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Re: [Xen-devel] [PATCH v2 for-4.7 13/14] oxenstored: fix error when shifting negative value

On 26/04/16 16:43, Wei Liu wrote:
> On Tue, Apr 26, 2016 at 04:37:49PM +0100, Andrew Cooper wrote:
>> On 26/04/16 16:35, Wei Liu wrote:
>>> The title is a bit too cryptic to me. Where do that shift happen?
>> Ocaml stores integers shifted left by one, and with the bottom bit set.
>> Values with the bottom bit clear are pointers into the GC'd heap. 
>> Values with the bottom bit set are integers, and need to be shifted by 1
>> bit to have calculations performed.
> This is better.
> Roger, can you add the above paragraphs to commit message? Thanks.

P.S. this is why Ocaml integers are 31 or 63 bits wide, and cause all
kinds of "fun" issues when interfacing with C which makes use of all
bits available in an integer.


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