bcd2.c

/*
* $Id: bcd2.c,v 1.2 2005/01/03 20:08:58 jms Exp $
*
* Revision History
* ===================
* $Log: bcd2.c,v $
* Revision 1.2  2005/01/03 20:08:58  jms
* change line terminations
*
* Revision 1.1.1.1  2004/11/24 23:31:45  jms
* re-establish external server
*
* Revision 1.1.1.1  2003/04/03 18:54:21  jms
* recreation after CVS crash
*
* Revision 1.1.1.1  2003/04/03 18:54:21  jms
* initial checkin
*
*
*/
/*
 * bcd.c: conversion routines for multi-byte arithmetic
 *
 * defined routines:
 * bin_bcd2(long binary, long *low_res, long *high_res)
 * bcd2_bin(long *dest, long bcd)
 * bcd2_add(long *bcd_low, long *bcd_high, long addend)
 * bcd2_sub(long *bcd_low, long *bcd_high, long subend)
 * bcd2_mul(long *bcd_low, long *bcd_high, long multiplier)
 * bcd2_div(long *bcd_low, long *bcd_high, long divisor)
 * long bcd2_mod(long *bcd_low, long *bcd_high, long modulo)
 * long bcd2_cmp(long *bcd_low, long *bcd_high, long compare)
 */
#include <stdio.h>
#include "bcd2.h"	/* for function prototypes */

#define DIGITS_PER_LONG 7
#define WORD_DIVISOR    10000000
#define GET_DIGIT(num, low, high) \
    ((num) >= DIGITS_PER_LONG)? \
        (high & (0xF << (4 * ((num) - DIGITS_PER_LONG)))) \
            >> (((num) - DIGITS_PER_LONG) * 4): \
        (low & (0xF << (4 * (num)))) >> ((num) * 4)
#define SET_DIGIT(value, num, low, high) \
    if ((num) >= DIGITS_PER_LONG) \
        { \
        *high &= \
            (0xFFFFFFF ^ (0xF << (4 * ((num) - DIGITS_PER_LONG)))); \
        *high |= (value << (4 * ((num) - DIGITS_PER_LONG))); \
        } \
    else \
        { \
        *low = (*low & (0xFFFFFFF ^ (0xF << (4 * (num))))); \
        *low |= (value << (4 * (num))); \
        }
int 
bin_bcd2(long binary, long *low_res, long *high_res)
{
    char number[15],
         *current;
    int count;  
    long *dest;

	*low_res = *high_res = 0;
    sprintf(number, "%014ld", binary);
    for (current = number, count=13; *current; current++, count--)
        {
        dest = (count < DIGITS_PER_LONG)?low_res:high_res;
        *dest = *dest << 4;
        *dest |= *current - '0';
        }
    return(0);
}

int
bcd2_bin(long *dest, long bcd)
{
    int count;
    long mask;
         
    count = DIGITS_PER_LONG - 1;
    mask = 0xF000000;
	*dest = 0;
    while (mask)
        {
        *dest *= 10;
        *dest += (bcd & mask) >> (4 * count);
        mask = mask >> 4;
        count -= 1;
        }
    return(0);
}

int
bcd2_add(long *bcd_low, long *bcd_high, long addend)
{
    long tmp_lo, tmp_hi, carry, res;
    int digit;

    bin_bcd2(addend, &tmp_lo, &tmp_hi);
    carry = 0;
    for (digit=0; digit < 14; digit++)
        {
        res = GET_DIGIT(digit, *bcd_low, *bcd_high); 
        res += GET_DIGIT(digit, tmp_lo, tmp_hi);
        res += carry;
        carry = res / 10;
        res %= 10;
        SET_DIGIT(res, digit, bcd_low, bcd_high);
        }
    return(carry);
}

int
bcd2_sub(long *bcd_low, long *bcd_high, long subend)
{
    long tmp_lo, tmp_hi, carry, res;
    int digit;

