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| <h5 class="subsubsection">9.4.2.1 Instruction Set Syntax</h5> |
| |
| <p>Two slightly different syntaxes are support for ARM and THUMB |
| instructions. The default, <code>divided</code>, uses the old style where |
| ARM and THUMB instructions had their own, separate syntaxes. The new, |
| <code>unified</code> syntax, which can be selected via the <code>.syntax</code> |
| directive, and has the following main features: |
| |
| <ul> |
| <li>Immediate operands do not require a <code>#</code> prefix. |
| |
| <li>The <code>IT</code> instruction may appear, and if it does it is validated |
| against subsequent conditional affixes. In ARM mode it does not |
| generate machine code, in THUMB mode it does. |
| |
| <li>For ARM instructions the conditional affixes always appear at the end |
| of the instruction. For THUMB instructions conditional affixes can be |
| used, but only inside the scope of an <code>IT</code> instruction. |
| |
| <li>All of the instructions new to the V6T2 architecture (and later) are |
| available. (Only a few such instructions can be written in the |
| <code>divided</code> syntax). |
| |
| <li>The <code>.N</code> and <code>.W</code> suffixes are recognized and honored. |
| |
| <li>All instructions set the flags if and only if they have an <code>s</code> |
| affix. |
| </ul> |
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