K64F CRC driver: Fix handling of CRC final XOR value

According to the test results final XOR was incorrectly handled by the CRC driver.
This patch fixes this issue.

Author: mprse

targets/TARGET_Freescale/TARGET_MCUXpresso_MCUS/TARGET_MCU_K64F/mbed_crc_api.c

@@ -50,7 +50,12 @@ void hal_crc_compute_partial_start(const crc_mbed_config_t* config)
   platform_config.seed               = config->initial_xor;
   platform_config.reflectIn          = config->reflect_in;
   platform_config.reflectOut         = config->reflect_out;
-  platform_config.complementChecksum = (config->final_xor == 0xFFFFFFFFU);
+  if ((width == kCrcBits16 && config->final_xor == 0xFFFFU) ||
+      (width == kCrcBits32 && config->final_xor == 0xFFFFFFFFU)) {
+      platform_config.complementChecksum = true;
+  } else {
+      platform_config.complementChecksum = false;
+  }
   platform_config.crcBits            = width;
   platform_config.crcResult          = kCrcFinalChecksum;
 
@@ -72,20 +77,31 @@ void hal_crc_compute_partial(const uint8_t *data, const size_t size)
 
 uint32_t hal_crc_get_result(void)
 {
-  if ((final_xor != 0x00000000U) && (final_xor != 0xFFFFFFFFU)) {
-    CRC_WriteData(CRC0, (uint8_t*)&final_xor, sizeof(final_xor));
-  }
-
-  switch (width)
-  {
-    case kCrcBits16:
-      return CRC_Get16bitResult(CRC0);
-    case kCrcBits32:
-      return CRC_Get32bitResult(CRC0);
-    default:
-      MBED_ASSERT("Unhandled switch case");
-      return 0;
-  }
+    uint32_t result;
+
+    const bool manual_final_xor = ((final_xor != 0x00000000U) &&
+                                   ((final_xor != 0xFFFFFFFFU && width == kCrcBits32) ||
+                                    (final_xor != 0xFFFFU && width == kCrcBits16)));
+
+    switch (width)
+    {
+        case kCrcBits16:
+            result = CRC_Get16bitResult(CRC0);
+            if (manual_final_xor) {
+                result ^= final_xor;
+                result &= 0xFFFF;
+            }
+            return result;
+        case kCrcBits32:
+            result = CRC_Get32bitResult(CRC0);
+            if (manual_final_xor) {
+                result ^= final_xor;
+            }
+            return result;
+        default:
+            MBED_ASSERT("Unhandled switch case");
+        return 0;
+    }
 }
 
 #endif // DEVICE_CRC