HGKeeper

use pregenerated CRC32 lookup tables for retain on Win32 and GNU/Linux

2019-01-06, Andrey Skvortsov

68f4f2d4516b

use pregenerated CRC32 lookup tables for retain on Win32 and GNU/Linux

This code could be possible reused on low-end targets with limited RAM.

code to generate lookup table:
[---------------------------------------------------------------------]

/* CRC lookup table and initial state. */
uint32_t crc32_table[256];

/* Generate CRC32 lookup table. */
void GenerateCRC32Table(void)
{
unsigned int i, j;
/* Use CRC-32-IEEE 802.3 polynomial 0x04C11DB7 (bit reflected). */
uint32_t poly = 0xEDB88320;

for (i = 0; i <= 0xFF; i++)
{
uint32_t c = i;
for (j = 0 ; j < 8 ; j++)
c = (c & 1) ? (c >> 1 ) ^ poly : (c >> 1);
crc32_table[i] = c;
}
}

void main(void)
{
GenerateCRC32Table();
int j=0;
for(int i=0; i<256; i++) {
printf("0x%08X, ", crc32_table[i]);
if (++j >= 8) {
j = 0;
printf("\n");
}
}
}
[---------------------------------------------------------------------]

/**************************************************************************

* Permission is hereby granted, free of charge, to any person obtaining

* a copy of this software and associated documentation files (the

* "Software"), to deal in the Software without restriction, including

* without limitation the rights to use, copy, modify, merge, publish,

* distribute, sublicense, and/or sell copies of the Software, and to

* permit persons to whom the Software is furnished to do so, subject to

* the following conditions:

* The above copyright notice and this permission notice shall be included

* in all copies or substantial portions of the Software.

* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

*********************************************************************/

#ifndef AI_H

#define AI_H

#include <stdbool.h>

#include <stdint.h>

#include "bacdef.h"

#include "bacerror.h"

#include "wp.h"

#include "rp.h"

#ifdef __cplusplus

extern "C" {

#endif /* __cplusplus */

typedef struct Analog_Input_descr {

/* pointer to IEC 61131-3 located variable that is mapped onto this BACnet object */

float *Located_Var_ptr;

uint32_t Object_Identifier; /* called object 'Instance' in the source code! */

char *Object_Name;

char *Description;

uint16_t Units;

/* stores the current value */

/* one entry per priority value */

float Present_Value;

unsigned Event_State:3;

bool Out_Of_Service;

} ANALOG_INPUT_DESCR;

void Analog_Input_Property_Lists(

const int **pRequired,

const int **pOptional,

const int **pProprietary);

bool Analog_Input_Valid_Instance(

uint32_t object_instance);

unsigned Analog_Input_Count(

void);

uint32_t Analog_Input_Index_To_Instance(

unsigned index);

unsigned Analog_Input_Instance_To_Index(

uint32_t object_instance);

bool Analog_Input_Object_Name(

uint32_t object_instance,

BACNET_CHARACTER_STRING * object_name);

int Analog_Input_Read_Property(

BACNET_READ_PROPERTY_DATA * rpdata);

bool Analog_Input_Write_Property(

BACNET_WRITE_PROPERTY_DATA * wp_data);

float Analog_Input_Present_Value(

uint32_t object_instance);

char *Analog_Input_Description(

uint32_t instance);

uint16_t Analog_Input_Units(

uint32_t instance);

bool Analog_Input_Out_Of_Service(

uint32_t instance);

void Analog_Input_Out_Of_Service_Set(

uint32_t instance,

bool oos_flag);

void Analog_Input_Init(

void);

#ifdef __cplusplus

}

#endif /* __cplusplus */

#endif

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