CpuUid: complete refactoring to meet review requirements

Hopefully all review items were addressed.

Author: MikeDK

drivers/CpuUid.cpp

@@ -22,59 +22,50 @@
 
 namespace mbed {
 
+uint8_t CpuUid::_uidbuf[MBED_CPU_UID_SIZE] = {0};
+uint8_t* CpuUid::_uidptr = NULL;
+char CpuUid::_strbuf[CPU_UID_STRING_BUFFER_SIZE] = {'\0'};
+char* CpuUid::_strptr = NULL;
+#ifndef MBED_CPU_UID_STR_SIZE_MAX
 const char CpuUid::_hexChars[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
+#endif
 
-CpuUid::CpuUid() : _data(NULL)
+CpuUid::CpuUid()
 {
-    _size = cpu_uid_get_length();
-#ifdef MBED_ASSERT
-    MBED_ASSERT(_size > 0);
-#endif
-    if (0 < _size) {
-        _data = new uint8_t[_size];
-        cpu_uid_get_uid(_data);
-    }
+    populate_uid_buf();
 }
 
 CpuUid::~CpuUid()
 {
-    if (_data) {
-        delete _data;
-    }
 }
 
-CpuUid::operator std::string()
+void CpuUid::populate_uid_buf()
 {
-    std::string str;
-    
-    for (int i = 0; i < _size; ++i) {
-        str += _hexChars[_data[i] >> 4];
-        str += _hexChars[_data[i] & 0x0F];
+    if (_uidptr == NULL) {
+        cpu_uid_get_uid(_uidbuf);
+        _uidptr = _uidbuf;
     }
-
-    return str;
 }
 
-CpuUid::operator cpu_uid_array_t()
+void CpuUid::populate_str_buf()
 {
-    cpu_uid_array_t array;
-    
-    for (int i = 0; i < _size; ++i) {
-        array.push_back(_data[i]);
-    }
-    
-    return array;
-}    
-
-uint8_t CpuUid::operator[](int x)
-{
-    if (x >= 0 && x < _size) {
-        return _data[x];
+    if (_strptr == NULL) {
+#ifdef MBED_CPU_UID_STR_SIZE_MAX
+        cpu_uid_get_str(_strbuf);
+        _strptr = _strbuf;
+#else
+        int pos = 0;
+        populate_uid_buf();
+        for (int i = 0; i < MBED_CPU_UID_SIZE; ++i) {
+            _strbuf[pos++] = _hexChars[_uidptr[i] >> 4];
+            _strbuf[pos++] = _hexChars[_uidptr[i] & 0x0F];
+        }
+        _strbuf[pos] = '\0';
+        _strptr = _strbuf;
+#endif
     }
-    
-    return 0x00;
 }
-    
+
 } // namespace mbed
 
 #endif

drivers/CpuUid.h

@@ -20,6 +20,12 @@
 
 #if defined(DEVICE_CPUUID) || defined(DOXYGEN_ONLY)
 
+#ifdef MBED_CPU_UID_STR_SIZE_MAX
+#define CPU_UID_STRING_BUFFER_SIZE  MBED_CPU_UID_STR_SIZE_MAX
+#else
+#define CPU_UID_STRING_BUFFER_SIZE (MBED_CPU_UID_SIZE * 2 + 1)
+#endif
+
 #include <string>
 #include <vector>
 
@@ -33,10 +39,6 @@ namespace mbed {
  */
 class CpuUid {
 public:
-    /** CPU UID array typedef
-     */
-    typedef std::vector<uint8_t> cpu_uid_array_t;
-    
     /** CpuUid constructor
      */
     CpuUid();
@@ -51,7 +53,7 @@ class CpuUid {
      */
     int size()
     {
-        return _size;
+        return MBED_CPU_UID_SIZE;
     }
 
     /** Get CPU UID data pointer
@@ -60,28 +62,41 @@ class CpuUid {
      */
     const uint8_t *data()
     {
-        return _data;
+        populate_uid_buf();
+        return _uidptr;
     }
 
-    /** Overload operator for std::string
+    /** Get CPU UID vendor string
      * 
-     * @return string object containing the CPU UID in uppercase hex letters in ascii format
-     */
-    operator std::string();
-    
-    /** Overload operator for cpu_uid_array_t
+     * @return Pointer to zero terminated uid vendor string
+     * 
+     * @note
+     * If vendor did not define MBED_CPU_UID_STR_SIZE_MAX, CpuUid driver will
+     * assume the HAL interface function cpu_uid_get_str() is not implemented
+     * on the target, and instead the driver will construct just an ASCII
+     * string out of the uid byte buffer contents.
      * 
-     * @return cpu_uid_array_t object containing the CPU UID
      */
-    operator cpu_uid_array_t();
+    const char *c_str()
+    {
+        populate_str_buf();
+        return _strptr;
+    }
 
