Intel 80286

NUMERIC PROGRAMMING EXAMPLES
CLEAR EXCEPTION FLAGS IN STATUS WORD
RESTORE MODIFIED STATE
IMAGE
MOV
FRSTOR
DE-ALLOCATE
MOV
BYTE PTR IBP-921, OH
IBP-941
STACK SPACE, RtSTORE
SP,BP
POP B P
/
RETURN TO INTERRUPTED CALCULATION
IRET
SAVE_ALL ENDP
CPU REGISTERS
Figure 4-3. Full-State Exception Handler (Cont'd.)
SAVE_ENVIRONMENT PROC
SAVE CPU REGISTERS, ALLOCATE STACK SPACE
FOR 80287 ENVIRONMENT
PUSH BP
MOV BP,SP
SUB SP,14
SAVE ENVIRONMENT, WAIT FOR COMPLETION,
ENABLE CPU INTERRUPTS
FNSTENV IBP-141
FWAIT
S T I
APPLICATION EXCEPTION-HANDLING CODE GOES HERE
CLEAR EXCEPTION FLAGS IN STATUS WORD
RESTORE MODIFIED
ENVIRONMENT IMAGE
MOV BYTE PTR IBP-121, OH
FLDENV IBP-141
DE-ALLOCATE STACK SPACE, RESTORE CPU REGISTERS
MOV SP,BP
POP BP
RETURN TO INTERRUPTED CALCULATION
IRE T
SAVE_ENVIRONMENT ENDP
Figure 4-4. Reduced-Latency Exception Handler
4-5
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