feat(app_update): add app description data and its functions

components/bootloader_support/include/esp_app_format.h

@@ -0,0 +1,38 @@
+// Copyright 2015-2019 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#pragma once
+
+#include <stdint.h>
+
+#define ESP_APP_DESC_MAGIC_WORD 0xABCD5432  /*!< The magic word for the esp_app_desc structure that is in DROM. */
+
+/**
+ * @brief Description about application.
+ */
+typedef struct {
+    uint32_t magic_word;        /*!< Magic word ESP_APP_DESC_MAGIC_WORD */
+    uint32_t secure_version;    /*!< Secure version */
+    uint32_t reserv1[2];        /*!< reserv1 */
+    char version[32];           /*!< Application version */
+    char project_name[32];      /*!< Project name */
+    char time[16];              /*!< Compile time */
+    char date[16];              /*!< Compile date*/
+    char idf_ver[32];           /*!< Version IDF */
+    uint8_t app_elf_sha256[32]; /*!< sha256 of elf file */
+    uint32_t reserv2[20];       /*!< reserv2 */
+} esp_app_desc_t;
+
+/** @cond */
+_Static_assert(sizeof(esp_app_desc_t) == 256, "esp_app_desc_t should be 256 bytes");
+/** @endcond */