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176 lines
8.2 KiB
HTML
176 lines
8.2 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<!-- Copyright (C) 1988-2018 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with the
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Invariant Sections being "Funding Free Software", the Front-Cover
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Texts being (a) (see below), and with the Back-Cover Texts being (b)
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(see below). A copy of the license is included in the section entitled
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"GNU Free Documentation License".
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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(b) The FSF's Back-Cover Text is:
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You have freedom to copy and modify this GNU Manual, like GNU
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software. Copies published by the Free Software Foundation raise
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funds for GNU development. -->
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<head>
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<title>SH Function Attributes (Using the GNU Compiler Collection (GCC))</title>
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<meta name="description" content="SH Function Attributes (Using the GNU Compiler Collection (GCC))">
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<meta name="keywords" content="SH Function Attributes (Using the GNU Compiler Collection (GCC))">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<link href="index.html#Top" rel="start" title="Top">
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Function-Attributes.html#Function-Attributes" rel="up" title="Function Attributes">
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<link href="SPU-Function-Attributes.html#SPU-Function-Attributes" rel="next" title="SPU Function Attributes">
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<link href="S_002f390-Function-Attributes.html#S_002f390-Function-Attributes" rel="prev" title="S/390 Function Attributes">
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</style>
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</head>
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<body lang="en">
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<a name="SH-Function-Attributes"></a>
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<div class="header">
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<p>
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Next: <a href="SPU-Function-Attributes.html#SPU-Function-Attributes" accesskey="n" rel="next">SPU Function Attributes</a>, Previous: <a href="S_002f390-Function-Attributes.html#S_002f390-Function-Attributes" accesskey="p" rel="prev">S/390 Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="SH-Function-Attributes-1"></a>
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<h4 class="subsection">6.31.28 SH Function Attributes</h4>
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<p>These function attributes are supported on the SH family of processors:
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</p>
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<dl compact="compact">
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<dt><code>function_vector</code></dt>
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<dd><a name="index-function_005fvector-function-attribute_002c-SH"></a>
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<a name="index-calling-functions-through-the-function-vector-on-SH2A"></a>
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<p>On SH2A targets, this attribute declares a function to be called using the
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TBR relative addressing mode. The argument to this attribute is the entry
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number of the same function in a vector table containing all the TBR
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relative addressable functions. For correct operation the TBR must be setup
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accordingly to point to the start of the vector table before any functions with
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this attribute are invoked. Usually a good place to do the initialization is
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the startup routine. The TBR relative vector table can have at max 256 function
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entries. The jumps to these functions are generated using a SH2A specific,
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non delayed branch instruction JSR/N @(disp8,TBR). You must use GAS and GLD
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from GNU binutils version 2.7 or later for this attribute to work correctly.
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</p>
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<p>In an application, for a function being called once, this attribute
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saves at least 8 bytes of code; and if other successive calls are being
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made to the same function, it saves 2 bytes of code per each of these
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calls.
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</p>
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</dd>
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<dt><code>interrupt_handler</code></dt>
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<dd><a name="index-interrupt_005fhandler-function-attribute_002c-SH"></a>
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<p>Use this attribute to
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indicate that the specified function is an interrupt handler. The compiler
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generates function entry and exit sequences suitable for use in an
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interrupt handler when this attribute is present.
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</p>
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</dd>
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<dt><code>nosave_low_regs</code></dt>
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<dd><a name="index-nosave_005flow_005fregs-function-attribute_002c-SH"></a>
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<p>Use this attribute on SH targets to indicate that an <code>interrupt_handler</code>
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function should not save and restore registers R0..R7. This can be used on SH3*
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and SH4* targets that have a second R0..R7 register bank for non-reentrant
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interrupt handlers.
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</p>
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</dd>
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<dt><code>renesas</code></dt>
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<dd><a name="index-renesas-function-attribute_002c-SH"></a>
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<p>On SH targets this attribute specifies that the function or struct follows the
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Renesas ABI.
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</p>
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</dd>
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<dt><code>resbank</code></dt>
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<dd><a name="index-resbank-function-attribute_002c-SH"></a>
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<p>On the SH2A target, this attribute enables the high-speed register
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saving and restoration using a register bank for <code>interrupt_handler</code>
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routines. Saving to the bank is performed automatically after the CPU
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accepts an interrupt that uses a register bank.
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</p>
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<p>The nineteen 32-bit registers comprising general register R0 to R14,
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control register GBR, and system registers MACH, MACL, and PR and the
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vector table address offset are saved into a register bank. Register
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banks are stacked in first-in last-out (FILO) sequence. Restoration
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from the bank is executed by issuing a RESBANK instruction.
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</p>
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</dd>
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<dt><code>sp_switch</code></dt>
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<dd><a name="index-sp_005fswitch-function-attribute_002c-SH"></a>
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<p>Use this attribute on the SH to indicate an <code>interrupt_handler</code>
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function should switch to an alternate stack. It expects a string
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argument that names a global variable holding the address of the
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alternate stack.
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</p>
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<div class="smallexample">
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<pre class="smallexample">void *alt_stack;
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void f () __attribute__ ((interrupt_handler,
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sp_switch ("alt_stack")));
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</pre></div>
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</dd>
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<dt><code>trap_exit</code></dt>
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<dd><a name="index-trap_005fexit-function-attribute_002c-SH"></a>
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<p>Use this attribute on the SH for an <code>interrupt_handler</code> to return using
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<code>trapa</code> instead of <code>rte</code>. This attribute expects an integer
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argument specifying the trap number to be used.
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</p>
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</dd>
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<dt><code>trapa_handler</code></dt>
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<dd><a name="index-trapa_005fhandler-function-attribute_002c-SH"></a>
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<p>On SH targets this function attribute is similar to <code>interrupt_handler</code>
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but it does not save and restore all registers.
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</p></dd>
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</dl>
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<hr>
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<div class="header">
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<p>
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Next: <a href="SPU-Function-Attributes.html#SPU-Function-Attributes" accesskey="n" rel="next">SPU Function Attributes</a>, Previous: <a href="S_002f390-Function-Attributes.html#S_002f390-Function-Attributes" accesskey="p" rel="prev">S/390 Function Attributes</a>, Up: <a href="Function-Attributes.html#Function-Attributes" accesskey="u" rel="up">Function Attributes</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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