bcd.c

基于AVRGCC的时钟DS1302的完整应用源代码

#include <avr/io.h>

#ifdef BCD_USE_TABLE

#include <avr/pgmspace.h >

const unsigned char PROGMEM bcd2bin_data[] = {
     0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 0, 0, 0, 0, 0, 0,
	10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 0, 0, 0, 0, 0, 0,
	20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 0, 0, 0, 0, 0, 0,
	30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 0, 0, 0, 0, 0, 0,
	40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 0, 0, 0, 0, 0, 0,
	50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 0, 0, 0, 0, 0, 0,
	60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 0, 0, 0, 0, 0, 0,
	70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 0, 0, 0, 0, 0, 0,
	80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 0, 0, 0, 0, 0, 0,
	90, 91, 92, 93, 94, 95, 96, 97, 98, 99
 };
  
 const unsigned char PROGMEM bin2bcd_data[] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99
 };
#endif

unsigned char bcd2bin(unsigned char n)
{
#ifdef BCD_USE_TABLE
	return pgm_read_byte(bcd2bin_data + n);
#else	
	unsigned char x = (n & 0xF0) >> 4;
	
	if (x > 9 || (n & 0x0F) > 9)
	{
		return 0;
	}
	else
	{
		return (x << 3) + (x << 1) + (n & 0x0F);
	}
#endif	
}

unsigned char bin2bcd(unsigned char n)
{
#ifdef BCD_USE_TABLE
	return pgm_read_byte(bin2bcd_data + n);
#else
	unsigned char result = 0;
	
	if (n > 99) return 0;
	while(n > 10)
	{
		++result;
		n -= 10;
	}
	return (result << 4) | n;
#endif	
}