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Note that interrupts are disabled during OSCtxSw and also during execution of OSTaskSwHook.
Figure 15.4 80x86 stack frames and FPU storage during a task-level context switch.
OSIntCtxSw()
OSIntCtxSw is called by OSIntExit to perform a context switch from an ISR (Interrupt Service Routine). Because OSIntCtxSw is called from an ISR, it is assumed that all the processorís integer registers are already properly saved onto the interrupted taskís stack.
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