<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">
I found one way...<div><br></div><div><div>(defun read-int64 (ptr)</div><div> (let ((v (read-uint64 ptr)))</div><div> (declare (type (unsigned-byte 64) v))</div><div> (if (logbitp 63 v)</div><div> (dpb v (byte 64 0) -1) ;; <-- better?</div><div> ;; else</div><div> v))</div><div><br></div><div> <span class="Apple-style-span" style="font-size: 12px; "><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 style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Dr. David McClain</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Chief Technical Officer</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Refined Audiometrics Laboratory</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">4391 N. Camino Ferreo</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Tucson, AZ 85750</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">email: <a href="mailto:dbm@refined-audiometrics.com">dbm@refined-audiometrics.com</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">phone: 1.520.390.3995</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">web: <a href="http://refined-audiometrics.com">http://refined-audiometrics.com</a></div><br class="Apple-interchange-newline"></span><span></span></span></span></span></span><br class="Apple-interchange-newline"> </div><br><div><div>On Sep 8, 2010, at 10:18, David McClain wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">I have a 64-bit integer obtained by the FLI from external storage. It was obtained by reading two 32-bit unsigned values and depositing them into a zero valued integer. Now I want to sign-extend the result so that if it has its MSB set, the value will be a twos-complement negative value.<div><br></div><div><div>(defun read-int64 (ptr)</div><div> (let ((v (read-uint64 ptr)))</div><div> (if (logbitp 63 v)</div><div> (- v #.(ash 1 64))</div><div> v)))</div><div><br></div><div>But this looks inelegant to me, requiring the storage of a constant #.(ash 1 64) used in a subtraction operation.</div><div><br></div><div>Been racking my brain on the BOOLE operations and the LOGNOT et al, looking for a more elegant solution to this. Not a high-value item, just curious.</div><div><br></div><div> <span class="Apple-style-span" style="font-family: Helvetica; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div><span class="Apple-style-span" style="font-size: 12px; ">Dr. David McClain</span></div><div><span class="Apple-style-span" style="font-size: 12px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Chief Technical Officer</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Refined Audiometrics Laboratory</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">4391 N. Camino Ferreo</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Tucson, AZ 85750</div><div style="min-height: 14px; margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">email: <a href="mailto:dbm@refined-audiometrics.com" target="_blank">dbm@refined-audiometrics.com</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">phone: 1.520.390.3995</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">web: <a href="http://www.refined-audiometrics.com/" target="_blank">http://www.refined-audiometrics.com</a></div><div><br></div></span></div></div></div></span><br class="Apple-interchange-newline"> </div> <br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">pro mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:pro@common-lisp.net">pro@common-lisp.net</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="http://common-lisp.net/cgi-bin/mailman/listinfo/pro">http://common-lisp.net/cgi-bin/mailman/listinfo/pro</a></div> </blockquote></div><br></div></body></html>