<html><head><base href="x-msg://2442/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; 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letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div><span class="Apple-style-span" style="font-size: medium;"><font class="Apple-style-span" color="#0000FF" face="'Gill Sans'">If we build on the libatomic_ops support then some types might end up with (slow) implementation using locks.</font></span></div></span></span></span></span></span></span></span></span></div></span></span>
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<br><div><div>On 20 Dec 2009, at 20:37, Jay K wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">No. Other sizes are often available such as 8, 16, 32 (on 64bit systems), 64 (on 32bit systems), 128 (on 64bit systems).<br>Maybe not 8, but there readily available examples of the others.<br><br>Search the web for:<br> _InterlockedIncrement16<span class="Apple-converted-space"> </span><a href="http://msdn.microsoft.com/en-us/library/2ddez55b.aspx">http://msdn.microsoft.com/en-us/library/2ddez55b.aspx</a><span class="Apple-converted-space"> </span><br> _InterlockedCompareExchange64<span class="Apple-converted-space"> </span><a href="http://msdn.microsoft.com/en-us/library/ttk2z1ws%28VS.85%29.aspx">http://msdn.microsoft.com/en-us/library/ttk2z1ws%28VS.85%29.aspx</a><span class="Apple-converted-space"> </span><br> _InterlockedCompareExchange128<span class="Apple-converted-space"> </span><a href="http://msdn.microsoft.com/en-us/library/bb514094.aspx">http://msdn.microsoft.com/en-us/library/bb514094.aspx</a><span class="Apple-converted-space"> </span><br><br>Some of this requires "newer" processors, for varying definitions of "newer" (including "fairly old").<br><br> - Jay<br><br><br>> Date: Sun, 20 Dec 2009 19:02:48 -0600<br>> From:<span class="Apple-converted-space"> </span><a href="mailto:rodney_bates@lcwb.coop">rodney_bates@lcwb.coop</a><br>> To:<span class="Apple-converted-space"> </span><a href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</a><br>> Subject: Re: [M3devel] Proposed Atomic Word.T interfaces.<br>><span class="Apple-converted-space"> </span><br>><span class="Apple-converted-space"> </span><br>><span class="Apple-converted-space"> </span><br>> Tony Hosking wrote:<br>> > Thanks for the typo fixes.<br>> ><span class="Apple-converted-space"> </span><br>> > On 20 Dec 2009, at 11:44, Rodney M. Bates wrote:<br>> ><span class="Apple-converted-space"> </span><br>> >> To be legal on ADDRESS, either another parallel interface or a set of parallel<br>> >> procedures would be needed. Or else, this interface would have to be known to<br>> >> the core language and allow predefined overloading, similar to builtin operators<br>> >> and functions. The syntax could still be that of an interface. I don't think<br>> >> any existing required interfaces do this now.<br>> ><span class="Apple-converted-space"> </span><br>> > Perhaps better to make it a generic interface and instantiate for ADDRESS and Word.T:<br>><span class="Apple-converted-space"> </span><br>> And would it be illegal to try to instantiate with any other type? I presume it would<br>> have to be a native word sized value for the implementation, and the Fetch operations<br>> would not have meaning for most other types.<br>><span class="Apple-converted-space"> </span><br>> Also, would the corresponding MODULE and its instantiations not be written in M3,<br>> but just builtin to the compiler, like Word?<br>><span class="Apple-converted-space"> </span><br>> ><span class="Apple-converted-space"> </span><br>> > GENERIC INTERFACE Atomic(Rep);<br>> ><span class="Apple-converted-space"> </span><br>> > TYPE T = Rep.T;<br>> ><span class="Apple-converted-space"> </span><br>> > TYPE<br>> > Order = { Relaxed, Release, Acquire, AcquireRelease, Sequential };<br>> > (* "Relaxed": The operation does not order memory.<br>> ><span class="Apple-converted-space"> </span><br>> > "Release": Performs a release operation on the affected memory locations,<br>> > thus making regular memory writes visible to other threads through the<br>> > variable to which it is applied.<br>> ><span class="Apple-converted-space"> </span><br>> > "Acquire": Performs an acquire operation on the affected memory<br>> > locations, thus making regular memory writes in other threads released<br>> > through the atomic variable to which it is applied, visible to the<br>> > current thread.