Intel 80287, 80286 manual Fnsave BP-941

NUMERIC PROGRAMMING EXAMPLES

ASSUME INITIALIZED

REENTRANTPROC

SAVE CPU REGISTERS, ALLOCATE STACK SPACE FOR 80287 STATE IMAGE

PUSH BP

MOV BP,SP

SUB SP,94

SAVE STATE, LOAD NEW CONTROL WORD, FOR COMPLETION, ENABLE CPU INTERRUPTS

FNSAVE [BP-941

FLDCW LOCAL_CONTROL S T I

APPLICATION EXCEPTION HANDLING CODE GOES HERE. AN UNMASKED EXCEPTION GENERATED HERE WILL CAUSE THE EXCEPTION HANDLER TO BE REENTERED. IF LOCAL STORAGE IS NEEDED, IT MUST BE ALLOCATED ON THE CPU STACK.

CLEAR EXCEPTION FLAGS IN STATUS WORD

RESTORE MODIFIED STATE IMAGE

MOV	BVTE PTR [BP-921, OH
FRSTOR	[BP-941
DE-ALLOCATE STACK SPACE, RESTORE CPU REGISTERS
MOV	SP,BP
POP	BP
RETURN ~O POINT OF INTERRUPTIOH
IRET
REENTRANT	ENDP

Figure 4-5.Reentrant Exception Handler

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