{"id":138,"date":"2014-07-28T16:33:43","date_gmt":"2014-07-28T16:33:43","guid":{"rendered":""},"modified":"2014-07-28T16:33:43","modified_gmt":"2014-07-28T16:33:43","slug":"","status":"publish","type":"post","link":"http:\/\/weizn.net\/?p=138","title":{"rendered":"[\u8f6c]\u8be6\u89e3C\u4e2dvolatile\u5173\u952e\u5b57"},"content":{"rendered":"

\n\tvolatile\u63d0\u9192\u7f16\u8bd1\u5668\u5b83\u540e\u9762\u6240\u5b9a\u4e49\u7684\u53d8\u91cf\u968f\u65f6\u90fd\u6709\u53ef\u80fd\u6539\u53d8\uff0c\u56e0\u6b64\u7f16\u8bd1\u540e\u7684\u7a0b\u5e8f\u6bcf\u6b21\u9700\u8981\u5b58\u50a8\u6216\u8bfb\u53d6\u8fd9\u4e2a\u53d8\u91cf\u7684\u65f6\u5019\uff0c\u90fd\u4f1a\u76f4\u63a5\u4ece\u53d8\u91cf\u5730\u5740\u4e2d\u8bfb\u53d6\u6570\u636e\u3002\u5982\u679c\u6ca1\u6709volatile\u5173\u952e\u5b57\uff0c\u5219\u7f16\u8bd1\u5668\u53ef\u80fd\u4f18\u5316\u8bfb\u53d6\u548c\u5b58\u50a8\uff0c\u53ef\u80fd\u6682\u65f6\u4f7f\u7528\u5bc4\u5b58\u5668\u4e2d\u7684\u503c\uff0c\u5982\u679c\u8fd9\u4e2a\u53d8\u91cf\u7531\u522b\u7684\u7a0b\u5e8f\u66f4\u65b0\u4e86\u7684\u8bdd\uff0c\u5c06\u51fa\u73b0\u4e0d\u4e00\u81f4\u7684\u73b0\u8c61\u3002\u4e0b\u9762\u4e3e\u4f8b\u8bf4\u660e\u3002\u5728DSP\u5f00\u53d1\u4e2d\uff0c\u7ecf\u5e38\u9700\u8981\u7b49\u5f85\u67d0\u4e2a\u4e8b\u4ef6\u7684\u89e6\u53d1\uff0c\u6240\u4ee5\u7ecf\u5e38\u4f1a\u5199\u51fa\u8fd9\u6837\u7684\u7a0b\u5e8f\uff1a
\nshort flag;
\nvoid test()
\n{
\ndo1();
\nwhile(flag==0);
\ndo2();
\n}\n<\/p>\n

\n\t    \u8fd9\u6bb5\u7a0b\u5e8f\u7b49\u5f85\u5185\u5b58\u53d8\u91cfflag\u7684\u503c\u53d8\u4e3a1(\u6000\u7591\u6b64\u5904\u662f0,\u6709\u70b9\u7591\u95ee,)\u4e4b\u540e\u624d\u8fd0\u884cdo2()\u3002\u53d8\u91cfflag\u7684\u503c\u7531\u522b\u7684\u7a0b\u5e8f\u66f4\u6539\uff0c\u8fd9\u4e2a\u7a0b\u5e8f\u53ef\u80fd\u662f\u67d0\u4e2a\u786c\u4ef6\u4e2d\u65ad\u670d\u52a1\u7a0b\u5e8f\u3002\u4f8b\u5982\uff1a\u5982\u679c\u67d0\u4e2a\u6309\u94ae\u6309\u4e0b\u7684\u8bdd\uff0c\u5c31\u4f1a\u5bf9DSP\u4ea7\u751f\u4e2d\u65ad\uff0c\u5728\u6309\u952e\u4e2d\u65ad\u7a0b\u5e8f\u4e2d\u4fee\u6539flag\u4e3a1\uff0c\u8fd9\u6837\u4e0a\u9762\u7684\u7a0b\u5e8f\u5c31\u80fd\u591f\u5f97\u4ee5\u7ee7\u7eed\u8fd0\u884c\u3002\u4f46\u662f\uff0c\u7f16\u8bd1\u5668\u5e76\u4e0d\u77e5\u9053flag\u7684\u503c\u4f1a\u88ab\u522b\u7684\u7a0b\u5e8f\u4fee\u6539\uff0c\u56e0\u6b64\u5728\u5b83\u8fdb\u884c\u4f18\u5316\u7684\u65f6\u5019\uff0c\u53ef\u80fd\u4f1a\u628aflag\u7684\u503c\u5148\u8bfb\u5165\u67d0\u4e2a\u5bc4\u5b58\u5668\uff0c\u7136\u540e\u7b49\u5f85\u90a3\u4e2a\u5bc4\u5b58\u5668\u