Read-Only register with fixed value is not comparable to readout

[trembel]

The following YAML:

VERSION: !Register
    adr: 0x7F
    reset_val: 0x41
    doc: Holds the version number of the IC, currently 0x41.
    layout: !Layout
      VERSION_NUMBER:
        bits: [0-7]
        access: [R]
        accepts: !Fixed 0x41

gets transpiled into the following C code:

// =============================================================================
// ==== VERSION Register =======================================================
// =============================================================================
// Holds the version number of the IC, currently 0x41.
// Fields:
//  - [7:0] VERSION_NUMBER (fixed: 0x41)

#define FH101RF_VERSION_ADDRESS  (0x7FU) //!< VERSION register address
#define FH101RF_VERSION_RESET_LE {0x41U} //!< VERSION register reset value
#define FH101RF_VERSION_RESET_BE {0x41U} //!< VERSION register reset value

// Register Layout Struct:

/**
 * @brief Holds the version number of the IC, currently 0x41.
 * @note use pack/unpack functions for conversion to/from packed binary value
 */
struct fh101rf_version {
  int dummy; // Register contains no variable fields.
};

// Layout struct conversion functions:

/**
 * @brief Convert @ref struct fh101rf_version struct to packed little-endian value.
 * @note use pack/unpack functions for conversion to/from packed binary value
 */
static inline void fh101rf_version_pack_le(const struct fh101rf_version *r, uint8_t val[1]) {
  // VERSION_NUMBER @ version[7:0]:
  val[0] &= (uint8_t)~0xFFU;
  val[0] |= (uint8_t)0x41; // Fixed value.
  (void)r;
}

/**
 * @brief Convert @ref struct fh101rf_version struct to packed big-endian value.
 * @note use pack/unpack functions for conversion to/from packed binary value
 */
static inline void fh101rf_version_pack_be(const struct fh101rf_version *r, uint8_t val[1]) {
  // VERSION_NUMBER @ version[7:0]:
  val[0] &= (uint8_t)~0xFFU;
  val[0] |= (uint8_t)0x41; // Fixed value.
  (void)r;
}

/** @brief Convert packed {endian} binary value to struct. */
static inline struct fh101rf_version fh101rf_version_unpack_le(const uint8_t val[1]) {
  struct fh101rf_version r = {0};
  (void)val;
  (void)r;
  return r;
}

/** @brief Convert packed {endian} binary value to struct. */
static inline struct fh101rf_version fh101rf_version_unpack_be(const uint8_t val[1]) {
  struct fh101rf_version r = {0};
  (void)val;
  (void)r;
  return r;
}

/**
 * @brief Validate struct
 * @returns 0 if valid.
 * @returns the position of the first invalid field if invalid.
 * Confirms that all enums are valid, and all values fit into respective fields
 */
static inline int fh101rf_validate_version(const struct fh101rf_version *r) {
  (void)r;
  return 0;
}

/**
 * @brief Attempt to convert packed {endian} binary value to struct.
 * @returns 0 if valid.
 * @returns the position of the first invalid field if invalid.
 */
static inline int fh101rf_version_try_unpack_le(const uint8_t val[1], struct fh101rf_version *r) {
  *r = fh101rf_version_unpack_le(val);
  return fh101rf_validate_version(r);
}

/**
 * @brief Attempt to convert packed {endian} binary value to struct.
 * @returns 0 if valid.
 * @returns the position of the first invalid field if invalid.
 */
static inline int fh101rf_version_try_unpack_be(const uint8_t val[1], struct fh101rf_version *r) {
  *r = fh101rf_version_unpack_be(val);
  return fh101rf_validate_version(r);
}

Unfortunately, this does not allow to do (pseudo code):

uint8_t result;
read_reg(VERSION_ADDRESS, &result);
struct fh101rf_version ver = fh101rf_version_unpack_le(&result);
ver.version_number == dev->version.version_number, as this field does not even exist.