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K-buitin Floats do not provide any hooks to convert a specific bit pattern into a single precision or double precision floating point value. #2383
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…ttern into a single precision or double precision floating point value.
Requirement: We need the ability to do the conversion as shown in examples:
Example 1:
bit-vector: 32' 01000001 01000110 00000000 00000000 === MInt(32, 1095106560)
convert to or from
Float(single precision): 12.375f.
Example 2:
bit-vector: 64' 0b0100000000101000110000000000000000000000000000000000000000000000 === MInt(64, 4623156123728347136)
convert to or from
Float(single precision): 12.375d.
Commit:
Provides two following two hooks:
1. float2mint(Float F, Int W): Converts a float point value F(single or double precision) to a BitVector or MInt of bitwidth W.
2. mint2float(MInt MI, Int Precision, Int Exponent): Converts a Bitvector or MInt to an single or double precision float point value.
The hooks are tested extensively using corner cases.
Note: The available hooks like float2Int or int2Float converts between the float and its integer equivalent and hence not suitable.
From example 2, int2Float(4623156123728347136) gives 4.623156123728347136 e+18
Some peculiarities of exiting mpfr library support:
1. While creating the BigFloat using BigFLoat constrcutor, we need to pass the unbiased exponent (mint(e1...e8) - 127) as the callee expects that. This is more evident from
https://github.com/kframework/mpfr-java/blob/a24d33c7589e285e840eaaba74368581dc15ebb3/src/main/java/org/kframework/mpfr/BigFloat.java#L357
where exponent is compared with mc.minExponent(-126) and mc.MaxExponent(+127).
2. For zero, BigFloat constructor expects -127 as opposed to -126 (a special exponent used for +/- zero). Inside the constructor, its converted back to 126. This is used to easily distinguish =/- zero and sub normals value from others.
https://github.com/kframework/mpfr-java/blob/a24d33c7589e285e840eaaba74368581dc15ebb3/src/main/java/org/kframework/mpfr/BigFloat.java#L364
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Can one of the admins verify this patch? |
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Jenkins: ok to test |
…aviour is to warn with an exception thrown, but the mvn -e clean verify make the wanr an error
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Requirement
We need the ability to do the conversion as shown in examples:
Commit:
Note
The available hooks like float2Int or int2Float converts between the float and its integer equivalent and hence not suitable.
From example 2, int2Float(4623156123728347136) gives 4.623156123728347136 e+18
Some peculiarities of exiting mpfr library support:
While creating the BigFloat using BigFLoat constrcutor, we need to pass the unbiased exponent (mint(e1...e8) - 127) as the callee expects that. This is more evident from
https://github.com/kframework/mpfr-java/blob/a24d33c7589e285e840eaaba74368581dc15ebb3/src/main/java/org/kframework/mpfr/BigFloat.java#L357
where exponent is compared with mc.minExponent(-126) and mc.MaxExponent(+127).
For zero, BigFloat constructor expects -127 as opposed to -126 (a special exponent used for +/- zero). Inside the constructor, its converted back to 126. This is used to easily distinguish =/- zero and sub normals value from others.
https://github.com/kframework/mpfr-java/blob/a24d33c7589e285e840eaaba74368581dc15ebb3/src/main/java/org/kframework/mpfr/BigFloat.java#L364
Please accept the request if it seems suitable to the k-developers.