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      1 // Copyright (c) 2010, Atmel Corporation.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are met:
      6 //     * Redistributions of source code must retain the above copyright
      7 //       notice, this list of conditions and the following disclaimer.
      8 //     * Redistributions in binary form must reproduce the above copyright
      9 //       notice, this list of conditions and the following disclaimer in the
     10 //       documentation and/or other materials provided with the distribution.
     11 //     * Neither the name of Atmel nor the
     12 //       names of its contributors may be used to endorse or promote products
     13 //       derived from this software without specific prior written permission.
     14 //
     15 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
     16 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
     17 // WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
     18 // DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
     19 // DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
     20 // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
     21 // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
     22 // ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     24 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25 
     26 #include <stdint.h>
     27 #include "SHA_Comm.h"
     28 #include "SHA_CommInterface.h"
     29 #include "SHA_TimeUtils.h"
     30 #include "SHA_Status.h"
     31 
     32 
     33 /** \brief Calculates CRC
     34  *
     35  * \param[in] data pointer to data for which CRC should be calculated
     36  * \param[in] count number of bytes in buffer
     37  * \return
     38  */
     39 uint16_t SHAC_CalculateCrc(uint8_t *data, uint8_t count) {
     40     uint8_t counter;
     41     uint16_t crc = 0x0000;
     42     uint16_t poly = 0x8005;
     43     uint16_t i;
     44     uint8_t nbit, cbit;
     45 
     46     for (counter = 0; counter < count; counter++) {
     47         for (i = 0x1; i < 0x100; i <<= 1) {
     48             nbit = (data[counter] & (uint8_t) i) ? 1 : 0;
     49             cbit = (0x8000 & crc) ? 1 : 0;
     50             crc <<= 1;
     51             if (nbit ^ cbit)
     52                 crc ^= poly;
     53         }
     54     }
     55 #ifdef BIGENDIAN
     56    crc = (crc << 8) | (crc >> 8);  // flip byte order
     57 #endif
     58 
     59    return crc;
     60 }
     61 
     62 
     63 uint8_t SHAC_Wakeup() {
     64     return(SHAP_WakeDevice());
     65 }
     66 
     67 
     68 /** \brief Runs a communication sequence: Append CRC to tx buffer, send command, delay, receive and verify response.
     69  *
     70  * The first byte in tx buffer must be its byte count.
     71  * If CRC or count of the response is incorrect, or a command byte got "nacked" (TWI),
     72  * this function requests to re-send the response.
     73  * If the response contains an error status, this function resends the command.
     74  *
     75  * \param[in] params pointer to parameter structure
     76  * \return status of the operation
     77  */
     78 int8_t SHAC_SendAndReceive(SHA_CommParameters *params) {
     79     uint8_t rxSize = params->rxSize;
     80     uint8_t *rxBuffer = params->rxBuffer;
     81     uint8_t *txBuffer = params->txBuffer;
     82     uint8_t count;
     83     uint8_t countMinusCrc;
     84     int8_t status;
     85     uint8_t nRetries;
     86     uint8_t i;
     87     uint8_t statusByte;
     88 
     89     if (!params)
     90         return SHA_BAD_PARAM;
     91     if (!params->txBuffer)
     92         return SHA_BAD_PARAM;
     93 
     94     count = txBuffer[SHA_BUFFER_POS_COUNT];
     95     countMinusCrc = count - 2;
     96     if (count < SHA_COMMAND_SIZE_MIN || rxSize < SHA_RESPONSE_SIZE_MIN || !rxBuffer)
     97         return SHA_BAD_PARAM;
     98 
     99     // Append CRC and send command.
    100     *((uint16_t *) (txBuffer + countMinusCrc)) = SHAC_CalculateCrc(txBuffer, countMinusCrc);
    101     status = SHAP_SendCommand(count, txBuffer);
    102 
    103     if (status != SHA_SUCCESS) {
    104         // Re-send command.
    105         status = SHAP_SendCommand(count, txBuffer);
    106         if (status != SHA_SUCCESS) {
    107             // We lost communication. Wait until device goes to sleep.
    108             //SHAP_Delay(WATCHDOG_TIMEOUT * 1000000);
    109             return status;
    110         }
    111     }
    112 
    113     // Wait for device to finish command execution.
    114     SHAP_Delay(params->executionDelay);
    115 
    116     // Receive response.
    117     nRetries = SHA_RETRY_COUNT;
    118     do {
    119         // Reset response buffer.
    120         for (i = 0; i < rxSize; i++)
    121             rxBuffer[i] = 0;
    122 
    123         status = SHAP_ReceiveResponse(rxSize, rxBuffer);
    124         if (status != SHA_SUCCESS && !rxBuffer[SHA_BUFFER_POS_COUNT]) {
    125             // We lost communication. Wait until device goes to sleep.
    126             //SHAP_Delay(WATCHDOG_TIMEOUT * 1000000);
    127             return status;
    128         }
    129 
    130         // Check whether we received a status packet instead of a full response.
    131         if (rxSize != SHA_RESPONSE_SIZE_MIN && rxBuffer[SHA_BUFFER_POS_COUNT] == SHA_RESPONSE_SIZE_MIN) {
    132             statusByte = rxBuffer[SHA_BUFFER_POS_STATUS];
    133             if (statusByte == SHA_STATUS_BYTE_PARSE)
    134                 return SHA_PARSE_ERROR;
    135             if (statusByte == SHA_STATUS_BYTE_EXEC)
    136                 return SHA_CMD_FAIL;
    137             if (statusByte != SHA_STATUS_BYTE_COMM)
    138                 return SHA_STATUS_UNKNOWN;
    139 
    140             // Communication error. Request device to re-transmit response.
    141             continue;
    142         }
    143 
    144         // Received response. Verify count and CRC.
    145         if (rxBuffer[SHA_BUFFER_POS_COUNT] != rxSize) {
    146             status = SHA_BAD_SIZE;
    147             continue;
    148         }
    149         countMinusCrc = rxSize - 2;
    150         status = (*((uint16_t *) (rxBuffer + countMinusCrc)) == SHAC_CalculateCrc(rxBuffer, countMinusCrc))
    151             ? SHA_SUCCESS : SHA_BAD_CRC;
    152     } while (nRetries-- && status != SHA_SUCCESS);
    153 
    154     return status;
    155 }
    156