Hexadecimal C string to decimal integer converter function.

HexToDec.h

#include <assert.h>

int hexToDec(char *hex) {
	int dec = 0;

	do {
		assert((*hex >= '0' && *hex <= '9') || (*hex >= 'A' && *hex <= 'F'));
		dec = (dec << 4) | ((*hex - ((*hex >= 'A') ? ('A' - 10) : '0')) & 0xF);
	} while (*++hex);

	return dec;
}