📄 ringqopen.htm
字号:
<html>
<head>
<!- Copyright (c) Go Ahead Software Inc., 1995-2000. All Rights Reserved. ->
<title>ringqOpen -- basic</title>
<link rel="stylesheet" href="../../../style/doc.css" type="text/css">
</head>
<body>
<table width="550"> <tr><td>
<table border=0 width=100% cellspacing=0 cellpadding=0 CLASS="apiTitle">
<tr>
<td class="titleLeft" align=left width="33%"><b> ringqOpen</b></td><td class="titleCenter" align=center width="33%"><b> basic</b></td><td class="titleRight" align=right width="33%"><B> EMF</B></td></tr>
</table><hr>
<h2>Synopsis</h2><p>Create a new ring queue for dynamic strings.</p><h2>Prototype</h2><pre>
#include "uemf.h"
int <b>ringqOpen</b>(ringq_t *rq, int increment, int maxsize);
</pre><h2>Parameters</h2><table width=100% BORDER="0" CELLPADDING="0" CELLSPACING="0">
<tr>
<td width="9%">rq</td><td width="91%">Pointer to a ringq_t struct that receives the new ring queue.</td></tr>
<tr>
<td width="9%">increment</td><td width="91%">The amount to increase the size of the ringq should it need
to grow.</td></tr>
<tr>
<td width="9%">maxsize</td><td width="91%">The upper limit beyond which the queue must not grow.</td></tr>
</table><h2>Description</h2><p> A ring queue allows maximum utilization of memory for data storage and is
ideal for input/output buffering. This module provides a highly efficient implementation
and a vehicle for dynamic strings. </p><p> <b>Caution</b>: This is a public implementation and callers have full access
to the queue structure and pointers. Change this module very carefully. </p><p>
This module follows the open/close model.
</p><p>
Operation of a ringq where rq is a pointer to a ringq:
</p><p>
rq->buflen contains the size of the buffer.<br>
rq->buf will point to the start of the buffer.<br>
rq->servp will point to the first (un-consumed) data byte.<br>
rq->endp will point to the next free location to which new data is added.<br>
rq->endbuf will point to one past the end of the buffer.
</p><p> E.g.: If the ringq contains the data "abcdef", it might look like: </p><pre>
+-------------------------------------------------------------------+
| | | | | | | | a | b | c | d | e | f | | | | |
+-------------------------------------------------------------------+
^ ^ ^ ^
| | | |
rq->buf rq->servp rq->endp rq->enduf
</pre><p> The queue is empty when servp == endp. This means that the queue will hold
at most rq->buflen -1 bytes. It is the filler's responsibility to ensure that
the ringq is never filled such that servp == endp. </p><p> It is the filler's responsibility to "wrap" the endp back to point to rq->buf
when the pointer steps past the end. Correspondingly, it is the consumers responsibility
to "wrap" the servp when it steps to rq->endbuf. The ringqPutc and ringqGetc
routines will do this automatically. </p><h2>Return Value</h2><p>
0 on success, -1 on error.
</p><h2>Example</h2><pre>
if (ringqOpen(&p.tagbuf, XML_INC, XML_MAX) < 0) {
return -1;
}
</pre><h2>Stability Classification</h2><p>Evolving.</p><h2></h2><h2></h2><h2>See Also</h2><p>
<a href="ringqPutBlk.htm">ringqPutBlk</a>,
<a href="ringqPutStr.htm">ringqPutStr</a>
</p></td></tr></table>
</body>
</html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -