Type ASSEMBLE
Source Lines : 139
Fixes Applied : 0
Most Recent Version : Thursday, December 7, 1978
Last Fix ID : [Unmodified]
Module
DMTSVC
Function
THE DMTSVC MODULE IS THE MSUP SVC INTERRUPT
HANDLER. DMTSVC RECEIVES CONTROL DIRECTLY ON AN
SVC INTERRUPT.
Attributes
REUSABLE, EXECUTABLE DISABLED ONLY
Operation
THE ONLY FUNCTION OF SVC WITHIN THE RSCS SYSTEM IS
TO "UNDISPATCH" (OR "FREEZE") AN EXECUTING TASK.
SVC IS NECESSARY TO PERFORM THIS FUNCTION SINCE
THE LEFT HALF OF THE ACTIVE PSW IS ACCESSABLE ONLY
THROUGH STORAGE OF THE PSW ON AN INTERRUPT. THE
SVC CODE IS NOT INSPECTED BY SUPEXT, AND IT
CURRENTLY HAS NO MEANING (SEE BELOW).
THE RUNNING TASK IS "UNDISPATCHED" ON AN SVC BY
MOVING THE LEFT HALF OF THE SVC OLD PSW TO THE
TASK SAVE AREA RESUME PSW FIELD, STORING THE
REGISTER CONTENTS ON INTERRUPT IN THE TASK SAVE
AREA, AND SETTING THE RESUME PSW ADDRESS FIELD TO
THE CONTENTS OF REG.14 ON INTERRUPT. SUPSVC
RETURNS CONTROL BY SETTING REG.14 TO THE ADDRESS
OF THE TASK ELEMENT OF THE "UNDISPATCHED" TASK,
AND LOADING A PSW WITH ALL MASK BITS SET OFF
(EXCEPT MACHINE CHECK) AND EXECUTION ADDRESS AS
STORED IN THE SVC OLD PSW.
Calls to Other Routines
NONE