diff --git a/components/nvs_flash/include/nvs_handle.hpp b/components/nvs_flash/include/nvs_handle.hpp index 2fe9ad98682..c50681857af 100644 --- a/components/nvs_flash/include/nvs_handle.hpp +++ b/components/nvs_flash/include/nvs_handle.hpp @@ -70,13 +70,14 @@ public: * For strings, the maximum length (including null character) is * 4000 bytes, if there is one complete page free for writing. * This decreases, however, if the free space is fragmented. - * Note that enums loose their type information when stored in NVS. Ensure that the correct - * enum type is used during retrieval with \ref get_item! + * Note that enums lose their type information when stored in NVS. Ensure that the correct + * enum type is used during retrieval with get_item. * * @return * - ESP_OK if value was set successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only - * - ESP_ERR_NVS_INVALID_NAME if key name doesn't satisfy constraints + * - ESP_ERR_NVS_KEY_TOO_LONG if key name exceeds the maximum length * - ESP_ERR_NVS_NOT_ENOUGH_SPACE if there is not enough space in the * underlying storage to save the value * - ESP_ERR_NVS_REMOVE_FAILED if the value wasn't updated because flash @@ -84,11 +85,31 @@ public: * update will be finished after re-initialization of nvs, provided that * flash operation doesn't fail again. * - ESP_ERR_NVS_VALUE_TOO_LONG if the string value is too long + * - other error codes from the underlying storage driver */ template esp_err_t set_item(const char *key, T value); - virtual - esp_err_t set_string(const char *key, const char* value) = 0; + + /** + * @brief set string for given key + * + * @param[in] key Key name. Maximal length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. + * @param[in] value The string to set. Maximum length (including null character) is 4000 bytes, + * if there is one complete page free for writing. + * + * @return + * - ESP_OK if value was set successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only + * - ESP_ERR_NVS_KEY_TOO_LONG if key name exceeds the maximum length + * - ESP_ERR_NVS_NOT_ENOUGH_SPACE if there is not enough space in the + * underlying storage to save the value + * - ESP_ERR_NVS_REMOVE_FAILED if the value wasn't updated because flash + * write operation has failed + * - ESP_ERR_NVS_VALUE_TOO_LONG if the string value is too long + * - other error codes from the underlying storage driver + */ + virtual esp_err_t set_string(const char *key, const char* value) = 0; /** * @brief get value for given key @@ -102,13 +123,15 @@ public: * @param[in] key Key name. Maximal length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. * @param value The output value. All integral types which are declared in ItemType as well as enums * are allowed. Note however that enums lost their type information when stored in NVS. - * Ensure that the correct enum type is used during retrieval with \ref get_item! + * Ensure that the correct enum type is used during retrieval with get_item. * * @return * - ESP_OK if the value was retrieved successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist - * - ESP_ERR_NVS_INVALID_NAME if key name doesn't satisfy constraints + * - ESP_ERR_NVS_TYPE_MISMATCH if the stored value type does not match the requested type * - ESP_ERR_NVS_INVALID_LENGTH if length is not sufficient to store data + * - other error codes from the underlying storage driver */ template esp_err_t get_item(const char *key, T &value); @@ -127,8 +150,9 @@ public: * * @return * - ESP_OK if value was set successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only - * - ESP_ERR_NVS_INVALID_NAME if key name doesn't satisfy constraints + * - ESP_ERR_NVS_KEY_TOO_LONG if key name exceeds the maximum length * - ESP_ERR_NVS_NOT_ENOUGH_SPACE if there is not enough space in the * underlying storage to save the value * - ESP_ERR_NVS_REMOVE_FAILED