53d8\u4e3a1\u3002\u5982\u679c\u4e0d\u5e78\u8fdb\u884c\u4e86\u8fd9\u6837\u7684\u4f18\u5316\uff0c\u90a3\u4e48while\u5faa\u73af\u5c31\u53d8\u6210\u4e86\u6b7b\u5faa\u73af\uff0c\u56e0\u4e3a\u5bc4\u5b58\u5668\u7684\u5185\u5bb9\u4e0d\u53ef\u80fd\u88ab\u4e2d\u65ad\u670d\u52a1\u7a0b\u5e8f\u4fee\u6539\u3002\u4e3a\u4e86\u8ba9\u7a0b\u5e8f\u6bcf\u6b21\u90fd\u8bfb\u53d6\u771f\u6b63flag\u53d8\u91cf\u7684\u503c\uff0c\u5c31\u9700\u8981\u5b9a\u4e49\u4e3a\u5982\u4e0b\u5f62\u5f0f\uff1a
\nvolatile short flag;
\n    \u9700\u8981\u6ce8\u610f\u7684\u662f\uff0c\u6ca1\u6709volatile\u4e5f\u53ef\u80fd\u80fd\u6b63\u5e38\u8fd0\u884c\uff0c\u4f46\u662f\u53ef\u80fd\u4fee\u6539\u4e86\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u7ea7\u522b\u4e4b\u540e\u5c31\u53c8\u4e0d\u80fd\u6b63\u5e38\u8fd0\u884c\u4e86\u3002\u56e0\u6b64\u7ecf\u5e38\u4f1a\u51fa\u73b0debug\u7248\u672c\u6b63\u5e38\uff0c\u4f46\u662frelease\u7248\u672c\u5374\u4e0d\u80fd\u6b63\u5e38\u7684\u95ee\u9898\u3002\u6240\u4ee5\u4e3a\u4e86\u5b89\u5168\u8d77\u89c1\uff0c\u53ea\u8981\u662f\u7b49\u5f85\u522b\u7684\u7a0b\u5e8f\u4fee\u6539\u67d0\u4e2a\u53d8\u91cf\u7684\u8bdd\uff0c\u5c31\u52a0\u4e0avolatile\u5173\u952e\u5b57\u3002\n<\/p>\n

\n\tvolatile\u7684\u672c\u610f\u662f\u201c\u6613\u53d8\u7684\u201d
\n      \u7531\u4e8e\u8bbf\u95ee\u5bc4\u5b58\u5668\u7684\u901f\u5ea6\u8981\u5feb\u8fc7RAM\uff0c\u6240\u4ee5\u7f16\u8bd1\u5668\u4e00\u822c\u90fd\u4f1a\u4f5c\u51cf\u5c11\u5b58\u53d6\u5916\u90e8RAM\u7684\u4f18\u5316\u3002\u6bd4\u5982\uff1a
\nstatic int i=0;
\nint main(void)
\n{
\n…
\nwhile (1)
\n{
\nif (i) do_something();
\n}
\n}
\n\/* Interrupt service routine. *\/
\nvoid ISR_2(void)
\n{
\ni=1;
\n}
\n    \u7a0b\u5e8f\u7684\u672c\u610f\u662f\u5e0c\u671bISR_2\u4e2d\u65ad\u4ea7\u751f\u65f6\uff0c\u5728main\u5f53\u4e2d\u8c03\u7528do_something\u51fd\u6570\uff0c\u4f46\u662f\uff0c\u7531\u4e8e\u7f16\u8bd1\u5668\u5224\u65ad\u5728main\u51fd\u6570\u91cc\u9762\u6ca1\u6709\u4fee\u6539\u8fc7i\uff0c\u56e0\u6b64\u53ef\u80fd\u53ea\u6267\u884c\u4e00\u6b21\u5bf9\u4ecei\u5230\u67d0\u5bc4\u5b58\u5668\u7684\u8bfb\u64cd\u4f5c\uff0c\u7136\u540e\u6bcf\u6b21if\u5224\u65ad\u90fd\u53ea\u4f7f\u7528\u8fd9\u4e2a\u5bc4\u5b58\u5668\u91cc\u9762\u7684\u201ci\u526f\u672c\u201d\uff0c\u5bfc\u81f4do_something\u6c38\u8fdc\u4e5f\u4e0d\u4f1a\u88ab\u8c03\u7528\u3002\u5982\u679c\u53d8\u91cf\u52a0\u4e0avolatile\u4fee\u9970\uff0c\u5219\u7f16\u8bd1\u5668\u4fdd\u8bc1\u5bf9\u6b64\u53d8\u91cf\u7684\u8bfb\u5199\u64cd\u4f5c\u90fd\u4e0d\u4f1a\u88ab\u4f18\u5316\uff08\u80af\u5b9a\u6267\u884c\uff09\u3002\u6b64\u4f8b\u4e2di\u4e5f\u5e94\u8be5\u5982\u6b64\u8bf4\u660e\u3002
\n    \u4e00\u822c\u8bf4\u6765\uff0cvolatile\u7528\u5728\u5982\u4e0b\u7684\u51e0\u4e2a\u5730\u65b9\uff1a
\n1\u3001\u4e2d\u65ad\u670d\u52a1\u7a0b\u5e8f\u4e2d\u4fee\u6539\u7684\u4f9b\u5176\u5b83\u7a0b\u5e8f\u68c0\u6d4b\u7684\u53d8\u91cf\u9700\u8981\u52a0volatile\uff1b
\n2\u3001\u591a\u4efb\u52a1\u73af\u5883\u4e0b\u5404\u4efb\u52a1\u95f4\u5171\u4eab\u7684\u6807\u5fd7\u5e94\u8be5\u52a0volatile\uff1b
\n3\u3001\u5b58\u50a8\u5668\u6620\u5c04\u7684\u786c\u4ef6\u5bc4\u5b58\u5668\u901a\u5e38\u4e5f\u8981\u52a0volatile\u8bf4\u660e\uff0c\u56e0\u4e3a\u6bcf\u6b21\u5bf9\u5b83\u7684\u8bfb\u5199\u90fd\u53ef\u80fd\u7531\u4e0d\u540c\u610f\u4e49\uff1b
\n\u53e6\u5916\uff0c\u4ee5\u4e0a\u8fd9\u51e0\u79cd\u60c5\u51b5\u7ecf\u5e38\u8fd8\u8981\u540c\u65f6\u8003\u8651\u6570\u636e\u7684\u5b8c\u6574\u6027\uff08\u76f8\u4e92\u5173\u8054\u7684\u51e0\u4e2a\u6807\u5fd7\u8bfb\u4e86\u4e00\u534a\u88ab\u6253\u65ad\u4e86\u91cd\u5199\uff09\uff0c\u57281\u4e2d\u53ef\u4ee5\u901a\u8fc7\u5173\u4e2d\u65ad\u6765\u5b9e\u73b0\uff0c2\u4e2d\u53ef\u4ee5\u7981\u6b62\u4efb\u52a1\u8c03\u5ea6\uff0c3\u4e2d\u5219\u53ea\u80fd\u4f9d\u9760\u786c\u4ef6\u7684\u826f\u597d\u8bbe\u8ba1\u4e86\u3002
\n\u4e8c\u3001volatile \u7684\u542b\u4e49
\n     volatile\u603b\u662f\u4e0e\u4f18\u5316\u6709\u5173\uff0c\u7f16\u8bd1\u5668\u6709\u4e00\u79cd\u6280\u672f\u53eb\u505a\u6570\u636e\u6d41\u5206\u6790\uff0c\u5206\u6790\u7a0b\u5e8f\u4e2d\u7684\u53d8\u91cf\u5728\u54ea\u91cc\u8d4b\u503c\u3001\u5728\u54ea\u91cc\u4f7f\u7528\u3001\u5728\u54ea\u91cc\u5931\u6548\uff0c\u5206\u6790\u7ed3\u679c\u53ef\u4ee5\u7528\u4e8e\u5e38\u91cf\u5408\u5e76\uff0c\u5e38\u91cf\u4f20\u64ad\u7b49\u4f18\u5316\uff0c\u8fdb\u4e00\u6b65\u53ef\u4ee5\u6b7b\u4ee3\u7801\u6d88\u9664\u3002\u4f46\u6709\u65f6\u8fd9\u4e9b\u4f18\u5316\u4e0d\u662f\u7a0b\u5e8f\u6240\u9700\u8981\u7684\uff0c\u8fd9\u65f6\u53ef\u4ee5\u7528volatile\u5173\u952e\u5b57\u7981\u6b62\u505a\u8fd9\u4e9b\u4f18\u5316\uff0cvolatile\u7684\u5b57\u9762\u542b\u4e49\u662f\u6613\u53d8\u7684\uff0c\u5b83\u6709\u4e0b\u9762\u7684\u4f5c\u7528\uff1a
\n 1 \u4e0d\u4f1a\u5728\u4e24\u4e2a\u64cd\u4f5c\u4e4b\u95f4\u628avolatile\u53d8\u91cf\u7f13\u5b58\u5728\u5bc4\u5b58\u5668\u4e2d\u3002\u5728\u591a\u4efb\u52a1\u3001\u4e2d\u65ad\u3001\u751a\u81f3setjmp\u73af\u5883\u4e0b\uff0c\u53d8\u91cf\u53ef\u80fd\u88ab\u5176\u4ed6\u7684\u7a0b\u5e8f\u6539\u53d8\uff0c\u7f16\u8bd1\u5668\u81ea\u5df1\u65e0\u6cd5\u77e5\u9053\uff0cvolatile\u5c31\u662f\u544a\u8bc9\u7f16\u8bd1\u5668\u8fd9\u79cd\u60c5\u51b5\u3002
