| <html lang="en"> |
| <head> |
| <title>AVR-Modifiers - Using as</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Using as"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="AVR-Syntax.html#AVR-Syntax" title="AVR Syntax"> |
| <link rel="prev" href="AVR_002dRegs.html#AVR_002dRegs" title="AVR-Regs"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU Assembler "as". |
| |
| Copyright (C) 1991-2019 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 |
| or any later version published by the Free Software Foundation; |
| with no Invariant Sections, with no Front-Cover Texts, and with no |
| Back-Cover Texts. A copy of the license is included in the |
| section entitled ``GNU Free Documentation License''. |
| |
| --> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="AVR-Modifiers"></a> |
| <a name="AVR_002dModifiers"></a> |
| <p> |
| Previous: <a rel="previous" accesskey="p" href="AVR_002dRegs.html#AVR_002dRegs">AVR-Regs</a>, |
| Up: <a rel="up" accesskey="u" href="AVR-Syntax.html#AVR-Syntax">AVR Syntax</a> |
| <hr> |
| </div> |
| |
| <h5 class="subsubsection">9.5.2.3 Relocatable Expression Modifiers</h5> |
| |
| <p><a name="index-AVR-modifiers-836"></a><a name="index-syntax_002c-AVR-837"></a> |
| The assembler supports several modifiers when using relocatable addresses |
| in AVR instruction operands. The general syntax is the following: |
| |
| <pre class="smallexample"> modifier(relocatable-expression) |
| </pre> |
| |
| <a name="index-symbol-modifiers-838"></a> |
| <dl> |
| <dt><code>lo8</code><dd> |
| This modifier allows you to use bits 0 through 7 of |
| an address expression as 8 bit relocatable expression. |
| |
| <br><dt><code>hi8</code><dd> |
| This modifier allows you to use bits 7 through 15 of an address expression |
| as 8 bit relocatable expression. This is useful with, for example, the |
| AVR ‘<samp><span class="samp">ldi</span></samp>’ instruction and ‘<samp><span class="samp">lo8</span></samp>’ modifier. |
| |
| <p>For example |
| |
| <pre class="smallexample"> ldi r26, lo8(sym+10) |
| ldi r27, hi8(sym+10) |
| </pre> |
| <br><dt><code>hh8</code><dd> |
| This modifier allows you to use bits 16 through 23 of |
| an address expression as 8 bit relocatable expression. |
| Also, can be useful for loading 32 bit constants. |
| |
| <br><dt><code>hlo8</code><dd> |
| Synonym of ‘<samp><span class="samp">hh8</span></samp>’. |
| |
| <br><dt><code>hhi8</code><dd> |
| This modifier allows you to use bits 24 through 31 of |
| an expression as 8 bit expression. This is useful with, for example, the |
| AVR ‘<samp><span class="samp">ldi</span></samp>’ instruction and ‘<samp><span class="samp">lo8</span></samp>’, ‘<samp><span class="samp">hi8</span></samp>’, ‘<samp><span class="samp">hlo8</span></samp>’, |
| ‘<samp><span class="samp">hhi8</span></samp>’, modifier. |
| |
| <p>For example |
| |
| <pre class="smallexample"> ldi r26, lo8(285774925) |
| ldi r27, hi8(285774925) |
| ldi r28, hlo8(285774925) |
| ldi r29, hhi8(285774925) |
| ; r29,r28,r27,r26 = 285774925 |
| </pre> |
| <br><dt><code>pm_lo8</code><dd> |
| This modifier allows you to use bits 0 through 7 of |
| an address expression as 8 bit relocatable expression. |
| This modifier useful for addressing data or code from |
| Flash/Program memory. The using of ‘<samp><span class="samp">pm_lo8</span></samp>’ similar |
| to ‘<samp><span class="samp">lo8</span></samp>’. |
| |
| <br><dt><code>pm_hi8</code><dd> |
| This modifier allows you to use bits 8 through 15 of |
| an address expression as 8 bit relocatable expression. |
| This modifier useful for addressing data or code from |
| Flash/Program memory. |
| |
| <br><dt><code>pm_hh8</code><dd> |
| This modifier allows you to use bits 15 through 23 of |
| an address expression as 8 bit relocatable expression. |
| This modifier useful for addressing data or code from |
| Flash/Program memory. |
| |
| </dl> |
| |
| </body></html> |
| |
