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Trying to Swap Byte on Floats
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Trying to Swap Byte on Floats


  • Subject: Trying to Swap Byte on Floats
  • From: "Peter J. Molfese" <email@hidden>
  • Date: Thu, 21 Jun 2007 01:40:46 -0400

Hi all-

I know that I'm missing the simple answer on this, but I'm trying to read float values out of a binary file. The binary file was encoded using a PowerPC big-endian format. I'm reading the binary file on an Intel-mac and trying to do the swapping of bits.

My code worked when I was running in Rosetta as follows:
int file_location = 26;
float SSR = *((const float *)([myFile bytes] + file_location));
file_location += 4;

Now on the intel-mac side in the conversion I've attempted the following:
1. Simple approach:
float SSR = EndianS32_BtoN(*((const float *)([myFile bytes] + file_location)));


2. Round-about:
float tempSSR = *((const float *)([myFile bytes] + file_location));
float SSR = NSConvertSwappedFloatToHost(NSConvertHostFloatToSwapped (tempSSR));


Approach #1 seems to give me a lot of numbers that are either 0 or very very small 1.2*10-13. Approach #2 gives me the same numbers as if I didn't swap the bits at all. Is there an easy way to read in the big-endian floats and convert them to little-endian that I'm missing?

Thanks,
Pete
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