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  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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  3. <!-- This file documents the GNU Assembler "as".
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  15. <title>Statements (Using as)</title>
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  24. <link href="Syntax.html#Syntax" rel="up" title="Syntax">
  25. <link href="Constants.html#Constants" rel="next" title="Constants">
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  56. <a name="Statements"></a>
  57. <div class="header">
  58. <p>
  59. Next: <a href="Constants.html#Constants" accesskey="n" rel="next">Constants</a>, Previous: <a href="Symbol-Intro.html#Symbol-Intro" accesskey="p" rel="prev">Symbol Intro</a>, Up: <a href="Syntax.html#Syntax" accesskey="u" rel="up">Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
  60. </div>
  61. <hr>
  62. <a name="Statements-1"></a>
  63. <h3 class="section">3.5 Statements</h3>
  64. <a name="index-statements_002c-structure-of"></a>
  65. <a name="index-line-separator-character"></a>
  66. <a name="index-statement-separator-character"></a>
  67. <p>A <em>statement</em> ends at a newline character (&lsquo;<samp>\n</samp>&rsquo;) or a
  68. <em>line separator character</em>. The line separator character is target
  69. specific and described in the <em>Syntax</em> section of each
  70. target&rsquo;s documentation. Not all targets support a line separator character.
  71. The newline or line separator character is considered to be part of the
  72. preceding statement. Newlines and separators within character constants are an
  73. exception: they do not end statements.
  74. </p>
  75. <a name="index-newline_002c-required-at-file-end"></a>
  76. <a name="index-EOF_002c-newline-must-precede"></a>
  77. <p>It is an error to end any statement with end-of-file: the last
  78. character of any input file should be a newline.
  79. </p>
  80. <p>An empty statement is allowed, and may include whitespace. It is ignored.
  81. </p>
  82. <a name="index-instructions-and-directives"></a>
  83. <a name="index-directives-and-instructions"></a>
  84. <p>A statement begins with zero or more labels, optionally followed by a
  85. key symbol which determines what kind of statement it is. The key
  86. symbol determines the syntax of the rest of the statement. If the
  87. symbol begins with a dot &lsquo;<samp>.</samp>&rsquo; then the statement is an assembler
  88. directive: typically valid for any computer. If the symbol begins with
  89. a letter the statement is an assembly language <em>instruction</em>: it
  90. assembles into a machine language instruction.
  91. Different versions of <code>as</code> for different computers
  92. recognize different instructions. In fact, the same symbol may
  93. represent a different instruction in a different computer&rsquo;s assembly
  94. language.
  95. </p>
  96. <a name="index-_003a-_0028label_0029"></a>
  97. <a name="index-label-_0028_003a_0029"></a>
  98. <p>A label is a symbol immediately followed by a colon (<code>:</code>).
  99. Whitespace before a label or after a colon is permitted, but you may not
  100. have whitespace between a label&rsquo;s symbol and its colon. See <a href="Labels.html#Labels">Labels</a>.
  101. </p>
  102. <p>For HPPA targets, labels need not be immediately followed by a colon, but
  103. the definition of a label must begin in column zero. This also implies that
  104. only one label may be defined on each line.
  105. </p>
  106. <div class="smallexample">
  107. <pre class="smallexample">label: .directive followed by something
  108. another_label: # This is an empty statement.
  109. instruction operand_1, operand_2, &hellip;
  110. </pre></div>
  111. <hr>
  112. <div class="header">
  113. <p>
  114. Next: <a href="Constants.html#Constants" accesskey="n" rel="next">Constants</a>, Previous: <a href="Symbol-Intro.html#Symbol-Intro" accesskey="p" rel="prev">Symbol Intro</a>, Up: <a href="Syntax.html#Syntax" accesskey="u" rel="up">Syntax</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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