Functions
void	CRCConfigSet (uint32_t ui32Base, uint32_t ui32CRCConfig)

void	CRCSeedSet (uint32_t ui32Base, uint32_t ui32Seed)

void	CRCDataWrite (uint32_t ui32Base, uint32_t ui32Data)

uint32_t	CRCResultRead (uint32_t ui32Base, bool bPPResult)

uint32_t	CRCDataProcess (uint32_t ui32Base, uint32_t *pui32DataIn, uint32_t ui32DataLength, bool bPPResult)

Detailed Description

Introduction

The CRC module driver provides a method for generating CRC checksums of various types. The configuration and feature highlights are:

Seed value for CRC operations is either all zeroes, all ones or a user defined value.
Accepts data as bytes or 4-byte words.
Optionally performs pre- and post-processing on the input data and checksum.

API Functions

The CRC API consists of functions for configuring the CRC module, processing data, and reading the resultant checksum.

Programming Example

The following example sets up the CRC for basic CRC32 operation with a starting seed of zero.

uint32_t g_ui32Result;
//
// Random data for generating CRC.
//
uint32_t g_ui32RandomData[16] =
{
    0x8a5f1b22, 0xcb935d29, 0xcc1ac092, 0x5dad8c9e, 
    0x6a83b39f, 0x8607dc60, 0xda0ba4d2, 0xf49b0fa2, 
    0xaf35d524, 0xffa8001d, 0xbcc931e8, 0x4a2c99ef,
    0x7fa297ab, 0xab943bae, 0x07c61cc4, 0x47c8627d
};
int
main(void)
{
    //
    // Enable the CRC module.
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_CCM0);
    //
    // Wait for the CRC module to be ready.
    //
    while(!SysCtlPeripheralReady(SYSCTL_PERIPH_CCM0))
    {
    }
    
    //
    // Configure the CRC module.
    //
    CRCConfigSet(EC_BASE, 
                 CRC_CFG_INIT_SEED | 
                 CRC_CFG_TYPE_P4C11DB7 |
                 CRC_CFG_SIZE_32BIT);
    //
    // Set the seed value.
    //
    CRCSeedSet(EC_BASE, 0x5a5a5a5a);
    //
    // Process the data and get the result.  The result should be 
    // 0x75fd6f5c.
    //
    g_ui32Result = CRCDataProcess(EC_BASE, g_ui32RandomData, 16, false);
}

Function Documentation

§ CRCConfigSet()

void CRCConfigSet	(	uint32_t	ui32Base,
		uint32_t	ui32CRCConfig
	)

Set the configuration of CRC functionality with the EC module.

Parameters

ui32Base	is the base address of the EC module.
ui32CRCConfig	is the configuration of the CRC engine.

This function configures the operation of the CRC engine within the EC module. The configuration is specified with the ui32CRCConfig argument. It is the logical OR of any of the following options:

CRC Initialization Value

CRC_CFG_INIT_SEED - Initialize with seed value
CRC_CFG_INIT_0 - Initialize to all '0s'
CRC_CFG_INIT_1 - Initialize to all '1s'

Input Data Size

CRC_CFG_SIZE_8BIT - Input data size of 8 bits
CRC_CFG_SIZE_32BIT - Input data size of 32 bits

Post Process Reverse/Inverse

CRC_CFG_RESINV - Result inverse enable
CRC_CFG_OBR - Output reverse enable

Input Bit Reverse

CRC_CFG_IBR - Bit reverse enable

Endian Control

CRC_CFG_ENDIAN_SBHW - Swap byte in half-word
CRC_CFG_ENDIAN_SHW - Swap half-word

Operation Type

CRC_CFG_TYPE_P8005 - Polynomial 0x8005
CRC_CFG_TYPE_P1021 - Polynomial 0x1021
CRC_CFG_TYPE_P4C11DB7 - Polynomial 0x4C11DB7
CRC_CFG_TYPE_P1EDC6F41 - Polynomial 0x1EDC6F41
CRC_CFG_TYPE_TCPCHKSUM - TCP checksum

Returns: None.

