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| <h4 class="subsection">9.42.2 Assembler Syntax</h4> |
| |
| <p><a name="index-syntax_002c-Xtensa-assembler-2009"></a><a name="index-Xtensa-assembler-syntax-2010"></a><a name="index-FLIX-syntax-2011"></a> |
| Block comments are delimited by ‘<samp><span class="samp">/*</span></samp>’ and ‘<samp><span class="samp">*/</span></samp>’. End of line |
| comments may be introduced with either ‘<samp><span class="samp">#</span></samp>’ or ‘<samp><span class="samp">//</span></samp>’. |
| |
| <p>Instructions consist of a leading opcode or macro name followed by |
| whitespace and an optional comma-separated list of operands: |
| |
| <pre class="smallexample"> <var>opcode</var> [<var>operand</var>, ...] |
| </pre> |
| <p>Instructions must be separated by a newline or semicolon. |
| |
| <p>FLIX instructions, which bundle multiple opcodes together in a single |
| instruction, are specified by enclosing the bundled opcodes inside |
| braces: |
| |
| <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> |
| <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: |
| |
| <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> |
| <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. |
| |
| <ul class="menu"> |
| <li><a accesskey="1" href="Xtensa-Opcodes.html#Xtensa-Opcodes">Xtensa Opcodes</a>: Opcode Naming Conventions. |
| <li><a accesskey="2" href="Xtensa-Registers.html#Xtensa-Registers">Xtensa Registers</a>: Register Naming. |
| </ul> |
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