Sparc Assembly

• We will take a look at writing programs on the sparc
• CSLAB60
• To log in
  • telnet cslab60[.cs.edinboro.edu]
  • use your normal username
  • use the default password we talk about in class
• the prompt is $
• You will probably want to change your password
  • $nispasswd
  • This will change your password on all of the sparcs
• You will possibly want to run bash
  • $ bash
• You may even want to start it when you log in
  • Normally you would do this with chsh
  • You can also add the line

    bash
         

  • To the last line of your .profile
• The editor is vi
  • This is somewhat cumbersome
  • A cheatsheet from Prof. Hillmanm
  • I will give a demo in class as well.
• ftp is supported as well.

• A first program
  • Assembly code goes in a file with the extension .s
  • one.s
  • There is some stuff here that we will eventually get to, but not yet
  • Comments start with a ! and completes the line
  • The first part

    .data
    
    ! We will call the c function printf, we need strings to feed it.
    
    msg0:  .ascii "The number is '%d'\n\0"
    
    .text
    
    ! all c programs mush have a main
    
         .global printf
         .global main
    

  • The start of the program

    main:
    
    !  Save the registers from the calling routine
    !  more on this later as well
    
            save    %sp, -64, %sp
    

  • Some acutal calculations

    ! here is the program, c = a + b
    
            set    3,%l0         ! a = 3
            set    4,%l2         ! b = 4
            add    %l0,%l2, %l3  ! c = a+b
    

  • Call the printf function

    !
    ! This section calls the c printf routine.
    !     printf("The number is '%d'\n\0", number);
    ! We will talk more about subroutine calls eventually
    ! For now,
    !     o0 contains the first parameter
    !     o1 contains the second parameter
    ! Call calls the routine
    ! There is a bds following the call
    !
            set   msg0, %o0  ! make msg0 a parameter to printf
            mov   %l3, %o1   ! make the value of r4 a parameter to printf
            call  printf     ! call printf
            nop              ! branch delay slot
    

  • Exit the program

    ! again, we will talk about what is going on here later, for now do this.
    
            mov 1, %g1         ! get ready to quit
            ta 0               ! exit
    

  • The entire code is here
  • Compile the program

    $ gcc -o one one.s
    

  • If everything worked out, you should be able to run the program now

    $ one
    

The Registers

• 32 general purpose registers
• R0 is the source of all zeros
• %r0-%r31 are all of the registers
• %g0-%g7 (r0-r7) global registers
• %o0-%o7 (r8-15) output registers
• %l0-%l7 (r16-23) local registers
• %i0-%i7 (r24-r31) input registers
• You are best to use l0-7 for local computations.

Some Instructions

• add r_src1, r_src2 or immediate, r_dest
• addcc - same as add, but sets the condition code register
• branch
  • All branches are of the form b?? dest
  • All can be annuled with b??,a dest
  • bn - branch never
  • bne
  • be
  • bg
  • bge
  • bl
  • ble
  • ba, b - branch always
• call label
• ld address, register
• nop
• st register, address
• sdiv r_src1, r_src2 or immediate, r_dest (signed divide, integer)
• smull r_src1, r_src2 or immediate, r_dest (signed multiply)
• sub r_src1, r_src2 or immediate, r_dest
• subcc r_src1, r_src2 or immediate, r_dest

Some Synthetic Instructions

• clr register
• cmp reg,reg_or_imm
• mov reg_or_imm, reg
• set val,reg ( or %g0, value, reg_dest)

Another Example

• Consider this code