Hello, I think that it is more secure to use stride in place of size, sometimes it is not the same value.
I use it in my own use of raw bindings Regards Gérard > Le 3 sept. 2016 à 10:03, Patrice Kouame via swift-users > <swift-users@swift.org> a écrit : > > Hi Jacob - > > I think you’re right. “capacity” should be the count of type T elements in my > buffer. So in my case that line should read > > let shadowPtr = constantBufferForFrame.contents().bindMemory(to: > ShadowPass.self, capacity: shadowPassData.count) > > The withMemoryRebound calls need similar adjustments. The pointer to MainPass > is actually a single structure to it should be safe to do this > > let mainPtr : UnsafeMutablePointer<MainPass> = shadowPtr.advanced(by: > 1).withMemoryRebound(to: MainPass.self, capacity: 1) { > $0.pointee = mainPassFrameData > } > > Whereas the unsafe pointer to <ObjectData> is actually a buffer of renderable > objects, so this should work: > > var ptr : UnsafeMutablePointer<ObjectData> = mainPtr.advanced(by: > 1).withMemoryRebound(to: ObjectData.self, capacity: objectsToRender) {_ in > } > > There are surely ways to refactor and simplify this, but I’m trying to retain > as much of the original sample code approach as possible. > > However, the compiler still segs badly. > Xcode also borks an internal error often. Only cleaning or restarting the > project can clear up that state. > Compilers (or Playgrounds for that matter) should never crash, and I’m not > sure where to file this bug : Swift or Apple radar against Xcode or both? I > now Xcode 8 is beta but…it’s been doing this for quite a while now... > > In both our “close to the metal” (no pun intended) cases, it seems like a lot > of churning for very little gain. Don’t you think? The easier, but “unsafe” > casting afforded previously did the trick with the normal caveats. > Don’t get me wrong, I love Swift and “get" all the neat type safety features. > Guess we can’t have our cake and eat it too, especially when interfacing with > “unsafe” C APIs. > > Anyway, back to rtfm … maybe some of the Swift Gods can chime in? ;-) > > I must be doing something stupid...Patrice > >> On Sep 3, 2016, at 2:32 AM, Jacob Bandes-Storch <jtban...@gmail.com> wrote: >> >> Hi Patrice, >> I don't have a solution for you, but I just wanted to point out what I think >> may be an error with your use of the new UnsafeRawPointer APIs: >> >> constantBufferForFrame.contents().bindMemory(to: ShadowPass.self, capacity: >> MemoryLayout<ShadowPass>.size) >> >> I believe the `capacity` should actually be the number of ShadowPass >> elements in the buffer, not the size of each element. Using `bindMemory(to: >> ShadowPass.self` already implies that MemoryLayout<ShadowPass>.size is the >> size of each element. >> >> More info at >> https://developer.apple.com/reference/swift/unsaferawpointer/2428875-bindmemory >> >> I just updated a small Metal project of mine to Swift 3. I ran into some >> compiler (playground) crashes, but it does seem to work most of the time. >> Although I only have 1 buffer :-) >> https://github.com/jtbandes/Metalbrot.playground >> >> Jacob >> >>> On Fri, Sep 2, 2016 at 11:00 AM, Patrice Kouame via swift-users >>> <swift-users@swift.org> wrote: >>> Hi all - >>> >>> I’m converting Apple’s Swift Sample "Adopting Metal II: Designing and >>> Implementing a Real-World Metal Renderer” in Xcode 8 beta6 to the latest >>> UnsafeMutablePointer API for untyped memory access. >>> Changes are necessary in MetalView.swift (Apple hasn’t updated their sample >>> code for the latest beta yet…) >>> The Swift Compiler crashes (Segmentation Fault: 11) on the attempt: >>> >>> // Grab a pointer to the constant buffer's data store >>> // Since we are using Swift, it is easier to cast the pointer to >>> the ShadowPass type to fill the constant buffer >>> // We need to make a copy of these so the block captures the >>> correct data >>> >>> // let shadowPtr = >>> UnsafeMutablePointer<ShadowPass>(constantBufferForFrame.contents()) >>> let shadowPtr = constantBufferForFrame.contents().bindMemory(to: >>> ShadowPass.self, capacity: MemoryLayout<ShadowPass>.size) >>> shadowPtr.pointee = shadowPassData[0] >>> >>> //More Swift specific stuff - advance pointer and cast to MainPass >>> >>> // let mainPtr = UnsafeMutablePointer<MainPass>(shadowPtr.advanced(by: >>> 1)) >>> // mainPtr.pointee = mainPassFrameData >>> let mainPtr : UnsafeMutablePointer<MainPass> = >>> shadowPtr.advanced(by: 1).withMemoryRebound(to: MainPass.self, capacity: >>> MemoryLayout<MainPass>.size) { >>> $0.pointee = mainPassFrameData >>> } >>> >>> //Advance and cast to ObjectData >>> >>> // var ptr = UnsafeMutablePointer<ObjectData>(mainPtr.advanced(by: 1)) >>> var ptr : UnsafeMutablePointer<ObjectData> = mainPtr.advanced(by: >>> 1).withMemoryRebound(to: ObjectData.self, capacity: >>> MemoryLayout<ObjectData>.size) {_ in >>> } >>> >>> let shadowOffset = 0 >>> let mainPassOffset = MemoryLayout<ShadowPass>.size + shadowOffset >>> let objectDataOffset = MemoryLayout<MainPass>.size + mainPassOffset >>> >>> // Update position of all the objects >>> if multithreadedUpdate { >>> DispatchQueue.concurrentPerform(iterations: objectsToRender) { >>> i in >>> let thisPtr = ptr.advanced(by: i) >>> _ = self.renderables[i].UpdateData(ptr, deltaTime: 1.0/60.0) >>> } >>> } >>> else { >>> for index in 0..<objectsToRender { >>> ptr = renderables[index].UpdateData(ptr, deltaTime: >>> 1.0/60.0) >>> } >>> } >>> >>> ptr = ptr.advanced(by: objectsToRender) >>> >>> _ = groundPlane!.UpdateData(ptr, deltaTime: 1.0/60.0) >>> >>> Any help is appreciated. I have the latest Xcode log handy if necessary. >>> Here’s a clip of the stack trace. >>> >>> 0 swift 0x000000010714a99d >>> PrintStackTraceSignalHandler(void*) + 45 >>> 1 swift 0x000000010714a3e6 SignalHandler(int) + 470 >>> 2 libsystem_platform.dylib 0x00007fff91461bba _sigtramp + 26 >>> 3 libsystem_platform.dylib 000000000000000000 _sigtramp + 1857676384 >>> 4 swift 0x00000001047207b3 (anonymous >>> namespace)::SILGenApply::visitExpr(swift::Expr*) + 51 >>> 5 swift 0x0000000104723ace (anonymous >>> namespace)::SILGenApply::visitApplyExpr(swift::ApplyExpr*) + 5182 >>> 6 swift 0x0000000104711cc1 >>> prepareApplyExpr(swift::Lowering::SILGenFunction&, swift::Expr*) + 273 >>> 7 swift 0x00000001047624e7 swift::ASTVisitor<(anonymous >>> namespace)::RValueEmitter, swift::Lowering::RValue, void, void, void, void, >>> void, swift::Lowering::SGFContext>::visit(swift::Expr*, >>> swift::Lowering::SGFContext) + 103 >>> 8 swift 0x0000000104762313 >>> swift::Lowering::SILGenFunction::emitExprInto(swift::Expr*, >>> swift::Lowering::Initialization*) + 195 >>> 9 swift 0x000000010474fbc3 >>> swift::Lowering::SILGenFunction::emitPatternBinding(swift::PatternBindingDecl*, >>> unsigned int) + 195 >>> 10 swift 0x00000001047077bd >>> swift::ASTVisitor<swift::Lowering::SILGenFunction, void, void, void, void, >>> void, void>::visit(swift::Decl*) + 125 >>> 11 swift 0x00000001047c0019 swift::ASTVisitor<(anonymous >>> namespace)::StmtEmitter, void, void, void, void, void, >>> void>::visit(swift::Stmt*) + 4169 >>> 12 swift 0x00000001047809ba >>> swift::Lowering::SILGenFunction::emitFunction(swift::FuncDecl*) + 314 >>> 13 swift 0x00000001046fd775 >>> swift::Lowering::SILGenModule::emitFunction(swift::FuncDecl*)::$_1::operator()(swift::SILFunction*) >>> const + 1877 >>> 14 swift 0x00000001046fc322 >>> swift::Lowering::SILGenModule::emitFunction(swift::FuncDecl*) + 626 >>> 15 swift 0x00000001047c7007 (anonymous >>> namespace)::SILGenType::emitType() + 1271 >>> 16 swift 0x00000001047c6a9e >>> swift::Lowering::SILGenModule::visitNominalTypeDecl(swift::NominalTypeDecl*) >>> + 30 >>> 17 swift 0x0000000104709093 >>> swift::Lowering::SILGenModule::emitSourceFile(swift::SourceFile*, unsigned >>> int) + 1795 >>> 18 swift 0x000000010470ad4d >>> swift::SILModule::constructSIL(swift::ModuleDecl*, swift::SILOptions&, >>> swift::FileUnit*, llvm::Optional<unsigned int>, bool, bool) + 1629 >>> 19 swift 0x00000001045621bf >>> performCompile(swift::CompilerInstance&, swift::CompilerInvocation&, >>> llvm::ArrayRef<char const*>, int&, swift::FrontendObserver*) + 19487 >>> 20 swift 0x000000010455b2c5 >>> swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, >>> swift::FrontendObserver*) + 17029 >>> 21 swift 0x000000010451888d main + 8685 >>> 22 libdyld.dylib 0x00007fff91255255 start + 1 >>> >>> >>> Patrice >>> >>> >>> _______________________________________________ >>> swift-users mailing list >>> swift-users@swift.org >>> https://lists.swift.org/mailman/listinfo/swift-users >>> >> > > _______________________________________________ > swift-users mailing list > swift-users@swift.org > https://lists.swift.org/mailman/listinfo/swift-users
_______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users