Intel 8253 - Page 319

AP-578
2/21/97 12:57 PM 24329102.DOC
INTEL CONFIDENTIAL
(until publication date)
21
PUSH EBP
.
.
MOV EBP, ESP
SUB ESP, 108 ; ALLOCATES 108 BYTES (32-bit PROTECTED MODE SIZE)
; SAVE STATE, LOAD NEW CONTROL WORD, RESTORE INTERRUPT ENABLE FLAG (IF)
FNSAVE [EBP-108]
FLDCW LOCAL_CONTROL
PUSH [EBP + OFFSET_TO_EFLAGS] ; COPY OLD EFLAGS TO STACK TOP
POPFD ; RESTORE IF TO VALUE BEFORE FPU EXCEPTION
.
.
;
; APPLICATION-DEPENDENT 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 STACK.
;
.
.
; CLEAR EXCEPTION FLAGS IN STATUS WORD (WHICH IS IN MEMORY)
; RESTORE MODIFIED STATE IMAGE
MOV BYTE PTR [EBP-104], 0H
FRSTOR [EBP-108]
; DE-ALLOCATE STACK SPACE, RESTORE REGISTERS
MOV ESP, EBP
.
.
POP EBP
;
; RETURN TO POINT OF INTERRUPTION
IRETD
REENTRANT ENDP