lwres/man/lwres_buffer.html

	lwres_buffer.html revision 8a66318e41ed14c5a88130e8c362610e8faa2121
8900b9eb2514c07047541833286428572493a9fdStéphane Graber<!--
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - Copyright (C) 2001  Internet Software Consortium.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi -
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - Permission to use, copy, modify, and distribute this software for any
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - purpose with or without fee is hereby granted, provided that the above
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57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi -
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi<!-- $Id: lwres_buffer.html,v 1.5 2004/03/05 08:32:19 marka Exp $ -->
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi<HTML
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><HEAD
a5ba96715d4ef264c43d4f187251de491ba198c0KATOH Yasufumi><TITLE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>lwres_buffer</TITLE
8900b9eb2514c07047541833286428572493a9fdStéphane Graber><META
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiNAME="GENERATOR"
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faefa7f8584a7d1567df2e6f1f9240a28a6466abStéphane GraberCLASS="REFENTRY"
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57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><H1
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiNAME="AEN1"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>lwres_buffer</A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></H1
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="REFNAMEDIV"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiNAME="AEN8"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><H2
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>Name</H2
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>lwres_buffer_init, lwres_buffer_invalidate, lwres_buffer_add, lwres_buffer_subtract, lwres_buffer_clear, lwres_buffer_first, lwres_buffer_forward, lwres_buffer_back, lwres_buffer_getuint8, lwres_buffer_putuint8, lwres_buffer_getuint16, lwres_buffer_putuint16, lwres_buffer_getuint32, lwres_buffer_putuint32, lwres_buffer_putmem, lwres_buffer_getmem&nbsp;--&nbsp;lightweight resolver buffer management</DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="REFSYNOPSISDIV"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><A
6127da6b3f5815028bee187ac98840cd94313841KATOH YasufumiNAME="AEN26"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><H2
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>Synopsis</H2
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCSYNOPSIS"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiNAME="AEN27"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><PRE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCSYNOPSISINFO"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>#include &lt;lwres/lwbuffer.h&gt;</PRE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_init</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, void *base, unsigned int length);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_invalidate</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH YasufumiCLASS="FUNCDEF"
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_add</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, unsigned int n);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_subtract</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, unsigned int n);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
36b33520f67cd1a83be8031fccc3c2d7d7255e06Stéphane Graber>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_clear</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_first</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_forward</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, unsigned int n);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_back</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, unsigned int n);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi>lwres_uint8_t
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_getuint8</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_putuint8</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, lwres_uint8_t val);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>lwres_uint16_t
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_getuint16</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_putuint16</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, lwres_uint16_t val);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>lwres_uint32_t
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_getuint32</CODE
a5ba96715d4ef264c43d4f187251de491ba198c0KATOH Yasufumi>(lwres_buffer_t *b);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><P
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
a5ba96715d4ef264c43d4f187251de491ba198c0KATOH Yasufumilwres_buffer_putuint32</CODE
a5ba96715d4ef264c43d4f187251de491ba198c0KATOH Yasufumi>(lwres_buffer_t *b, lwres_uint32_t val);</CODE
a5ba96715d4ef264c43d4f187251de491ba198c0KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_putmem</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, const unsigned char *base, unsigned int length);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="FUNCDEF"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>void
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilwres_buffer_getmem</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>(lwres_buffer_t *b, unsigned char *base, unsigned int length);</CODE
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><DIV
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="REFSECT1"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiNAME="AEN106"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></A
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><H2
dc421f3aac1f0e516c763dd156629a8ed2a7b4caKATOH Yasufumi>DESCRIPTION</H2
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>These functions provide bounds checked access to a region of memory
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumiwhere data is being read or written.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiThey are based on, and similar to, the
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi<TT
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="LITERAL"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>isc_buffer_</TT
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumifunctions in the ISC library.</P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><P
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>A buffer is a region of memory, together with a set of related
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumisubregions.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiThe <SPAN
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="emphasis"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><I
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="EMPHASIS"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>used region</I
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></SPAN
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi> and the
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi<SPAN
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="emphasis"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi><I
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiCLASS="EMPHASIS"
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi>available</I
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi></SPAN
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumi> region are disjoint, and
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumitheir union is the buffer's region.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiThe used region extends from the beginning of the buffer region to the
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumilast used byte.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiThe available region extends from one byte greater than the last used
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumibyte to the end of the  buffer's region.
57da8c32f85c0255efa61ee32e260068afdaa565KATOH YasufumiThe size of the used region can be changed using various
57da8c32f85c0255efa61ee32e260068afdaa565KATOH Yasufumibuffer commands.
Initially, the used region is empty.</P
><P
>The used region is further subdivided into two disjoint regions: the
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>consumed region</I
></SPAN
> and the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>remaining region</I
></SPAN
>.
The union of these two regions is the used region.
The consumed region extends from the beginning of the used region to
the byte before the <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>current</I
></SPAN
> offset (if any).
The <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>remaining</I
></SPAN
> region the current pointer to the end of the used
region.
The size of the consumed region can be changed using various
buffer commands.
Initially, the consumed region is empty.</P
><P
>The <SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>active region</I
></SPAN
> is an (optional) subregion of the remaining
region.
It extends from the current offset to an offset in the
remaining region.
Initially, the active region is empty.
If the current offset advances beyond the chosen offset,
the active region will also be empty.</P
><P
><PRE
CLASS="PROGRAMLISTING"
>
   /------------entire length---------------\\
   /----- used region -----\\/-- available --\\
   +----------------------------------------+
   | consumed  | remaining |                |
   +----------------------------------------+
   a           b     c     d                e

  a == base of buffer.
  b == current pointer.  Can be anywhere between a and d.
  c == active pointer.  Meaningful between b and d.
  d == used pointer.
  e == length of buffer.

