MicroBitStorage.h

00001 /*
00002 The MIT License (MIT)
00003 
00004 Copyright (c) 2016 British Broadcasting Corporation.
00005 This software is provided by Lancaster University by arrangement with the BBC.
00006 
00007 Permission is hereby granted, free of charge, to any person obtaining a
00008 copy of this software and associated documentation files (the "Software"),
00009 to deal in the Software without restriction, including without limitation
00010 the rights to use, copy, modify, merge, publish, distribute, sublicense,
00011 and/or sell copies of the Software, and to permit persons to whom the
00012 Software is furnished to do so, subject to the following conditions:
00013 
00014 The above copyright notice and this permission notice shall be included in
00015 all copies or substantial portions of the Software.
00016 
00017 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00018 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00019 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
00020 THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00021 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
00022 FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
00023 DEALINGS IN THE SOFTWARE.
00024 */
00025 
00026 #ifndef MICROBIT_STORAGE_H
00027 #define MICROBIT_STORAGE_H
00028 
00029 #include "mbed.h"
00030 #include "MicroBitConfig.h"
00031 #include "ManagedString.h"
00032 #include "ErrorNo.h"
00033 
00034 #define MICROBIT_STORAGE_MAGIC       0xCAFE
00035 
00036 #define MICROBIT_STORAGE_BLOCK_SIZE             48
00037 #define MICROBIT_STORAGE_KEY_SIZE               16
00038 #define MICROBIT_STORAGE_VALUE_SIZE             MICROBIT_STORAGE_BLOCK_SIZE - MICROBIT_STORAGE_KEY_SIZE
00039 
00040 #define MICROBIT_STORAGE_STORE_PAGE_OFFSET      17      //Use the page just above the BLE Bond Data.
00041 #define MICROBIT_STORAGE_SCRATCH_PAGE_OFFSET    19      //Use the page just below the BLE Bond Data.
00042 
00043 struct KeyValuePair
00044 {
00045     uint8_t key[MICROBIT_STORAGE_KEY_SIZE];
00046     uint8_t value[MICROBIT_STORAGE_VALUE_SIZE];
00047 };
00048 
00049 struct KeyValueStore
00050 {
00051     uint32_t magic;
00052     uint32_t size;
00053 
00054     KeyValueStore(uint32_t magic, uint32_t size)
00055     {
00056         this->magic = magic;
00057         this->size = size;
00058     }
00059 
00060     KeyValueStore()
00061     {
00062         this->magic = 0;
00063         this->size = 0;
00064     }
00065 };
00066 
00067 
00068 /**
00069   * Class definition for the MicroBitStorage class.
00070   * This allows reading and writing of small blocks of data to FLASH memory.
00071   *
00072   * This class operates as a key value store, it allows the retrieval, addition
00073   * and deletion of KeyValuePairs.
00074   *
00075   * The first 8 bytes are reserved for the KeyValueStore struct which gives core
00076   * information such as the number of KeyValuePairs in the store, and whether the
00077   * store has been initialised.
00078   *
00079   * After the KeyValueStore struct, KeyValuePairs are arranged contiguously until
00080   * the end of the block used as persistent storage.
00081   *
00082   * |-------8-------|--------48-------|-----|---------48--------|
00083   * | KeyValueStore | KeyValuePair[0] | ... | KeyValuePair[N-1] |
00084   * |---------------|-----------------|-----|-------------------|
00085   */
00086 class MicroBitStorage
00087 {
00088     /**
00089       * Function for copying words from one location to another.
00090       *
00091       * @param from the address to copy data from.
00092       *
00093       * @param to the address to copy the data to.
00094       *
00095       * @param sizeInWords the number of words to copy
00096       */
00097     void flashCopy(uint32_t* from, uint32_t* to, int sizeInWords);
00098 
00099     /**
00100       * Function for populating the scratch page with a KeyValueStore.
00101       *
00102       * @param store the KeyValueStore struct to write to the scratch page.
00103       */
00104     void scratchKeyValueStore(KeyValueStore store);
00105 
00106     /**
00107       * Function for populating the scratch page with a KeyValuePair.
00108       *
00109       * @param pair the KeyValuePair struct to write to the scratch page.
00110       *
00111       * @param flashPointer the pointer in flash where this KeyValuePair resides. This pointer
00112       * is used to determine the offset into the scratch page, where the KeyValuePair should
00113       * be written.
