calculating checksum of struct

[VYoun]

Hello,

I need to calculate checksum over a struct I have defined. Can anyone please help me with this?

The data is structured as below:

typedef struct eeprom_struct {
 
//	char serial_number[5];
	float detector_comp_ch0;
	float detector_comp_ch1;
	float detector_comp_ch2;
	float detector_comp_ch3;
	float detector_comp_ch4;
	float detector_comp_ch5;
	float detector_comp_ch6;
	float detector_comp_ch7;
	char serial_number[14];
	uint checksum;
 
 
} eeprom_struct;
 

I know this is not directly related to STM32 MCUs, but I really need to solve this, and could not get an answer anywhere else.

Thank you in advance for your help.

Best regards,

Vouria

[Tesla DeLorean]

eeprom_struct foo;

...

foo.checksum = crc32(0xFFFFFFFF, sizeof(eeprom_struct) - sizeof(uint), (void *)&foo); // A crc with initial value, length in bytes, byte pointer to buffer

[VYoun]

Thanks a lot, should I write the crc32 function?

[Tesla DeLorean]

That or some other summing algorithm, wasn't clear what part of the problem was posing the challenge here.

[Piranha]

> could not get an answer anywhere else

O, you poor one! There are not a single example... https://lmgtfy.com/?q=CRC+example+C&iie=1

> should I write the crc32 function?

No, it will write itself, you just sit and wait for a it to happen.

[VYoun]

thank you very much for your help, the problem is that the function is to calculate CRC and I am looking for checksum

[Tesla DeLorean]

This all seems like mundane C coding,

uint sum32(int size, uint8_t *ptr)

{

uint sum = 0;

while(size--) sum += *ptr++; // sum bytes over buffer

return(sum);

}

[Piranha]

CRC is also a checksum. Oh, but you need The Checksum - the one without a name/algoritm. Here is the code for it:

foo.checksum = 0xF001;

It's also superior compared to other checksums - it never fails!

[VYoun]

thank you for your reply

[waclawek.jan]

> I need to calculate checksum over a struct I have defined.

Why?

JW

[Tesla DeLorean]

Integrity, establish it has been written completely? Usual stuff I'd imagine.