Computer Science 281

Fifth Exercise Set

Purpose

• To work with bit manipulation instructions and integer multiplication

Due:  Friday, March 15

Probable worth: 10 pts. each

• Following the scheme outlined in class on Friday, March 8, write an assembly language program scanf.s with entry points as follows:

  /*
   Test program to decode a floating point
   number
  */
     
   .global fsgn
   
  fsgn: save %sp, -96, %sp
     
  (some code)
     
   ret
   restore
   
     
   .global fexp
  fexp: save %sp, -96, %sp
     
  (some code)
     
   ret
   restore
   
   .global ffract
  ffract: save %sp, -96, %sp
     
  (some code)
     
   ret
   restore

to be called by the program scanfmain.c in the directory ~matthews/cs281

• The programs muldivmain.c and muldiv.s in ~matthews/cs281 contain a main program in c which accepts two integers and an assembly language program containing entry points for assembly language routines to multiply, divide, and mod the two input integers. Each of these currenltly uses calls to .mul, .div, and .rem. Replace the call to .mul with a multiply routine using the mulscc instruction as described in the textbook.
• I had intended to ask you also to do the .div and .rem routines, but decided that doing the .mul routine would be sufficient for what we want to learn about these routines. Doing the other two routines (correctly and on time) would be worth another 5 points of extra credit.