\n2 \u4e0d\u505a\u5e38\u91cf\u5408\u5e76\u3001\u5e38\u91cf\u4f20\u64ad\u7b49\u4f18\u5316\uff0c\u6240\u4ee5\u50cf\u4e0b\u9762\u7684\u4ee3\u7801\uff1a
\nvolatile int i = 1;
\nif (i > 0) …
\nif\u7684\u6761\u4ef6\u4e0d\u4f1a\u5f53\u4f5c\u65e0\u6761\u4ef6\u771f\u3002
\n3 \u5bf9volatile\u53d8\u91cf\u7684\u8bfb\u5199\u4e0d\u4f1a\u88ab\u4f18\u5316\u6389\u3002\u5982\u679c\u4f60\u5bf9\u4e00\u4e2a\u53d8\u91cf\u8d4b\u503c\u4f46\u540e\u9762\u6ca1\u7528\u5230\uff0c\u7f16\u8bd1\u5668\u5e38\u5e38\u53ef\u4ee5\u7701\u7565\u90a3\u4e2a\u8d4b\u503c\u64cd\u4f5c\uff0c\u7136\u800c\u5bf9Memory Mapped IO\u7684\u5904\u7406\u662f\u4e0d\u80fd\u8fd9\u6837\u4f18\u5316\u7684\u3002
\n    \u524d\u9762\u6709\u4eba\u8bf4volatile\u53ef\u4ee5\u4fdd\u8bc1\u5bf9\u5185\u5b58\u64cd\u4f5c\u7684\u539f\u5b50\u6027\uff0c\u8fd9\u79cd\u8bf4\u6cd5\u4e0d\u5927\u51c6\u786e\uff0c\u5176\u4e00\uff0cx86\u9700\u8981LOCK\u524d\u7f00\u624d\u80fd\u5728SMP\u4e0b\u4fdd\u8bc1\u539f\u5b50\u6027\uff0c\u5176\u4e8c\uff0cRISC\u6839\u672c\u4e0d\u80fd\u5bf9\u5185\u5b58\u76f4\u63a5\u8fd0\u7b97\uff0c\u8981\u4fdd\u8bc1\u539f\u5b50\u6027\u5f97\u7528\u522b\u7684\u65b9\u6cd5\uff0c\u5982atomic_inc\u3002
\n    \u5bf9\u4e8ejiffies\uff0c\u5b83\u5df2\u7ecf\u58f0\u660e\u4e3avolatile\u53d8\u91cf\uff0c\u6211\u8ba4\u4e3a\u76f4\u63a5\u7528jiffies++\u5c31\u53ef\u4ee5\u4e86\uff0c\u6ca1\u5fc5\u8981\u7528\u90a3\u79cd\u590d\u6742\u7684\u5f62\u5f0f\uff0c\u56e0\u4e3a\u90a3\u6837\u4e5f\u4e0d\u80fd\u4fdd\u8bc1\u539f\u5b50\u6027\u3002
\n    \u4f60\u53ef\u80fd\u4e0d\u77e5\u9053\u5728Pentium\u53ca\u540e\u7eedCPU\u4e2d\uff0c\u4e0b\u9762\u4e24\u7ec4\u6307\u4ee4
\ninc jiffies
\n;;
\nmov jiffies, %eax
\ninc %eax
\nmov %eax, jiffies
\n\u4f5c\u7528\u76f8\u540c\uff0c\u4f46\u4e00\u6761\u6307\u4ee4\u53cd\u800c\u4e0d\u5982\u4e09\u6761\u6307\u4ee4\u5feb\u3002
\n\u4e09\u3001\u7f16\u8bd1\u5668\u4f18\u5316 \u2192 C\u5173\u952e\u5b57volatile \u2192 memory\u7834\u574f\u63cf\u8ff0\u7b26zz\n<\/p>\n

\n\t    \u201cmemory\u201d\u6bd4\u8f83\u7279\u6b8a\uff0c\u53ef\u80fd\u662f\u5185\u5d4c\u6c47\u7f16\u4e2d\u6700\u96be\u61c2\u90e8\u5206\u3002\u4e3a\u89e3\u91ca\u6e05\u695a\u5b83\uff0c\u5148\u4ecb\u7ecd\u4e00\u4e0b\u7f16\u8bd1\u5668\u7684\u4f18\u5316\u77e5\u8bc6\uff0c\u518d\u770bC\u5173\u952e\u5b57volatile\u3002\u6700\u540e\u53bb\u770b\u8be5\u63cf\u8ff0\u7b26\u3002
\n1\u3001\u7f16\u8bd1\u5668\u4f18\u5316\u4ecb\u7ecd
