predicates.h

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#pragma once
 
#include "libmicroemu/internal/result.h"
#include "libmicroemu/register_details.h"
#include "libmicroemu/special_register_id.h"
#include "libmicroemu/types.h"
#include <cstddef>
#include <cstdint>
#include <string_view>
 
namespace libmicroemu::internal {

class Predicates {
public:
  template <typename TCpuAccessor> static bool IsThreadMode(const TCpuAccessor &cpua) {
    const auto sys_ctrl = cpua.template ReadSpecialRegister<SpecialRegisterId::kSysCtrl>();
    const auto exec_mode = sys_ctrl & SysCtrlRegister::kExecModeMsk;
    return exec_mode == SysCtrlRegister::kExecModeThread;
  }

  template <typename TCpuAccessor> static bool IsHandlerMode(const TCpuAccessor &cpua) {
    const auto sys_ctrl = cpua.template ReadSpecialRegister<SpecialRegisterId::kSysCtrl>();
    const auto exec_mode = sys_ctrl & SysCtrlRegister::kExecModeMsk;
    return exec_mode == SysCtrlRegister::kExecModeHandler;
  }

  template <typename TCpuAccessor> static bool IsMainStack(const TCpuAccessor &cpua) {
    using SId = SpecialRegisterId;
    auto sys_ctrl = cpua.template ReadSpecialRegister<SId::kSysCtrl>();
    auto spsel = sys_ctrl & SysCtrlRegister::kControlSpSelMsk;
    return spsel == 0U;
  }

  template <typename TCpuAccessor> static bool IsProcessStack(const TCpuAccessor &cpua) {
    using SId = SpecialRegisterId;
    auto sys_ctrl = cpua.template ReadSpecialRegister<SId::kSysCtrl>();
    auto spsel = sys_ctrl & SysCtrlRegister::kControlSpSelMsk;
    return spsel != 0U;
  }

  template <typename TCpuAccessor> static bool IsCurrentModePrivileged(TCpuAccessor &cpua) {
    // see Armv7-M Architecture Reference Manual Issue E.e p.512
    auto sys_ctrl = cpua.template ReadSpecialRegister<SpecialRegisterId::kSysCtrl>();
    const auto exec_mode = sys_ctrl & SysCtrlRegister::kExecModeMsk;
    const auto is_handler_mode = exec_mode == SysCtrlRegister::kExecModeHandler;
    const auto is_privileged = (sys_ctrl & SysCtrlRegister::kControlNPrivMsk) == 0U;
 
    return (is_handler_mode || is_privileged);
  }

  template <typename TCpuAccessor> static bool IsThumbMode(TCpuAccessor &cpua) {
    const auto epsr = cpua.template ReadSpecialRegister<SpecialRegisterId::kEpsr>();
    const bool is_thumb = (epsr & static_cast<u32>(EpsrRegister::kTMsk)) != 0U;
 
    return is_thumb;
  }
 
private:
  Predicates() = delete;
  ~Predicates() = delete;
  Predicates(const Predicates &r_src) = delete;
  Predicates &operator=(const Predicates &r_src) = delete;
  Predicates(Predicates &&r_src) = delete;
  Predicates &operator=(Predicates &&r_src) = delete;
};
 
} // namespace libmicroemu::internal