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| author | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
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| committer | alk3pInjection <webmaster@raspii.tech> | 2024-02-04 16:16:35 +0800 |
| commit | abdaadbcae30fe0c9a66c7516798279fdfd97750 (patch) | |
| tree | 00a54a6e25601e43876d03c1a4a12a749d4a914c /share/doc/gcc/AVR-Built_002din-Functions.html | |
https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads
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diff --git a/share/doc/gcc/AVR-Built_002din-Functions.html b/share/doc/gcc/AVR-Built_002din-Functions.html new file mode 100644 index 0000000..ab4a7ae --- /dev/null +++ b/share/doc/gcc/AVR-Built_002din-Functions.html @@ -0,0 +1,198 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- This file documents the use of the GNU compilers. + +Copyright (C) 1988-2023 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 the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). A copy of the license is included in the section entitled +"GNU Free Documentation License". + +(a) The FSF's Front-Cover Text is: + +A GNU Manual + +(b) The FSF's Back-Cover Text is: + +You have freedom to copy and modify this GNU Manual, like GNU + software. Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>Using the GNU Compiler Collection (GCC): AVR Built-in Functions</title> + +<meta name="description" content="Using the GNU Compiler Collection (GCC): AVR Built-in Functions"> +<meta name="keywords" content="Using the GNU Compiler Collection (GCC): AVR Built-in Functions"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Indices.html#Indices" rel="index" title="Indices"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Target-Builtins.html#Target-Builtins" rel="up" title="Target Builtins"> +<link href="Blackfin-Built_002din-Functions.html#Blackfin-Built_002din-Functions" rel="next" title="Blackfin Built-in Functions"> +<link href="ARM-ARMv8_002dM-Security-Extensions.html#ARM-ARMv8_002dM-Security-Extensions" rel="previous" title="ARM ARMv8-M Security Extensions"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en_US" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="AVR-Built_002din-Functions"></a> +<div class="header"> +<p> +Next: <a href="Blackfin-Built_002din-Functions.html#Blackfin-Built_002din-Functions" accesskey="n" rel="next">Blackfin Built-in Functions</a>, Previous: <a href="ARM-ARMv8_002dM-Security-Extensions.html#ARM-ARMv8_002dM-Security-Extensions" accesskey="p" rel="previous">ARM ARMv8-M Security Extensions</a>, Up: <a href="Target-Builtins.html#Target-Builtins" accesskey="u" rel="up">Target Builtins</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="AVR-Built_002din-Functions-1"></a> +<h4 class="subsection">6.60.10 AVR Built-in Functions</h4> + +<p>For each built-in function for AVR, there is an equally named, +uppercase built-in macro defined. That way users can easily query if +or if not a specific built-in is implemented or not. For example, if +<code>__builtin_avr_nop</code> is available the macro +<code>__BUILTIN_AVR_NOP</code> is defined to <code>1</code> and undefined otherwise. +</p> +<dl compact="compact"> +<dt><code>void __builtin_avr_nop (void)</code></dt> +<dt><code>void __builtin_avr_sei (void)</code></dt> +<dt><code>void __builtin_avr_cli (void)</code></dt> +<dt><code>void __builtin_avr_sleep (void)</code></dt> +<dt><code>void __builtin_avr_wdr (void)</code></dt> +<dt><code>unsigned char __builtin_avr_swap (unsigned char)</code></dt> +<dt><code>unsigned int __builtin_avr_fmul (unsigned char, unsigned char)</code></dt> +<dt><code>int __builtin_avr_fmuls (char, char)</code></dt> +<dt><code>int __builtin_avr_fmulsu (char, unsigned char)</code></dt> +<dd><p>These built-in functions map to the respective machine +instruction, i.e. <code>nop</code>, <code>sei</code>, <code>cli</code>, <code>sleep</code>, +<code>wdr</code>, <code>swap</code>, <code>fmul</code>, <code>fmuls</code> +resp. <code>fmulsu</code>. The