if the value wasn't updated because flash @@ -136,39 +160,58 @@ public: * update will be finished after re-initialization of nvs, provided that * flash operation doesn't fail again. * - ESP_ERR_NVS_VALUE_TOO_LONG if the value is too long + * - other error codes from the underlying storage driver * - * @note compare to \ref nvs_set_blob in nvs.h + * @note compare to nvs_set_blob() in nvs.h */ virtual esp_err_t set_blob(const char *key, const void* blob, size_t len) = 0; /** - * @brief get value for given key + * @brief get string value for given key * - * These functions retrieve the data of an entry, given its key. If key does not + * Retrieves the string data of an entry, given its key. If key does not * exist, or the requested variable type doesn't match the type which was used * when setting a value, an error is returned. * - * In case of any error, out_value is not modified. - * - * Both functions expect out_value to be a pointer to an already allocated variable - * of the given type. - * - * It is suggested that nvs_get/set_str is used for zero-terminated short C strings, and - * nvs_get/set_blob is used for arbitrary data structures and long C strings. + * In case of any error, out_str is not modified. * * @param[in] key Key name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. - * @param out_str/ Pointer to the output value. - * out_blob - * @param[inout] len The length of the output buffer pointed to by out_str/out_blob. - * Use \c get_item_size to query the size of the item beforehand. + * @param[out] out_str Pointer to the output string buffer. + * @param[in] len The length of the output buffer pointed to by out_str. + * Use get_item_size to query the size of the item beforehand. * * @return * - ESP_OK if the value was retrieved successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist - * - ESP_ERR_NVS_INVALID_NAME if key name doesn't satisfy constraints + * - ESP_ERR_NVS_TYPE_MISMATCH if the stored value type does not match the requested type * - ESP_ERR_NVS_INVALID_LENGTH if length is not sufficient to store data + * - other error codes from the underlying storage driver */ virtual esp_err_t get_string(const char *key, char* out_str, size_t len) = 0; + + /** + * @brief get blob value for given key + * + * Retrieves the binary data of an entry, given its key. If key does not + * exist, or the requested variable type doesn't match the type which was used + * when setting a value, an error is returned. + * + * In case of any error, out_blob is not modified. + * + * @param[in] key Key name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. + * @param[out] out_blob Pointer to the output blob buffer. + * @param[in] len The length of the output buffer pointed to by out_blob. + * Use get_item_size to query the size of the item beforehand. + * + * @return + * - ESP_OK if the value was retrieved successfully + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist + * - ESP_ERR_NVS_TYPE_MISMATCH if the stored value type does not match the requested type + * - ESP_ERR_NVS_INVALID_LENGTH if length is not sufficient to store data + * - other error codes from the underlying storage driver + */ virtual esp_err_t get_blob(const char *key, void* out_blob, size_t len) = 0; /** @@ -179,9 +222,12 @@ public: * @param[out] size Size of the item, if it exists. * For strings, this size includes the zero terminator. * - * @return - ESP_OK if the item with specified type and key exists. Its size will be returned via \c size. - * - ESP_ERR_NVS_NOT_FOUND if an item with the requested key and type doesn't exist or any other - * error occurs. + * @return + * - ESP_OK if the item with specified type and key exists. Its size will be returned via size. + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_NOT_FOUND if an item with the requested key and type