Basic Operations In "Eit" Processing - Fujitsu FR Family Instruction Manual

CHAPTER 4 RESET AND "EIT" PROCESSING
4.2

Basic Operations in "EIT" Processing

Interrupts, exceptions and traps are similar operations applied under partially differing
conditions. Each "EIT" event involves terminating execution of instructions, saving
information for restarting, and branching to a designated processing program.
■ Basic Operations in "EIT" Processing
The FR family device processes "EIT" events as follows.
(1) The vector table indicated by the table base register (TBR) and the number corresponding to the
particular "EIT" event are used to determine the entry address for the processing program for the
"EIT".
(2) For restarting purposes, the contents of the old program counter (PC) and the old program status (PS)
are saved to the stack area designated by the system stack pointer (SSP).
(3) After the processing flow is completed, the presence of new "EIT" sources is determined.
Figure 4.2-1shows the operations in the "EIT" processing sequence.
Instruction at which EIT event is detected
Canceled instruction
Canceled instruction
(1) Vector address calculation and new PC setting
(2) SSP update and PS save
EIT sequence
(3) SSP update and PC save
(4) Detection of new EIT event
First instruction in EIT handler sequence (branching instruction)
Note:
For a description of pipeline operations, see Section "5.1 Pipeline Operation".
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Figure 4.2-1 "EIT" Processing Sequence
IF ID EX MA WB
IF ID xxxx xxxx xxxx
IF xxxx xxxx xxxx xxxx
ID(1) EX(1) MA(1) WB(1)
ID(2) EX(2) MA(2) WB(2)
ID(3) EX(3) MA(3) WB(3)
ID(4) EX(4) MA(4) WB(4)
IF ID EX MA PC