Windows Embedded CE 6.0中斷機制介紹
本文繼續介紹Windows Embedded CE 6.0和Windows桌面系統內部一些知識。
Windows Embedded CE 6.0中斷機制
下圖為Windows Embedded CE 6.0中斷模型：
(1).設備發起一個硬件中斷。->
(2).內核(Kernel.DLL)響應該中斷，并call對應的中斷服務例程(ISR)。->
(3).中斷服務例程快速處理該中斷。->
(4).驅動中的中斷服務線程(IST)被通知處理該中斷，這里內核使用Event通知IST。
這個過程中涉及到的ISR和IST都會處理中斷，但有所不同，前者的中斷級別更高，所做的工作也很簡單，而后者做主要的處理工作。具體請看以下的介紹。
"Real-time applications use interrupts to respond to external events in a timely manner. To do this, Windows Embedded CE 6.0 breaks interrupt processing into two steps: an interrupt service routine (ISR) and an interrupt service thread (IST). The ISR runs immediately to identify and mask the interrupt, and perform any high priority tasks. The corresponding IST is a normal system thread (although typically of high priority) and can perform the bulk of the handling that is not time critical. This two stage model allows the operating system to maximize the amount of time the system is able to respond to other high priority interrupts.
The kernel is able to handle a total of 64 interrupts from external sources, some of which are predefined (e.g. system timer interrupt, real time clock etc). Devices that have more than 64 interrupt sources that need to be exposed (rare) must implement a mechanism to share interrupt identifiers. Typically this is done by multiplexing related interrupts together in the ISR, and demultiplexing them in the IST.”
關于Windows Embedded CE 6.0中斷機制在此就介紹這么多，更詳細的內容等我慢慢消化了再介紹。
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