T-Kernel Specification (1.B0.02)

2.3. INTERRUPT HANDLING 11
precedence
priority
Hight 〈Priority 1〉
✻
〈Priority 2〉
✲ Task B ✲ Task C ✲ Task D ✲
❄
Low 〈Priority 3〉
✲
Task E
✲
Figure 2.3: Precedence After Task B Goes To RUN State
precedence
priority
Hight 〈Priority 1〉
✻
〈Priority 2〉
✲ Task C ✲ Task D ✲
❄
Low 〈Priority 3〉
✲
Task E
✲
Figure 2.4: Precedence After Task B Goes To WAIT State
Note that after a task goes from SUSPEND state to a run state, it has the lowest precedence among
tasks of the same priority. In a virtual memory system, since a task is made to wait for paging by putting
the task in SUSPEND state, in such a system the task precedence changes as a result of a paging wait.
precedence
priority
Hight 〈Priority 1〉
✻
〈Priority 2〉
✲ Task C ✲ Task D ✲ Task B ✲
❄
Low 〈Priority 3〉
✲
Task E
✲
Figure 2.5: Precedence After Task B WAIT State Is Released
2.3 Interrupt Handling
Interrupts in the T-Kernel specification include both external interrupts from devices and interrupts
due to CPU exceptions. One interrupt handler may be defined for each interrupt number. Interrupt
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T-Kernel 1.B0.02