[squeak-dev] LittleSmalltalk and loading od 2004 .pr

H. Hirzel hannes.hirzel at gmail.com
Mon Jul 2 09:02:08 UTC 2018

On 7/1/18, K K Subbu <kksubbu.ml at gmail.com> wrote:
> I dug into this a little deeper today as it gave me an opportunity to
> study ImageSegments. I extracted the cs from 001 and used a binary
> editor to search for version number. I found one sequence 16r64006619
> which decodes to a big-endian 6502 ImageSegment. In 002, I found the
> sequence 16r66190073 which decodes to a little-endian segment.
> When I dropped 001 pr into Squeak 5.2alpha (18120/64b/Ubuntu) and
> examined the resulting error stack I found something strange.
> Before the endian check in LegacyImageSegment>>#comeFullyUpOnReload,

The method

needs more comments and probably some refactoring into smaller easier
understandable methods.

Some more notes may go here: http://wiki.squeak.org/squeak/1280


> instance is already created in DataStream>>#next method assuming
> little-endian, so segment ivar first word is 16r66190064. Therefore, the
> endianness check in:
> ImageSegment>>endianness
> ... ^(segment first bitShift: -24) asCharacter == $d ifTrue: [#big]
> ifFalse: [#little]
> ends up checking the wrong byte for  endianness. I changed this code to
> check for both $s and $d and confirmed that endian check is incorrect at
> this point.
> I got stuck here. How should one fix this error?
> Regards .. Subbu

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