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Chapter 9: Debugger Commands
Program Interrupt Add
Program Interrupt Add
The Program Interrupt Add command causes a simulated program interrupt
after a specified number of clock cycles (< cycle_count> ) have been executed.
The pseudo register @cycle is used to keep track of the clock cycle count,
allowing the interrupt frequency to be precisely timed. The maximum number
allowed for < cycle_count> is (2**32)-1.
Interrupt Level
The interrupt level must be between 1 and 7 inclusive. A maximum of 16
interrupts, including multiple interrupts at the same level, can be waiting or
pending.
Pending Interrupts
Once an interrupt is initiated, it remains pending until the status register's
interrupt mask bits allow the interrupt to occur. The interrupt mask bits in the
status register can change as a result of processor instructions, or because of
user intervention.
Interrupt Recognition
An interrupt is recognized if the interrupt level specified is higher than the
interrupt mask bits. Interrupts that have a level of 7 are always recognized
(level 7 is the nonmaskable interrupt). Once an interrupt is recognized,
interrupt processing begins before the next instruction fetch. On reset, all
interrupt mask bits are set, allowing only level 7 interrupts to be recognized.
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