<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">2014-09-22 22:34 GMT+02:00 Bert Freudenberg <span dir="ltr"><<a href="mailto:bert@freudenbergs.de" target="_blank">bert@freudenbergs.de</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><br>
On 22.09.2014, at 22:21, Ron Teitelbaum <<a href="mailto:ron@usmedrec.com">ron@usmedrec.com</a>> wrote:<br>
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>> From: Bert Freudenberg<br>
>> Sent: Monday, September 22, 2014 4:00 PM<br>
>><br>
>> I just found out why PNG decoding was broken in SqueakJS [*]. Wouldn't<br>
>> have believed that any code actually relied on the following behavior:<br>
>><br>
>> | a |<br>
>> a := (1 to: 20) asArray.<br>
>> a replaceFrom: 11 to: 20 with: a startingAt: 8.<br>
>><br>
>> ==> #(1 2 3 4 5 6 7 8 9 10 8 9 10 8 9 10 8 9 10 8)<br>
>><br>
> That's funky! Hope it wasn't my code! Seems wrong to not copy the array<br>
> before modifying it (Like your buggy VM did).<br>
<br>
</span>It's not a copy. It moved the numbers 8-17 to index 11. Which is what I erroneously had assumed to be the desired behavior.<br>
<span class="HOEnZb"><font color="#888888"><br>
- Bert -<br>
</font></span><div class="HOEnZb"><div class="h5"><br></div></div></blockquote><div><br></div><div>It's a known problem.<br></div><div>The primitive should use memmove rather than memcpy.<br></div><div>So the solution is quite simple, it's just that it's waiting for a good soul to integrate it.<br></div><div><br> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">
> Ron<br>
><br>
>> In my (buggy) VM it answered<br>
>><br>
>> ==> #(1 2 3 4 5 6 7 8 9 10 8 9 10 11 12 13 14 15 16 17)<br>
>><br>
>> which apparently did not at all match what The Creators intended ;)<br>
>><br>
>> - Bert -<br>
>><br>
>> [*] specifically, #decompressBlock:with:<br>
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