<br>> ><span class="Apple-converted-space"> </span><br>> > "AcquireRelease": The operation has both acquire and release semantics.<br>> ><span class="Apple-converted-space"> </span><br>> > "Sequential": The operation has both acquire and release semantics, and<br>> > in addition, has sequentially-consistent operation ordering. *)<br>> ><span class="Apple-converted-space"> </span><br>> > CONST IsLockFree = Rep.IsLockFree;<br>> > (* True if the operations are lock-free, false otherwise. *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE Store(VAR var: T; val: T; order := Order.Sequential);<br>> > (* Atomically replace the value in "var" with "val". Memory is affected as<br>> > per "order". The "order" shall be neither "Acquire" nor<br>> > "AcquireRelease". *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE Load(READONLY var: T; order := Order.Sequential): T;<br>> > (* Atomically return the value in "var". Memory is affected as per "order".<br>> > The "order" shall be neither "Release" nor "AcquireRelease". *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE Swap(VAR var: T; val: T; order := Order.Sequential): T;<br>> > (* Atomically replace the value in "var" with "val". Returns the value of<br>> > "var" immediately before the effects. Memory is affected as per order.<br>> > This is a read-modify-write operation and synchronizes with any<br>> > evaluation that reads the updated value. *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE CompareSwap(VAR var, expected: T;<br>> > desired: T; order := Order.Sequential): BOOLEAN;<br>> > (* Atomically, compares the value in "var" for equality with that in<br>> > "expected", and if true, replaces the value in "var" with "desired", and<br>> > if false, updates the value in "expected" with the value in "var".<br>> > Returns the result of the comparison. The "order" shall be neither<br>> > "Release" nor "AcquireRelease". This is a read-modify-write operation<br>> > and synchronizes with any evaluation that reads the updated value. The<br>> > effect of the CompareSwap operation is:<br>> ><span class="Apple-converted-space"> </span><br>> > IF var = expected THEN var := desired ELSE expected := var;<br>> ><span class="Apple-converted-space"> </span><br>> > The CompareSwap operation may fail spuriously, that is return false while<br>> > leaving the value in "expected" unchanged. A consequence of spurious<br>> > failure is that nearly all uses of CompareSwap will be in a loop:<br>> ><span class="Apple-converted-space"> </span><br>> > expected := Atomic.Load(current);<br>> > DO<br>> > desired := function(expected);<br>> > WHILE NOT Atomic.CompareSwap(current, expected, desired);<br>> > *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE Fence(VAR var: T; order := Order.Sequential);<br>> > (* Memory is affected as per "order". Synchronizes with any operation on<br>> > the same variable. The "order" shall not be "Relaxed". *)<br>> ><span class="Apple-converted-space"> </span><br>> > PROCEDURE FetchPlus (VAR var: T; incr: T; order := Sequential): T;<br>> > PROCEDURE FetchMinus(VAR var: T; decr: T; order := Sequential): T;<br>> > PROCEDURE FetchOr (VAR var: T; mask: T; order := Sequential): T;<br>> > PROCEDURE FetchXOr (VAR var: T; mask: T; order := Sequential): T;<br>> > PROCEDURE FetchAnd (VAR var: T; mask: T; order := Sequential): T;<br>> > (* Atomically replace the value in "var" with the result of the operation<br>> > applied to the value in "var" and the given operand. Memory is affected<br>> > as per "order". These operations are read-modify-write operations and<br>> > synchronize with any evaluation that reads the updated value. Returns<br>> > the value of "var" immediately before the effects.<br>> ><span class="Apple-converted-space"> </span><br>> > For signed integral types, arithmetic is defined to use two's-complement<br>> > representation. There are no undefined results. For address types, the<br>> > result may be an undefined address, but the operations otherwise have no<br>> > undefined behavior. *)<br>> ><span class="Apple-converted-space"> </span><br>> > END Atomic.<br>> ><span class="Apple-converted-space"> </span><br>> ><span class="Apple-converted-space"> </span><br></div></span></blockquote></div><br></body></html>