[Cuis-dev] BMP Reader broken

[Juan Vuletich]

Thanks Dave!

Cheers,

On 3/18/2024 5:02 PM, lewis--- via Cuis-dev wrote:
>
> Thanks Juan, I made the updates to the Smalltalk source (VMMaker and 
> VMMaker.oscog packages) and pushed the generated C code to the github 
> and SVN repositories.
>
> CC to the vm-dev list for info.
>
> Dave
>
>
> On 2024-03-18 18:16, Juan Vuletich via Cuis-dev wrote:
>
>> Hi Dave,
>>
>> On 3/18/2024 12:35 PM, lewis--- via Cuis-dev wrote:
>>>
>>>  Hi Juan,
>>>
>>> On 2024-03-17 18:17, Juan Vuletich via Cuis-dev wrote:
>>>
>>>     Hi Dave,
>>>
>>>     On 3/16/2024 6:22 PM, lewis--- via Cuis-dev wrote:As I said in a
>>>     separate email, Vanessa found the origin of the problem, and the
>>>     fix is now at GitHub.
>>>
>>>     Still, as you say, the primitive fails, both in Cuis and Squeak,
>>>     but only the first time it is called. The lines are read in
>>>     reverse order, so the line that is first copied is actually the
>>>     last one.
>>>
>>>     In #read24BmpLine:into:startingAt:width:, at the start of the
>>>     fallback code, I added this line: `{formBitsIndex+width.
>>>     formBits size} print.`. Then tried to load Hilaire's BMP. In the
>>>     Transcript I got #(63601 63600). So, in BMPReadWriterPlugin.c,
>>>     the lines that read:
>>>
>>>         if (!(((formBitsIndex + width) <= formBitsSize)
>>>     && ((width * 3) <= pixelLineSize))) {
>>>             return primitiveFail();
>>>
>>>     should actually read
>>>
>>>         if (!(((formBitsIndex + width - 1) <= formBitsSize)
>>>     && ((width * 3) <= pixelLineSize))) {
>>>             return primitiveFail();
>>>
>>>     and the primitive will not fail.
>>>
>>>     It is a minor bug, with no practical consequences, so this is
>>>     not really important. But I found this while investigating the
>>>     BMP read failure, and I thought it was worth commenting.
>>>
>>>     Thanks,
>>>
>>>
>>> The expression appears in both 
>>> BMPReadWriterPlugin>>primitiveRead24BmpLine and 
>>> BMPReadWriterPlugin>>primitiveWrite24BmpLine. Can you please confirm 
>>> my assumption that the same fix should be applied to both methods? 
>>> Sorry if this is obvious but I just want to be sure.
>>>
>>> Thanks!
>>>
>>> Dave
>>>
>>
>> Yep. Checking the code in both methods it is pretty clear that they 
>> are analogous. In any case, I did some quick testing, and in both 
>> cases the primitive fails exactly once and for the same value of the 
>> parameters. The tweak should be same in both cases.
>>
>> Thanks!
>> -- 
>> Juan Vuletich
>> cuis.st
>> github.com/jvuletich
>> researchgate.net/profile/Juan-Vuletich
>> independent.academia.edu/JuanVuletich
>> patents.justia.com/inventor/juan-manuel-vuletich
>> linkedin.com/in/juan-vuletich-75611b3
>> twitter.com/JuanVuletich
>>


-- 
Juan Vuletich
cuis.st
github.com/jvuletich
researchgate.net/profile/Juan-Vuletich
independent.academia.edu/JuanVuletich
patents.justia.com/inventor/juan-manuel-vuletich
linkedin.com/in/juan-vuletich-75611b3
twitter.com/JuanVuletich

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