doesn't exist + * - ESP_ERR_NVS_TYPE_MISMATCH if the stored value type does not match the requested type + * - other error codes from the underlying storage driver */ virtual esp_err_t get_item_size(ItemType datatype, const char *key, size_t &size) = 0; @@ -189,61 +235,112 @@ public: * @brief Checks whether key exists and optionally returns also data type of associated entry. * * @param[in] key Key name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. - * @param[out] nvstype Nvs data type to of entry, if it exists. + * @param[out] nvstype Nvs data type of entry, if it exists. * - * @return - ESP_OK if NVS entry for key provided was found. Data type will be returned via \c nvstype. - * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist. - * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is NULL. - * - ESP_FAIL if there is an internal error; most likely due to corrupted - * NVS partition (only if NVS assertion checks are disabled). - * - other error codes from the underlying storage driver. + * @return + * - ESP_OK if NVS entry for key provided was found. Data type will be returned via nvstype. + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist + * - ESP_FAIL if there is an internal error; most likely due to corrupted + * NVS partition (only if NVS assertion checks are disabled) + * - other error codes from the underlying storage driver */ virtual esp_err_t find_key(const char* key, nvs_type_t &nvstype) = 0; /** * @brief Erases an entry. + * + * @param[in] key Key name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. Shouldn't be empty. + * + * @return + * - ESP_OK if erase operation was successful + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only + * - ESP_ERR_NVS_NOT_FOUND if the requested key doesn't exist + * - other error codes from the underlying storage driver */ virtual esp_err_t erase_item(const char* key) = 0; /** - * Erases all entries in the scope of this handle. The scope may vary, depending on the implementation. + * @brief Erases all entries in the scope of this handle. * - * @not If you want to erase the whole nvs flash (partition), refer to \ref + * The scope may vary, depending on the implementation (typically the opened namespace). + * + * @note If you want to erase the whole NVS flash partition, use nvs_flash_erase() / + * nvs_flash_erase_partition() instead. + * + * @return + * - ESP_OK if erase operation was successful + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only + * - other error codes from the underlying storage driver */ virtual esp_err_t erase_all() = 0; /** - * Purges all erased entries in the scope of this handle. The scope may vary, depending on the implementation. + * @brief Purges all erased entries in the scope of this handle. + * + * The scope may vary, depending on the implementation. + * + * @return + * - ESP_OK if purge operation was successful + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - ESP_ERR_NVS_READ_ONLY if storage handle was opened as read only + * - other error codes from the underlying storage driver */ virtual esp_err_t purge_all() = 0; /** - * Commits all changes done through this handle so far. + * @brief Commits all changes done through this handle so far. + * * Currently, NVS writes to storage right after the set and get functions, * but this is not guaranteed. + * + * @return + * - ESP_OK if commit was successful + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid + * - other error codes from the underlying storage driver */ virtual esp_err_t commit() = 0; /** * @brief Calculate all entries in the scope of the handle. * - * @param[out] used_entries Returns amount of used entries from a namespace on success. - * + * @param[out] usedEntries Returns amount of used entries from a namespace on success. * * @return - * - ESP_OK if the changes have been written