> On Jun 26, 2017, at 3:41 PM, Roderick Mann <rm...@latencyzero.com> wrote: > >> >> On Jun 26, 2017, at 10:20 , Charles Srstka <cocoa...@charlessoft.com >> <mailto:cocoa...@charlessoft.com>> wrote: >> >> Rats, I was hoping that one of the reasons about being so explicit what >> we’re going to access and where with bindMemory() and friends would be to >> take care of these sorts of issues. >> >> In that case, the simplest way to do it is probably just this: >> >> let crc = (UInt16(myData[myData.endIndex]) << 8) | >> UInt16(myData[myData.endIndex - 1]) >> >> (or the reverse, depending on the endianness of the source data) > > Ah. I was doing it like this, but I guess I don't really need to, do I? > > let count = self.count > let ourCRC = self.withUnsafeBytes > { (inPtr: UnsafePointer<UInt8>) -> UInt16 in > let b1 = UInt16(inPtr[count - 2]) > let b2 = UInt16(inPtr[count - 1]) > let b = (b1 << 8) | b2 > return b > }
Doing it via the pointer might be a smidge faster, but I kinda doubt you’ll notice it. Charles
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