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This may not be sufficiently random for concurrent execution, where it may lead to correlated generated series in different threads, or for small embedded systems that have an unsigned int type with a width of 16 bits. Note that the POSIX standard specifies a minimum width of 32 bits for unsigned int. Depending on the application and the desired level of security, a programmer may choose alternative ways to seed PRNGs. In general, hardware is more capable than software of generating real random numbers (for example, by sampling the thermal noise of a diode).
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