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[Cs-dev] table opcodes also for non-power-of-two tables?

Date2010-07-26 12:05
Fromjoachim heintz
Subject[Cs-dev] table opcodes also for non-power-of-two tables?
does anyone know, or can see from the code, whether the table and  
table(i)w opcodes can be used also for non powof2 table sizes?
i am a bit confused because it seems to work (i just made a test) but  
i am not sure if this is pure hazard.

thanks -

	joachim

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Date2010-07-26 16:34
Fromjpff@cs.bath.ac.uk
SubjectRe: [Cs-dev] table opcodes also for non-power-of-two tables?
table(i)w uses masking for wrapping and so is power-of-two only

table on the otherhabd seems to allow any size

"      /* Previously this code limited the upper range of the indx to
       * the table length - for instance 8.  Then the result was ANDed
       * with a mask (for instance 7).
       *
       * This meant that when the input index was 8 or above, it got
       * reduced to 0.  What we want is for it to stick at the index
       * which reads the last value from the table - in this example
       * from location 7.
       *
       * So instead of limiting to the table length, we limit to
       * (table length - 1).  */
"

==John ff
> does anyone know, or can see from the code, whether the table and
> table(i)w opcodes can be used also for non powof2 table sizes?
> i am a bit confused because it seems to work (i just made a test) but
> i am not sure if this is pure hazard.
>
> thanks -
>
> 	joachim



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Date2010-07-26 17:27
Fromjoachim heintz
SubjectRe: [Cs-dev] table opcodes also for non-power-of-two tables?
thanks!

	joachim


Am 26.07.2010 um 17:34 schrieb jpff@cs.bath.ac.uk:

>
> table(i)w uses masking for wrapping and so is power-of-two only
>
> table on the otherhabd seems to allow any size
>
> "      /* Previously this code limited the upper range of the indx to
>       * the table length - for instance 8.  Then the result was ANDed
>       * with a mask (for instance 7).
>       *
>       * This meant that when the input index was 8 or above, it got
>       * reduced to 0.  What we want is for it to stick at the index
>       * which reads the last value from the table - in this example
>       * from location 7.
>       *
>       * So instead of limiting to the table length, we limit to
>       * (table length - 1).  */
> "
>
> ==John ff
>> does anyone know, or can see from the code, whether the table and
>> table(i)w opcodes can be used also for non powof2 table sizes?
>> i am a bit confused because it seems to work (i just made a test) but
>> i am not sure if this is pure hazard.
>>
>> thanks -
>>
>> 	joachim
>
>
>
> ------------------------------------------------------------------------------
> The Palm PDK Hot Apps Program offers developers who use the
> Plug-In Development Kit to bring their C/C++ apps to Palm for a share
> of $1 Million in cash or HP Products. Visit us here for more details:
> http://ad.doubleclick.net/clk;226879339;13503038;l?
> http://clk.atdmt.com/CRS/go/247765532/direct/01/
> _______________________________________________
> Csound-devel mailing list
> Csound-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/csound-devel
>


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