    bin_bcd2(subend, &tmp_lo, &tmp_hi);
    carry = 0;
    for (digit=0; digit < 14; digit++)
        {
        res = GET_DIGIT(digit, *bcd_low, *bcd_high); 
        res -= GET_DIGIT(digit, tmp_lo, tmp_hi);
        res -= carry;
        if (res < 0) 
			{
			res += 10;
			carry = 1;
			}
        SET_DIGIT(res, digit, bcd_low, bcd_high);
        }
    return(carry);
}

int
bcd2_mul(long *bcd_low, long *bcd_high, long multiplier)
{
    long tmp_lo, tmp_hi, carry, m_lo, m_hi, m1, m2;
    int udigit, ldigit, res;

    tmp_lo = *bcd_low;
    tmp_hi = *bcd_high;
    bin_bcd2(multiplier, &m_lo, &m_hi);
    *bcd_low = 0;
    *bcd_high = 0;
    carry = 0;
    for (ldigit=0; ldigit < 14; ldigit++)
        {
        m1 = GET_DIGIT(ldigit, m_lo, m_hi); 
        carry = 0;
        for (udigit=0; udigit < 14; udigit++)
            {
            m2 = GET_DIGIT(udigit, tmp_lo, tmp_hi);
            res = m1 * m2;
            res += carry;
            if (udigit + ldigit < 14)
                {
                carry = GET_DIGIT(udigit + ldigit, *bcd_low, *bcd_high);
                res += carry;
                }
            carry = res / 10;
            res %= 10;
            if (udigit + ldigit < 14)
                SET_DIGIT(res, udigit + ldigit, bcd_low, bcd_high);
            }
        }
    return(carry);
}

int
bcd2_div(long *bcd_low, long *bcd_high, long divisor)
{
    long tmp_lo, tmp_hi, carry, d1, res, digit;
    

    carry = 0;
    tmp_lo = *bcd_low;
    tmp_hi = *bcd_high;
    *bcd_low = *bcd_high = 0;
    for (digit=13; digit >= 0; digit--)
        {
        d1 = GET_DIGIT(digit, tmp_lo, tmp_hi);
        d1 += 10 * carry; 
        res = d1 / divisor;
        carry = d1 % divisor;
        SET_DIGIT(res, digit, bcd_low, bcd_high);
        }
    return(carry);
}

long
bcd2_mod(long *bcd_low, long *bcd_high, long modulo)
{
	long tmp_low, tmp_high;

	tmp_low = *bcd_low;
	tmp_high = *bcd_high;
	while (tmp_high || tmp_low > modulo)
		bcd2_sub(&tmp_low, &tmp_high, modulo);
	return(tmp_low);
}

long
bcd2_cmp(long *low1, long *high1, long comp)
{
	long temp = 0;

    bcd2_bin(&temp, *high1);
	if (temp > 214) 
		return(1);
    bcd2_bin(&temp, *low1);
	return(temp - comp);
}

#ifdef TEST_BCD
#include <values.h>

main()
{
long bin, low_bcd, high_bcd;
int i;

bin = MAXINT;
printf("%ld\n", bin);
bin_bcd2(bin, &low_bcd, &high_bcd);
printf("%ld  %ld\n", high_bcd, low_bcd);
bin = 0;
bcd2_bin(&bin, high_bcd);
bcd2_bin(&bin, low_bcd);
printf( "%ld\n", bin);
for (i=9; i >= 0; i--)
    printf("%dth digit in %d is %d\n", 
        i, bin, GET_DIGIT(i, low_bcd, high_bcd));
bcd2_add(&low_bcd, &high_bcd, MAXINT);
bin = 0;
bcd2_bin(&bin, high_bcd);
high_bcd = bin;
bin = 0;
bcd2_bin(&bin, low_bcd);
low_bcd = bin;
printf( "%ld%07ld\n", high_bcd, low_bcd);
bin_bcd2(14, &low_bcd, &high_bcd);
bcd2_mul(&low_bcd, &high_bcd, 23L);
bin = 0;
bcd2_bin(&bin, high_bcd);
bcd2_bin(&bin, low_bcd);
printf( "%ld\n", bin);
bcd2_div(&low_bcd, &high_bcd, 10L);
bin = 0;
bcd2_bin(&bin, high_bcd);
bcd2_bin(&bin, low_bcd);
printf( "%ld\n", bin);
}
#endif /* TEST */