<div dir="auto">What do you gain from this?</div><div class="gmail_extra"><br><div class="gmail_quote">On Mar 8, 2018 9:19 AM, "Andrew Martin" <<a href="mailto:andrew.thaddeus@gmail.com">andrew.thaddeus@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Let's say I have a gc-managed byte array of length 19. GHC promises that byte arrays are machine-word-aligned on the front end. That is, on a 64-bit machine, this array starts on a memory address that divide 8 evenly. However, the back end will certainly be unaligned. So, these two calls will be fine:<div><br></div><div>- indexWordArray# myArr# 0#</div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">- indexWordArray# myArr# 1#</span><br clear="all" style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><br>But this one is non-deterministic:</div><div><br></div><div><span style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:small;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">- indexWordArray# myArr# 2#</span></div><div><br></div><div>Some of the bytes in the word will have garbage in them. However, this could always be masked out with a bit mask (you have to know the platform endianness for this to work right). Is this safe? I doubt think this could ever cause a segfault but I wanted to check.<br clear="all"><div><br></div>-- <br><div class="m_8465154875905407592gmail_signature" data-smartmail="gmail_signature">-Andrew Thaddeus Martin</div>
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