INTERRUPTS
11-29
11
Checking Pending Interrupts — The interrupt controller compares each pending interrupt’s priority
with the current process priority. If process priority changes, posted interrupts of higher priority are
then serviced. Comparing the process priority to posted interrupt priority is handled differently for
hardware and software interrupts. Each hardware interrupt is assigned a specific priority when the
processor is configured. The priority of all posted hardware interrupts is continually compared to
the current process priority. Software interrupts are posted in the interrupt table in external
memory. The highest priority posted in this table is also saved in an on-chip software priority
register; this register is continually compared to the current process priority.
Servicing Interrupts — If the process priority falls below that of any posted interrupt, the interrupt
is serviced. The comparator signals the core to begin a microcode sequence to perform the
interrupt context switch and branch to the first instruction of the interrupt routine.
Figure 11-12
illustrates interrupt controller function. For best performance, the interrupt flow for
hardware interrupt sources is implemented entirely in hardware.
The comparator signals the core only when a posted interrupt is a higher priority than the process
priority. Because the comparator function is implemented in hardware, microcode cycles are never
consumed unless an interrupt is serviced.
Summary of Contents for i960 Jx
Page 1: ...Release Date December 1997 Order Number 272483 002 i960 Jx Microprocessor Developer s Manual ...
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Page 25: ...1 INTRODUCTION ...
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Page 35: ...2 DATA TYPES AND MEMORY ADDRESSING MODES ...
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Page 47: ...3 PROGRAMMING ENVIRONMENT ...
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Page 73: ...4 CACHE AND ON CHIP DATA RAM ...
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Page 85: ...5 INSTRUCTION SET OVERVIEW ...
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Page 111: ...6 INSTRUCTION SET REFERENCE ...
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Page 233: ...7 PROCEDURE CALLS ...
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Page 257: ...8 FAULTS ...
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Page 291: ...9 TRACING AND DEBUGGING ...
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Page 309: ...10 TIMERS ...
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Page 325: ...11 INTERRUPTS ...
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Page 369: ...12 INITIALIZATION AND SYSTEM REQUIREMENTS ...
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Page 413: ...13 MEMORY CONFIGURATION ...
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Page 429: ...14 EXTERNAL BUS ...
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Page 469: ...15 TEST FEATURES ...
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Page 493: ...A CONSIDERATIONS FOR WRITING PORTABLE CODE ...
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Page 503: ...B OPCODES AND EXECUTION TIMES ...
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Page 515: ...C MACHINE LEVEL INSTRUCTION FORMATS ...
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Page 523: ...D REGISTER AND DATA STRUCTURES ...
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Page 551: ...GLOSSARY ...
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Page 561: ...INDEX ...
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