\n     \u5185\u5b58\u8bbf\u95ee\u901f\u5ea6\u8fdc\u4e0d\u53caCPU\u5904\u7406\u901f\u5ea6\uff0c\u4e3a\u63d0\u9ad8\u673a\u5668\u6574\u4f53\u6027\u80fd\uff0c\u5728\u786c\u4ef6\u4e0a\u5f15\u5165\u786c\u4ef6\u9ad8\u901f\u7f13\u5b58Cache\uff0c\u52a0\u901f\u5bf9\u5185\u5b58\u7684\u8bbf\u95ee\u3002\u53e6\u5916\u5728\u73b0\u4ee3CPU\u4e2d\u6307\u4ee4\u7684\u6267\u884c\u5e76\u4e0d\u4e00\u5b9a\u4e25\u683c\u6309\u7167\u987a\u5e8f\u6267\u884c\uff0c\u6ca1\u6709\u76f8\u5173\u6027\u7684\u6307\u4ee4\u53ef\u4ee5\u4e71\u5e8f\u6267\u884c\uff0c\u4ee5\u5145\u5206\u5229\u7528CPU\u7684\u6307\u4ee4\u6d41\u6c34\u7ebf\uff0c\u63d0\u9ad8\u6267\u884c\u901f\u5ea6\u3002\u4ee5\u4e0a\u662f\u786c\u4ef6\u7ea7\u522b\u7684\u4f18\u5316\u3002\u518d\u770b\u8f6f\u4ef6\u4e00\u7ea7\u7684\u4f18\u5316\uff1a\u4e00\u79cd\u662f\u5728\u7f16\u5199\u4ee3\u7801\u65f6\u7531\u7a0b\u5e8f\u5458\u4f18\u5316\uff0c\u53e6\u4e00\u79cd\u662f\u7531\u7f16\u8bd1\u5668\u8fdb\u884c\u4f18\u5316\u3002\u7f16\u8bd1\u5668\u4f18\u5316\u5e38\u7528\u7684\u65b9\u6cd5\u6709\uff1a\u5c06\u5185\u5b58\u53d8\u91cf\u7f13\u5b58\u5230\u5bc4\u5b58\u5668\uff1b\u8c03\u6574\u6307\u4ee4\u987a\u5e8f\u5145\u5206\u5229\u7528CPU\u6307\u4ee4\u6d41\u6c34\u7ebf\uff0c\u5e38\u89c1\u7684\u662f\u91cd\u65b0\u6392\u5e8f\u8bfb\u5199\u6307\u4ee4\u3002\u5bf9\u5e38\u89c4\u5185\u5b58\u8fdb\u884c\u4f18\u5316\u7684\u65f6\u5019\uff0c\u8fd9\u4e9b\u4f18\u5316\u662f\u900f\u660e\u7684\uff0c\u800c\u4e14\u6548\u7387\u5f88\u597d\u3002\u7531\u7f16\u8bd1\u5668\u4f18\u5316\u6216\u8005\u786c\u4ef6\u91cd\u65b0\u6392\u5e8f\u5f15\u8d77\u7684\u95ee\u9898\u7684\u89e3\u51b3\u529e\u6cd5\u662f\u5728\u4ece\u786c\u4ef6\uff08\u6216\u8005\u5176\u4ed6\u5904\u7406\u5668\uff09\u7684\u89d2\u5ea6\u770b\u5fc5\u987b\u4ee5\u7279\u5b9a\u987a\u5e8f\u6267\u884c\u7684\u64cd\u4f5c\u4e4b\u95f4\u8bbe\u7f6e\u5185\u5b58\u5c4f\u969c\uff08memory barrier\uff09\uff0clinux \u63d0\u4f9b\u4e86\u4e00\u4e2a\u5b8f\u89e3\u51b3\u7f16\u8bd1\u5668\u7684\u6267\u884c\u987a\u5e8f\u95ee\u9898\u3002
\nvoid Barrier(void)
\n     \u8fd9\u4e2a\u51fd\u6570\u901a\u77e5\u7f16\u8bd1\u5668\u63d2\u5165\u4e00\u4e2a\u5185\u5b58\u5c4f\u969c\uff0c\u4f46\u5bf9\u786c\u4ef6\u65e0\u6548\uff0c\u7f16\u8bd1\u540e\u7684\u4ee3\u7801\u4f1a\u628a\u5f53\u524dCPU\u5bc4\u5b58\u5668\u4e2d\u7684\u6240\u6709\u4fee\u6539\u8fc7\u7684\u6570\u503c\u5b58\u5165\u5185\u5b58\uff0c\u9700\u8981\u8fd9\u4e9b\u6570\u636e\u7684\u65f6\u5019\u518d\u91cd\u65b0\u4ece\u5185\u5b58\u4e2d\u8bfb\u51fa\u3002
\n2\u3001C\u8bed\u8a00\u5173\u952e\u5b57volatile
