Hi,
I'm performing crc computation on K24 chip during run-time. As the address range to compute the crc is quite huge, it is broken up into several cycles. How to have the chip start a new calculation using an intermediate crc value from the previous calculation?
For example:
cycle 1: crc1 = Calculated crc from address 0x0001 to 0x0020
cycle 2: crc2 = calculated crc from crc1 and address 0x0021 to 0x0040
and so on...
How should crc1 be parsed in during cycle 2? As seed value or as a data?
Here's my code but it doesn't work:
<code>
static uint32_t Crc32(uint32_t const * const pData, uint32_t numLongs, uint32_t initCrc)
{
// Steps #1 and #2
CRC_CTRL = (CRC_CTRL_TOT(2U)) | // Input bits & bytes are transposed
(CRC_CTRL_TOTR(2U)) | // Output bits & bytes are transposed
(0UL << CRC_CTRL_WAS_SHIFT) | // Ready to write data
(1UL << CRC_CTRL_TCRC_SHIFT); // 32-bit CRC
// Step #3
CRC_GPOLY = 0x04C11DB7; // CRC32 polynomial
// Step #4 - Indicate seed will be written
CRC_CTRL = (CRC_CTRL_TOT(2U)) | // Input bits & bytes are transposed
(CRC_CTRL_TOTR(2U)) | // Output bits & bytes are transposed
(1UL << CRC_CTRL_WAS_SHIFT) | // Ready to write seed
(1UL << CRC_CTRL_TCRC_SHIFT); // 32-bit CRC
// Step #5 - Write seed
CRC_DATA = initCrc;
// Step #6 - Indicate that data follows
CRC_CTRL = (CRC_CTRL_TOT(2U)) | // Input bits & bytes are transposed
(CRC_CTRL_TOTR(2U)) | // Output bits & bytes are transposed
(0UL << CRC_CTRL_WAS_SHIFT) | // Ready to write data
(1UL << CRC_CTRL_TCRC_SHIFT); // 32-bit CRC
// Step #7 - Write the data values.
for (uint32_t i = 0; i < numLongs; i++)
{
CRC_DATA = pData[i];
}
// Step #8 - Return CRC result.
return CRC_DATA;
}
// Note: the following is a pseudo code just to illustrate the logic
// The following doesn't work. What's wrong?
main()
{
while (!crcDone)
{
readData(&data[0]);
if (cycle1)
{
crc = crc32(data[0], numBytes, 0xFFFFFFFFUL);
}
else
{
crc = crc32(data[0], numBytes, crc);
}
}
CompareCrcWithStoredCrc();
}
// I have also tried the following but it doesn't work either:
main()
{
while (!crcDone)
{
readData(&data[4]);
if (cycle1)
{
crc = crc32(data[4], numBytes, 0x0UL);
}
else
{
memcpy(&data[0], &crc, 4);
crc = crc32(data[0], numBytes+4, 0x0UL);
}
}
CompareCrcWithStoredCrc();
}
<code>
Appreciate some advice. Thanks!
