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bcdd.c
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bcdd.c
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/*FILE*****************************************************************/
/* File Id: bcd.c. */
/* Author: Stan Milam. */
/* Date Written: 31-Jan-95. */
/* Description: */
/* Routines to manage binary coded decimal. */
/* */
/* bcd_to_double() - Convert BCD to type double value. */
/* double_to_bcd() - Convert double type value to BCD. */
/* */
/* Placed in the public domain by the author, 8-Sep-95 */
/* */
/*****************************************************************FILE*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <float.h>
#include <math.h>
#include "snipmath.h"
/*FUNCTION*************************************************************/
/* Name: bcd_to_double(). */
/* */
/* Description: */
/* This function will convert buffer containing binary coded dec- */
/* imal to a double. */
/* */
/* Arguments: */
/* void *buf - Address of buffer containing binary coded */
/* decimal number. */
/* size_t buflen- Length of the buffer. */
/* int digits- The number of digits to the right of the */
/* decimal point. */
/* */
/* Return Value: */
/* A value of type double which should be the equivalent of the */
/* BCD value. */
/* */
/**********************************************************************/
double bcd_to_double(void *buf, size_t len, int digits)
{
double rv = 0.0;
char *buffer = (char *) buf;
size_t high, low, index, max = len - 1;
digits = abs(digits);
/******************************************************************/
/* Loop through the buffer repeatedly extracting the high and low */
/* 4 bits from each byte and calculating the return value. */
/******************************************************************/
for (index = 0; index < max; index++)
{
low = buffer[index] & 0x0f;
high = (buffer[index] & 0xf0) >> 4;
rv = (( rv * 10.0 + high ) * 10.0 + low);
}
/******************************************************************/
/* The first byte of the buffer contains the lowest order digit */
/* in the upper 4 bits and the sign in the lower 4 bits. */
/******************************************************************/
low = buffer[max] & 0x0f;
high = (buffer[max] & 0xf0) >> 4;
rv = rv * 10.0 + high;
if (digits > 0)
rv /= pow(10, digits);
if (low == 0x0d)
rv = -rv;
return rv;
}
/*FUNCTION*************************************************************/
/* Name: double_to_bcd(). */
/* */
/* Description: */
/* This function will convert a value of type double to a legit- */
/* mate Binary Coded Decimal (BCD) value. */
/* */
/* Arguments: */
/* double arg - The value to be converted. */
/* char *buf - The buffer where the BCD value is stored. */
/* size_t length - The number of significant digits to store in */
/* BCD buffer. */
/* size_t digits - The number of digits to the right of the */
/* decimal point to be stored in the BCD */
/* buffer. */
/* */
/* Return Value: */
/* An integer value indicating the length of the BCD value in the */
/* buffer. -1 is returned if an error occured. */
/* */
/*************************************************************FUNCTION*/
int double_to_bcd(double arg, char *buf, size_t length, size_t digits )
{
char wrkbuf[50], format[DBL_DIG + 1];
int y_sub, x_sub, rv, negative=0;
/******************************************************************/
/* Do a couple of sanity checks first. */
/******************************************************************/
if ((length == 0 && digits == 0) || (length + digits > DBL_DIG))
rv = -1;
else
{
/**************************************************************/
/* If the double argument is negative make a note of it and */
/* con- vert the value to be positive. */
/**************************************************************/
if (arg < 0.0)
{
arg = -arg;
negative = 1;
}
/**************************************************************/
/* Adjust for decimal digits. */
/**************************************************************/
if (digits > 0)
{
length += digits;
arg *= pow( 10, digits );
}
/**************************************************************/
/* Build the format string, build the string and compute the */
/* return value. */
/**************************************************************/
sprintf( format, "%%0%d.0f", length );
sprintf( wrkbuf, format, floor( arg ) );
if ((rv = (length / 2 ) + (length / 2 != 0)) == 0)
rv = 1;
/**************************************************************/
/* Compute the subscript values and clear the BCD buffer. */
/**************************************************************/
y_sub = rv - 1;
x_sub = strlen( wrkbuf ) - 1;
memset( buf, 0, y_sub + 1 );
/**************************************************************/
/* Plug in the sign bits and first BCD digit. */
/**************************************************************/
buf[y_sub] = negative == 1 ? 0xd : 0xc;
buf[y_sub--] |= ( ( wrkbuf[x_sub--] - '0' ) << 4 );
/**************************************************************/
/* While we have more digits to plug.... */
/**************************************************************/
while ( --length > 0 )
{
/**********************************************************/
/* Do the low nibble of the BCD byte. */
/**********************************************************/
buf[y_sub] = wrkbuf[x_sub--] - '0';
if (--length <= 0)
break;
/**********************************************************/
/* Now do the high nibble. */
/**********************************************************/
buf[y_sub--] |= ((wrkbuf[x_sub--] - '0') << 4);
}
}
return rv;
}
/* */
#ifdef TEST
typedef struct {
double value, expect;
int length, digits;
} TEST_T;
int main(void)
{
double rv, value;
char wrkbf[25];
int rc, x_sub, y_sub, size, len, digits;
char format[] = " %10.3f %d %d %d ";
TEST_T testvals[] = {
{ 12345.67, 123.45, 5, 0 },
{ 12345.67, 12345.0, 5, 1 },
{ 12345.67, 12345.67, 4, 3 },
{ 12345.678, 2345.67, 1, 2 },
{ -12345.00, -12345.00, 8, 2 },
{ -1234.56, -12345.00, 5, 3 },
{ 1234.567, 0.60, 1, 3 }
};
size = sizeof( testvals ) / sizeof( TEST_T );
printf(" Double Length Digits Return\n");
printf(" Argument Argument Argument Value Buffer\n");
printf(" ================================================="
"=========\n");
for (x_sub = 0; x_sub < size; x_sub++)
{
len = testvals[x_sub].length;
digits = testvals[x_sub].digits;
value = testvals[x_sub].value;
rc = double_to_bcd(value, wrkbf, len, digits);
if (rc > 0)
{
printf( format, value, len, digits, rc );
for ( y_sub = 0; y_sub < rc; y_sub++ )
printf("%02X ", wrkbf[y_sub]);
printf("\n");
}
}
return 0;
}
#endif