300 lines
5.8 KiB
HTML
300 lines
5.8 KiB
HTML
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<!DOCTYPE HTML>
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<HTML LANG="en-us"
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><HEAD
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><TITLE
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>logbitp | Common Lisp Nova Spec</TITLE
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><META CHARSET="US-ASCII"
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><LINK REL="canonical" HREF="f_logbitp.html"
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><LINK REL="next" HREF="f_logcount.html" TYPE="text/html" TITLE="logcount"
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><LINK REL="prev" HREF="f_logand.html" TYPE="text/html" TITLE="logand, logandc1, logandc2, logeqv, logior, lognand, lognor, lognot, logorc1, logorc2, logxor"
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><LINK REL="up" HREF="12_2_Numbers_Dictionary.html" TYPE="text/html" TITLE="12.2 Numbers Dictionary"
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><LINK REL="start" HREF="index.html" TYPE="text/html" TITLE="Common Lisp Nova Spec"
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><META NAME="VIEWPORT" CONTENT="width=device-width, initial-scale=1.0"
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><LINK REL="STYLESHEET" HREF="dpans.css%3F3909942064.css"
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><SCRIPT SRC="dpans.js%3F3909942064"
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></SCRIPT
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><SCRIPT SRC="apropos.js%3F3909942064"
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></SCRIPT
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></HEAD
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><BODY
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><DIV
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><DIV CLASS="topnav"
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><DIV CLASS="breadcrumb"
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><SPAN CLASS="breadcrumb-item"
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><A HREF="index.html"
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>Common Lisp Nova Spec</A
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></SPAN
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="12_Numbers.html"
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>12. Numbers</A
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></SPAN
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="12_2_Numbers_Dictionary.html"
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>12.2 Numbers Dictionary</A
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></SPAN
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="f_logbitp.html"
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>logbitp</A
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></SPAN
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></DIV
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><DIV CLASS="apropos"
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><DIV CLASS="apropos-io"
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><A HREF="f_logand.html" CLASS="prev"
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>←</A
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><SPAN ID="apropos-label"
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>Apropos </SPAN
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><INPUT ID="apropos" AUTOFOCUS="AUTOFOCUS" PLACEHOLDER="Type here to search" ONINPUT="aproposInput(this);" ONKEYUP="aproposKeyup(event);" ONCHANGE="aproposChange(this);" ONFOCUS="aproposFocus(this);" ONFOCUSOUT="aproposFocusout(this);"
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><A HREF="f_logcount.html" CLASS="next"
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>→</A
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></DIV
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><DIV ID="apropos-res"
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></DIV
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></DIV
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></DIV
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><DIV CLASS="matter"
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><DIV CLASS="com"
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><DIV CLASS="begincom"
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><HR
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><TABLE WIDTH="100%" CELLSPACING="0" CELLPADDING="0"
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><TR
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><TD ALIGN="LEFT" VALIGN="BASELINE" WIDTH="100%" CLASS="name"
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="logbitp"
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></SPAN
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><B
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>logbitp</B
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></TD
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><TD ALIGN="RIGHT" VALIGN="BASELINE" WIDTH="0" NOWRAP="NOWRAP" CLASS="ftype"
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><I
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>Function</I
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></TD
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></TR
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></TABLE
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><HR
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></DIV
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><UL CLASS="subtoc"
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></UL
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><DL
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><DT
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><B
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>Syntax</B
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></DT
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><DD
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><P CLASS="j"
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><B
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>logbitp</B
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> <SPAN CLASS="cmssi"
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>index</SPAN
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> <SPAN CLASS="cmssi"
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>integer</SPAN
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> <SPAN CLASS="arrow"
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>→</SPAN
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> <SPAN CLASS="cmssi"
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>generalized-boolean</SPAN
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></P
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></DD
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><DT
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><B
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>Arguments and Values</B
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></DT
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><DD
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><P CLASS="j"
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><VAR CLASS="param"
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>index</VAR
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> — a non-negative <A HREF="26_1_Glossary.html#integer"
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><EM CLASS="term"
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>integer</EM
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></A
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>integer</VAR
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> — an <A HREF="26_1_Glossary.html#integer"
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><EM CLASS="term"
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>integer</EM
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></A
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>generalized-boolean</VAR
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> — a <A HREF="26_1_Glossary.html#generalized_boolean"
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><EM CLASS="term"
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>generalized boolean</EM
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></A
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>.</P
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></DD
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><DT
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><B
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>Description</B
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></DT
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><DD
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><P CLASS="j"
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><A HREF="f_logbitp.html" CLASS="funref"
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><B
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>logbitp</B