successfully. - * Return param used_entries will be filled valid value. + * - ESP_OK if usedEntries was filled with a valid value + * - ESP_ERR_NVS_INVALID_HANDLE if handle has been closed or is invalid * - ESP_ERR_NVS_NOT_INITIALIZED if the storage driver is not initialized. - * Return param used_entries will be filled 0. - * - ESP_ERR_INVALID_ARG if nvs_stats equal to NULL. - * - Other error codes from the underlying storage driver. - * Return param used_entries will be filled 0. + * Return param usedEntries will be filled with 0. + * - other error codes from the underlying storage driver. + * Return param usedEntries will be filled with 0. */ virtual esp_err_t get_used_entry_count(size_t& usedEntries) = 0; protected: + /** + * @brief Set an item of a given datatype. + * + * @param[in] datatype Item data type. + * @param[in] key Key name. + * @param[in] data Pointer to the value to store. + * @param[in] dataSize Size of the value in bytes. + * + * @return esp_err_t result codes matching set_item / set_blob. + */ virtual esp_err_t set_typed_item(ItemType datatype, const char *key, const void* data, size_t dataSize) = 0; + /** + * @brief Get an item of a given datatype. + * + * @param[in] datatype Item data type. + * @param[in] key Key name. + * @param[out] data Pointer to the output buffer. + * @param[in] dataSize Size of the output buffer in bytes. + * + * @return esp_err_t result codes matching get_item / get_blob. + */ virtual esp_err_t get_typed_item(ItemType datatype, const char *key, void* data, size_t dataSize) = 0; }; @@ -253,16 +350,23 @@ protected: * The handle is automatically closed on destruction. The scope of the handle is the namespace ns_name * in a particular partition partition_name. * The parameters partition_name, ns_name and open_mode have the same meaning and restrictions as the parameters - * part_name, name and open_mode in \ref nvs_open_from_partition, respectively. + * part_name, namespace_name and open_mode in nvs_open_from_partition(), respectively. * - * @param err an optional pointer to an esp_err_t result of the open operation, having the same meaning as the return - * value in \ref nvs_open_from_partition: + * @param[in] partition_name Label of the NVS partition to open. + * @param[in] ns_name Namespace name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. + * @param[in] open_mode NVS_READONLY, NVS_READWRITE, or NVS_READWRITE_PURGE. + * @param[out] err Optional pointer to an esp_err_t result of the open operation, having the same meaning + * as the return value of nvs_open_from_partition(): * - ESP_OK if storage handle was opened successfully + * - ESP_ERR_INVALID_ARG if partition_name or ns_name is NULL * - ESP_ERR_NVS_NOT_INITIALIZED if the storage driver is not initialized - * - ESP_ERR_NVS_PART_NOT_FOUND if the partition with label "nvs" is not found - * - ESP_ERR_NVS_NOT_FOUND id namespace doesn't exist yet and + * - ESP_ERR_NVS_PART_NOT_FOUND if the partition with the specified name is not found + * - ESP_ERR_NVS_NOT_FOUND if namespace doesn't exist yet and * mode is NVS_READONLY - * - ESP_ERR_NVS_INVALID_NAME if namespace name doesn't satisfy constraints + * - ESP_ERR_NVS_KEY_TOO_LONG if namespace name exceeds the maximum length + * - ESP_ERR_NO_MEM if memory could not be allocated for the internal structures + * - ESP_ERR_NVS_NOT_ENOUGH_SPACE if there is no space for a new entry or there are too many different + * namespaces (maximum allowed different namespaces: 254) * - ESP_ERR_NOT_ALLOWED if the NVS partition is read-only and mode is NVS_READWRITE * - other error codes from the underlying storage driver * @@ -274,8 +378,28 @@ std::unique_ptr open_nvs_handle_from_partition(const char *partition_ esp_err_t *err = nullptr); /** - * @brief This function does the same as \ref open_nvs_handle_from_partition but uses the default nvs