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byte swapping 32-bit float and weird od results
Post 302317361 by GoDonkeys on Monday 18th of May 2009 08:57:09 PM
05-18-2009
byte swapping 32-bit float and weird od results
I'm attempting to read a file that is composed of complex 32-bit floating point values on Solaris 10 that came from a 64-bit Red Hat computer.
When I first tried reading the file, it looked like there was a byte-swapping problem and after running the od command on the file Solaris and Red Hat computers, I saw that they were indeed swapped (every other byte). So, I wrote a little Java program that would swap every other byte and the result was the at the byte-level, the files were the same on both computers. The following is the result of running 'od -x' on the file, showing the first 32-bits which represent the real portion of the first complex number:
f8a6 be03 cd76 bc99
What's weird is that when I run 'od -f' on both computers to see the 32-bit floating point value, I get different results! On the Red Hat computer I get: -1.288782e-01 and on the Solaris computer I get: -2.7055474e+34
. How can I have the same byte level file yet come up with completely different values when I try to print out the bytes as 32-bit floats?
This is really messing me up trying to write a C++ program to read this file on the Solaris computer. I'm getting the same value in my C++ code as what I see when I run 'od -f' on the Solaris computer. I've tried just about everything that I can think of and haven't been able to get past this.
Does anyone have any idea on what's going on with the od command between the Red Hat and Solaris computers? Any ideas on how to get my C++ code to give me the correct value for the 32-bit float?
When I first tried reading the file, it looked like there was a byte-swapping problem and after running the od command on the file Solaris and Red Hat computers, I saw that they were indeed swapped (every other byte). So, I wrote a little Java program that would swap every other byte and the result was the at the byte-level, the files were the same on both computers. The following is the result of running 'od -x' on the file, showing the first 32-bits which represent the real portion of the first complex number:
f8a6 be03 cd76 bc99
What's weird is that when I run 'od -f' on both computers to see the 32-bit floating point value, I get different results! On the Red Hat computer I get: -1.288782e-01 and on the Solaris computer I get: -2.7055474e+34
. How can I have the same byte level file yet come up with completely different values when I try to print out the bytes as 32-bit floats?This is really messing me up trying to write a C++ program to read this file on the Solaris computer. I'm getting the same value in my C++ code as what I see when I run 'od -f' on the Solaris computer. I've tried just about everything that I can think of and haven't been able to get past this.
Does anyone have any idea on what's going on with the od command between the Red Hat and Solaris computers? Any ideas on how to get my C++ code to give me the correct value for the 32-bit float?
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LEARN ABOUT OPENSOLARIS
lx
lx(5) Standards, Environments, and Macros lx(5) NAME
lx - Linux branded zone DESCRIPTION
The lx brand uses the branded zones framework described in brands(5) to enable Linux binary applications to run unmodified on a machine with a Solaris Operating System kernel. The lx brand includes the tools necessary to install a CentOS 3.x or Red Hat Enterprise Linux 3.x distribution inside a non-global zone. The brand supports the execution of 32-bit Linux applications on x86/x64 machines running the Solaris system in either 32-bit or 64-bit mode. Supported Linux Distributions The lx brand emulates the system call interfaces provided by the Linux 2.4.21 kernel, as modified by Red Hat in the RHEL 3.x distributions. This kernel provides the system call interfaces consumed by the glibc version 2.3.2 released by Red Hat. In addition, the lx brand partially emulates the Linux /dev and /proc interfaces. Configuration and Administration The lx brand supports the whole root non-global zone model. All of the required linux packages are installed into the private file systems of the zone. The zonecfg(1M) utility is used to configure an lx branded zone. Once a branded zone has been installed, that zone's brand cannot be changed or removed. The zoneadm(1M) utility is used to report the zone's brand type and administer the zone. The zlogin(1) utility is used to log in to the zone. Application Support The lx zone only supports user-level Linux applications. You cannot use Linux device drivers, Linux kernel modules, or Linux file systems from inside an lx zone. You cannot add any non-standard Solaris devices to a Linux zone. Any attempt to do so will result in a zone that zonecfg(1M) will refuse to verify. You cannot run Solaris applications inside an lx zone. Solaris debugging tools such as DTrace (see dtrace(1M)) and mdb (see mdb(1)) can be applied to Linux processes executing inside the zone, but the tools themselves must be running in the global zone. Any core files generated are produced in the Solaris format, and such files can only be debugged with Solaris tools. ATTRIBUTES
See attributes(5) for a description of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWlxr, SUNWlxu | +-----------------------------+-----------------------------+ |Interface Stability |Evolving | +-----------------------------+-----------------------------+ SEE ALSO
mdb(1), zlogin(1), zonename(1), dtrace(1M), zoneadm(1M), zonecfg(1M), brands(5), zones(5), lx_systrace(7D) SunOS 5.11 19 Sep 2006 lx(5)