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kaushiksangam
Joined: 09 Apr 2006
Posts: 14
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 22 Aug 2006 14:27 Fixed point operations in C |
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I want to emulate an algorithm in C before actually writing to hardware.
This algorithm invovles lot of multiplications and additions of real numbers. Hence, I want to use fixed point operations(to represent real numbers) in C to emulate the algorithm.
Can someone please tell me or give me an example of how to perform fixed point operations in C.
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jagan326
Joined: 22 Aug 2006
Posts: 3
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| 22 Aug 2006 16:18 Re: Fixed point operations in C |
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| hey can u give me the details of this topic
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kaushiksangam
Joined: 09 Apr 2006
Posts: 14
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| 22 Aug 2006 16:30 Re: Fixed point operations in C |
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It is about the implementation of a Brain State in a Box (BSB) algorithm. Before implementinng this in hardware, i would want to emulate the same in C.
Already have implemented algorithm in C through floating point oprations.
I can also send you the code of the implementation.
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neuralc
Joined: 06 Nov 2001
Posts: 270
Helped: 5
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| 22 Aug 2006 19:11 Fixed point operations in C |
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Why dont use floating point?
Which up are you using?
NeuralC
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alvarorahul
Joined: 13 Apr 2005
Posts: 112
Helped: 5
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| 23 Aug 2006 5:13 Fixed point operations in C |
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u can use an array of two integers for each number then, for example
0.004676 can be stored as
var1=4676 and var2= -3 u can u short int for the var2 coz im assuming that ur powers would not vary too much
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neuralc
Joined: 06 Nov 2001
Posts: 270
Helped: 5
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| 24 Aug 2006 13:02 Fixed point operations in C |
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| This is floating point....
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lambtron
Joined: 02 Nov 2005
Posts: 256
Helped: 26
Location: Portland, OR
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| 24 Aug 2006 16:53 Re: Fixed point operations in C |
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| kaushiksangam wrote: |
| Can someone please tell me or give me an example of how to perform fixed point operations in C. |
Have a look at this: http://www.embedded.com/98/9804fe2.htm
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louisnells
Joined: 08 May 2006
Posts: 212
Helped: 13
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| 25 Aug 2006 6:13 Re: Fixed point operations in C |
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Hi,
Fixed point operations in C is not that difficult to implement.
Lets say we are storing numbers in 8.24 format. So we can use a 32 bit un-signed integer for that. We are going to store the integer 8 bits in the MSB side and the fractional 24 bits on the LSB side (as we always represent in digital form - Little Endian). Then may be you should write a small library for fixed operations. Then implement operations like multiplication as bit-wise operations.
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rme_elektroda
Joined: 04 Oct 2006
Posts: 6
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| 05 Oct 2006 10:27 Re: Fixed point operations in C |
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Probably useful link
http://www.embedded.com/showArticle.jhtml?articleID=15201575
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