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comparison docs/manual.docbook.sgml @ 210:5d969517db74
Added condundefzero pragma
Added pragma condundefzero to allow the assembler to treat symbols that are
undefined in a conditional expression as if their value had been set to
zero.
| author | William Astle <lost@l-w.ca> |
|---|---|
| date | Sat, 09 Jun 2012 16:25:19 -0600 |
| parents | 07e1fac76321 |
| children | 2cc599f1bebf |
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| 209:52d9dd71f555 | 210:5d969517db74 |
|---|---|
| 1670 is referenced.</para> | 1670 is referenced.</para> |
| 1671 | 1671 |
| 1672 <para>It is important to note that this pragma will not work as expected in | 1672 <para>It is important to note that this pragma will not work as expected in |
| 1673 all cases when using the object file assembly target. It is intended for | 1673 all cases when using the object file assembly target. It is intended for |
| 1674 use only when the assembler will be producing the final binary.</para> | 1674 use only when the assembler will be producing the final binary.</para> |
| 1675 | |
| 1676 <varlistentry> | |
| 1677 <term>condundefzero</term> | |
| 1678 <listitem> | |
| 1679 | |
| 1680 <para>This pragma will cause the assembler to change the way it handles | |
| 1681 symbols in conditional expressions. Ordinarily, any symbol that is not | |
| 1682 defined prior to the conditional will throw an undefined symbol error. With | |
| 1683 this pragma in effect, symbols that are not yet defined at the point the | |
| 1684 conditional is encountered will be treated as zero.</para> | |
| 1685 | |
| 1686 <para>This is not the default because it encourages poor code design. One | |
| 1687 should use the "IFDEF" or "IFNDEF" conditionals to test for the presence of | |
| 1688 a symbol.</para> | |
| 1689 | |
| 1690 <para>It is important to note that if a symbol is defined but it does not | |
| 1691 yet evaluate to a constant value at the point where the conditional appears, | |
| 1692 the assembler will still complain about a non constant condition.</para> | |
| 1693 | |
| 1675 | 1694 |
| 1676 </listitem> | 1695 </listitem> |
| 1677 </varlistentry> | 1696 </varlistentry> |
| 1678 | 1697 |
| 1679 </variablelist> | 1698 </variablelist> |