Module Loaders and binders

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Module Loaders and binders

  1. 1. MODULE LOADERSAND BINDERS
  2. 2. PROBLEM S WITH DLLDISADVANTAGE OF DLL IS THAT IT IS NECESSARY TOALLOCATE,RELOCATE,LINK AND LOAD ALL OF SUBROUTINES EACH TIME TO EXECUTE A PROGRAM.LOADING PROCESS IS EXTREMELY TIMECONSUMING.REQUIRES MORE SPACE.
  3. 3. SOLUTIONPROBLEM IS SOLVED BY DIVIDING THELOADING PROCESS INTO TWO SEPARATE PROGRAMS A BINDER AND A MODULE LOADER.
  4. 4. MODULE LOADERA MODULE LOADER HAS TO PHYSICALLY LOAD THEMODULE TO CORE.MAIN FUNCTION : LOADING OTHERS AREPERFORMED BY BINDER(ALLOCATION,RELOCATIONAND LINKING).THE OUTPUT FILE OF THE BINDER IS LOADED INTOTHE MEMORY.
  5. 5. BINDERBINDS THE SUB ROUTINES TOGETHER RATHERTHAN PLACING THE RELOACTED AND LINKED TEXTDIRECTLY INTO MEMORY.OUTPUT OF A BINDER IS FILE OR A CARD DECK.THE OUTPUT FILE IS READY TO BE LOADED INTOMEMORY ALSO CALLED AS LOAD MODULE.
  6. 6. BINDERMAIN FUNCTION OF THE BINDER IS TOALLOCATE,RELOCATE AND LINK IT.TWO MAJOR CLASSES OF BINDERS ARE CORE IMAGE BINDER LINKAGE EDITOR
  7. 7. CORE IMAGE BINDERLOOKS LIKE A ABSOLUTE LOADER FILE.SPECIFIC CORE ALLOCATION OF THE PROGRAM ISDONE WHILE BINDING THE SUB ROUTINESTOGETHER.LOOKS LIKE AN ACTUAL SNAPSHOT OR IMAGE OFTHE CORE HENCE CALLED CORE IMAGE BINDER.THIS ONE IS SIMPLE WORKS RELATIVELY FAST.
  8. 8. LINKAGE EDITORKEEPS TRACK OF RELOCATION.FUNCTIONS: PREPARE A SINGLE LOAD MODULE AND ADJUST ALL THE ADDRESS W.R.T. OFFSET LOCATION. PREPARE A LOAD MODULE WHICH COMBINES WITH OTHER OBJECT MODULES. AT CORRECT LOCATIONS IN LOAD MODULE, COPY THE BINARY MACHINE INSTRUCTIONS AND DATA TO PREPARE TO EXECUTE MODULE.THE WORKING OF THIS BINDER IS PRETTY COMPLEXBUT ALLOWS FLEXIBLE ALLOCATION AND LOADINGSCHEME.
  9. 9. REFERENCES SYSTEMS PROGRAMMING,JOHNJ DONOVAN.
  10. 10. THANK YOU !!!

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