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diff --git a/doc/libstddjb/alloc.html b/doc/libstddjb/alloc.html new file mode 100644 index 0000000..e17fcc7 --- /dev/null +++ b/doc/libstddjb/alloc.html @@ -0,0 +1,98 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>skalibs: the alloc library interface</title> + <meta name="Description" content="skalibs: the alloc library interface" /> + <meta name="Keywords" content="skalibs c unix alloc library libstddjb" /> + <!-- <link rel="stylesheet" type="text/css" href="http://skarnet.org/default.css" /> --> + </head> +<body> + +<p> +<a href="index.html">libstddjb</a><br /> +<a href="../libskarnet.html">libskarnet</a><br /> +<a href="../index.html">skalibs</a><br /> +<a href="http://skarnet.org/software/">Software</a><br /> +<a href="http://skarnet.org/">skarnet.org</a> +</p> + +<h1> The <tt>alloc</tt> library interface </h1> + +<p> + The following functions are declared in the <tt>skalibs/alloc.h</tt> header, +and implemented in the <tt>libskarnet.a</tt> or <tt>libskarnet.so</tt> library. +</p> + +<h2> General information </h2> + +<p> + <tt>alloc</tt> is the skalibs heap memory manager. It's actually a +wrapper for the +<a href="http://www.opengroup.org/onlinepubs/9699919799/functions/malloc.html">malloc()</a> +series of functions; it unifies a few system-dependent <tt>malloc</tt> +behaviours. It's also the API to implement and preload if for some +reason you need to plug in your own allocator: replacing <tt>alloc()</tt> +is much easier than replacing <tt>malloc()</tt> safely. +</p> + +<p> +<strong> As a general rule, you should not be using the <tt>alloc</tt> +interface directly. </strong> Allocating and freeing individual cells +in the heap is a recipe for heap fragmentation, as well as cell +tracking nightmares leading to memory leaks. <strong> You should use +the higher-level <a href="stralloc.html">stralloc</a> and +<a href="genalloc.html">genalloc</a> interfaces </strong> to handle dynamic +arrays of objects. +</p> + +<p> + C's lack of automatic management of heap memory is not a drawback: it's +a feature of the language. It allows for code that is one or two orders +of magnitude faster than the equivalent in a higher-level language, +and very low on resources consumption. However, it requires more attention +from the programmer. Good APIs can significantly reduce the difficulty of +keeping track of every heap-allocated cell, and every smart programmer +should favor them over basic interfaces like <tt>malloc()</tt>. +</p> + +<p> + <tt>alloc</tt> is used internally by skalibs to implement +<a href="stralloc.html">stralloc</a>, and nowhere else. +</p> + +<h2> Functions </h2> + +<p> +<code> char *alloc (unsigned int len) </code> <br /> +Allocates a block of <em>len</em> bytes in the heap and returns a pointer +to the start of the block (or NULL if it failed). Though the pointer type +is <tt>char *</tt>, the block of memory is correctly aligned for any type +of object. If <em>len</em> is 0, the function returns a pointer that +cannot be written to, but that is <em>not null</em>. Note that this is +different from the required C99 behaviour for <tt>malloc()</tt>. +</p> + +<p> +<code> void alloc_free (void *p) </code> <br /> +Frees the block of heap memory pointed to by <em>p</em>. +</p> + +<p> +<code> int alloc_realloc (char **p, unsigned int newlen) </code> <br /> +Redimension the block of heap memory pointed to by *<em>p</em> to +<em>newlen</em> bytes. The block may have to be moved, in which case +*<em>p</em> will be modified. Normally returns 1; if an error occurred, +returns 0 and sets errno, and neither *<em>p</em> nor its contents are +modified. +</p> + +<p> +<code> int alloc_re (char **p, unsigned int oldlen, unsigned int newlen) </code> <br /> +Legacy interface for reallocation. It works like <tt>alloc_realloc</tt>, +except that the original block length must be provided as the <em>oldlen</em> +argument. +</p> + +</body> +</html> |