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| <a name="Xtensa-Syntax"></a> |
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| Next: <a href="Xtensa-Optimizations.html#Xtensa-Optimizations" accesskey="n" rel="next">Xtensa Optimizations</a>, Previous: <a href="Xtensa-Options.html#Xtensa-Options" accesskey="p" rel="prev">Xtensa Options</a>, Up: <a href="Xtensa_002dDependent.html#Xtensa_002dDependent" accesskey="u" rel="up">Xtensa-Dependent</a> [<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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| <a name="Assembler-Syntax"></a> |
| <h4 class="subsection">9.52.2 Assembler Syntax</h4> |
| <a name="index-syntax_002c-Xtensa-assembler"></a> |
| <a name="index-Xtensa-assembler-syntax"></a> |
| <a name="index-FLIX-syntax"></a> |
| |
| <p>Block comments are delimited by ‘<samp>/*</samp>’ and ‘<samp>*/</samp>’. End of line |
| comments may be introduced with either ‘<samp>#</samp>’ or ‘<samp>//</samp>’. |
| </p> |
| <p>If a ‘<samp>#</samp>’ appears as the first character of a line then the whole |
| line is treated as a comment, but in this case the line could also be |
| a logical line number directive (see <a href="Comments.html#Comments">Comments</a>) or a preprocessor |
| control command (see <a href="Preprocessing.html#Preprocessing">Preprocessing</a>). |
| </p> |
| <p>Instructions consist of a leading opcode or macro name followed by |
| whitespace and an optional comma-separated list of operands: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"><var>opcode</var> [<var>operand</var>, …] |
| </pre></div> |
| |
| <p>Instructions must be separated by a newline or semicolon (‘<samp>;</samp>’). |
| </p> |
| <p>FLIX instructions, which bundle multiple opcodes together in a single |
| instruction, are specified by enclosing the bundled opcodes inside |
| braces: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">{ |
| [<var>format</var>] |
| <var>opcode0</var> [<var>operands</var>] |
| </pre><pre class="smallexample"><var>opcode1</var> [<var>operands</var>] |
| </pre><pre class="smallexample"><var>opcode2</var> [<var>operands</var>] |
| … |
| } |
| </pre></div> |
| |
| <p>The opcodes in a FLIX instruction are listed in the same order as the |
| corresponding instruction slots in the TIE format declaration. |
| Directives and labels are not allowed inside the braces of a FLIX |
| instruction. A particular TIE format name can optionally be specified |
| immediately after the opening brace, but this is usually unnecessary. |
| The assembler will automatically search for a format that can encode the |
| specified opcodes, so the format name need only be specified in rare |
| cases where there is more than one applicable format and where it |
| matters which of those formats is used. A FLIX instruction can also be |
| specified on a single line by separating the opcodes with semicolons: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample">{ [<var>format</var>;] <var>opcode0</var> [<var>operands</var>]; <var>opcode1</var> [<var>operands</var>]; <var>opcode2</var> [<var>operands</var>]; … } |
| </pre></div> |
| |
| <p>If an opcode can only be encoded in a FLIX instruction but is not |
| specified as part of a FLIX bundle, the assembler will choose the |
| smallest format where the opcode can be encoded and |
| will fill unused instruction slots with no-ops. |
| </p> |
| <table class="menu" border="0" cellspacing="0"> |
| <tr><td align="left" valign="top">• <a href="Xtensa-Opcodes.html#Xtensa-Opcodes" accesskey="1">Xtensa Opcodes</a>:</td><td> </td><td align="left" valign="top">Opcode Naming Conventions. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Xtensa-Registers.html#Xtensa-Registers" accesskey="2">Xtensa Registers</a>:</td><td> </td><td align="left" valign="top">Register Naming. |
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| Next: <a href="Xtensa-Optimizations.html#Xtensa-Optimizations" accesskey="n" rel="next">Xtensa Optimizations</a>, Previous: <a href="Xtensa-Options.html#Xtensa-Options" accesskey="p" rel="prev">Xtensa Options</a>, Up: <a href="Xtensa_002dDependent.html#Xtensa_002dDependent" accesskey="u" rel="up">Xtensa-Dependent</a> [<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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