CRC configuration for online values

[Catosh]

Hi All, 

I am trying to implement the CRC-32/BZIP2 using the HW crc. My reference is this site.

I am able to compute the ieee_CRC32 with following parameters:

 CRC->CTRL = 1<<31 | // Type Of Transpose For Writes: Bits in bytes are transposed; bytes are not transposed
1<<29 | // Type Of Transpose For Read: 10b - Both bits in bytes and bytes are transposed
1<<26 | // Complement Read Of CRC Data Register;
1<<25 | // CRC Data Register as seed 
1<<24 ; // TCRC32 bit

CRC->DATAu.DATA = 0xffffffff; 
CRC->CTRL &= ~(uint32_t)(1<<25); // CRC Data Register as data
CRC->GPOLY = 0x04C11DB7;

input -> 2000f000, expected output -> 0xAFEE8C04, correct.

Now, 

I am not able to replicate any of the other combinations, for example the second line. 

Is there any detailed guide or some reference where I can look in detail how to configure the HW Crc peripheral on the S23K? Or in general a guide to understand how to map common poly/algos into hw crc?

Thanks and best regards,

L.T.

[lukaszadrapa]

Hi,

it's just necessary to find the right combination of TOT, TOTR and FXOR bit fields.

For CRC-32, use:

TOT = 0b01, TOTR = 0b10, FXOR = 0b1

or

TOT = 0b10, TOTR = 0b10, FXOR = 0b1

For CRC-32/BZIP2, use:

TOT = 0b00, TOTR = 0b00, FXOR = 0b1

or

TOT = 0b11, TOTR = 0b00, FXOR = 0b1

Frankly, I didn't have time to study the differences between individual algorithms, so I used brutal force method which was faster - I wrote simple code which tries all the combinations and then I compared the results...

Hope it helps anyway...

Regards,

Lukas