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Bit manipulation for Big_int #4641

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vicuna opened this issue Nov 7, 2008 · 1 comment
Closed

Bit manipulation for Big_int #4641

vicuna opened this issue Nov 7, 2008 · 1 comment
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@vicuna
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vicuna commented Nov 7, 2008

Original bug ID: 4641
Reporter: andrejbauer
Assigned to: @xavierleroy
Status: closed (set by @xavierleroy on 2011-05-29T10:14:20Z)
Resolution: fixed
Priority: normal
Severity: feature
Version: 3.10.2
Fixed in version: 3.12.0+dev
Category: ~DO NOT USE (was: OCaml general)
Related to: #4652
Monitored by: yoiwa

Bug description

The Big_int module in the Num library would benefit greatly from two simple additions: functions which can shift numbers left and right a given number of bits (the equivalent of asl, lsl, asr, lsr for the type int). Please consider adding them. I am willing to write a patch if someone tells me they will consider it.

Additional information

I am implementing real number computation in Ocaml, for which I am using the MPFR library. Since MPFR is hard to compile and link with Ocaml (requires a bunch of other tools and libraries), I have decided to reimplement dyadic rationals in "pure" Ocaml. To my shock I discovered that the Big_int package doesn't have the bit shifting operations. So now I have to divide by powers of two, which is really inefficient.

@vicuna
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vicuna commented Apr 1, 2009

Comment author: @xavierleroy

On the CVS trunk, I added big_int implementations for bitwise operations, shifts, and bit extraction. More testing is welcome. If all goes well, this will be released in 3.12.0.

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