     /** Overload operator for byte pointer
      * 
      * @return Pointer to uid data buffer
      */
     operator const uint8_t*()
     {
-        return _data;
+        populate_uid_buf();
+        return _uidptr;
+    }
+    
+    operator const char*()
+    {
+        populate_str_buf();
+        return _strptr;
     }
 
     /** Overload operator for array subscript
@@ -90,13 +105,27 @@ class CpuUid {
      * 
      * @return Byte located at index x
      */
-    uint8_t operator[](int x);
+    uint8_t operator[](int x)
+    {
+        if (x >= 0 && x < MBED_CPU_UID_SIZE) {
+            populate_uid_buf();
+            return _uidptr[x];
+        }
+
+        return 0x00;
+    }
 
 private:
-    uint8_t *_data;
-    int _size;
+    void populate_uid_buf();
+    void populate_str_buf();
 
+    static uint8_t _uidbuf[MBED_CPU_UID_SIZE];
+    static uint8_t* _uidptr;
+    static char _strbuf[CPU_UID_STRING_BUFFER_SIZE];
+    static char* _strptr;
+#ifndef MBED_CPU_UID_STR_SIZE_MAX
     static const char _hexChars[16];
+#endif
 };
 
 } // namespace mbed

hal/cpu_uid_api.h

@@ -23,6 +23,14 @@
 
 #if DEVICE_CPUUID
 
+#ifndef MBED_CPU_UID_SIZE
+#error "CPU UID Vendor implementation must define macro MBED_CPU_UID_SIZE with the uid size in bytes!"
+#endif
+
+#ifndef MBED_CPU_UID_STR_SIZE_MAX
+#warning "CPU UID max vendor string length not defined! cpu_uid_get_str() HAL interface is disabled!"
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -32,25 +40,26 @@ extern "C" {
  * @{
  */
 
-
-/** Get length of CPU UID in bytes
- * 
- * @return Number of uid bytes
- * 
- * @note
- *  Shall be used by the driver to get the needed size of the byte buffer.
- *  Target implementation must return a value higher than 0 or the driver will assert.
- * 
- */
-int cpu_uid_get_length(void);
-
 /** Get CPU UID data bytes
  * 
- * @param uid Byte buffer for uid. Must at least be of size obtained by call to cpu_uid_get_length()
+ * @param uid Byte buffer for uid. Must be of size MBED_CPU_UID_SIZE
  *
  */
 void cpu_uid_get_uid(uint8_t *uid);
 
+#ifdef MBED_CPU_UID_STR_SIZE_MAX
+/** Get UID vendor string
+ * 
+ * @param str Character buffer for vendor specific UID string. Must be of size MBED_CPU_UID_STR_SIZE_MAX
+ * 
+ * @note
+ * Implementing this function on target side can be used to provide a vendor specific
+ * string describing the contents of the UID.
+ * The string length including terminating zero character must not exceed MBED_CPU_UID_STR_SIZE_MAX bytes!
+ * 
+ */
+void cpu_uid_get_str(char *str);
+#endif
 
 /**@}*/
 

targets/TARGET_NORDIC/TARGET_NRF5/cpu_uid_api.c

@@ -43,24 +43,15 @@
 #include "nrf.h"
 #include "cpu_uid_api.h"
 
-#define UID_LENGTH      8
 #define UID_WORDS       2
 
-int cpu_uid_get_length(void)
-{
-    return UID_LENGTH;
-}
-
 void cpu_uid_get_uid(uint8_t *uid)
 {
     int pos = 0;
 
-    for (int i = (UID_WORDS-1); i >= 0; --i)
-    {
-        for (int j = 3; j >= 0; --j)
-        {
-            uid[pos] = (uint8_t)((NRF_FICR->DEVICEID[i] >> (j*8)) & 0xFF);
-            ++pos;
+    for (int i = (UID_WORDS-1); i >= 0; --i) {
+        for (int j = 3; j >= 0; --j) {
+            uid[pos++] = (uint8_t)((NRF_FICR->DEVICEID[i] >> (j*8)) & 0xFF);
         }
     }
 }