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Count Leading Zeros

Note: This was originally posted on 6th April 2009 at http://forums.arm.com

Using the ARM9 CLZ instruction - I am wondering, generally, how often would it be required to use this function and does it justify its inclusion?
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  • Note: This was originally posted on 7th April 2009 at http://forums.arm.com

    Normalization is the act of shifting the fractional part in order to make the left bit of the fractional point is one. This normalization is used in IEEE-754 compatible binary floating-point addition/subtraction. Let say you 20 leading zeros in the sum result, you may need 20 instructions to shift left "˜1' to become MSB and count the leading zeros. This count will be used to set the exponent value. Now the CLZ helps to have one instruction to find the count of leading zeros. This will speed up the normalization during binary floating-point addition/subtraction. One of widely used application is the Digital Signal Processing.
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  • Note: This was originally posted on 7th April 2009 at http://forums.arm.com

    Normalization is the act of shifting the fractional part in order to make the left bit of the fractional point is one. This normalization is used in IEEE-754 compatible binary floating-point addition/subtraction. Let say you 20 leading zeros in the sum result, you may need 20 instructions to shift left "˜1' to become MSB and count the leading zeros. This count will be used to set the exponent value. Now the CLZ helps to have one instruction to find the count of leading zeros. This will speed up the normalization during binary floating-point addition/subtraction. One of widely used application is the Digital Signal Processing.
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