thread-local stack
  std::vector<int32_t> stack;
 
  // Call stack for return addresses
  std::vector<uint32_t> callStack;
 
  // Frame stack for saving local variable values during recursion
  std::vector<std::vector<int32_t>> frameStack;
 
  static nsbaci::types::ThreadID nextThreadId;
 
  // friend the scheduler
};
 
}  // namespace nsbaci::services::runtime

namespace nsbaci::types {

using ThreadQueue = std::queue<nsbaci::services::runtime::Thread>;
 
}  // namespace nsbaci::types
 
#endif  // NSBACI_SERVICES_RUNTIME_THREAD_H