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#include <stdio.h>

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/* size of NVRAM in bytes */

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#define NVRAM_MAX_SIZE 262144

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/* size of block in byte */

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#define NVRAM_BLOCK_SIZE 256

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#define NVRAM_FILE_NAME "__nvram__"

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FILE *nvram_file = NULL;

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void iat_flash_read_regs();

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void iat_flash_write_regs();

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void iat_flash_write_page(unsigned int);

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void iat_flash_read_page(unsigned int);

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short data_len; /* 0 to NVRAM_BLOCK_SIZE bytes */

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short data_num_pages;

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unsigned int *data_page = NULL;

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unsigned int data_addr;

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unsigned int *regs_page = NULL;

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int iat_init()

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{

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	int i;

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	nvram_file = fopen(NVRAM_FILE_NAME, "wr");

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	if (nvram_file  == NULL)

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		return -1;

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	int n = NVRAM_BLOCK_SIZE / sizeof(unsigned int);

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	/* some actions to initialise the flash */

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	data_len = 0;

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	data_num_pages = 0;

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	data_page = (unsigned int *)malloc(sizeof(unsigned int) * n);

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	memset(data_page, 0, sizeof(unsigned int)*n);

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	if (data_page == NULL)

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		return -1;

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	regs_page = (unsigned int *)malloc(sizeof(unsigned int) * n);

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	memset(regs_page, 0, sizeof(unsigned int)*n);

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	if (regs_page == NULL)

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		return -2;

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	iat_flash_read_regs();

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	/* start the data at the location specified in the registers */ 

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	if (0) /* for now it is 0, but put here a test to know whether

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                  or not the NVRAM has been written before */

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		data_addr = regs_page[1];

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	else

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		data_addr = NVRAM_BLOCK_SIZE; /* let start at block 1 */

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	/* create a file the size of the simulated NVRAM */

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	for(i=0; i<NVRAM_MAX_SIZE/NVRAM_BLOCK_SIZE + 1; i++)

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		fwrite(data_page, sizeof(unsigned int), n, nvram_file);

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	return 0;

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}

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void iat_end()

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{

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	iat_flash_write_page(data_addr);

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	iat_flash_write_regs();

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	fclose(nvram_file);

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}

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void iat_flash_read_regs()

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{

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	fseek(nvram_file, 0, SEEK_SET);

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	fread(regs_page, sizeof(unsigned int), NVRAM_BLOCK_SIZE, nvram_file);

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}

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void iat_flash_write_regs()

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{

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	fseek(nvram_file, 0, SEEK_SET);

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	fwrite(regs_page, sizeof(unsigned int), NVRAM_BLOCK_SIZE, nvram_file);

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}

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void iat_flash_read_page(unsigned int addr)

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{

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	fseek(nvram_file, addr*sizeof(unsigned int), SEEK_SET);

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	fread(data_page, sizeof(unsigned int), NVRAM_BLOCK_SIZE, nvram_file);

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}

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void iat_flash_write_page(unsigned int addr)

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{

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	fseek(nvram_file, addr*sizeof(unsigned int), SEEK_SET);

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	fwrite(data_page, sizeof(unsigned int), NVRAM_BLOCK_SIZE, nvram_file);

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}

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/*------------------------------------------------------*/

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int main()

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{

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	iat_init();

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	iat_end();

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}

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/*------------------------------------------------------*/