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comparison docs/manual.docbook.sgml @ 117:8e2523061ce9
Document the new autobranchlength pragma
| author | lost@l-w.ca |
|---|---|
| date | Tue, 09 Aug 2011 18:16:41 -0600 |
| parents | c0aedb1584af |
| children | d90ab253471e |
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| 116:7b0716264251 | 117:8e2523061ce9 |
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| 1599 <para>Lines where this pragma is in effect will not appear in the assembly | 1599 <para>Lines where this pragma is in effect will not appear in the assembly |
| 1600 listing. Also, any symbols defined under this pragma will not show up in | 1600 listing. Also, any symbols defined under this pragma will not show up in |
| 1601 the symbol list. This is most useful in include files to avoid spamming the | 1601 the symbol list. This is most useful in include files to avoid spamming the |
| 1602 assembly listing with dozens, hundreds, or thousands of irrelevant | 1602 assembly listing with dozens, hundreds, or thousands of irrelevant |
| 1603 symbols.</para> | 1603 symbols.</para> |
| 1604 | |
| 1605 </listitem> | |
| 1606 </varlistentry> | |
| 1607 | |
| 1608 <varlistentry> | |
| 1609 <term>autobranchlength</term> | |
| 1610 <listitem> | |
| 1611 | |
| 1612 <para>One of the perennial annoyances for 6809 programmers is that the | |
| 1613 mneumonics for the short and long branch instructions are different (bxx vs. | |
| 1614 lbxx), which is at odds with the rest of the instruction set. This pragma | |
| 1615 is a solution to those annoying byte overflow errors that short branch | |
| 1616 instructions tend to aquire.</para> | |
| 1617 | |
| 1618 <para>When this pragma is in effect, which is not the default, whenever any | |
| 1619 relative branch instruction is used, its size will be automatically | |
| 1620 determined based on the actual distance to the destination. In other words, | |
| 1621 one can write code with long or short branches everywhere and the assembler | |
| 1622 will choose a size for the branch.</para> | |
| 1623 | |
| 1624 <para>Also, while this pragma is in effect, the > and < symbols can be used | |
| 1625 to force the branch size, analogous to their use for other instructions with | |
| 1626 < forcing 8 bit offsets and > forcing 16 bit offets.</para> | |
| 1627 | |
| 1628 <para>Because this pragma leads to source that is incompatible with other | |
| 1629 assemblers, it is strongly recommended that it be invoked using the PRAGMA | |
| 1630 directive within the source code rather than on the command line or via the | |
| 1631 *PRAGMA directive. This way, an error will be raised if someone tries to | |
| 1632 * assemble the code under a different assembler.</para> | |
| 1633 | |
| 1634 | |
| 1604 | 1635 |
| 1605 </listitem> | 1636 </listitem> |
| 1606 </varlistentry> | 1637 </varlistentry> |
| 1607 | 1638 |
| 1608 </variablelist> | 1639 </variablelist> |