\n     C\u8bed\u8a00\u5173\u952e\u5b57volatile\uff08\u6ce8\u610f\u5b83\u662f\u7528\u6765\u4fee\u9970\u53d8\u91cf\u800c\u4e0d\u662f\u4e0a\u9762\u4ecb\u7ecd\u7684__volatile__\uff09\u8868\u660e\u67d0\u4e2a\u53d8\u91cf\u7684\u503c\u53ef\u80fd\u5728\u5916\u90e8\u88ab\u6539\u53d8\uff0c\u56e0\u6b64\u5bf9\u8fd9\u4e9b\u53d8\u91cf\u7684\u5b58\u53d6\u4e0d\u80fd\u7f13\u5b58\u5230\u5bc4\u5b58\u5668\uff0c\u6bcf\u6b21\u4f7f\u7528\u65f6\u9700\u8981\u91cd\u65b0\u5b58\u53d6\u3002\u8be5\u5173\u952e\u5b57\u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e0b\u7ecf\u5e38\u4f7f\u7528\uff0c\u56e0\u4e3a\u5728\u7f16\u5199\u591a\u7ebf\u7a0b\u7684\u7a0b\u5e8f\u65f6\uff0c\u540c\u4e00\u4e2a\u53d8\u91cf\u53ef\u80fd\u88ab\u591a\u4e2a\u7ebf\u7a0b\u4fee\u6539\uff0c\u800c\u7a0b\u5e8f\u901a\u8fc7\u8be5\u53d8\u91cf\u540c\u6b65\u5404\u4e2a\u7ebf\u7a0b\uff0c\u4f8b\u5982\uff1a
\nDWORD __stdcall threadFunc(LPVOID signal)
\n{
\nint* intSignal=reinterpret_cast<int*>(signal);
\n*intSignal=2;
\nwhile(*intSignal!=1)
\nsleep(1000);
\nreturn 0;
\n}
\n     \u8be5\u7ebf\u7a0b\u542f\u52a8\u65f6\u5c06intSignal \u7f6e\u4e3a2\uff0c\u7136\u540e\u5faa\u73af\u7b49\u5f85\u76f4\u5230intSignal \u4e3a1 \u65f6\u9000\u51fa\u3002\u663e\u7136intSignal\u7684\u503c\u5fc5\u987b\u5728\u5916\u90e8\u88ab\u6539\u53d8\uff0c\u5426\u5219\u8be5\u7ebf\u7a0b\u4e0d\u4f1a\u9000\u51fa\u3002\u4f46\u662f\u5b9e\u9645\u8fd0\u884c\u7684\u65f6\u5019\u8be5\u7ebf\u7a0b\u5374\u4e0d\u4f1a\u9000\u51fa\uff0c\u5373\u4f7f\u5728\u5916\u90e8\u5c06\u5b83\u7684\u503c\u6539\u4e3a1\uff0c\u770b\u4e00\u4e0b\u5bf9\u5e94\u7684\u4f2a\u6c47\u7f16\u4ee3\u7801\u5c31\u660e\u767d\u4e86\uff1a
\nmov ax,signal
\nlabel:
\nif(ax!=1)
\ngoto label
\n     \u5bf9\u4e8eC\u7f16\u8bd1\u5668\u6765\u8bf4\uff0c\u5b83\u5e76\u4e0d\u77e5\u9053\u8fd9\u4e2a\u503c\u4f1a\u88ab\u5176\u4ed6\u7ebf\u7a0b\u4fee\u6539\u3002\u81ea\u7136\u5c31\u628a\u5b83cache\u5728\u5bc4\u5b58\u5668\u91cc\u9762\u3002\u8bb0\u4f4f\uff0cC \u7f16\u8bd1\u5668\u662f\u6ca1\u6709\u7ebf\u7a0b\u6982\u5ff5\u7684\uff01\u8fd9\u65f6\u5019\u5c31\u9700\u8981\u7528\u5230volatile\u3002volatile \u7684\u672c\u610f\u662f\u6307\uff1a\u8fd9\u4e2a\u503c\u53ef\u80fd\u4f1a\u5728\u5f53\u524d\u7ebf\u7a0b\u5916\u90e8\u88ab\u6539\u53d8\u3002\u4e5f\u5c31\u662f\u8bf4\uff0c\u6211\u4eec\u8981\u5728threadFunc\u4e2d\u7684intSignal\u524d\u9762\u52a0\u4e0avolatile\u5173\u952e\u5b57\uff0c\u8fd9\u65f6\u5019\uff0c\u7f16\u8bd1\u5668\u77e5\u9053\u8be5\u53d8\u91cf\u7684\u503c\u4f1a\u5728\u5916\u90e8\u6539\u53d8\uff0c\u56e0\u6b64\u6bcf\u6b21\u8bbf\u95ee\u8be5\u53d8\u91cf\u65f6\u4f1a\u91cd\u65b0\u8bfb\u53d6\uff0c\u6240\u4f5c\u7684\u5faa\u73af\u53d8\u4e3a\u5982\u4e0b\u9762\u4f2a\u7801\u6240\u793a\uff1a