partition + * @brief Open NVS handle from the default NVS partition. + * + * This function does the same as open_nvs_handle_from_partition() but uses the default nvs partition * instead of a partition_name parameter. + * + * @param[in] ns_name Namespace name. Maximum length is (NVS_KEY_NAME_MAX_SIZE-1) characters. + * @param[in] open_mode NVS_READONLY, NVS_READWRITE, or NVS_READWRITE_PURGE. + * @param[out] err Optional pointer to an esp_err_t result of the open operation: + * - ESP_OK if storage handle was opened successfully + * - ESP_ERR_INVALID_ARG if ns_name is NULL + * - ESP_ERR_NVS_NOT_INITIALIZED if the storage driver is not initialized + * - ESP_ERR_NVS_PART_NOT_FOUND if the partition with label "nvs" is not found + * - ESP_ERR_NVS_NOT_FOUND if namespace doesn't exist yet and + * mode is NVS_READONLY + * - ESP_ERR_NVS_KEY_TOO_LONG if namespace name exceeds the maximum length + * - ESP_ERR_NO_MEM if memory could not be allocated for the internal structures + * - ESP_ERR_NVS_NOT_ENOUGH_SPACE if there is no space for a new entry or there are too many different + * namespaces (maximum allowed different namespaces: 254) + * - ESP_ERR_NOT_ALLOWED if the NVS partition is read-only and mode is NVS_READWRITE + * - other error codes from the underlying storage driver + * + * @return unique pointer of an nvs handle on success, an empty unique pointer otherwise */ std::unique_ptr open_nvs_handle(const char *ns_name, nvs_open_mode_t open_mode, diff --git a/docs/doxygen/Doxyfile b/docs/doxygen/Doxyfile index 29b16cb209b..27ea222396d 100644 --- a/docs/doxygen/Doxyfile +++ b/docs/doxygen/Doxyfile @@ -340,6 +340,7 @@ INPUT = \ $(PROJECT_PATH)/components/mbedtls/port/psa_driver/include/psa_crypto_driver_esp_aes_contexts.h \ $(PROJECT_PATH)/components/nvs_flash/include/nvs_flash.h \ $(PROJECT_PATH)/components/nvs_flash/include/nvs.h \ + $(PROJECT_PATH)/components/nvs_flash/include/nvs_handle.hpp \ $(PROJECT_PATH)/components/nvs_flash/include/nvs_bootloader.h \ $(PROJECT_PATH)/components/nvs_sec_provider/include/nvs_sec_provider.h \ $(PROJECT_PATH)/components/openthread/include/esp_openthread_border_router.h \ diff --git a/docs/en/api-reference/storage/nvs_flash.rst b/docs/en/api-reference/storage/nvs_flash.rst index 0d4aac34c57..8c0ac1c546a 100644 --- a/docs/en/api-reference/storage/nvs_flash.rst +++ b/docs/en/api-reference/storage/nvs_flash.rst @@ -76,7 +76,7 @@ Namespaces To mitigate potential conflicts in key names between different components, NVS assigns each key-value pair to one of the namespaces. Namespace names follow the same rules as key names, i.e., the maximum length is 15 characters. Furthermore, there can be no more than 254 different namespaces in one NVS partition. Namespace name is specified in the :cpp:func:`nvs_open` or :cpp:type:`nvs_open_from_partition` call. This call returns an opaque handle, which is used in subsequent calls to the ``nvs_get_*``, ``nvs_set_*``, and :cpp:func:`nvs_commit` functions. This way, a handle is associated with a namespace and partition, and key names will not collide with same names in other namespaces. -The open mode parameter controls the access level and security behavior: +The ``open_mode`` parameter controls the access level and security behavior: - ``NVS_READONLY``: Read-only access. All write operations will be rejected. - ``NVS_READWRITE``: Standard read-write access. Erased data is marked as deleted but remains in flash. @@ -86,6 +86,22 @@ The open mode parameter controls the access level and security behavior: Namespaces with the same name in different NVS partitions are considered as separate namespaces. +C++ API +^^^^^^^ + +In addition to the C API described above, NVS provides a C++ class interface in :component_file:`nvs_flash/include/nvs_handle.hpp` (namespace ``nvs``). + +Use ``nvs::open_nvs_handle()`` or ``nvs::open_nvs_handle_from_partition()`` to open a namespace. These functions return a ``std::unique_ptr``. The handle is closed automatically when the unique pointer is destroyed (RAII), so there is no need to call a separate close function. + +``nvs::NVSHandle`` provides methods that mirror the C API, including: + +- ``set_item`` / ``get_item`` — typed get/set for integral, floating-point, and enum types +- ``set_string`` / ``get_string`` — string values +- ``set_blob`` / ``get_blob`` — binary blob values +- ``commit``, ``erase_item``, ``erase_all``, ``purge_all``, ``find_key``, and related helpers + +The ``open_mode`` values (``NVS_READONLY``, ``NVS_READWRITE``, ``NVS_READWRITE_PURGE``) and key and namespace constraints are the same as for the C API. See the :ref:`API Reference ` below for full class and function documentation, and :example:`storage/nvs/nvs_rw_value_cxx` for a complete example. + NVS Iterators ^^^^^^^^^^^^^ @@ -264,7 +280,7 @@ You can find code examples in the :example:`storage/nvs` directory of ESP-IDF ex :example:`storage/nvs/nvs_rw_value_cxx` - This example does exactly the same as :example:`storage/nvs/nvs_rw_value`, except that it uses the C++ NVS handle class. + This example does exactly the same as :example:`storage/nvs/nvs_rw_value`, except that it uses the C++ NVS handle class (``nvs::NVSHandle`` via ``nvs::open_nvs_handle()``). :example:`storage/nvs/nvs_statistics` @@ -552,9 +568,13 @@ At build time the mode NVS will use for accessing its underlying storage can be +.. _nvs-api-reference: + API Reference ------------- .. include-build-file:: inc/nvs_flash.inc .. include-build-file:: inc/nvs.inc + +.. include-build-file:: inc/nvs_handle.inc diff --git a/docs/zh_CN/api-reference/storage/nvs_flash.rst b/docs/zh_CN/api-reference/storage/nvs_flash.rst index 7a85231adf2..7b5a87cf1ee 100644 --- a/docs/zh_CN/api-reference/storage/nvs_flash.rst +++ b/docs/zh_CN/api-reference/storage/nvs_flash.rst @@ -76,7 +76,7 @@ NVS 的操作对象为键值对，其中键是 ASCII 字符串，当前支持的 为减少不同组件之间键名的潜在冲突，NVS 将每个键值对分配到一个命名空间。命名空间的命名规则遵循键名的命名规则，例如，最多可占 15 个字符。此外，单个 NVS 分区最多只能容纳 254 个不同的命名空间。命名空间的名称在调用 :cpp:func:`nvs_open` 或 :cpp:type:`nvs_open_from_partition` 中指定。调用后将返回一个不透明句柄，用于后续调用 ``nvs_get_*``、``nvs_set_*`` 和 :cpp:func:`nvs_commit` 函数。这样，句柄就与命名空间和分区关联，键名不会与其他命名空间中的同名键发生冲突。 -open mode 参数控制访问级别和安全行为： +``open_mode`` 参数控制访问级别和安全行为： - ``NVS_READONLY``：只读访问权限。所有写操作将被拒绝。 - ``NVS_READWRITE``：标准读写访问权限。被擦除的数据会被标记为已删除，但仍保留在 flash 中。 @@ -86,6 +86,22 @@ open mode 参数控制访问级别和安全行为： 在不同的 NVS 分区中，同名的命名空间被视为相互独立的命名空间。 +C++ API +^^^^^^^ + +除上文所述的 C API 外，NVS 还在 :component_file:`nvs_flash/include/nvs_handle.hpp` 中提供了 C++ 类接口（命名空间 ``nvs``）。 + +使用 ``nvs::open_nvs_handle()`` 或 ``nvs::open_nvs_handle_from_partition()`` 打开命名空间。这些函数返回 ``std::unique_ptr``。当该 ``std::unique_ptr`` 被销毁时，句柄会自动关闭（RAII），因此无需另行调用关闭函数。 + +``nvs::NVSHandle`` 提供与 C API 对应的方法，包括： + +- ``set_item`` / ``get_item`` — 面向整型、浮点型和枚举类型的类型化读写 +- ``set_string`` / ``get_string`` — 字符串值 +- ``set_blob`` / ``get_blob`` — 二进制 blob 值 +- ``commit``、``erase_item``、``erase_all``、``purge_all``、``find_key`` 及相关辅助方法 + +``open_mode`` 的取值（ ``NVS_READONLY``、``NVS_READWRITE``、``NVS_READWRITE_PURGE``）以及键名和命名空间约束与 C API 相同。完整的类与函数说明见下文 :ref:`API 参考 `，完整示例见 :example:`storage/nvs/nvs_rw_value_cxx`。 + NVS 迭代器 ^^^^^^^^^^^^^ @@ -264,7 +280,7 @@ ESP-IDF :example:`storage/nvs` 目录下提供了数个代码示例： :example:`storage/nvs/nvs_rw_value_cxx` - 这个例子与 :example:`storage/nvs/nvs_rw_value` 完全一样，只是使用了 C++ 的 NVS 句柄类。 + 这个例子与 :example:`storage/nvs/nvs_rw_value` 完全一样，只是使用了 C++ 的 NVS 句柄类（通过 ``nvs::open_nvs_handle()`` 获取 ``nvs::NVSHandle``）。 :example:`storage/nvs/nvs_statistics` @@ -552,9 +568,13 @@ NVS 正常运行所需的默认最小空间为 12 KiB (``0x3000``)，即至少 +.. _nvs-api-reference: + API 参考 ------------- .. include-build-file:: inc/nvs_flash.inc .. include-build-file:: inc/nvs.inc + +.. include-build-file:: inc/nvs_handle.inc