Mbed OS Reference | UUID.h Source File

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 /* mbed Microcontroller Library
  * Copyright (c) 2006-2020 ARM Limited
  *
  * SPDX-License-Identifier: Apache-2.0
  *
  * 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.
  */
 
 #ifndef MBED_UUID_H__
 #define MBED_UUID_H__
 
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <algorithm>
 
 #include "ble/common/blecommon.h"
 
 /**
  * @file
  * @addtogroup ble
  * @{
  * @addtogroup common
  * @{
  */
 
 /**
  * Convert a character containing an hexadecimal digit into an unsigned integer.
  *
  * @param[in] c Hexadecimal digit in a character representation.
  *
  * @return The corresponding value as unsigned integer.
  */
 static uint8_t char2int(char c)
 {
     if ((c >= '0') && (c <= '9')) {
         return c - '0';
     } else if ((c >= 'a') && (c <= 'f')) {
         return c - 'a' + 10;
     } else if ((c >= 'A') && (c <= 'F')) {
         return c - 'A' + 10;
     } else {
         return 0;
     }
 }
 
 /**
  * Representation of a Universally Unique Identifier (UUID).
  *
  * UUIDs are 128-bit wide numbers used to identify data type and elements in
  * many layers of the Bluetooth specification.
  *
  * Two representations of UUIDS exist:
  *   - 16-bit UUIDs: Shortened representation of the 128 bit UUID
  *     0000xxxx-0000-1000-8000-00805F9B34FB where xxxx is the 16 bit UUID.
  *     Values of those UUIDs are defined by the Bluetooth body. The short
  *     representation saves bandwidth during protocol transactions.
  *   - 128-bit UUIDs: Complete representation of a UUID. They are commonly
  *     used for user defined UUID.
  *
  * This class acts as an adapter over these two kinds of UUIDs to allow
  * indiscriminate use of both forms in Mbed BLE APIs.
  *
  * @note 32-bit UUID representation is not supported currently.
  */
 class UUID {
 public:
 
     /**
      * Enumeration of the types of UUIDs.
      */
     enum UUID_Type_t {
         /**
          * 16-bit wide UUID representation.
          */
         UUID_TYPE_SHORT = 0,
 
         /**
          * 128-bit wide UUID representation.
          */
         UUID_TYPE_LONG  = 1
     };
 
     /**
      * Enumeration of byte ordering.
      *
      * It is used to construct 128-byte UUIDs.
      */
     typedef enum {
         /**
          * Most significant byte first (at the smallest address).
          */
         MSB,
 
         /**
          * Least significant byte first (at the smallest address).
          */
         LSB
     } ByteOrder_t;
 
     /**
      * Type for a 16-bit UUID.
      */
     typedef uint16_t ShortUUIDBytes_t;
 
     /**
      * Length in bytes of a long UUID.
      */
     static const unsigned LENGTH_OF_LONG_UUID = 16;
 
     /**
      * Type for a 128-bit UUID.
      */
     typedef uint8_t LongUUIDBytes_t[LENGTH_OF_LONG_UUID];
 
     /**
      * Maximum length for the string representation of a UUID excluding the null
      * terminator.
      *
      * The string is composed of two characters per byte plus four '-'
      * characters.
      */
     static const unsigned MAX_UUID_STRING_LENGTH = LENGTH_OF_LONG_UUID * 2 + 4;
 
 public:
 
     /**
      * Construct a 128-bit UUID from a string.
      *
      * @param[in] stringUUID Human readable representation of the UUID following
      * the format XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX.
      *
      * @note Upper and lower case are supported.
      * @note Hyphens are optional. The string must include at most four hyphens.
      *
      * @note Internally, the UUID is stored in the little endian order as a
      * 16-byte array.
      */
     UUID(const char* stringUUID) :
         type(UUID_TYPE_LONG),
         baseUUID(),
         shortUUID(0)
     {
         bool nibble = false;
         uint8_t byte = 0;
         size_t baseIndex = 0;
         uint8_t tempUUID[LENGTH_OF_LONG_UUID];
 
         /*
          * Iterate through string; abort if NULL is encountered prematurely.
          * Ignore up to four hyphens.
          */
         for (size_t index = 0; (index < MAX_UUID_STRING_LENGTH) && (baseIndex < LENGTH_OF_LONG_UUID); index++) {
             if (stringUUID[index] == '\0') {
                 /* Error abort */
                 break;
             } else if (stringUUID[index] == '-') {
                 /* Ignore hyphen */
                 continue;
             } else if (nibble) {
                 /* Got second nibble */
                 byte |= char2int(stringUUID[index]);
                 nibble = false;
 
                 /* Store copy */
                 tempUUID[baseIndex++] = byte;
             } else {
                 /* Got first nibble */
                 byte = char2int(stringUUID[index]) << 4;
                 nibble = true;
             }
         }
 
         /* Populate internal variables if string was successfully parsed */
         if (baseIndex == LENGTH_OF_LONG_UUID) {
             setupLong(tempUUID, UUID::MSB);
         } else {
             const uint8_t sig[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
                                     0x80, 0x00, 0x00, 0x80, 0x5F, 0x9B, 0x34, 0xFB };
             setupLong(sig, UUID::MSB);
         }
     }
 
     /**
      * Construct a new UUID from a 128-bit representation.
      *
      * @param[in] longUUID The 128-bit (16-byte) of the UUID value.
      * @param[in] order Bytes order of @p longUUID.
      */
     UUID(const LongUUIDBytes_t longUUID, ByteOrder_t order = UUID::MSB) : type(UUID_TYPE_LONG), baseUUID(), shortUUID(0) {
         setupLong(longUUID, order);
     }
 
