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97 lines
4.3 KiB
HTML
97 lines
4.3 KiB
HTML
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<!-- This manual describes how to install and use the GNU multiple precision
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arithmetic library, version 6.1.0.
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Copyright 1991, 1993-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document under
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the terms of the GNU Free Documentation License, Version 1.3 or any later
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<title>Memory Management (GNU MP 6.1.0)</title>
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<meta name="description" content="How to install and use the GNU multiple precision arithmetic library, version 6.1.0.">
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<meta name="keywords" content="Memory Management (GNU MP 6.1.0)">
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<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
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<link href="GMP-Basics.html#GMP-Basics" rel="up" title="GMP Basics">
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<link href="Reentrancy.html#Reentrancy" rel="next" title="Reentrancy">
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<a name="Memory-Management"></a>
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<div class="header">
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<p>
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Next: <a href="Reentrancy.html#Reentrancy" accesskey="n" rel="next">Reentrancy</a>, Previous: <a href="Parameter-Conventions.html#Parameter-Conventions" accesskey="p" rel="prev">Parameter Conventions</a>, Up: <a href="GMP-Basics.html#GMP-Basics" accesskey="u" rel="up">GMP Basics</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Memory-Management-1"></a>
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<h3 class="section">3.6 Memory Management</h3>
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<a name="index-Memory-management"></a>
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<p>The GMP types like <code>mpz_t</code> are small, containing only a couple of sizes,
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and pointers to allocated data. Once a variable is initialized, GMP takes
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care of all space allocation. Additional space is allocated whenever a
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variable doesn’t have enough.
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</p>
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<p><code>mpz_t</code> and <code>mpq_t</code> variables never reduce their allocated space.
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Normally this is the best policy, since it avoids frequent reallocation.
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Applications that need to return memory to the heap at some particular point
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can use <code>mpz_realloc2</code>, or clear variables no longer needed.
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</p>
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<p><code>mpf_t</code> variables, in the current implementation, use a fixed amount of
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space, determined by the chosen precision and allocated at initialization, so
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their size doesn’t change.
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</p>
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<p>All memory is allocated using <code>malloc</code> and friends by default, but this
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can be changed, see <a href="Custom-Allocation.html#Custom-Allocation">Custom Allocation</a>. Temporary memory on the stack is
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also used (via <code>alloca</code>), but this can be changed at build-time if
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desired, see <a href="Build-Options.html#Build-Options">Build Options</a>.
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</p>
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