[GHC] #11143: Feature request: Add index/read/write primops with byte offset for ByteArray#

[GHC]

#11143: Feature request: Add index/read/write primops with byte offset for
ByteArray#
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        Reporter:  vagarenko         |                Owner:  sjakobi
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:  newcomers
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4433
       Wiki Page:                    |
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Comment (by vagarenko):

 Replying to [comment:10 sjakobi]:
 > Replying to [comment:9 vagarenko]:
 > > Replying to [comment:8 sjakobi]:
 > > > * They relieve the user from doing the byte offset computation.
 > > Then what does that `Int# {-byte offset-}` parameter mean?
 >
 > What I meant is that the user doesn't need to compute the total offset.
 While a user may use the API you proposed like
 > {{{#!hs
 > indexByteInt16Array# ba (byte_offset + type_offset * int16_size)
 >
 > }}}
 I still don't understand. What is total offset? What are `byte_offset` and
 `type_offset`?

 By `byte_offset` you mean number of bytes from the start of the array `ba`
 to the sought value of type `Int#`, correct?

 Then what is `type_offset`? Number of `Int16` elements before the sought
 element? But my motivation for this ticket was to be able to store values
 of different types in a `ByteArray#`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11143#comment:11>
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