     /**
      * Creates a new 16-bit UUID.
      *
      * The Bluetooth standard body defines 16-bit wide UUIDs. They are the
      * shortened version of the UUID 0000xxxx-0000-1000-8000-00805F9B34FB, where
      * xxxx is the value of the 16-bit UUID.
      *
      * @attention 16-bit UUIDs are not used in user defined data type or
      * user defined element ID.
      *
      * @param[in] _shortUUID 16-bit part of the standard UUID.
      *              The short UUID value.
      *
      * @note User defined UUIDs are commonly named vendor-specific UUIDs across
      * the Bluetooth literature.
      */
     UUID(ShortUUIDBytes_t _shortUUID) :
         type(UUID_TYPE_SHORT),
         baseUUID(),
         shortUUID(_shortUUID) {
     }
 
     /**
      * UUID copy constructor.
      *
      * @param[in] source The UUID to copy.
      */
     UUID(const UUID &source)
     {
         type      = source.type;
         shortUUID = source.shortUUID;
         memcpy(baseUUID, source.baseUUID, LENGTH_OF_LONG_UUID);
     }
 
     /**
      * UUID copy assignment.
      *
      * @param[in] source The UUID to copy.
      */
     UUID& operator=(const UUID &source) = default;
 
     /**
      * Default constructor.
      *
      * Construct an invalid UUID.
      *
      * @post shortOrLong() returns the value UUID_TYPE_SHORT.
      * @post getShortUUID() returns the value BLE_UUID_UNKNOWN.
      */
     UUID() :
         type(UUID_TYPE_SHORT),
         shortUUID(BLE_UUID_UNKNOWN) {
     }
 
     /**
      * Replace existing value with a 128-bit UUID.
      *
      * @param[in] longUUID New 16-byte wide UUID value.
      * @param[in] order Byte ordering of @p longUUID.
      */
     void setupLong(const LongUUIDBytes_t longUUID, ByteOrder_t order = UUID::MSB)
     {
         type = UUID_TYPE_LONG;
         if (order == UUID::MSB) {
             /*
              * Switch endian. Input is big-endian, internal representation
              * is little endian.
              */
             std::reverse_copy(longUUID, longUUID + LENGTH_OF_LONG_UUID, baseUUID);
         } else {
             std::copy(longUUID, longUUID + LENGTH_OF_LONG_UUID, baseUUID);
         }
         shortUUID = (uint16_t)((baseUUID[13] << 8) | (baseUUID[12]));
     }
 
 public:
     /**
      * Return the internal type of the UUID.
      *
      * @return UUID_TYPE_SHORT if the UUID is 16-bit wide.
      * @return UUID_TYPE_LONG if the UUID is 128-bit wide.
      */
     UUID_Type_t shortOrLong() const
     {
         return type;
     }
 
     /**
      * Get a pointer to the UUID value based on the current UUID type.
      *
      * @return A pointer to an uint16_t object if the UUID is 16 bits long.
      * @return A pointer to an array of 16 bytes if the UUID is 128 bits long.
      */
     const uint8_t *getBaseUUID() const
     {
         if (type == UUID_TYPE_SHORT) {
             return (const uint8_t*)&shortUUID;
         } else {
             return baseUUID;
         }
     }
 
     /**
      * Get the uint16_t value of the UUID.
      *
      * @attention This function is not used on long UUIDs.
      *
      * @return The value of the shortened UUID.
      */
     ShortUUIDBytes_t getShortUUID() const
     {
         return shortUUID;
     }
 
     /**
      * Get the length (in bytes) of the internal UUID representation.
      *
      * @return sizeof(ShortUUIDBytes_t) if the UUID type is UUID_TYPE_SHORT.
      * @return LENGTH_OF_LONG_UUID if the UUID type is UUID_TYPE_LONG.
      */
     uint8_t getLen() const
     {
         return ((type == UUID_TYPE_SHORT) ?
             sizeof(ShortUUIDBytes_t) :
             LENGTH_OF_LONG_UUID);
     }
 
     /**
      * Equal to operator between UUIDs.
      *
      * @param[in] other The UUID to compare to this.
      *
      * @return true if both UUIDs are equal and false otherwise.
      */
     bool operator== (const UUID &other) const
     {
         if ((this->type == UUID_TYPE_SHORT) && (other.type == UUID_TYPE_SHORT) &&
             (this->shortUUID == other.shortUUID)) {
             return true;
         }
 
         if ((this->type == UUID_TYPE_LONG) && (other.type == UUID_TYPE_LONG) &&
             (memcmp(this->baseUUID, other.baseUUID, LENGTH_OF_LONG_UUID) == 0)) {
             return true;
         }
 
         return false;
     }
 
     /**
      * Not equal to operator.
      *
      * @param[in] other The UUID compared to this.
      *
      * @return true if both UUIDs are not equal and false otherwise.
      */
     bool operator!= (const UUID &other) const
     {
         return !(*this == other);
     }
 
 private:
     /**
      * Representation type of the UUID.
      */
     UUID_Type_t type;
 
     /**
      * Container of UUID value if the UUID type is equal to UUID_TYPE_LONG.
      */
     LongUUIDBytes_t  baseUUID;
 
     /**
      * Container of UUID value if the UUID type is equal to UUID_TYPE_SHORT.
      */
     ShortUUIDBytes_t shortUUID;
 };
 
 /**
  * @}
  * @}
  */
 
 #endif // ifndef MBED_UUID_H__
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