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CPP_coding_guidelines.md

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C++ LibMcuLL Coding guidelines

Introduction

This document contains the naming conventions and programming idioms used by C++ LibMcuLL. Some architecture things might be defined here but they will be split off in their own design documents.

Naming things

Here is how we name various object types:

  • namespaces: camelcase

Peripheral hardware

Peripheral hardware is defined in their own header files related to a specific microcontroller. First the proper namespaces are defined for the peripheral:

namespace libMcuLL {
namespace hw {
namespace device {

Then a structure definition is made where each of the fields map to a hardware register:

struct peripheral {
  volatile std::uint32_t CTRL; /**< Control register */
  volatile std::uint32_t STAT; /**< Status register */
  volatile std::uint32_t DAT;  /**< Data register */
  union {
    union {                     /**< Some composite register structure */
      volatile std::uint32_t U; /**<  Unified register */
      struct {
        volatile std::uint16_t L; /**<  VALUE[i].L  Access to L value */
        volatile std::uint16_t H; /**<  VALUE[i].H  Access to H value */
      };
    } VALUE[sizeIndicator];

    const union {
      volatile std::uint32_t U; /**<  Unified register */
      struct {
        volatile std::uint16_t L; /**<  SHADOW[i].L  Access to L value */
        volatile std::uint16_t H; /**<  SHADOW[i].H  Access to H value */
      };
    } SHADOW[sizeIndicator];
  };
};

Next up are the register namespaces, each namespace holds all the settings to one register and if needed some formatting functions.

namespace CTRL {
constexpr inline std::uint32_t RESERVED_MASK = 0x00000FFF; /**< register mask for allowed bits */
constexpr inline std::uint32_t BIT_A = (1 << 0);           /**< Bit A */
constexpr inline std::uint32_t BIT_B = (1 << 1);           /**< Bit B */
constexpr inline std::uint32_t BIT_C = (1 << 2);           /**< Bit C */
constexpr inline std::uint32_t FIELD_A_MASK = (0xF << 3)   /**< Bit field A */
/**
 * @brief Format A field
 *
 * @param Some value
 * @return formatted data for FIELD_A
 */
constexpr inline std::uint32_t FIELD_A(std::uint32_t prescale) {
  return prescale << 3;
}
constexpr inline std::uint32_t FIELD_A_MASK = (0xF << 7)   /**< Bit field B */
/**
 * @brief Format B field
 *
 * @param Some value
 * @return formatted data for FIELD_B
 */
constexpr inline std::uint32_t FIELD_B(std::uint32_t prescale) {
  return prescale << 7;
}
} //namespace CTRL
namespace STAT {
constexpr inline std::uint32_t RESERVED_MASK = 0x00000FFF; /**< register mask for allowed bits */
constexpr inline std::uint32_t STATUS_A_MASK = (1 << 0);   /**< status A mask */
constexpr inline std::uint32_t STATUS_B_MASK = (1 << 1);   /**< status B mask */
} // namespace STAT

Peripheral software