\nlabel:
\nmov ax,signal
\nif(ax!=1)
\ngoto label
\n3\u3001Memory
\n      \u6709\u4e86\u4e0a\u9762\u7684\u77e5\u8bc6\u5c31\u4e0d\u96be\u7406\u89e3Memory\u4fee\u6539\u63cf\u8ff0\u7b26\u4e86\uff0cMemory\u63cf\u8ff0\u7b26\u544a\u77e5GCC\uff1a
\n1\uff09\u4e0d\u8981\u5c06\u8be5\u6bb5\u5185\u5d4c\u6c47\u7f16\u6307\u4ee4\u4e0e\u524d\u9762\u7684\u6307\u4ee4\u91cd\u65b0\u6392\u5e8f\uff1b\u4e5f\u5c31\u662f\u5728\u6267\u884c\u5185\u5d4c\u6c47\u7f16\u4ee3\u7801\u4e4b\u524d\uff0c\u5b83\u524d\u9762\u7684\u6307\u4ee4\u90fd\u6267\u884c\u5b8c\u6bd5
\n2\uff09\u4e0d\u8981\u5c06\u53d8\u91cf\u7f13\u5b58\u5230\u5bc4\u5b58\u5668\uff0c\u56e0\u4e3a\u8fd9\u6bb5\u4ee3\u7801\u53ef\u80fd\u4f1a\u7528\u5230\u5185\u5b58\u53d8\u91cf\uff0c\u800c\u8fd9\u4e9b\u5185\u5b58\u53d8\u91cf\u4f1a\u4ee5\u4e0d\u53ef\u9884\u77e5\u7684\u65b9\u5f0f\u53d1\u751f\u6539\u53d8\uff0c\u56e0\u6b64GCC\u63d2\u5165\u5fc5\u8981\u7684\u4ee3\u7801\u5148\u5c06\u7f13\u5b58\u5230\u5bc4\u5b58\u5668\u7684\u53d8\u91cf\u503c\u5199\u56de\u5185\u5b58\uff0c\u5982\u679c\u540e\u9762\u53c8\u8bbf\u95ee\u8fd9\u4e9b\u53d8\u91cf\uff0c\u9700\u8981\u91cd\u65b0\u8bbf\u95ee\u5185\u5b58\u3002
\n     \u5982\u679c\u6c47\u7f16\u6307\u4ee4\u4fee\u6539\u4e86\u5185\u5b58\uff0c\u4f46\u662fGCC \u672c\u8eab\u5374\u5bdf\u89c9\u4e0d\u5230\uff0c\u56e0\u4e3a\u5728\u8f93\u51fa\u90e8\u5206\u6ca1\u6709\u63cf\u8ff0\uff0c\u6b64\u65f6\u5c31\u9700\u8981\u5728\u4fee\u6539\u63cf\u8ff0\u90e8\u5206\u589e\u52a0\u201cmemory\u201d\uff0c\u544a\u8bc9GCC \u5185\u5b58\u5df2\u7ecf\u88ab\u4fee\u6539\uff0cGCC \u5f97\u77e5\u8fd9\u4e2a\u4fe1\u606f\u540e\uff0c\u5c31\u4f1a\u5728\u8fd9\u6bb5\u6307\u4ee4\u4e4b\u524d\uff0c\u63d2\u5165\u5fc5\u8981\u7684\u6307\u4ee4\u5c06\u524d\u9762\u56e0\u4e3a\u4f18\u5316Cache \u5230\u5bc4\u5b58\u5668\u4e2d\u7684\u53d8\u91cf\u503c\u5148\u5199\u56de\u5185\u5b58\uff0c\u5982\u679c\u4ee5\u540e\u53c8\u8981\u4f7f\u7528\u8fd9\u4e9b\u53d8\u91cf\u518d\u91cd\u65b0\u8bfb\u53d6\u3002
\n     \u4f7f\u7528\u201cvolatile\u201d\u4e5f\u53ef\u4ee5\u8fbe\u5230\u8fd9\u4e2a\u76ee\u7684\uff0c\u4f46\u662f\u6211\u4eec\u5728\u6bcf\u4e2a\u53d8\u91cf\u524d\u589e\u52a0\u8be5\u5173\u952e\u5b57\uff0c\u4e0d\u5982\u4f7f\u7528\u201cmemory\u201d\u65b9\u4fbf\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"

