Microprocessor with operating system - independent multitasking operation supporting random number generator

摘要

A microprocessor that includes a random number generator (RNG) that saves and restores its own state on a task switch without operating system (OS) support. The RNG includes a control and status register (CSR) for storing control values that affect the generation of random numbers. The CSR is not saved and restored by the OS. The RNG shadows the CSR with an SSE register that is saved and restored by the OS. A new instruction loads the CSR, and also loads the shadowed SSE register. Whenever the SSE register is restored from memory, the RNG sets a flag indicating that a possible task switch occurred. Whenever the processor executes a new instruction that stores the random data to memory, it checks the flag and copies the control values from the SSE register to the CSR if the flag is true, discards previously generated bytes, and restarts random number generation.