convert hex to bcd in c

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erodeboy

Joined: 15 Nov 2005
Posts: 86
Helped: 1
Location: India

12 Mar 2006 3:27 hex to bcd

how to convert a hex value to bcd using keil c

SphinX

Joined: 25 Jan 2002
Posts: 1069
Helped: 28
Location: EGYPT

12 Mar 2006 7:52 hex to bcd conversion in c

Salam,

You didn't mention what is the length of the hex 8 bit, 16 bits ...etc

Ok here is a simple method to convert hex (8bit) to bcd

One restriction that method is vaild fot numbers 0 - 99 only.

for example if you want to convert 99 to bcd

1- divide 99 by 10
2- put the result in the high nibble of the result variable
3- put the reminder in the low nibble of the result variable

This method is very easy to implement in C like this

Code:

unsigned char hex2bcd (unsigned char x)
{
unsigned char y;
y = (x / 10) << 4;
y = y | (x % 10);
return (y);
}

Where X is the Hex , and Y is the result

Enjoy

Bye

silvio

Joined: 31 Dec 2001
Posts: 801
Helped: 90

12 Mar 2006 7:57 hex to bcd conversion c code

Quote:

From fmayr(at)electronic.tu-graz.ac.at Thu Feb 6 10:24:30 1997
Date: Wed, 05 Feb 1997 15:36:00 +0100
From: Friedrich Mayr <fmayr(at)electronic.tu-graz.ac.at>
To: 8051code(at)keil.com
Subject: Fast LONG to BCD conversion

This function was written within the Keil C51 environment
by Dr. Roehrer (Inst. f. Elektronik, TU-Graz) and me
to be called from a C - Program as: "void bin2bcd(void)"

The following global variable (must be located in the
internal RAM of the processor, "data" or "idata" ) is
used both to pass the argument (a "long" value) to the
function, as well as to receive the result (6 digits):

union
{
unsigned char buf[6];
long in;
} idata U_b;

The purpose of the code is to convert a signed long value
to BCD - code with leading sign if needed. Values exceeding
the range of 6(-:5) Digits should all be displayed by '-'.
The usage of memory was critical because no external RAM is
present in the system, so only the Accu, B, R1, R2, R3, R4
are used aside of the digit- (and argument-) buffer "U_b".

The trick applied in the function is to use a
"small" (nibble by nibble) division and the extensive
use of the '51 - opcodes XCHD and SWAP.
This results in very fast execution.
The function can easily be modified for example
to time-calculations or extended to the full "long"
range .

http://www.boerde.de/~matthias/m8051/bin2bcd.zip