interrupt

问题 When an interrupt comes to CPU, it is handled by saving current address location prior jumping into the handler if it is acknowledged. Otherwise it is ignored. I wonder whether an assembly instruction call is interrupted. For example, mvi a, 03h ; put 3 value into acc. in 8080 assembly Can be the one line instruction interrupted? Or if not, it is atomic?? Is there always a guarantee that "one line assembly instruction" is always atomic?? What if there is no "lock" keyword i.e. in 8080

问题 I'm writing a user space program and a kernel space device driver. Goal: Once an interrupt occurs, user space program needs to do something quickly. My naive method: User space program uses ioctl to call wait_event_interruptible(), kernel ISR calls wake_up_interruptible() to wake up user space program. It turns out that it takes too much time from interrupt to user space. Is there any better way? Thanks! 回答1: There is a similar question asked here: Notify gpio interrupt to user space from a

问题 In my code, I use QueueUserAPC to interrupt the main thread from his current work in order to invoke some callback first before going back to his previous work. std::string buffer; std::tr1::shared_ptr<void> hMainThread; VOID CALLBACK myCallback (ULONG_PTR dwParam) { FILE * f = fopen("somefile", "a"); fprintf(f, "CALLBACK WAS INVOKED!\n"); fclose(f); } void AdditionalThread () { // download some file using synchronous wininet and store the // HTTP response in buffer QueueUserAPC(myCallback,

问题 what is tail chaining of Interrupts which is supported by NVIC in ARM Cortex M3. 回答1: Tail-chaining is back-to-back processing of exceptions without the overhead of state saving and restoration between interrupts. The processor skips the pop of eight registers and push of eight registers when exiting one ISR and entering another because this has no effect on the stack contents. Cortex™-M3 Technical Reference Manual Which basically means, handling pending interrupts without repeating the

问题 Is it possible to use graphic card clock from a windows application? More specifically - is it possible to somehow make graphic card to send interrupts on clock events (tick?) and hook to it from a software? What I am trying to say is that PC clocks arent good. precision clocks cost a lot of money plus they are difficult when it comes to colo (GPS signal is not available and atomic clocks cost an arm and a leg and more). I read that new graphic cards have precision clocks on them. So my

问题 How can I make my program interrupt an already running for loop when it receives the "K" character from a serial port ? The code is : import serial from time import sleep ser = serial.Serial(port='/dev/ttyUSB0',baudrate=9600,parity=serial.PARITY_NONE,stopbits=serial.STOPBITS_ONE,bytesize=serial.EIGHTBITS,timeout=0) while 1: for line in ser.read(1): input+=chr(line) if input == 'S': for x in range (1 , 10): # this is the loop i want to break print(x) sleep(1) if input == 'K': print('K received

问题 My understanding is that when a NIC adapter receives new packets, the top half handler uses DMA to copy data from the RX buffer to the main memory. I think this handler should not exit or release the INT pin before the transmission is completed, otherwise new packets would corrupt the old ones. However, DMA is generally considered asynchronous and itself requires the interrupt mechanism to notify the CPU that data transmission is done. Thus my question, is DMA actually synchronous here, or

问题 I have a limit switch attached to an arduino Mega 2650 for motion control. The limit switch's two Normally Open contacts are connected to an Arduino Pin and ground, such that when the Limit Switch is engaged, the Arduino Pin gets short circuited to ground. As expected, I have bouncing issues with this setup. I confirmed it using counters in my ISRs. Finally, I wrote the following code that seems to reliably identify whether my limit switch is engaged or disengaged at any given point in time.

问题 I have a method which, conceptually, looks something like: Object f(Object o1) { Object o2 = longProcess1(o1); Object o3 = longProcess2(o2); return longProcess3(o3); } Where the processes themselves might also be compound: Object longProcess1(Object o1) { Object o2 = longSubProcess1(o1); return longSubProcess2(o2); } And so forth, with the different processes potentially sitting in different modules. Most of the processes are long because they are computationally expensive, not IO-bound. So

问题 As known there are two approach to avoid some overheads of hardware interrupts in highload networks, when there are too many hardware interrupts, that switching to them takes too much time. It is very important for performance and choosing approach of programm style. NAPI (New API) - Does not use hardware interrupts , and polls the Ethernet-device every certain period of time. The Linux kernel uses the interrupt-driven mode by default and only switches to polling mode when the flow of