References ASSERT, CCM_O_CRCCTRL, CRC_CFG_ENDIAN_SBHW, CRC_CFG_ENDIAN_SHW, CRC_CFG_IBR, CRC_CFG_INIT_0, CRC_CFG_INIT_1, CRC_CFG_INIT_SEED, CRC_CFG_OBR, CRC_CFG_RESINV, CRC_CFG_SIZE_32BIT, CRC_CFG_SIZE_8BIT, CRC_CFG_TYPE_P1021, CRC_CFG_TYPE_P1EDC6F41, CRC_CFG_TYPE_P4C11DB7, CRC_CFG_TYPE_P8005, CRC_CFG_TYPE_TCPCHKSUM, and HWREG.

§ CRCSeedSet()

void CRCSeedSet	(	uint32_t	ui32Base,
		uint32_t	ui32Seed
	)

Write the seed value for CRC operations in the EC module.

Parameters

ui32Base	is the base address of the EC module.
ui32Seed	is the seed value.

This function writes the seed value for use with CRC operations in the EC module. This value is the start value for CRC operations. If this value is not written, then the residual seed from the previous operation is used as the starting value.

Note: The seed must be written only if CRC_CFG_INIT_SEED is set with the CRCConfigSet() function.

References ASSERT, CCM_O_CRCSEED, and HWREG.

§ CRCDataWrite()

void CRCDataWrite	(	uint32_t	ui32Base,
		uint32_t	ui32Data
	)

Write data into the EC module for CRC operations.

Parameters

ui32Base	is the base address of the EC module.
ui32Data	is the data to be written.

This function writes either 8 or 32 bits of data into the EC module for CRC operations. The distinction between 8 and 32 bits of data is made when the CRC_CFG_SIZE_8BIT or CRC_CFG_SIZE_32BIT flag is set using the CRCConfigSet() function.

When writing 8 bits of data, ensure the data is in the least significant byte position. The remaining bytes should be written with zero. For example, when writing 0xAB, ui32Data should be 0x000000AB.

Returns: None

References ASSERT, CCM_O_CRCDIN, and HWREG.

§ CRCResultRead()

uint32_t CRCResultRead	(	uint32_t	ui32Base,
		bool	bPPResult
	)

Reads the result of a CRC operation in the EC module.

Parameters

ui32Base	is the base address of the EC module.
bPPResult	is true to read the post-processed result, or false to read the unmodified result.

This function reads either the unmodified CRC result or the post processed CRC result from the EC module. The post-processing options are selectable through CRC_CFG_RESINV and CRC_CFG_OBR parameters in the CRCConfigSet() function.

Returns: The CRC result.

References ASSERT, CCM_O_CRCRSLTPP, CCM_O_CRCSEED, and HWREG.

Referenced by CRCDataProcess().

§ CRCDataProcess()

uint32_t CRCDataProcess	(	uint32_t	ui32Base,
		uint32_t *	pui32DataIn,
		uint32_t	ui32DataLength,
		bool	bPPResult
	)

Process data to generate a CRC with the EC module.

Parameters

ui32Base	is the base address of the EC module.
pui32DataIn	is a pointer to an array of data that is processed.
ui32DataLength	is the number of data items that are processed to produce the CRC.
bPPResult	is true to read the post-processed result, or false to read the unmodified result.

This function processes an array of data to produce a CRC result.

The data in the array pointed to be pui32DataIn is either an array of bytes or an array or words depending on the selection of the input data size options CRC_CFG_SIZE_8BIT and CRC_CFG_SIZE_32BIT.

This function returns either the unmodified CRC result or the post- processed CRC result from the EC module. The post-processing options are selectable through CRC_CFG_RESINV and CRC_CFG_OBR parameters.

Returns: The CRC result.

References ASSERT, CCM_CRCCTRL_SIZE, CCM_O_CRCCTRL, CCM_O_CRCDIN, CRCResultRead(), and HWREG.