00114       */
00115     void scratchKeyValuePair(KeyValuePair pair, uint32_t* flashPointer);
00116 
00117     public:
00118 
00119     /**
00120       * Default constructor.
00121       *
00122       * Creates an instance of MicroBitStorage which acts like a KeyValueStore
00123       * that allows the retrieval, addition and deletion of KeyValuePairs.
00124       */
00125     MicroBitStorage();
00126 
00127     /**
00128       * Writes the given number of bytes to the address specified.
00129       *
00130       * @param buffer the data to write.
00131       *
00132       * @param address the location in memory to write to.
00133       *
00134       * @param length the number of bytes to write.
00135       *
00136       * @note currently not implemented.
00137       */
00138     int writeBytes(uint8_t *buffer, uint32_t address, int length);
00139 
00140     /**
00141       * Method for erasing a page in flash.
00142       *
00143       * @param page_address Address of the first word in the page to be erased.
00144       */
00145     void flashPageErase(uint32_t * page_address);
00146 
00147     /**
00148       * Method for writing a word of data in flash with a value.
00149       *
00150       * @param address Address of the word to change.
00151       *
00152       * @param value Value to be written to flash.
00153       */
00154     void flashWordWrite(uint32_t * address, uint32_t value);
00155 
00156     /**
00157       * Places a given key, and it's corresponding value into flash at the earliest
00158       * available point.
00159       *
00160       * @param key the unique name that should be used as an identifier for the given data.
00161       *            The key is presumed to be null terminated.
00162       *
00163       * @param data a pointer to the beginning of the data to be persisted.
00164       *
00165       * @param dataSize the size of the data to be persisted
00166       *
00167       * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if the key or size is too large,
00168       *         MICROBIT_NO_RESOURCES if the storage page is full
00169       */
00170     int put(const char* key, uint8_t* data, int dataSize);
00171 
00172 
00173     /**
00174       * Places a given key, and it's corresponding value into flash at the earliest
00175       * available point.
00176       *
00177       * @param key the unique name that should be used as an identifier for the given data.
00178       *
00179       * @param data a pointer to the beginning of the data to be persisted.
00180       *
00181       * @param dataSize the size of the data to be persisted
00182       *
00183       * @return MICROBIT_OK on success, MICROBIT_INVALID_PARAMETER if the key or size is too large,
00184       *         MICROBIT_NO_RESOURCES if the storage page is full
00185       */
00186     int put(ManagedString key, uint8_t* data, int dataSize);
00187 
00188     /**
00189       * Retreives a KeyValuePair identified by a given key.
00190       *
00191       * @param key the unique name used to identify a KeyValuePair in flash.
00192       *
00193       * @return a pointer to a heap allocated KeyValuePair struct, this pointer will be
00194       *         NULL if the key was not found in storage.
00195       *
00196       * @note it is up to the user to free memory after use.
00197       */
00198     KeyValuePair* get(const char* key);
00199 
00200     /**
00201       * Retreives a KeyValuePair identified by a given key.
00202       *
00203       * @param key the unique name used to identify a KeyValuePair in flash.
00204       *
00205       * @return a pointer to a heap allocated KeyValuePair struct, this pointer will be
00206       *         NULL if the key was not found in storage.
00207       *
00208       * @note it is up to the user to free memory after use.
00209       */
00210     KeyValuePair* get(ManagedString key);
00211 
00212     /**
00213       * Removes a KeyValuePair identified by a given key.
00214       *
00215       * @param key the unique name used to identify a KeyValuePair in flash.
00216       *
00217       * @return MICROBIT_OK on success, or MICROBIT_NO_DATA if the given key
00218       *         was not found in flash.
00219       */
00220     int remove(const char* key);
00221 
00222     /**
00223       * Removes a KeyValuePair identified by a given key.
00224       *
00225       * @param key the unique name used to identify a KeyValuePair in flash.
00226       *
00227       * @return MICROBIT_OK on success, or MICROBIT_NO_DATA if the given key
00228       *         was not found in flash.
00229       */
00230     int remove(ManagedString key);
00231 
00232     /**
00233       * The size of the flash based KeyValueStore.
00234       *
00235       * @return the number of entries in the key value store
00236       */
00237     int size();
00238 };
00239 
00240 #endif