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| <a name="The-GNU-Assembler"></a> |
| <h3 class="section">1.2 The GNU Assembler</h3> |
| |
| |
| <p><small>GNU</small> <code>as</code> is really a family of assemblers. |
| If you use (or have used) the <small>GNU</small> assembler on one architecture, you |
| should find a fairly similar environment when you use it on another |
| architecture. Each version has much in common with the others, |
| including object file formats, most assembler directives (often called |
| <em>pseudo-ops</em>) and assembler syntax. |
| </p> |
| <a name="index-purpose-of-GNU-assembler"></a> |
| <p><code>as</code> is primarily intended to assemble the output of the |
| <small>GNU</small> C compiler <code>gcc</code> for use by the linker |
| <code>ld</code>. Nevertheless, we’ve tried to make <code>as</code> |
| assemble correctly everything that other assemblers for the same |
| machine would assemble. |
| Any exceptions are documented explicitly (see <a href="Machine-Dependencies.html#Machine-Dependencies">Machine Dependencies</a>). |
| This doesn’t mean <code>as</code> always uses the same syntax as another |
| assembler for the same architecture; for example, we know of several |
| incompatible versions of 680x0 assembly language syntax. |
| </p> |
| |
| <p>Unlike older assemblers, <code>as</code> is designed to assemble a source |
| program in one pass of the source file. This has a subtle impact on the |
| <kbd>.org</kbd> directive (see <a href="Org.html#Org"><code>.org</code></a>). |
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