[Vm-dev] Reed Solomon plugins & performance slow down

[Robert Withers]

Alright, Eliot! I finally got the changes made. You know that time when you have 2 images and you do the work in one and forget, then delete that one and have to recode all those changes? Exactly.

Nonetheless, I got the changes made and did a test of creating a ByteArray in a primitive/computation method:

> #fecAddOrSubtractPolySelfCoefficients:selfCount:otherCoefficients:otherCount:.

In my case, I decided to create the result ByteArray in the computation method and return the resultOop to the primitive for #methodReturnValue:. Here is the primitive, followed by the computation method. This seems to work as I compiled and tested it. One consideration is that if we are in a primitive and call another, like happens in the decode methods, then I must remember to #interpreterProxy firstIndexableField: resultOop to access the array again (pass as argument to yet another compute method, for instance). Is this the best approach?

> resultOop := self
> fecAddOrSubtractPolySelfCoefficients: selfCoefficients
> selfCount: selfCount
> otherCoefficients: otherCoefficients
> otherCount: otherCount.
>
> ^ interpreterProxy failed
> ifTrue: [interpreterProxy primitiveFail]
> ifFalse: [interpreterProxy methodReturnValue: resultOop].

And the computation method

> resultOop := interpreterProxy
> instantiateClass: interpreterProxy classByteArray
> indexableSize: (selfCount max: otherCount).
> result := interpreterProxy firstIndexableField: resultOop.
>
> ^ resultOop

---
Kindly,
Robert

On 6/5/21 7:39 PM, Eliot Miranda wrote:

> Hi Robert,
>
> _,,,^..^,,,_ (phone)
>
>> On Jun 4, 2021, at 11:52 AM, Robert Withers
>> [<robert.withers at pm.me>](mailto:robert.withers at pm.me)
>> wrote:
>>
>> fieldSize := interpreterProxy stackIntegerValue: 1.
>>     coefficientsOop := interpreterProxy stackObjectValue: 0.
>
> Since you check for isBytes: below you can use stackValue:. isBytes: can safely be passed any object, including immediates.  So the stackObjectValue: call implies a redundant validation.
>
>> (interpreterProxy isIntegerValue: fieldSize)
>>         ifFalse: [ ^interpreterProxy primitiveFailFor: PrimErrBadArgument ].
>
> This is implicit. stackIntegerValue: fails if the object is not a SmallInteger (retiring zero) and otherwise answers its integerValue. So you should check if stackIntegerValue: fails since its return value will always answer true to isIntegerValue:
>
>> (interpreterProxy isBytes: coefficientsOop)
>>         ifFalse: [ ^interpreterProxy primitiveFailFor: PrimErrBadArgument ].
>
> I would write
>
> fieldSize := interpreterProxy stackIntegerValue: 1.
>     coefficientsOop := interpreterProxy stackValue: 0.
>
>     (interpreterProxy failed not
>      and: [interpreterProxy isBytes: coefficientsOop])
>         ifFalse: [ ^interpreterProxy primitiveFailFor: PrimErrBadArgument ].
>
> or
>
> fieldSizeOop := interpreterProxy stackValue: 1.
>     coefficientsOop := interpreterProxy stackValue: 0.
>
>     ((interpreterProxy isIntegerObject: fieldSizeOop)
>      and: [interpreterProxy isBytes: coefficientsOop])
>         ifFalse: [ ^interpreterProxy primitiveFailFor: PrimErrBadArgument ].
>
>     fieldSize := interpreterProxy integerValueOf: fieldSizeOop.
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