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></A
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> is used to test the value of a particular bit in <VAR CLASS="param"
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>integer</VAR
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>, that is treated as if it were binary. The value of <A HREF="f_logbitp.html" CLASS="funref"
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><B
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>logbitp</B
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></A
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> is <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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> if the bit in <VAR CLASS="param"
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>integer</VAR
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> whose index is <VAR CLASS="param"
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>index</VAR
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> (that is, its weight is 2<SUP CLASS="sup"
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><I CLASS="i"
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><I
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>index</I
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></I
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></SUP
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>) is a one-bit; otherwise it is <A HREF="26_1_Glossary.html#false"
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><EM CLASS="term"
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>false</EM
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></A
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>. </P
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><P CLASS="j"
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>Negative <VAR CLASS="param"
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>integers</VAR
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> are treated as if they were in two’s-complement notation.</P
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></DD
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><DT
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><B
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>Examples</B
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></DT
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><DD
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><PRE CLASS="screen"
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>(logbitp 1 1) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#false"
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><EM CLASS="term"
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>false</EM
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></A
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>
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(logbitp 0 1) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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>
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(logbitp 3 10) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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>
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(logbitp 1000000 -1) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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>
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(logbitp 2 6) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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>
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(logbitp 0 6) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#false"
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><EM CLASS="term"
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>false</EM
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></A
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></PRE
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></DD
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><DT
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><B
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>Exceptional Situations</B
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></DT
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><DD
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><P CLASS="j"
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>Should signal an error of <A HREF="26_1_Glossary.html#type"
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><EM CLASS="term"
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>type</EM
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></A
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> <A HREF="t_type-error.html" CLASS="typeref"
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><B
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>type-error</B
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></A
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> if <VAR CLASS="param"
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>index</VAR
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> is not a non-negative <A HREF="26_1_Glossary.html#integer"
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><EM CLASS="term"
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>integer</EM
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></A
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>. Should signal an error of <A HREF="26_1_Glossary.html#type"
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><EM CLASS="term"
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>type</EM
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></A
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> <A HREF="t_type-error.html" CLASS="typeref"
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><B
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>type-error</B
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></A
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> if <VAR CLASS="param"
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>integer</VAR
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> is not an <A HREF="26_1_Glossary.html#integer"
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><EM CLASS="term"
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>integer</EM
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></A
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>.</P
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></DD
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><DT
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><B
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>Notes</B
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></DT
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><DD
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><PRE CLASS="screen"
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>(logbitp <VAR CLASS="param"
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>k</VAR
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> <VAR CLASS="param"
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>n</VAR
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>) <SPAN CLASS="cmsy"
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><SPAN STYLE="font-size:16px;vertical-align:-2px"
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>≡</SPAN
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></SPAN
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> (ldb-test (byte 1 <VAR CLASS="param"
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>k</VAR
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>) <VAR CLASS="param"
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>n</VAR
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>)</PRE
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></DD
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></DL
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></DIV
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></DIV
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><DIV CLASS="footer"
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><DIV CLASS="btmnav"
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><A HREF="f_logand.html" CLASS="prev"
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>←</A
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><A HREF="f_logcount.html" CLASS="next"
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>→</A
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></DIV
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><DIV CLASS="trail"
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>Conversion to HTML copyright 2023 by Gilbert Baumann</DIV
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></DIV
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></DIV
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><SCRIPT
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>domReady();</SCRIPT
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></BODY
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>
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