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comp.lang.ruby

unpacking network long that contain ints

Joe Van Dyk

4/2/2005 2:21:00 AM

Hi,

I have a binary file that contains a bunch of unsigned longs in
network byte order. Each long contains 4 unsigned ints.

In C, I'd do:
rgb_long = ntohl(rgb_long);

/* Extract out the red, green, and blue elements from the
* RGB long. */
red = rgb_long << 0 >> 24;
green = rgb_long << 8 >> 24;
blue = rgb_long << 16 >> 24;

In Ruby, I have:
# I have the long in host byte order, but it's now a FixNum.
rgb = binary_data.unpack("N")[0]

# Works, but byte order is messed up
r, g, b = binary_data.unpack("CCCC")

Ideas?

Thanks,
joe
3 Answers

YANAGAWA Kazuhisa

4/2/2005 4:36:00 PM

0

In Message-Id: <c715e64050401182020434e4c@mail.gmail.com>
Joe Van Dyk <joevandyk@gmail.com> writes:

> # Works, but byte order is messed up
> r, g, b = binary_data.unpack("CCCC")

irb(main):011:0> [0x123456].pack('N').unpack('C4').map {|e| '%x'%e}
=> ["0", "12", "34", "56"]

What do you mean by "messed up"? or do I missed something obvious?


--
kjana@dm4lab.to April 3, 2005
Better late than never.

guitarannie

6/6/2010 1:49:00 AM

0

Ron Carter and his clones?

guitarannie

6/6/2010 1:51:00 AM

0

Oh yeah and where's his bass? ;-)