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<TITLE>Footnotes</TITLE>
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<A NAME=S99>
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<H1>TDF Guide, Issue 4.0 </H1>
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<H3>January 1998</H3>
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<IMG SRC="../images/no_next.gif" ALT="next section">
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<IMG SRC="../images/no_prev.gif" ALT="previous section">
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<A HREF="guide1.html"><IMG SRC="../images/top.gif" ALT="current document"></A>
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<A HREF="../index.html"><IMG SRC="../images/home.gif" ALT="TenDRA home page">
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</A>
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<IMG SRC="../images/no_index.gif" ALT="document index"><P>
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<HR>
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<H2><A NAME=70>Footnote 1</A></H2>
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There are facilities to allow extensions to the number of constructors,
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so it is not quite as simple as this<P>
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<HR>
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<H2><A NAME=71>Footnote 2</A></H2>
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The "tld" UNITs gives usage information for namess to aid
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the linker, tld, to discover which namess have definitions and some
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usage information. The C producer also optionally constructs "diagnostics"
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UNITs (to give run-time diagnostic information).<P>
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<HR>
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<H2><A NAME=72>Footnote 3</A></H2>
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There is a similar distinction between tags introduced to be locals
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of a procedure using identify and variable (see
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<A HREF="guide7.html#35">section 5.3.1</A>)<P>
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<HR>
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<H2><A NAME=73>Footnote 4</A></H2>
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Note that is not generally true for C bitfields; most C ABIs have
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(different) rules for putting in padding bits depending on the size
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of the bitfield and its relation with the natural alignments. This
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is a fruitful source of errors in data exchange between different
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C ABIs For more on similar limitations of bitfields in TDF (see
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<A HREF="guide9.html#16">Assigning and extracting bitfields</A>).<P>
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<HR>
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<H2><A NAME=74>Footnote 5</A></H2>
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The vararg construction in C are implemented by giving more actuals
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than formals; the extra parameters are accessed by offset arithmetic
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with a pointer to a formal, using parameter_alignment to pad the offsets.<P>
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<HR>
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<H2><A NAME=75>Footnote 6</A></H2>
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If a formal parameter is to be used in this way, it should be marked
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as having out_par ACCESS in its corresponding TAGSHACC in <I>callers_intro</I>.
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<HR>
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<H2><A NAME=76>Footnote 7</A></H2>
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However see also initial_value in <A HREF="guide5.html#19">section
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3.2</A><P>
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<HR>
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<H2><A NAME=78>Footnote 8</A></H2>
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Exercise for the reader: what are the SORTs of these parameters?<P>
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The current C producer does this for some of the constructs, but not
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in any systematic manner; perhaps it will change.<P>
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<HR>
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<H2><A NAME=79>Footnote 9</A></H2>
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The order-specifying constructors are conditional, identify, repeat,
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labelled, sequence and variable<P>
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<HR>
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<H2><A NAME=80>Footnote 10</A></H2>
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A sufficient condition for not side-effecting in this sense is that
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there are no apply_procs or local_allocs in E; that any assignments
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in E are to variables defined in E; and that any branches in E are
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to labels defined in conditionals in E<P>
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<HR>
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<H2><A NAME=81>Footnote 11</A></H2>
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There are analogous rules for labelled and repeat with unused LABELs.<P>
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<HR>
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<H2><A NAME=82>Footnote 12</A></H2>
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This has to be modified if B contains any uses of local_free_all or
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last_local.<P>
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<HR>
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<H2><A NAME=83>Footnote 13</A></H2>
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However, we may find that the mapping of a constraint allows extra
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relationships for a class of architectures which do not hold in all
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generality; this may mean that some constructions are defined on this
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class while still being undefined in others (see <A HREF="guide15.html#0">section
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13</A>).<P>
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<HR>
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<H2><A NAME=84>Footnote 14</A></H2>
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I could equally have given simply shape_offset(sh_int) for S_i, but
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the above formulation is more uniform with respect to selection OFFSETs.<P>
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<HR>
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<H2><A NAME=85>Footnote 15</A></H2>
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For most architectures, these definition are dependent only on a few
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constants such as the maximum length of bitfield., expessed as tokens
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for the target. The precise specification of such target dependent
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tokens is of current interest outside the scope of this document.<P>
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<HR>
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<P><I>Part of the <A HREF="../index.html">TenDRA Web</A>.<BR>Crown
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Copyright © 1998.</I></P>
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</HTML>
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