Convert packed integer from AS400

Working from the info in this link (and Figure 88 to which it refers):

http://publib.boulder.ibm.com/iseries/v5r2/ic2924/books/c0925083170.htm

I've come up with the following conversion method assuming you can retrieve the packed field as a byte array from the AS400 server.

As packed decimals can be up to 29 digits long, only .NET's decimal type is large enough to deal accurately with them and so the method returns a decimal rather than an int, long or double:

using System;

class Program

{

static void Main()

{

byte[] bytes = new byte[3];

bytes[0] = 2 * 16 + 1;

bytes[1] = 5 * 16 + 4;

bytes[2] = 4 * 16 + 15;

decimal d = FromPackedDecimal(bytes);

Console.WriteLine(d); // 21544

Console.ReadKey();

}

static decimal FromPackedDecimal(byte[] bytes)

{

if (bytes == null || bytes.Length == 0)

{

throw new ArgumentException ("Byte array can't be null or empty");

}

int len = bytes.Length;

// get low order byte

byte lob = bytes[len - 1];

// get sign nybble

int nybble = lob % 16;

int sign;

if (nybble == 15)

{

sign = 1;

}

else if (nybble == 13)

{

sign = -1;

}

else

{

throw new ArgumentException("Low order byte contains unrecognized sign");

}

decimal result = lob / 16;

if (len > 1)

{

decimal multiplier = 1m;

for(int i = len - 2; i >= 0; i--)

{

multiplier *= 10m;

result += multiplier * (bytes[i] % 16);

multiplier *= 10m;

result += multiplier * (bytes[i] / 16);

}

return result * sign;

}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

Vulpes13y ago
Working from the info in this link (and Figure 88 to which it refers):

http://publib.boulder.ibm.com/iseries/v5r2/ic2924/books/c0925083170.htm

I've come up with the following conversion method assuming you can retrieve the packed field as a byte array from the AS400 server.

As packed decimals can be up to 29 digits long, only .NET's decimal type is large enough to deal accurately with them and so the method returns a decimal rather than an int, long or double:

using System;

class Program
{
static void Main()
{
byte[] bytes = new byte[3];
bytes[0] = 2 * 16 + 1;
bytes[1] = 5 * 16 + 4;
bytes[2] = 4 * 16 + 15;
decimal d = FromPackedDecimal(bytes);
Console.WriteLine(d); // 21544
Console.ReadKey();
}

static decimal FromPackedDecimal(byte[] bytes)
{
if (bytes == null || bytes.Length == 0)
{
throw new ArgumentException ("Byte array can't be null or empty");
}

int len = bytes.Length;
// get low order byte
byte lob = bytes[len - 1];
// get sign nybble
int nybble = lob % 16;
int sign;

if (nybble == 15)
{
sign = 1;
}
else if (nybble == 13)
{
sign = -1;
}
else
{
throw new ArgumentException("Low order byte contains unrecognized sign");
}

decimal result = lob / 16;

if (len > 1)
{
decimal multiplier = 1m;

for(int i = len - 2; i >= 0; i--)
{
multiplier *= 10m;
result += multiplier * (bytes[i] % 16);
multiplier *= 10m;
result += multiplier * (bytes[i] / 16);
}
}

return result * sign;
}
}
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