> ## Documentation Index
> Fetch the complete documentation index at: https://notevil.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# CAPLfunctionCrcCalculateCRC32

[Open topic with navigation](../../../../../CANoeDEFamily.htm#Topics/CAPLFunctions/Other/E2EProtection/CAPLfunctionCrcCalculateCRC32.md)

**CAPL Functions** » [General](../CAPLGeneralStartPage.md) » [Function Overview](../CAPLfunctionsGeneralOverview.md) » Crc\_CalculateCRC32

# Crc\_CalculateCRC32

[Valid for](../../../Shared/FeatureAvailability.md): CANoe DE • CANoe:lite DE • CANoe4SW DE • CANoe4SW:lite DE

## Function Syntax

```plaintext theme={null}
long Crc_CalculateCRC32 (byte data[], dword dataSize, dword dataOffset, dword crcLength, dword crcStartValue, dword firstCall, dword& crcCalculated);
```

## Description

Calculates the corresponding checksum for CRC32 based on the data. The calculation of the CRC value corresponds to IEEE-802.3 CRC32.

## Parameters

* **data**: Payload data for which the checksum is to be calculated.
* **dataSize**: Length of data block to be calculated in bytes.
* **dataOffset**: Start index for the calculation of the CRC in the payload data.
* **crcLength**: The length of the data for the CRC is calculated.
* **crcStartValue**: CRC initial value depending on whether it is the first call or a subsequent call. Value is ignored if **firstCall** is **1**.
* **firstCall**: Flag for first call or a subsequent call. Possible values are **0** (subsequent call) or **1** (first call).
* **crcCalculated**: Calculated CRC32 value.

## Return Values

* **0**: Successful
* **-1**: Not successful: CRC length must not be 0
* **-2**: Not successful: Offset must not be greater or equal length
* **-3**: Not successful: Length outside array range
* **-4**: Not successful: Summary of Length and offset are outside array range

## Example

```plaintext theme={null}
// first CALL, Offset '0'
on key 'a'
{
  long  retval;
  dword crc;
  byte  data[9] = {0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39};

  retval = Crc_CalculateCRC32(data, elcount (data), 0, elcount (data), 0, 1, crc);
  write("CRC of data: 0x%X", crc);
}

// first CALL, Offset '2', Length - 2
on key 'b'
{
  long  retval;
  dword crc;
  byte  data[11] = {0xAA ,0xAA,0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39};

  retval = Crc_CalculateCRC32(data, elcount (data), 2, elcount (data) -2, 0, 1, crc);
  write("CRC of data: 0x%X", crc);
}
```