Subversion Repositories neo430

// #################################################################################################
// #  < neo430_crc.c - CRC module helper functions >                                               #
// # ********************************************************************************************* #
// # BSD 3-Clause License                                                                          #
// #                                                                                               #
// # Copyright (c) 2020, Stephan Nolting. All rights reserved.                                     #
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// # permitted provided that the following conditions are met:                                     #
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// #    permission.                                                                                #
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// # ********************************************************************************************* #
// # The NEO430 Processor - https://github.com/stnolting/neo430                                    #
// #################################################################################################
 
#include "neo430.h"
#include "neo430_crc.h"
 
 
/* ------------------------------------------------------------
 * INFO Compute CRC16 from buffer
 * PARAM start_val: Start value for CRC shift register
 * PARAM polynomial: 16-bit polynomial XOR mask
 * PARAM data: Pointer to BYTE input data array
 * PARAM length: Number of elements in input data array
 * RETURN CRC16 result
 * ------------------------------------------------------------ */
uint16_t neo430_crc16(uint16_t start_val, uint16_t polynomial, uint8_t *data, uint16_t length) {
 
  CRC_POLY_LO = polynomial;
  CRC_RESX = start_val;
 
  while(length) {
    CRC_CRC16IN = (uint16_t)(*data++); // no wait required here
    length--;
  }
 
  return CRC_RESX;
}
 
 
/* ------------------------------------------------------------
 * INFO Compute CRC32 from buffer
 * PARAM start_val: Start value for CRC shift register
 * PARAM polynomial: 32-bit polynomial XOR mask
 * PARAM data: Pointer to BYTE input data array
 * PARAM length: Number of elements in input data array
 * RETURN CRC32 result
 * ------------------------------------------------------------ */
uint32_t neo430_crc32(uint32_t start_val, uint32_t polynomial, uint8_t *data, uint16_t length) {
 
  CRC_POLY32bit = polynomial;
  CRC_R32bit = start_val;
 
  while(length) {
    CRC_CRC32IN = (uint16_t)(*data++); // no wait required here
    length--;
  }
 
  return CRC_R32bit;
}
 
 
/* ------------------------------------------------------------
 * INFO Initialize start value for CRC16
 * PARAM 16-bit CRC shift reg start value
 * ------------------------------------------------------------ */
void neo430_crc16_set_start_value(uint16_t start_val) {
 
  CRC_RESX = start_val;
}
 
 
/* ------------------------------------------------------------
 * INFO Initialize start value for CRC32
 * PARAM 32-bit CRC shift reg start value
 * ------------------------------------------------------------ */
void neo430_crc32_set_start_value(uint32_t start_val) {
 
  CRC_R32bit = start_val;
}
 
 
/* ------------------------------------------------------------
 * INFO Set polynomial mask for CRC16
 * PARAM 16-bit CRC16 polynomial XOR mask
 * ------------------------------------------------------------ */
void neo430_crc16_set_polynomial(uint16_t poly) {
 
  CRC_POLY_LO = poly;
}
 
 
/* ------------------------------------------------------------
 * INFO Set polynomial mask for CRC32
 * PARAM 32-bit CRC16 polynomial XOR mask
 * ------------------------------------------------------------ */
void neo430_crc32_set_polynomial(uint32_t poly) {
 
  CRC_POLY32bit = poly;
}
 
 
/* ------------------------------------------------------------
 * INFO Compute CRC16 for one new data byte
 * PARAM 8-bit data input
 * RETURN Current result of CRC16 shift reg
 * ------------------------------------------------------------ */
uint16_t neo430_crc16_iterate(uint8_t data) {
 
  CRC_CRC16IN = (uint16_t)data;
  asm volatile ("nop");
  return CRC_RESX;
}
 
 
/* ------------------------------------------------------------
 * INFO Compute CRC32 for one new data byte
 * PARAM 8-bit data input
 * RETURN Current result of CRC32 shift reg
 * ------------------------------------------------------------ */
uint32_t neo430_crc32_iterate(uint8_t data) {
 
  CRC_CRC32IN = (uint16_t)data;
  asm volatile ("nop");
  return CRC_R32bit;
}