three <code>fmul*</code> built-ins are implemented +as library call if no hardware multiplier is available. +</p> +</dd> +<dt><code>void __builtin_avr_delay_cycles (unsigned long ticks)</code></dt> +<dd><p>Delay execution for <var>ticks</var> cycles. Note that this +built-in does not take into account the effect of interrupts that +might increase delay time. <var>ticks</var> must be a compile-time +integer constant; delays with a variable number of cycles are not supported. +</p> +</dd> +<dt><code>char __builtin_avr_flash_segment (const __memx void*)</code></dt> +<dd><p>This built-in takes a byte address to the 24-bit +<a href="Named-Address-Spaces.html#AVR-Named-Address-Spaces">address space</a> <code>__memx</code> and returns +the number of the flash segment (the 64 KiB chunk) where the address +points to. Counting starts at <code>0</code>. +If the address does not point to flash memory, return <code>-1</code>. +</p> +</dd> +<dt><code>uint8_t __builtin_avr_insert_bits (uint32_t map, uint8_t bits, uint8_t val)</code></dt> +<dd><p>Insert bits from <var>bits</var> into <var>val</var> and return the resulting +value. The nibbles of <var>map</var> determine how the insertion is +performed: Let <var>X</var> be the <var>n</var>-th nibble of <var>map</var> +</p><ol> +<li> If <var>X</var> is <code>0xf</code>, +then the <var>n</var>-th bit of <var>val</var> is returned unaltered. + +</li><li> If X is in the range 0…7, +then the <var>n</var>-th result bit is set to the <var>X</var>-th bit of <var>bits</var> + +</li><li> If X is in the range 8…<code>0xe</code>, +then the <var>n</var>-th result bit is undefined. +</li></ol> + +<p>One typical use case for this built-in is adjusting input and +output values to non-contiguous port layouts. Some examples: +</p> +<div class="smallexample"> +<pre class="smallexample">// same as val, bits is unused +__builtin_avr_insert_bits (0xffffffff, bits, val); +</pre></div> + +<div class="smallexample"> +<pre class="smallexample">// same as bits, val is unused +__builtin_avr_insert_bits (0x76543210, bits, val); +</pre></div> + +<div class="smallexample"> +<pre class="smallexample">// same as rotating bits by 4 +__builtin_avr_insert_bits (0x32107654, bits, 0); +</pre></div> + +<div class="smallexample"> +<pre class="smallexample">// high nibble of result is the high nibble of val +// low nibble of result is the low nibble of bits +__builtin_avr_insert_bits (0xffff3210, bits, val); +</pre></div> + +<div class="smallexample"> +<pre class="smallexample">// reverse the bit order of bits +__builtin_avr_insert_bits (0x01234567, bits, 0); +</pre></div> + +</dd> +<dt><code>void __builtin_avr_nops (unsigned count)</code></dt> +<dd><p>Insert <var>count</var> <code>NOP</code> instructions. +The number of instructions must be a compile-time integer constant. +</p> +</dd> +</dl> + +<p>There are many more AVR-specific built-in functions that are used to +implement the ISO/IEC TR 18037 “Embedded C” fixed-point functions of +section 7.18a.6. You don’t need to use these built-ins directly. +Instead, use the declarations as supplied by the <code>stdfix.h</code> header +with GNU-C99: +</p> +<div class="smallexample"> +<pre class="smallexample">#include <stdfix.h> + +// Re-interpret the bit representation of unsigned 16-bit +// integer <var>uval</var> as Q-format 0.16 value. +unsigned fract get_bits (uint_ur_t uval) +{ + return urbits (uval); +} +</pre></div> + +<hr> +<div class="header"> +<p> +Next: <a href="Blackfin-Built_002din-Functions.html#Blackfin-Built_002din-Functions" accesskey="n" rel="next">Blackfin Built-in Functions</a>, Previous: <a href="ARM-ARMv8_002dM-Security-Extensions.html#ARM-ARMv8_002dM-Security-Extensions" accesskey="p" rel="previous">ARM ARMv8-M Security Extensions</a>, Up: <a href="Target-Builtins.html#Target-Builtins" accesskey="u" rel="up">Target Builtins</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Indices.html#Indices" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |