{"id":3173,"date":"2024-02-16T18:01:01","date_gmt":"2024-02-16T10:01:01","guid":{"rendered":""},"modified":"2024-02-16T18:01:01","modified_gmt":"2024-02-16T10:01:01","slug":"\u5de7\u593a\u5929\u5de5\u7684kfifo","status":"publish","type":"post","link":"https:\/\/mushiming.com\/3173.html","title":{"rendered":"\u5de7\u593a\u5929\u5de5\u7684kfifo"},"content":{"rendered":"<p><span style=\"font-size:18px;\">\u672c\u6587\u5df2\u6709\u4fee\u8ba2\u7248\u672c\uff1a\u300a\u5de7\u593a\u5929\u5de5\u7684kfifo\uff08\u4fee\u8ba2\u7248\uff09\u300b\uff0c\u6b22\u8fce\u524d\u5f80\u9605\u8bfb\u3002<\/span><\/p>\n<p><\/p>\n<p>Linux kernel\u91cc\u9762\u4ece\u6765\u5c31\u4e0d\u7f3a\u5c11\u7b80\u6d01\uff0c\u4f18\u96c5\u548c\u9ad8\u6548\u7684\u4ee3\u7801\uff0c\u53ea\u662f\u6211\u4eec\u7f3a\u5c11\u53d1\u73b0\u548c\u54c1\u5473\u7684\u773c\u5149\u3002\u5728Linux kernel\u91cc\u9762\uff0c\u7b80\u6d01\u5e76\u4e0d\u8868\u793a\u4ee3\u7801\u4f7f\u7528\u795e\u51fa\u9b3c\u6ca1\u7684\u8d85\u7136\u6280\u5de7\uff0c\u76f8\u53cd\uff0c\u5b83\u4f7f\u7528\u7684\u4e0d\u8fc7\u662f\u5927\u5bb6\u975e\u5e38\u719f\u6089\u7684\u57fa\u7840\u6570\u636e\u7ed3\u6784\uff0c\u4f46\u662fkernel\u5f00\u53d1\u8005\u80fd\u4ece\u57fa\u7840\u7684\u6570\u636e\u7ed3\u6784\u4e2d\uff0c\u63d0\u70bc\u51fa\u4f18\u7f8e\u7684\u7279\u6027\u3002<\/p>\n<p>kfifo\u5c31\u662f\u8fd9\u6837\u7684\u4e00\u7c7b\u4f18\u7f8e\u4ee3\u7801\uff0c\u5b83\u5341\u5206\u7b80\u6d01\uff0c\u7edd\u65e0\u591a\u4f59\u7684\u4e00\u884c\u4ee3\u7801\uff0c\u5374\u975e\u5e38\u9ad8\u6548\u3002\u5173\u4e8ekfifo\u4fe1\u606f\u5982\u4e0b\uff1a<\/p>\n<p><span style=\"color:#0000ff\">\u672c\u6587\u5206\u6790\u7684\u539f\u4ee3\u7801\u7248\u672c\uff1a2.6.24.4<\/span><\/p>\n<p><span style=\"color:#0000ff\">kfifo\u7684\u5b9a\u4e49\u6587\u4ef6\uff1akernel\/kfifo.c<\/span><\/p>\n<p><span style=\"color:#0000ff\">kfifo\u7684\u5934\u6587\u4ef6\uff1a&nbsp; include\/linux\/kfifo.h<\/span><\/p>\n<p><strong>1. kfifo\u6982\u8ff0<\/strong><\/p>\n<p>kfifo\u662f\u5185\u6838\u91cc\u9762\u7684\u4e00\u4e2aFirst In First Out\u6570\u636e\u7ed3\u6784\uff0c\u5b83\u91c7\u7528\u73af\u5f62\u5faa\u73af\u961f\u5217\u7684\u6570\u636e\u7ed3\u6784\u6765\u5b9e\u73b0\uff1b\u5b83\u63d0\u4f9b\u4e00\u4e2a\u65e0\u8fb9\u754c\u7684\u5b57\u8282\u6d41\u670d\u52a1\uff0c\u6700\u91cd\u8981\u7684\u4e00\u70b9\u662f\uff0c\u5b83\u4f7f\u7528\u5e76\u884c\u65e0\u9501\u7f16\u7a0b\u6280\u672f\uff0c\u5373\u5f53\u5b83\u7528\u4e8e\u53ea\u6709\u4e00\u4e2a\u5165\u961f\u7ebf\u7a0b\u548c\u4e00\u4e2a\u51fa\u961f\u7ebf\u7a0b\u7684\u573a\u60c5\u65f6\uff0c\u4e24\u4e2a\u7ebf\u7a0b\u53ef\u4ee5\u5e76\u53d1\u64cd\u4f5c\uff0c\u800c\u4e0d\u9700\u8981\u4efb\u4f55\u52a0\u9501\u884c\u4e3a\uff0c\u5c31\u53ef\u4ee5\u4fdd\u8bc1kfifo\u7684\u7ebf\u7a0b\u5b89\u5168\u3002<\/p>\n<p>kfifo\u4ee3\u7801\u65e2\u7136\u80a9\u8d1f\u7740\u8fd9\u4e48\u591a\u7279\u6027\uff0c\u90a3\u6211\u4eec\u5148\u4e00\u655d\u5b83\u7684\u4ee3\u7801\uff1a<\/p>\n<p><textarea name=\"code\" class=\"cpp:showcolumns\">struct kfifo {<br \/>\n    unsigned char *buffer;    \/* the buffer holding the data *\/<br \/>\n    unsigned int size;    \/* the size of the allocated buffer *\/<br \/>\n    unsigned int in;    \/* data is added at offset (in % size) *\/<br \/>\n    unsigned int out;    \/* data is extracted from off. (out % size) *\/<br \/>\n    spinlock_t *lock;    \/* protects concurrent modifications *\/<br \/>\n};<\/textarea> <\/p>\n<p>&nbsp;<\/p>\n<p>\u8fd9\u662fkfifo\u7684\u6570\u636e\u7ed3\u6784\uff0ckfifo\u4e3b\u8981\u63d0\u4f9b\u4e86\u4e24\u4e2a\u64cd\u4f5c\uff0c__kfifo_put(\u5165\u961f\u64cd\u4f5c)\u548c__kfifo_get(\u51fa\u961f\u64cd\u4f5c)\u3002 \u5b83\u7684\u5404\u4e2a\u6570\u636e\u6210\u5458\u5982\u4e0b\uff1a<\/p>\n<p>buffer\uff0c \u7528\u4e8e\u5b58\u653e\u6570\u636e\u7684\u7f13\u5b58<\/p>\n<p>size,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; buffer\u7a7a\u95f4\u7684\u5927\u5c0f\uff0c\u5728\u521d\u5316\u65f6\uff0c\u5c06\u5b83\u5411\u4e0a\u6269\u5c55\u62102\u7684\u5e42<\/p>\n<p>lock,&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \u5982\u679c\u4f7f\u7528\u4e0d\u80fd\u4fdd\u8bc1\u4efb\u4f55\u65f6\u95f4\u6700\u591a\u53ea\u6709\u4e00\u4e2a\u8bfb\u7ebf\u7a0b\u548c\u5199\u7ebf\u7a0b\uff0c\u9700\u8981\u4f7f\u7528\u8be5lock\u5b9e\u65bd\u540c\u6b65\u3002<\/p>\n<p>in, out,&nbsp; \u548cbuffer\u4e00\u8d77\u6784\u6210\u4e00\u4e2a\u5faa\u73af\u961f\u5217\u3002 in\u6307\u5411buffer\u4e2d\u961f\u5934\uff0c\u800c\u4e14out\u6307\u5411buffer\u4e2d\u7684\u961f\u5c3e\uff0c\u5b83\u7684\u7ed3\u6784\u5982\u793a\u56fe\u5982\u4e0b\uff1a<\/p>\n<p><span style=\"color:#0000ff\">+--------------------------------------------------------------+<br \/>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&lt;----------data----------&gt;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | <br \/>+--------------------------------------------------------------+ <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^&nbsp; <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; in&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; out<\/span><\/p>\n<p>\u5f53\u7136\uff0c\u5185\u6838\u5f00\u53d1\u8005\u4f7f\u7528\u4e86\u4e00\u79cd\u66f4\u597d\u7684\u6280\u672f\u5904\u7406\u4e86in, out\u548cbuffer\u7684\u5173\u7cfb\uff0c\u6211\u4eec\u5c06\u5728\u4e0b\u9762\u8fdb\u884c\u8be6\u7ec6\u7684\u5206\u6790\u3002<\/p>\n<p><strong>2. kfifo_alloc \u5206\u914dkfifo\u5185\u5b58\u548c\u521d\u59cb\u5316\u5de5\u4f5c<\/strong><\/p>\n<p>&nbsp;<\/p>\n<p><textarea name=\"code\" class=\"cpp:showcolumns\">struct kfifo *kfifo_alloc(unsigned int size, gfp_t gfp_mask, spinlock_t *lock)<br \/>\n{<br \/>\n    unsigned char *buffer;<br \/>\n    struct kfifo *ret; <\/p>\n<p>    \/*<br \/>\n     * round up to the next power of 2, since our 'let the indices<br \/>\n     * wrap' tachnique works only in this case.<br \/>\n     *\/<br \/>\n    if (size &amp; (size - 1)) {<br \/>\n        BUG_ON(size &gt; 0x80000000);<br \/>\n        size = roundup_pow_of_two(size);<br \/>\n    } <\/p>\n<p>    buffer = kmalloc(size, gfp_mask);<br \/>\n    if (!buffer)<br \/>\n        return ERR_PTR(-ENOMEM); <\/p>\n<p>    ret = kfifo_init(buffer, size, gfp_mask, lock); <\/p>\n<p>    if (IS_ERR(ret))<br \/>\n        kfree(buffer); <\/p>\n<p>    return ret;<br \/>\n} <\/p>\n<p><\/textarea><\/p>\n<p>\u8fd9\u91cc\u503c\u5f97\u4e00\u63d0\u7684\u662f\uff0ckfifo-&gt;size\u7684\u503c\u603b\u662f\u5728\u8c03\u7528\u8005\u4f20\u8fdb\u6765\u7684size\u53c2\u6570\u7684\u57fa\u7840\u4e0a\u54112\u7684\u5e42\u6269\u5c55\uff0c\u8fd9\u662f\u5185\u6838\u4e00\u8d2f\u7684\u505a\u6cd5\u3002\u8fd9\u6837\u7684\u597d\u5904\u4e0d\u8a00\u800c\u55bb--\u5bf9kfifo-&gt;size\u53d6\u6a21\u8fd0\u7b97\u53ef\u4ee5\u8f6c\u5316\u4e3a\u4e0e\u8fd0\u7b97\uff0c\u5982\u4e0b\uff1a<\/p>\n<p>kfifo-&gt;in % kfifo-&gt;size \u53ef\u4ee5\u8f6c\u5316\u4e3a kfifo-&gt;in &amp; (kfifo-&gt;size \u2013 1)<\/p>\n<p>\u5728kfifo_alloc\u51fd\u6570\u4e2d\uff0c\u4f7f\u7528size &amp; (size \u2013 1)\u6765\u5224\u65adsize \u662f\u5426\u4e3a2\u5e42\uff0c\u5982\u679c\u6761\u4ef6\u4e3a\u771f\uff0c\u5219\u8868\u793asize\u4e0d\u662f2\u7684\u5e42\uff0c\u7136\u540e\u8c03\u7528roundup_pow_of_two\u5c06\u4e4b\u5411\u4e0a\u6269\u5c55\u4e3a2\u7684\u5e42\u3002 \u8fd9\u4e9b\u90fd\u662f\u5f88\u5e38\u7528\u7684\u6280\u5de7\uff0c\u53ea\u4e0d\u8fc7\u5927\u5bb6\u6ca1\u6709\u5c06\u5b83\u4eec\u7ed3\u5408\u8d77\u6765\u4f7f\u7528\u800c\u5df2\uff0c\u4e0b\u9762\u8981\u5206\u6790\u7684__kfifo_put\u548c__kfifo_get\u5219\u662f\u5c06kfifo-&gt;size\u7684\u7279\u70b9\u53d1\u6325\u5230\u4e86\u6781\u81f4\u3002<\/p>\n<p>&nbsp;<\/p>\n<p><strong>3. __kfifo_put\u548c__kfifo_get\uff0c\u5de7\u5999\u7684\u5165\u961f\u548c\u51fa\u961f\u64cd\u4f5c\uff0c\u65e0\u9501\u5e76\u53d1<\/strong><\/p>\n<p>__kfifo_put\u662f\u5165\u961f\u64cd\u4f5c\uff0c\u5b83\u5148\u5c06\u6570\u636e\u653e\u5165buffer\u91cc\u9762\uff0c\u6700\u540e\u624d\u4fee\u6539in\u53c2\u6570\uff1b__kfifo_get\u662f\u51fa\u961f\u64cd\u4f5c\uff0c\u5b83\u5148\u5c06\u6570\u636e\u4ecebuffer\u4e2d\u79fb\u8d70\uff0c\u6700\u540e\u624d\u4fee\u6539out\u3002\u4f60\u4f1a\u53d1\u73b0in\u548cout\u4e24\u8005\u5404\u53f8\u5176\u804c\u3002\u8ba1\u7b97\u673a\u79d1\u5b66\u5bb6\u5df2\u7ecf\u8bc1\u660e\uff0c\u5f53\u53ea\u6709\u4e00\u4e2a\u8bfb\u7ecf\u7a0b\u548c\u4e00\u4e2a\u5199\u7ebf\u7a0b\u5e76\u53d1\u64cd\u4f5c\u65f6\uff0c\u4e0d\u9700\u8981\u4efb\u4f55\u989d\u5916\u7684\u9501\uff0c\u5c31\u53ef\u4ee5\u786e\u4fdd\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u4e5f\u5373kfifo\u4f7f\u7528\u4e86\u65e0\u9501\u7f16\u7a0b\u6280\u672f\uff0c\u4ee5\u63d0\u9ad8kernel\u7684\u5e76\u53d1\u3002<\/p>\n<p>\u4e0b\u9762\u662f__kfifo_put\u548c__kfifo_get\u7684\u4ee3\u7801<\/p>\n<p>&nbsp;<\/p>\n<p><textarea name=\"code\" class=\"cpp:showcolumns\">unsigned int __kfifo_put(struct kfifo *fifo,<br \/>\n             unsigned char *buffer, unsigned int len)<br \/>\n{<br \/>\n    unsigned int l; <\/p>\n<p>    len = min(len, fifo-&gt;size - fifo-&gt;in + fifo-&gt;out); <\/p>\n<p>    \/*<br \/>\n     * Ensure that we sample the fifo-&gt;out index -before- we<br \/>\n     * start putting bytes into the kfifo.<br \/>\n     *\/ <\/p>\n<p>    smp_mb(); <\/p>\n<p>    \/* first put the data starting from fifo-&gt;in to buffer end *\/<br \/>\n    l = min(len, fifo-&gt;size - (fifo-&gt;in &amp; (fifo-&gt;size - 1)));<br \/>\n    memcpy(fifo-&gt;buffer + (fifo-&gt;in &amp; (fifo-&gt;size - 1)), buffer, l); <\/p>\n<p>    \/* then put the rest (if any) at the beginning of the buffer *\/<br \/>\n    memcpy(fifo-&gt;buffer, buffer + l, len - l); <\/p>\n<p>    \/*<br \/>\n     * Ensure that we add the bytes to the kfifo -before-<br \/>\n     * we update the fifo-&gt;in index.<br \/>\n     *\/ <\/p>\n<p>    smp_wmb(); <\/p>\n<p>    fifo-&gt;in += len; <\/p>\n<p>    return len;<br \/>\n}<\/p>\n<p>unsigned int __kfifo_get(struct kfifo *fifo,<br \/>\n             unsigned char *buffer, unsigned int len)<br \/>\n{<br \/>\n    unsigned int l; <\/p>\n<p>    len = min(len, fifo-&gt;in - fifo-&gt;out); <\/p>\n<p>    \/*<br \/>\n     * Ensure that we sample the fifo-&gt;in index -before- we<br \/>\n     * start removing bytes from the kfifo.<br \/>\n     *\/ <\/p>\n<p>    smp_rmb(); <\/p>\n<p>    \/* first get the data from fifo-&gt;out until the end of the buffer *\/<br \/>\n    l = min(len, fifo-&gt;size - (fifo-&gt;out &amp; (fifo-&gt;size - 1)));<br \/>\n    memcpy(buffer, fifo-&gt;buffer + (fifo-&gt;out &amp; (fifo-&gt;size - 1)), l); <\/p>\n<p>    \/* then get the rest (if any) from the beginning of the buffer *\/<br \/>\n    memcpy(buffer + l, fifo-&gt;buffer, len - l); <\/p>\n<p>    \/*<br \/>\n     * Ensure that we remove the bytes from the kfifo -before-<br \/>\n     * we update the fifo-&gt;out index.<br \/>\n     *\/ <\/p>\n<p>    smp_mb(); <\/p>\n<p>    fifo-&gt;out += len; <\/p>\n<p>    return len;<br \/>\n} <\/p>\n<p><\/textarea> <\/p>\n<p>&nbsp;<\/p>\n<p>\u8ba4\u771f\u8bfb\u4e24\u904d\u5427\uff0c\u6211\u4e5f\u8bfb\u4e86\u591a\u6b21\uff0c\u6bcf\u6b21\u603b\u662f\u6709\u65b0\u53d1\u73b0\uff0c\u56e0\u4e3ain, out\u548csize\u7684\u5173\u7cfb\u592a\u5de7\u5999\u4e86\uff0c\u7adf\u7136\u80fd\u5229\u7528\u4e0aunsigned int\u56de\u7ed5\u7684\u7279\u6027\u3002<\/p>\n<p>\u539f\u6765\uff0ckfifo\u6bcf\u6b21\u5165\u961f\u6216\u51fa\u961f\uff0ckfifo-&gt;in\u6216kfifo-&gt;out\u53ea\u662f\u7b80\u5355\u5730kfifo-&gt;in\/kfifo-&gt;out += len\uff0c\u5e76\u6ca1\u6709\u5bf9kfifo-&gt;size \u8fdb\u884c\u53d6\u6a21\u8fd0\u7b97\u3002\u56e0\u6b64kfifo-&gt;in\u548ckfifo-&gt;out\u603b\u662f\u4e00\u76f4\u589e\u5927\uff0c\u76f4\u5230unsigned in\u6700\u5927\u503c\u65f6\uff0c\u53c8\u4f1a\u7ed5\u56de\u52300\u8fd9\u4e00\u8d77\u59cb\u7aef\u3002\u4f46\u59cb\u7ec8\u6ee1\u8db3kfifo-&gt;out &lt; kfifo-&gt;in\uff0c\u9664\u975ekfifo-&gt;in\u56de\u7ed5\u5230\u4e860\u7684\u90a3\u4e00\u7aef\uff0c\u5373\u4f7f\u5982\u6b64\uff0c\u4ee3\u7801\u4e2d\u8ba1\u7b97\u957f\u5ea6\u7684\u6027\u8d28\u4ecd\u7136\u662f\u4fdd\u6301\u7684\u3002<\/p>\n<p>\u6211\u4eec\u5148\u7528\u7b80\u5355\u7684\u4f8b\u5b50\u6765\u5f62\u8c61\u8bf4\u660e\u8fd9\u4e9b\u6027\u8d28\u5427\uff1a<\/p>\n<p><span style=\"color:#0000ff\">+----------------------------------------+ <br \/>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&lt;\u2014data---&gt;|&nbsp; | <br \/>+----------------------------------------+ <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^ <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; out&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; in<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>\u4e0a\u56fe\u7684out\u548cin\u4e3akfifo-&gt;buffer\u7684\u51fa\u961f\u6570\u636e\u548c\u5165\u961f\u6570\u636e\u7684\u4e00\u4e0b\uff0c\u65b9\u6846\u4e3abuffer\u7684\u5185\u5b58\u533a\u57df\u3002\u5f53\u6709\u6570\u636e\u5165\u961f\u65f6\uff0c\u90a3\u4e48in\u7684\u503c\u53ef\u80fd\u8d85\u8fc7kfifo-&gt;size\u7684\u503c\uff0c\u90a3\u4e48\u6211\u4eec\u4f7f\u7528\u53e6\u4e00\u4e2a\u865a\u62df\u7684\u65b9\u6846\u6765\u8868\u793ain\u53d8\u5316\u540e\uff0c\u5728buffer\u5185\u5bf9kfifo-&gt;size\u53d6\u6a21\u7684\u503c\u3002\u5982\u4e0b\u56fe\u5982\u6807\uff1a<\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"color:#0000ff\">&nbsp;&nbsp;&nbsp;&nbsp; \u771f\u5b9e\u7684buffer\u5185\u5b58&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \u865a\u62df\u7684buffer\u5185\u5b58\uff0c\u65b9\u4fbf\u67e5\u770bin\u5bf9kfifo-&gt;size\u53d6\u6a21\u540e\u5728buffer\u7684\u4e0b\u6807<br \/>+----------------------------------------+ +------------------------------------+<br \/>|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&lt;\u2014data-------|&nbsp; |---------&gt;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<br \/>+----------------------------------------+ +------------------------------------+<br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^ <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; | <br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; out&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; in<\/span><\/p>\n<p>\u5f53\u7528\u6237\u8c03\u7528__kfifo_put\u51fd\u6570\uff0c\u5165\u961f\u7684\u6570\u636e\u4f7fkfifo\u7684\u5185\u5b58\u5173\u7cfb\uff0c\u5f15\u8d77\u4e0a\u8ff0\u4e24\u56fe\u7684\u53d8\u5316\u65f6\uff0c\u8981\u62f7\u8d1d\u4e24\u6b21\u5185\u5b58\u3002<\/p>\n<p>\u56e0\u4e3a\u5165\u961f\u6570\u636e\uff0c\u4e00\u90e8\u5b58\u653e\u5728kfifo-&gt;buffer\u7684\u5c3e\u90e8\uff0c\u53e6\u4e00\u90e8\u5206\u5b58\u653e\u5728kfifo-&gt;buffer\u7684\u5934\u90e8\uff0c\u8ba1\u7b97\u516c\u5f0f\u975e\u5e38\u7b80\u5355\u3002<\/p>\n<p>l = kfifo-&gt;size \u2013 kfifo-&gt;in &amp; (kfifo-&gt;size \u2013 1) \u8868\u793ain\u4e0b\u6807\u5230buffer\u672b\u5c3e\uff0c\u8fd8\u6709\u591a\u5c11\u7a7a\u95f4\u3002<\/p>\n<p>\u5982\u679clen\u8868\u793a\u9700\u8981\u62f7\u8d1d\u7684\u957f\u5ea6\u7684\u8bdd\uff0c\u90a3\u4e48len - l\u5219\u8868\u793a\u6709\u591a\u5c11\u5b57\u8282\u9700\u8981\u62f7\u8d1d\u5230buffer\u5f00\u59cb\u4e4b\u5904\u3002<\/p>\n<p>\u8fd9\u6837\uff0c\u6211\u4eec\u8bfb__kfifo_put\u4ee3\u7801\u5c31\u5f88\u5bb9\u6613\u4e86\u3002<\/p>\n<p>len = min(len, fifo-&gt;size - fifo-&gt;in + fifo-&gt;out); <\/p>\n<p>fifo-&gt;in \u2013 fifo-&gt;out\u8868\u793a\u961f\u5217\u91cc\u9762\u5df2\u4f7f\u7528\u7684\u7a7a\u95f4\u5927\u5c0f\uff0cfifo-&gt;size - (fifo-&gt;in \u2013 fifo-&gt;out)\u8868\u793a\u961f\u5217\u672a\u4f7f\u7528\u7684\u7a7a\u95f4\uff0c<\/p>\n<p>\u56e0\u6b64en = min(\u2026)\uff0c\u53d6\u4e24\u8005\u4e4b\u5c0f\uff0c\u8868\u793a\u5b9e\u9645\u8981\u62f7\u8d1d\u7684\u5b57\u8282\u6570\u3002<\/p>\n<p>\u62f7\u8d1dlen\u4e2a\u5b57\u7b26\u6570\uff0cfifo-&gt;in\u5230buffer\u672b\u5c3e\u6240\u5269\u7684\u7a7a\u95f4\u662f\u591a\u5c11\uff0c\u8fd9\u91cc\u9762\u8ba1\u7b97\uff1a<\/p>\n<p>l = min(len, fifo-&gt;size - (fifo-&gt;in &amp; (fifo-&gt;size - 1))); <br \/>memcpy(fifo-&gt;buffer + (fifo-&gt;in &amp; (fifo-&gt;size - 1)), buffer, l); <\/p>\n<p>\/* then put the rest (if any) at the beginning of the buffer *\/ <br \/>memcpy(fifo-&gt;buffer, buffer + l, len - l);<\/p>\n<p>l\u8868\u793alen\u6216fifo-&gt;in\u5230buffer\u672b\u5c3e\u6240\u5269\u7684\u7a7a\u8fdb\u884c\u95f4\u5927\u5c0f\u7684\u6700\u5c0f\u503c\uff0c\u56e0\u4e3a\u9700\u8981\u62f7l\u5b57\u8282\u5230fifo-&gt;buffer + fifo-&gt;in\u7684\u4f4d\u7f6e\u4e0a\uff1b\u90a3\u4e48\u5269\u4e0b\u8981\u62f7\u8d1d\u5230buffer\u5f00\u59cb\u4e4b\u5904\u7684\u957f\u5ea6\u4e3alen \u2013 l\uff0c\u5f53\u7136\uff0c\u6b64\u503c\u53ef\u80fd\u4f1a\u4e3a0\uff0c\u4e3a0 \u65f6\uff0cmemcpy\u51fd\u6570\u4e0d\u8fdb\u884c\u4efb\u4f55\u62f7\u8d1d\u3002<\/p>\n<p>\u6240\u6709\u7684\u62f7\u8d1d\u5b8c\u6210\u540e\uff08\u53ef\u80fd\u662f\u4e00\u6b21\uff0c\u4e5f\u53ef\u80fd\u662f\u4e24\u6b21memcpy)\uff0cfifo-&gt;in \u76f4\u63a5+= len\uff0c\u4e0d\u9700\u8981\u53d6\u6a21\u8fd0\u7b97\u3002<\/p>\n<p>\u5199\u5230\u8fd9\u91cc\uff0c\u7ec6\u5fc3\u7684\u8bfb\u8005\u4f1a\u53d1\u73b0\uff0c\u5982\u679cfifo-&gt;in\u8d85\u8fc7\u4e86unsigned int\u7684\u6700\u5927\u503c\u65f6\uff0c\u800c\u56de\u7ed5\u52300\u8fd9\u4e00\u7aef\uff0c\u4e0a\u8ff0\u7684\u8ba1\u7b97\u516c\u5f0f\u8fd8\u6b63\u786e\u5417\uff1f \u7b54\u6848\u662f\u80af\u5b9a\u7684\u3002<\/p>\n<p>\u56e0\u4e3afifo-&gt;size\u7684\u5927\u5c0f\u662f2\u7684\u5e42\uff0c\u800cunsigned int\u7a7a\u95f4\u7684\u5927\u5c0f\u662f2^32\uff0c\u540e\u8005\u521a\u597d\u662f\u524d\u8005\u7684\u500d\u6570\u3002\u5982\u679c\u4ece\u4e0a\u8ff0\u4e24\u4e2a\u56fe\u7684\u65b9\u5f0f\u6765\u63cf\u8ff0\uff0c\u5219\u8868\u793aunsigned int\u7a7a\u95f4\u7684\u6570\u8f74\u4e0a\u521a\u597d\u53ef\u4ee5\u5212\u6210\u4e00\u5b9a\u6570\u91cf\u4e2akfifo-&gt;size\u5927\u5c0f\u65b9\u6846\uff0c\u6ca1\u6709\u957f\u5ea6\u591a\u4f59\u3002\u8fd9\u6837\uff0cfifo-&gt;in\/fifo-&gt;out\u5bf9fifo-&gt;size\u53d6\u6a21\u540e\uff0c\u521a\u597d\u843d\u540e\u5bf9\u5e94\u7684\u4f4d\u7f6e\u4e0a\u3002<\/p>\n<p>\u73b0\u5728\u5047\u8bbe\u5f80kfifo\u52a0\u5165\u6570\u636e\u540e\uff0c\u4f7f\u7528fifo-&gt;in &lt; fifo-&gt;out\u5173\u7cfb\uff0c\u5982\u4e0b\uff1a<\/p>\n<p><span style=\"color:#0000ff\">+----------------------------------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; +------------------------------------+<br \/>|\u2014data\u2014&gt;|&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; \u2026\u2026&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&lt;--data------|<br \/>+----------------------------------------+&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; +------------------------------------+<br \/>|--------------------------------------------------------------------------------------------------------&gt;|<br \/>0&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 0xffffffff<br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ^<br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; |<br \/>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; in&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; out<\/span><\/p>\n<p>&nbsp;<\/p>\n<p>\u5047\u8bbekfifo\u4e2d\u6570\u636e\u7684\u957f\u5ea6\u4e3aldata\uff0c\u90a3\u4e48fifo-&gt;in\u548cfifo-&gt;out\u6709\u8fd9\u6837\u7684\u5173\u7cfb\uff1afifo-&gt;in = fifo-&gt;out + ldata\uff0c\u5e76\u4e14fifo-&gt;in &lt; fifo-&gt;out\u3002\u8fd9\u8bf4\u660efifo-&gt;in \u56de\u7ed5\u52300\u8fd9\u4e00\u6bb5\u4e86\uff0c\u5c3d\u7ba1\u5982\u6b64\uff0cfifo-&gt;in\u548cfifo-&gt;out\u7684\u5dee\u8ddd\u8fd8\u662f\u4fdd\u6301\u7684\uff0c\u6ca1\u6709\u53d8\u5316\u3002\u5373fifo-&gt;in \u2013 fifo-&gt;out\u4ecd\u7136\u662fldata, \u90a3\u4e48\u6b64\u65f6\u7684\u53ef\u7528\u7a7a\u95f4\u662ffifo-&gt;size \u2013 ldata = fifo-&gt;size - (fifo-&gt;in \u2013 fifo-&gt;out) = fifo-&gt;size \u2013 fifo-&gt;in + fifo-&gt;out\u3002 <\/p>\n<p>\u56e0\u6b64\u65e0\u8bbafifo-&gt;in\u548cfifo-&gt;out\u8c01\u5927\u8c01\u5c0f\uff0c\u8ba1\u7b97fifo\u5269\u4f59\u7a7a\u95f4\u5927\u5c0f\u7684\u516c\u5f0ffifo-&gt;size \u2013 fifo-&gt;in + fifo-&gt;out\u90fd\u6b63\u786e\uff0c\u6545\u53ef\u4ee5\u4fdd\u8bc1__kfifo_put\u51fd\u6570\u91cc\u9762\u7684\u957f\u5ea6\u8ba1\u7b97\u5747\u662f\u6b63\u786e\u7684\u3002<\/p>\n<p>__kfifo_get\u51fd\u6570\u4f7f\u7528fifo-&gt;in \u2013 fifo-&gt;out\u6765\u8ba1\u7b97fifo\u5185\u6570\u636e\u7684\u7a7a\u95f4\u957f\u5ea6\uff0c\u7136\u540e\u518d\u540e\u9700\u8981\u51fa\u961f\u7684\u6570\u636e\uff0c\u662f\u5426\u9700\u8981\u4e24\u6b21\u62f7\u8d1d\u3002\u5176\u4e2d\u539f\u7406\u548c\u65b9\u6cd5\u90fd\u548c__kfifo_put\u662f\u4e00\u6837\u7684\u3002<\/p>\n<p><strong>4. \u603b\u7ed3<\/strong><\/p>\n<p>\u8bfb\u5b8ckfifo\u4ee3\u7801\uff0c\u4ee4\u6211\u60f3\u8d77\u90a3\u9996\u8bd7\u201c\u4f17\u91cc\u5bfb\u4ed6\u5343\u767e\u5ea6\uff0c\u9ed8\u7136\u56de\u9996\uff0c\u90a3\u4eba\u6b63\u5728\u706f\u706b\u9611\u73ca\u5904\u201d\u3002\u4e0d\u77e5\u4f60\u662f\u5426\u548c\u6211\u4e00\u6837\uff0c\u603b\u60f3\u8ffd\u6c42\u7b80\u6d01\uff0c\u9ad8\u8d28\u91cf\u548c\u53ef\u8bfb\u6027\u7684\u4ee3\u7801\uff0c\u5f53\u7528\u5c3d\u5404\u79cd\u65b9\u6cd5\uff0c\u6c5f\u90de\u624d\u5c3d\u4e4b\u65f6\uff0c\u624d\u53d1\u73b0Linux kernel\u91cc\u9762\u7684\u4ee3\u7801\u5c31\u662f\u6211\u4eec\u5bfb\u627e\u548c\u5b66\u4e60\u7684\u5bf9\u8c61\u3002<\/p>\n<div id=\"clustrmaps-widget\">\n <a target=\"_blank\" href=\"http:\/\/www2.clustrmaps.com\/user\/a76263ae\" rel=\"nofollow noopener noreferrer\"><img decoding=\"async\" src=\"http:\/\/www2.clustrmaps.com\/stats\/maps-no_clusters\/blog.csdn.net-linyt-thumb.jpg\" =\"\" =\"Locations of visitors to this page\" alt=\"\u5de7\u593a\u5929\u5de5\u7684kfifo (https:\/\/mushiming.com\/)  \u7b2c1\u5f20\" title=\"\u5de7\u593a\u5929\u5de5\u7684kfifo  \u7b2c1\u5f20-\u7a46\u4e16\u660e\u535a\u5ba2\" ><\/a>\n<\/div>\n","protected":false},"excerpt":{"rendered":"\u5de7\u593a\u5929\u5de5\u7684kfifo\u4f60\u4eb2\u81ea\u5199\u8fc7\u5faa\u73af\u961f\u5217\u7684\u4ee3\u7801\u5417\uff1fLinuxkernel\u5c31\u63d0\u4f9b\u4e86\u4e00\u4e2akfifo\u6570\u636e\u7ed3\u6784\uff0c\u65e0\u8bba\u8d28\u91cf\uff0c\u6548\u7387\u548c\u53ef\u8bfb\u6027\uff0c\u5747\u5c5e\u4e8e\u4e0a\u4e58","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"_links":{"self":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/3173"}],"collection":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/comments?post=3173"}],"version-history":[{"count":0,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/posts\/3173\/revisions"}],"wp:attachment":[{"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/media?parent=3173"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/categories?post=3173"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mushiming.com\/wp-json\/wp\/v2\/tags?post=3173"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}