| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1992-2015 Free Software Foundation, Inc. |
| Contributed by Cygnus Support. Written by Julia Menapace, Jim Kingdon, |
| and David MacKenzie. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with no |
| Invariant Sections, with no Front-Cover Texts, and with no Back-Cover |
| Texts. A copy of the license is included in the section entitled "GNU |
| Free Documentation License". --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>STABS: Arrays</title> |
| |
| <meta name="description" content="STABS: Arrays"> |
| <meta name="keywords" content="STABS: Arrays"> |
| <meta name="resource-type" content="document"> |
| <meta name="distribution" content="global"> |
| <meta name="Generator" content="makeinfo"> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> |
| <link href="index.html#Top" rel="start" title="Top"> |
| <link href="Symbol-Types-Index.html#Symbol-Types-Index" rel="index" title="Symbol Types Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Types.html#Types" rel="up" title="Types"> |
| <link href="Strings.html#Strings" rel="next" title="Strings"> |
| <link href="Subranges.html#Subranges" rel="prev" title="Subranges"> |
| <style type="text/css"> |
| <!-- |
| a.summary-letter {text-decoration: none} |
| blockquote.smallquotation {font-size: smaller} |
| div.display {margin-left: 3.2em} |
| div.example {margin-left: 3.2em} |
| div.indentedblock {margin-left: 3.2em} |
| div.lisp {margin-left: 3.2em} |
| div.smalldisplay {margin-left: 3.2em} |
| div.smallexample {margin-left: 3.2em} |
| div.smallindentedblock {margin-left: 3.2em; font-size: smaller} |
| div.smalllisp {margin-left: 3.2em} |
| kbd {font-style:oblique} |
| pre.display {font-family: inherit} |
| pre.format {font-family: inherit} |
| pre.menu-comment {font-family: serif} |
| pre.menu-preformatted {font-family: serif} |
| pre.smalldisplay {font-family: inherit; font-size: smaller} |
| pre.smallexample {font-size: smaller} |
| pre.smallformat {font-family: inherit; font-size: smaller} |
| pre.smalllisp {font-size: smaller} |
| span.nocodebreak {white-space:nowrap} |
| span.nolinebreak {white-space:nowrap} |
| span.roman {font-family:serif; font-weight:normal} |
| span.sansserif {font-family:sans-serif; font-weight:normal} |
| ul.no-bullet {list-style: none} |
| --> |
| </style> |
| |
| |
| </head> |
| |
| <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> |
| <a name="Arrays"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Strings.html#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="Subranges.html#Subranges" accesskey="p" rel="prev">Subranges</a>, Up: <a href="Types.html#Types" accesskey="u" rel="up">Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| <hr> |
| <a name="Array-Types"></a> |
| <h3 class="section">5.5 Array Types</h3> |
| |
| <p>Arrays use the ‘<samp>a</samp>’ type descriptor. Following the type descriptor |
| is the type of the index and the type of the array elements. If the |
| index type is a range type, it ends in a semicolon; otherwise |
| (for example, if it is a type reference), there does not |
| appear to be any way to tell where the types are separated. In an |
| effort to clean up this mess, IBM documents the two types as being |
| separated by a semicolon, and a range type as not ending in a semicolon |
| (but this is not right for range types which are not array indexes, |
| see <a href="Subranges.html#Subranges">Subranges</a>). I think probably the best solution is to specify |
| that a semicolon ends a range type, and that the index type and element |
| type of an array are separated by a semicolon, but that if the index |
| type is a range type, the extra semicolon can be omitted. GDB (at least |
| through version 4.9) doesn’t support any kind of index type other than a |
| range anyway; I’m not sure about dbx. |
| </p> |
| <p>It is well established, and widely used, that the type of the index, |
| unlike most types found in the stabs, is merely a type definition, not |
| type information (see <a href="String-Field.html#String-Field">String Field</a>) (that is, it need not start with |
| ‘<samp><var>type-number</var>=</samp>’ if it is defining a new type). According to a |
| comment in GDB, this is also true of the type of the array elements; it |
| gives ‘<samp>ar1;1;10;ar1;1;10;4</samp>’ as a legitimate way to express a two |
| dimensional array. According to AIX documentation, the element type |
| must be type information. GDB accepts either. |
| </p> |
| <p>The type of the index is often a range type, expressed as the type |
| descriptor ‘<samp>r</samp>’ and some parameters. It defines the size of the |
| array. In the example below, the range ‘<samp>r1;0;2;</samp>’ defines an index |
| type which is a subrange of type 1 (integer), with a lower bound of 0 |
| and an upper bound of 2. This defines the valid range of subscripts of |
| a three-element C array. |
| </p> |
| <p>For example, the definition: |
| </p> |
| <div class="example"> |
| <pre class="example">char char_vec[3] = {'a','b','c'}; |
| </pre></div> |
| |
| <p>produces the output: |
| </p> |
| <div class="example"> |
| <pre class="example">.stabs "char_vec:G19=ar1;0;2;2",32,0,0,0 |
| .global _char_vec |
| .align 4 |
| _char_vec: |
| .byte 97 |
| .byte 98 |
| .byte 99 |
| </pre></div> |
| |
| <p>If an array is <em>packed</em>, the elements are spaced more |
| closely than normal, saving memory at the expense of speed. For |
| example, an array of 3-byte objects might, if unpacked, have each |
| element aligned on a 4-byte boundary, but if packed, have no padding. |
| One way to specify that something is packed is with type attributes |
| (see <a href="String-Field.html#String-Field">String Field</a>). In the case of arrays, another is to use the |
| ‘<samp>P</samp>’ type descriptor instead of ‘<samp>a</samp>’. Other than specifying a |
| packed array, ‘<samp>P</samp>’ is identical to ‘<samp>a</samp>’. |
| </p> |
| <p>An open array is represented by the ‘<samp>A</samp>’ type descriptor followed by |
| type information specifying the type of the array elements. |
| </p> |
| <p>An N-dimensional dynamic array is represented by |
| </p> |
| <div class="example"> |
| <pre class="example">D <var>dimensions</var> ; <var>type-information</var> |
| </pre></div> |
| |
| <p><var>dimensions</var> is the number of dimensions; <var>type-information</var> |
| specifies the type of the array elements. |
| </p> |
| <p>A subarray of an N-dimensional array is represented by |
| </p> |
| <div class="example"> |
| <pre class="example">E <var>dimensions</var> ; <var>type-information</var> |
| </pre></div> |
| |
| <p><var>dimensions</var> is the number of dimensions; <var>type-information</var> |
| specifies the type of the array elements. |
| </p> |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Strings.html#Strings" accesskey="n" rel="next">Strings</a>, Previous: <a href="Subranges.html#Subranges" accesskey="p" rel="prev">Subranges</a>, Up: <a href="Types.html#Types" accesskey="u" rel="up">Types</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Symbol-Types-Index.html#Symbol-Types-Index" title="Index" rel="index">Index</a>]</p> |
| </div> |
| |
| |
| |
| </body> |
| </html> |