  a-e == entire length of buffer.
  a-d == used region.
  a-b == consumed region.
  b-d == remaining region.
  b-c == optional active region.</PRE
></P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_init()</TT
>
initializes the
<SPAN
CLASS="TYPE"
>lwres_buffer_t</SPAN
>
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>
and assocates it with the memory region of size
<TT
CLASS="PARAMETER"
><I
>length</I
></TT
>
bytes starting at location
<TT
CLASS="PARAMETER"
><I
>base.</I
></TT
></P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_invalidate()</TT
>
marks the buffer
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>
as invalid.  Invalidating a buffer after use is not required,
but makes it possible to catch its possible accidental use.</P
><P
>The functions
<TT
CLASS="FUNCTION"
>lwres_buffer_add()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_buffer_subtract()</TT
>
respectively increase and decrease the used space in
buffer
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>
by
<TT
CLASS="PARAMETER"
><I
>n</I
></TT
>
bytes.
<TT
CLASS="FUNCTION"
>lwres_buffer_add()</TT
>
checks for buffer overflow and
<TT
CLASS="FUNCTION"
>lwres_buffer_subtract()</TT
>
checks for underflow.
These functions do not allocate or deallocate memory.
They just change the value of
<TT
CLASS="STRUCTFIELD"
><I
>used</I
></TT
>.</P
><P
>A buffer is re-initialised by
<TT
CLASS="FUNCTION"
>lwres_buffer_clear()</TT
>.
The function sets
<TT
CLASS="STRUCTFIELD"
><I
>used</I
></TT
> ,
<TT
CLASS="STRUCTFIELD"
><I
>current</I
></TT
>
and
<TT
CLASS="STRUCTFIELD"
><I
>active</I
></TT
>
to zero.</P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_first</TT
>
makes the consumed region of buffer
<TT
CLASS="PARAMETER"
><I
>*p</I
></TT
>
empty by setting
<TT
CLASS="STRUCTFIELD"
><I
>current</I
></TT
>
to zero (the start of the buffer).</P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_forward()</TT
>
increases the consumed region of buffer
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>
by
<TT
CLASS="PARAMETER"
><I
>n</I
></TT
>
bytes, checking for overflow.
Similarly,
<TT
CLASS="FUNCTION"
>lwres_buffer_back()</TT
>
decreases buffer
<TT
CLASS="PARAMETER"
><I
>b</I
></TT
>'s
consumed region by
<TT
CLASS="PARAMETER"
><I
>n</I
></TT
>
bytes and checks for underflow.</P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_getuint8()</TT
>
reads an unsigned 8-bit integer from
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>
and returns it.
<TT
CLASS="FUNCTION"
>lwres_buffer_putuint8()</TT
>
writes the unsigned 8-bit integer
<TT
CLASS="PARAMETER"
><I
>val</I
></TT
>
to buffer
<TT
CLASS="PARAMETER"
><I
>*b</I
></TT
>.</P
><P
><TT
CLASS="FUNCTION"
>lwres_buffer_getuint16()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_buffer_getuint32()</TT
>
are identical to
<TT
CLASS="FUNCTION"
>lwres_buffer_putuint8()</TT
>
except that they respectively read an unsigned 16-bit or 32-bit integer
in network byte order from
<TT
CLASS="PARAMETER"
><I
>b</I
></TT
>.
Similarly,
<TT
CLASS="FUNCTION"
>lwres_buffer_putuint16()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_buffer_putuint32()</TT
>
writes the unsigned 16-bit or 32-bit integer
<TT
CLASS="PARAMETER"
><I
>val</I
></TT
>
to buffer
<TT
CLASS="PARAMETER"
><I
>b</I
></TT
>,
in network byte order.</P
><P
>Arbitrary amounts of data are read or written from a lightweight
resolver buffer with
<TT
CLASS="FUNCTION"
>lwres_buffer_getmem()</TT
>
and
<TT
CLASS="FUNCTION"
>lwres_buffer_putmem()</TT
>
respectively.
<TT
CLASS="FUNCTION"
>lwres_buffer_putmem()</TT
>
copies
<TT
CLASS="PARAMETER"
><I
>length</I
></TT
>
bytes of memory at
<TT
CLASS="PARAMETER"
><I
>base</I
></TT
>
to
<TT
CLASS="PARAMETER"
><I
>b</I
></TT
>.
Conversely,
<TT
CLASS="FUNCTION"
>lwres_buffer_getmem()</TT
>
copies
<TT
CLASS="PARAMETER"
><I
>length</I
></TT
>
bytes of memory from
<TT
CLASS="PARAMETER"
><I
>b</I
></TT
>
to
<TT
CLASS="PARAMETER"
><I
>base</I
></TT
>.</P
></DIV
></BODY
></HTML
>