| <html lang="en"> |
| <head> |
| <title>Obstacks - The GNU C Library</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The GNU C Library"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="Memory-Allocation.html#Memory-Allocation" title="Memory Allocation"> |
| <link rel="prev" href="Allocation-Debugging.html#Allocation-Debugging" title="Allocation Debugging"> |
| <link rel="next" href="Variable-Size-Automatic.html#Variable-Size-Automatic" title="Variable Size Automatic"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU C library. |
| |
| This is Edition 0.12, last updated 2007-10-27, |
| of `The GNU C Library Reference Manual', for version |
| 2.8 (Sourcery G++ Lite 2011.03-41). |
| |
| Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, |
| 2003, 2007, 2008, 2010 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 ``Free Software Needs Free Documentation'' |
| and ``GNU Lesser General Public License'', the Front-Cover texts being |
| ``A GNU Manual'', and with the Back-Cover Texts as in (a) below. A |
| copy of the license is included in the section entitled "GNU Free |
| Documentation License". |
| |
| (a) The FSF's Back-Cover Text is: ``You have the freedom to |
| copy and modify this GNU manual. Buying copies from the FSF |
| supports it in developing GNU and promoting software freedom.''--> |
| <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> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Obstacks"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Variable-Size-Automatic.html#Variable-Size-Automatic">Variable Size Automatic</a>, |
| Previous: <a rel="previous" accesskey="p" href="Allocation-Debugging.html#Allocation-Debugging">Allocation Debugging</a>, |
| Up: <a rel="up" accesskey="u" href="Memory-Allocation.html#Memory-Allocation">Memory Allocation</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">3.2.4 Obstacks</h4> |
| |
| <p><a name="index-obstacks-300"></a> |
| An <dfn>obstack</dfn> is a pool of memory containing a stack of objects. You |
| can create any number of separate obstacks, and then allocate objects in |
| specified obstacks. Within each obstack, the last object allocated must |
| always be the first one freed, but distinct obstacks are independent of |
| each other. |
| |
| <p>Aside from this one constraint of order of freeing, obstacks are totally |
| general: an obstack can contain any number of objects of any size. They |
| are implemented with macros, so allocation is usually very fast as long as |
| the objects are usually small. And the only space overhead per object is |
| the padding needed to start each object on a suitable boundary. |
| |
| <ul class="menu"> |
| <li><a accesskey="1" href="Creating-Obstacks.html#Creating-Obstacks">Creating Obstacks</a>: How to declare an obstack in your program. |
| <li><a accesskey="2" href="Preparing-for-Obstacks.html#Preparing-for-Obstacks">Preparing for Obstacks</a>: Preparations needed before you can |
| use obstacks. |
| <li><a accesskey="3" href="Allocation-in-an-Obstack.html#Allocation-in-an-Obstack">Allocation in an Obstack</a>: Allocating objects in an obstack. |
| <li><a accesskey="4" href="Freeing-Obstack-Objects.html#Freeing-Obstack-Objects">Freeing Obstack Objects</a>: Freeing objects in an obstack. |
| <li><a accesskey="5" href="Obstack-Functions.html#Obstack-Functions">Obstack Functions</a>: The obstack functions are both |
| functions and macros. |
| <li><a accesskey="6" href="Growing-Objects.html#Growing-Objects">Growing Objects</a>: Making an object bigger by stages. |
| <li><a accesskey="7" href="Extra-Fast-Growing.html#Extra-Fast-Growing">Extra Fast Growing</a>: Extra-high-efficiency (though more |
| complicated) growing objects. |
| <li><a accesskey="8" href="Status-of-an-Obstack.html#Status-of-an-Obstack">Status of an Obstack</a>: Inquiries about the status of an obstack. |
| <li><a accesskey="9" href="Obstacks-Data-Alignment.html#Obstacks-Data-Alignment">Obstacks Data Alignment</a>: Controlling alignment of objects in obstacks. |
| <li><a href="Obstack-Chunks.html#Obstack-Chunks">Obstack Chunks</a>: How obstacks obtain and release chunks; |
| efficiency considerations. |
| <li><a href="Summary-of-Obstacks.html#Summary-of-Obstacks">Summary of Obstacks</a> |
| </ul> |
| |
| </body></html> |
| |
