#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <fcntl.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>
#define DEV "/dev/i2c/0"
#define EEPROM_ADDR 0x50

int i2cdev;

void i2c_readpage(unsigned char page_start, unsigned char *dest) {
	// Read 8-byte page
	
	if (write(i2cdev, &page_start, 1) != 1)
		perror("address_write");
	
	if (read(i2cdev, dest, 8) != 8)
		perror("data_read");
}

void i2c_writepage(unsigned char page_start, unsigned char *src) {
	// Write 8-byte page
	unsigned char buf[9];
	
	buf[0] = page_start;
	memcpy(buf + 1, src, 8);
	
	if (write(i2cdev, buf, 9) != 9)
		perror("data_write");
	
	while (write(i2cdev, "\x00", 1) != 1) // Busy loop
		usleep(1000);
	
	i2c_readpage(page_start, buf); // Verify
	
	if (memcmp(buf, src, 8) != 0)
		fprintf(stderr, "I2C eeprom data compare failed\n");
}

void savefile(char *filename) {
	FILE *file = fopen(filename, "w");
	
	int addr, i;
	unsigned char buf[8];
	
	for (addr = 0; addr < 0x100; addr += 8) {
		i2c_readpage(addr, buf);
		
		for (i = 0; i < 8; i++) {
			fprintf(file, "%02x ", buf[i]);
		}
		fprintf(file, "// 0x%02x - 0x%02x\n", addr, addr + 7);
	}
	fclose(file);
}

void loadfile(char *filename) {
	FILE *file = fopen(filename, "r");
	
	int addr = 0;
	char linebuf[256];
	unsigned char buf[8];
	
	while (fgets(linebuf, 256, file) && addr < 0x100) {
		int i;
		char *p = linebuf;
		for (i = 0; i < 8; i++) {
			buf[i] = strtol(p, NULL, 16);
			p += 3;
			if (!isspace(*(p - 1)))
				fprintf(stderr, "Invalid format at 0x%02x\n", addr);
		}
		
		i2c_writepage(addr, buf);
		addr += 8;
	}
	
	fclose(file);
}

int main(int argc, char *argv[]) {
	if (argc != 3) {
		fprintf(stderr, "Usage: %s load|save file\n", argv[0]);
		exit(1);
	}
	
	i2cdev = open(DEV, O_RDWR);
	
	if (i2cdev < 0)
		perror("open");
	
	if (ioctl(i2cdev, I2C_SLAVE, EEPROM_ADDR) < 0)
		perror("ioctl");
	
	if (strcmp(argv[1], "load") == 0) {
		loadfile(argv[2]);
	} else if (strcmp(argv[1], "save") == 0) {
		savefile(argv[2]);
	} else {
		fprintf(stderr, "Invalid command %s\n", argv[1]);
	}
	
	return 0;
}