© Thomas Kunz 2000
SCE 574
94
   Control Flow
äWhat if we want to make use of the concept of subroutines?
äJumps and Jump Tables
äJMP   (Unconditionally Jump to a location)
äJMP Register/Memory_Label
äLike a “Go TO” statement
äJMP   End_Switch
äOR
äMOV BX,OFFSET End_Switch
äJMP   BX
äCan be used for indirect calls (will see soon)
äSubroutines
äCALL  to call a subroutine
äRET     to return from a subroutine
äSoftware Interrupts
äSpecial type of indirect call used to simulate hardware interrupts
äFor Debugging, to execute routines within the OS and device drivers
äINT, IRET (Interrupt, Interrupt return)
Jump to a memory
location
Jump to a memory
location via a register