\n\tvolatile\u63d0\u9192\u7f16\u8bd1\u5668\u5b83\u540e\u9762\u6240\u5b9a\u4e49\u7684\u53d8\u91cf\u968f\u65f6\u90fd\u6709\u53ef\u80fd\u6539\u53d8\uff0c\u56e0\u6b64\u7f16\u8bd1\u540e\u7684\u7a0b\u5e8f\u6bcf\u6b21\u9700\u8981\u5b58\u50a8\u6216\u8bfb\u53d6\u8fd9\u4e2a\u53d8\u91cf\u7684\u65f6\u5019\uff0c\u90fd\u4f1a\u76f4\u63a5\u4ece\u53d8\u91cf\u5730\u5740\u4e2d\u8bfb\u53d6\u6570\u636e\u3002\u5982\u679c\u6ca1\u6709volatile\u5173\u952e\u5b57\uff0c\u5219\u7f16\u8bd1\u5668\u53ef\u80fd\u4f18\u5316\u8bfb\u53d6\u548c\u5b58\u50a8\uff0c\u53ef\u80fd\u6682\u65f6\u4f7f\u7528\u5bc4\u5b58\u5668\u4e2d\u7684\u503c\uff0c\u5982\u679c\u8fd9\u4e2a\u53d8\u91cf\u7531\u522b\u7684\u7a0b\u5e8f\u66f4\u65b0\u4e86\u7684\u8bdd\uff0c\u5c06\u51fa\u73b0\u4e0d\u4e00\u81f4\u7684\u73b0\u8c61\u3002\u4e0b\u9762\u4e3e\u4f8b\u8bf4\u660e\u3002\u5728DSP\u5f00\u53d1\u4e2d\uff0c\u7ecf\u5e38\u9700\u8981\u7b49\u5f85\u67d0\u4e2a\u4e8b\u4ef6\u7684\u89e6\u53d1\uff0c\u6240\u4ee5\u7ecf\u5e38\u4f1a\u5199\u51fa\u8fd9\u6837\u7684\u7a0b\u5e8f\uff1a
\nshort flag;
\n…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[324],"tags":[],"class_list":["post-138","post","type-post","status-publish","format-standard","hentry"],"yoast_head":"\n[\u8f6c]\u8be6\u89e3C\u4e2dvolatile\u5173\u952e\u5b57 - Wayne's Blog<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"http:\/\/weizn.net\/?p=138\" \/>\n<meta property=\"og:locale\" content=\"zh_CN\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[\u8f6c]\u8be6\u89e3C\u4e2dvolatile\u5173\u952e\u5b57 - Wayne's Blog\" \/>\n<meta property=\"og:description\" content=\"volatile\u63d0\u9192\u7f16\u8bd1\u5668\u5b83\u540e\u9762\u6240\u5b9a\u4e49\u7684\u53d8\u91cf\u968f\u65f6\u90fd\u6709\u53ef\u80fd\u6539\u53d8\uff0c\u56e0\u6b64\u7f16\u8bd1\u540e\u7684\u7a0b\u5e8f\u6bcf\u6b21\u9700\u8981\u5b58\u50a8\u6216\u8bfb\u53d6\u8fd9\u4e2a\u53d8\u91cf\u7684\u65f6\u5019\uff0c\u90fd\u4f1a\u76f4\u63a5\u4ece\u53d8\u91cf\u5730\u5740\u4e2d\u8bfb\u53d6\u6570\u636e\u3002\u5982\u679c\u6ca1\u6709volatile\u5173\u952e\u5b57\uff0c\u5219\u7f16\u8bd1\u5668\u53ef\u80fd\u4f18\u5316\u8bfb\u53d6\u548c\u5b58\u50a8\uff0c\u53ef\u80fd\u6682\u65f6\u4f7f\u7528\u5bc4\u5b58\u5668\u4e2d\u7684\u503c\uff0c\u5982\u679c\u8fd9\u4e2a\u53d8\u91cf\u7531\u522b\u7684\u7a0b\u5e8f\u66f4\u65b0\u4e86\u7684\u8bdd\uff0c\u5c06\u51fa\u73b0\u4e0d\u4e00\u81f4\u7684\u73b0\u8c61\u3002\u4e0b\u9762\u4e3e\u4f8b\u8bf4\u660e\u3002\u5728DSP\u5f00\u53d1\u4e2d\uff0c\u7ecf\u5e38\u9700\u8981\u7b49\u5f85\u67d0\u4e2a\u4e8b\u4ef6\u7684\u89e6\u53d1\uff0c\u6240\u4ee5\u7ecf\u5e38\u4f1a\u5199\u51fa\u8fd9\u6837\u7684\u7a0b\u5e8f\uff1a short flag; 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