stm32: Improve the CRC function to support fully accumulate

Tested on DISCO_L476VG and NUCLEO_L476RG

Author: kevinong0108

targets/TARGET_STM/mbed_crc_api.c

@@ -7,50 +7,104 @@
 
 static CRC_HandleTypeDef current_state;
 static uint32_t final_xor;
-
+static uint32_t crc_mask;
+
+/*  STM32 CRC preipheral features
+  +-------------------------+-----------------------+---------------+---------------+
+  | Feature                 | F1/L1/F2/F4 series    | F0 series     | L0/F3/L4/F7   |
+  +-========================+=======================+===============+===============+
+  | Reversibility option    |          NO           |              YES              |
+  | on I/O data             |                       |                               |
+  +-------------------------+-----------------------+---------------+---------------+
+  | CRC initial Value       | Fixed to 0xFFFFFFFF   | Programmable  | Programmable  |
+  |                         |                       | on 32 bits    | on 8,16,32    |
+  +-------------------------+-----------------------+---------------+---------------+
+  | Handled data size in bit|                  32                   | 8,16,32       |
+  +-------------------------+---------------------------------------+---------------+
+  | Polynomial size in bit  |                  32                   | 7,8,16,32     |
+  +-------------------------+---------------------------------------+---------------+
+  | Polynomial coefficients |         Fixed to 0x4C11DB7            | Programmable  |
+  +-------------------------+---------------------------------------+---------------+
+ */
 bool hal_crc_is_supported(const crc_mbed_config_t *config)
 {
     if (config == NULL) {
         return false;
     }
 
-    if (config->polynomial != POLY_32BIT_ANSI) {
+#if defined(TARGET_STM32F1) || defined(TARGET_STM32F2) || defined(TARGET_STM32F4) || defined(TARGET_STM32L1)
+    if (config->width != HAL_CRC_LENGTH_32B || config->polynomial != POLY_32BIT_ANSI ||
+        config->initial_xor != 0xFFFFFFFF || config->reflect_in || config->reflect_out) {
         return false;
     }
-
-    if (config->width != 32) {
+#elif defined(TARGET_STM32F0)
+    if (config->width != HAL_CRC_LENGTH_32B || config->polynomial != POLY_32BIT_ANSI) {
         return false;
     }
-
-    if ((config->final_xor != 0xFFFFFFFFU) && (config->final_xor != 0)) {
+#else
+    /* TARGET_STM32L0, TARGET_STM32F3, TARGET_STM32L4, TARGET_STM32F7 */
+    if (config->width != HAL_CRC_LENGTH_32B && config->width != HAL_CRC_LENGTH_16B &&
+        config->width != HAL_CRC_LENGTH_8B && config->width != HAL_CRC_LENGTH_7B) {
         return false;
     }
+#endif
 
     return true;
 }
 
+static uint32_t get_crc_mask(int width)
+{
+    return (width < 8 ? ((1u << 8) - 1) : (uint32_t)((uint64_t)(1ull << width) - 1));
+}
+
 void hal_crc_compute_partial_start(const crc_mbed_config_t *config)
 {
     MBED_ASSERT(hal_crc_is_supported(config));
 
     __HAL_RCC_CRC_CLK_ENABLE();
 
     final_xor = config->final_xor;
+    crc_mask = get_crc_mask(config->width);
 
     current_state.Instance                     = CRC;
+#if !defined(TARGET_STM32F1) && !defined(TARGET_STM32F2) && !defined(TARGET_STM32F4) && !defined(TARGET_STM32L1)
     current_state.InputDataFormat              = CRC_INPUTDATA_FORMAT_BYTES;
-    current_state.Init.DefaultPolynomialUse    = DEFAULT_POLYNOMIAL_ENABLE;
+    current_state.Init.DefaultPolynomialUse    = DEFAULT_POLYNOMIAL_DISABLE;
     current_state.Init.DefaultInitValueUse     = DEFAULT_INIT_VALUE_DISABLE;
     current_state.Init.InitValue               = config->initial_xor;
-    current_state.Init.CRCLength               = CRC_POLYLENGTH_32B;
+    current_state.Init.GeneratingPolynomial    = config->polynomial;
+
+	switch (config->width)
+	{
+	case HAL_CRC_LENGTH_32B:
+		current_state.Init.CRCLength = CRC_POLYLENGTH_32B;
+		break;
+
+	case HAL_CRC_LENGTH_16B:
+		current_state.Init.CRCLength = CRC_POLYLENGTH_16B;
+		break;
+	case HAL_CRC_LENGTH_8B:
+		current_state.Init.CRCLength = CRC_POLYLENGTH_8B;
+		break;
+	case HAL_CRC_LENGTH_7B:
+		current_state.Init.CRCLength = CRC_POLYLENGTH_7B;
+		break;
+	default:
+		MBED_ASSERT(false);
+		break;
+	}
+
     current_state.Init.InputDataInversionMode  =
         config->reflect_in ? CRC_INPUTDATA_INVERSION_BYTE
         : CRC_INPUTDATA_INVERSION_NONE;
     current_state.Init.OutputDataInversionMode =
         config->reflect_out ? CRC_OUTPUTDATA_INVERSION_ENABLE
         : CRC_OUTPUTDATA_INVERSION_DISABLE;
+#endif
 
-    HAL_CRC_Init(&current_state);
+	if (HAL_CRC_Init(&current_state) != HAL_OK)	{
+		MBED_ASSERT(false);
+	}
 }
 
 void hal_crc_compute_partial(const uint8_t *data, const size_t size)
@@ -62,9 +116,29 @@ void hal_crc_compute_partial(const uint8_t *data, const size_t size)
 
 uint32_t hal_crc_get_result(void)
 {
-    const uint32_t result = current_state.Instance->DR;
-
-    return (final_xor == 0xFFFFFFFFU) ? ~result : result;
+    uint32_t result = current_state.Instance->DR;
+
+#if !defined(TARGET_STM32F1) && !defined(TARGET_STM32F2) && !defined(TARGET_STM32F4) && !defined(TARGET_STM32L1)
+    /* The CRC-7 SD needs to shift left by 1 bit after obtaining the result, but the output
+     * inversion of CRC peripheral will convert the result before shift left by 1 bit, so
+     * the result seems to have shifted after the conversion.
+     * 
+     * Example:
+     *  [Gerenal setps]
+     *  1. Before output inversion: 0x75 (0111 0101)
+     *  2. Left shift by 1 bit:     0xEA (1110 1010)
+     *  3. After output inversion:  0x57 (0101 0111)
+     *  
+     *  [STM32 CRC peripheral steps]
+     *  1. Before output inversion: 0x75 (0111 0101)
+     *  2. After output inversion:  0x57 (0101 0111) <= no needs shift again
+     */
+    if (current_state.Init.CRCLength == CRC_POLYLENGTH_7B &&
+        current_state.Init.GeneratingPolynomial == POLY_7BIT_SD &&
+        current_state.Init.OutputDataInversionMode == CRC_OUTPUTDATA_INVERSION_DISABLE)
+        result = result << 1;
+#endif
+    return (result ^ final_xor) & crc_mask;
 }
 
 #endif // DEVICE_CRC