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| author | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-18 18:55:44 +0000 |
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| committer | Laurent Bercot <ska-skaware@skarnet.org> | 2014-09-18 18:55:44 +0000 |
| commit | 3534b428629be185e096be99e3bd5fdfe32d5544 (patch) | |
| tree | 210ef3198ed66bc7f7b7bf6a85e4579f455e5a36 /doc/libstddjb/bitarray.html | |
| download | skalibs-3534b428629be185e096be99e3bd5fdfe32d5544.tar.xz | |
initial commit with rc for skalibs-2.0.0.0
Diffstat (limited to 'doc/libstddjb/bitarray.html')
| -rw-r--r-- | doc/libstddjb/bitarray.html | 131 |
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diff --git a/doc/libstddjb/bitarray.html b/doc/libstddjb/bitarray.html new file mode 100644 index 0000000..1f88c3d --- /dev/null +++ b/doc/libstddjb/bitarray.html @@ -0,0 +1,131 @@ +<html> + <head> + <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> + <meta http-equiv="Content-Language" content="en" /> + <title>skalibs: the bitarray library interface</title> + <meta name="Description" content="skalibs: the bitarray library interface" /> + <meta name="Keywords" content="skalibs c unix bitarray 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>bitarray</tt> library interface </h1> + +<p> + The following functions are declared in the <tt>skalibs/bitarray.h</tt> header, +and implemented in the <tt>libskarnet.a</tt> or <tt>libskarnet.so</tt> library. +</p> + +<h2> General information </h2> + +<p> + <tt>bitarray</tt> is a set of primitives to operate efficiently on +large bitfields. +</p> + +<p> + A bitfield is represented by a pre-allocated block of +<tt>unsigned char</tt>; <tt>bitarray</tt> does not care if that +block has been BSS-, stack- or heap-allocated. Bitfields that +can grow in size should be stored in a +<a href="stralloc.html">stralloc</a>. +</p> + +<p> + Bits in a bitfield of length <em>n</em> are numbered from 0 to <em>n</em>-1. +</p> + +<h2> Functions </h2> + +<p> +<code> unsigned int bitarray_div8 (unsigned int n) </code> <br /> +Returns the minimum number of bytes needed to store a field of <em>n</em> bits. + +</p> + +<p> +<code> void bitarray_clearsetn (unsigned char *s, unsigned int start, unsigned int len, int h) </code> <br /> +Sets (if <em>h</em> is nonzero) or clears (if <em>h</em> is zero) +<em>len</em> bits in field <em>s</em>, starting at bit <em>start</em>. +</p> + +<p> +<code> void bitarray_clearn (unsigned char *s, unsigned int start, unsigned int len) </code> <br /> +Clears <em>len</em> bits in field <em>s</em>, starting at bit <em>start</em>. +</p> + +<p> +<code> void bitarray_setn (unsigned char *s, unsigned int start, unsigned int len) </code> <br /> +Sets <em>len</em> bits in field <em>s</em>, starting at bit <em>start</em>. +</p> + +<p> +<code> int bitarray_peek (unsigned char const *s, unsigned int n) </code> <br /> +Returns the value of the <em>n</em>th bit in field <em>s</em>. +</p> + +<p> +<code> void bitarray_poke (unsigned char *s, unsigned int n, int h) </code> <br /> +Sets (if <em>h</em> is nonzero) or clears (if <em>h</em> is zero) +the <em>n</em>th bit in field <em>s</em>. +</p> + +<p> +<code> void bitarray_clear (unsigned char *s, unsigned int n) </code> <br /> +Clears the <em>n</em>th bit in field <em>s</em>. +</p> + +<p> +<code> void bitarray_set (unsigned char *s, unsigned int n) </code> <br /> +Sets the <em>n</em>th bit in field <em>s</em>. +</p> + +<p> +<code> int bitarray_testandpoke (unsigned char *s, unsigned int n, int h) </code> <br /> +Sets (if <em>h</em> is nonzero) or clears (if <em>h</em> is zero) +the <em>n</em>th bit in field <em>s</em>, +and returns the previous value of that bit. +</p> + +<p> +<code> int bitarray_testandclear (unsigned char *s, unsigned int n) </code> <br /> +Clear the <em>n</em>th bit in field <em>s</em>, +and returns the previous value of that bit. +</p> + +<p> +<code> int bitarray_testandset (unsigned char *s, unsigned int n) </code> <br /> +Sets the <em>n</em>th bit in field <em>s</em>, +and returns the previous value of that bit. +</p> + +<p> +<code> unsigned int bitarray_first (unsigned char const *s, unsigned int len, int h) </code> <br /> +Returns the number of the first set (if <em>h</em> is nonzero) or clear +(if <em>h</em> is zero) bit in <em>s</em>, <em>len</em> being +the total number of bits. If all bits in <em>s</em> are the negation of +<em>h</em>, then <em>len</em> is returned. +</p> + +<p> +<code> unsigned int bitarray_firstclear (unsigned char const *s, unsigned int len) </code> <br /> +Returns the number of the first clear bit in <em>s</em>, <em>len</em> being +the total number of bits. If all bits in <em>s</em> are set, <em>len</em> is returned. +</p> + +<p> +<code> unsigned int bitarray_firstset (unsigned char const *s, unsigned int len) </code> <br /> +Returns the number of the first set bit in <em>s</em>, <em>len</em> being +the total number of bits. If all bits in <em>s</em> are clear, <em>len</em> is returned. +</p> + +</body> +</html> |