Intro to SPIM

1
Intro to SPIM

• Justin Fiore
• Nathan Parish

2
Installing SPIM on Windows

• Download pcspim.zip from the SPIM website
  http//www.cs.wisc.edu/larus/SPIM/pcspim.zip
• It is also linked to on Dr. Lees page for this
  class
• Unzip it
• Run Setup.exe

3
Installing SPIM on Linux from Source

• Download http//www.cs.wisc.edu/larus/SPIM/spim.t
  ar.gz
• Unzip it tar xvzf spim.tar.gz
• cd spim-7.3/spim
• make
• cd ../xspim
• kmkmf
• make

4
Installing SPIM on Ubuntu Linux

• Open the Synaptic Package Manager
• Click Settings-Repositories
• Select one of the Binary repositories and click
  Edit
• Check Non-free (Multiverse), and click OK
• Click Close
• Click Reload
• Search for spim
• Select the spim program and install it (this will
  install xspim also)
• NOTE This was done on Ubuntu Linux 6.06 LTS
  (Dapper Drake)

5
Text Segment

• Your instructions are displayed here
• From left to right
• Address where the instruction is stored
• Binary machine code for the instruction
• Assembly instruction (with registers represented
  as numbers)
• Line number in your assembly source
• Assembly instruction from your source (with
  registers as s0, v0, etc)
• Pseudo Instructions will be converted to one or
  more assembly instructions

6
Message Segment

• Prints messages from SPIM such as
• Loading the exception handler
• Loading your assembly file
• Any errors that SPIM encounters

7
Register Segment

• Displays the register contents
• Displays PC, Stack Pointer, Frame Pointer, etc.
• Very important when debugging your code

8
Data Segment

• Displays the Data segment of memory.
• Heap (starts at Data)
• Stack (starts at Stack)
• Addresses are Byte Addressed
• Data is stored in words
• Data is represented in hexidecimal

9
Data Segment Example

• 0x10010000 0x65704f0a 0x69746172
  0x20736e6f 0x70707553
• 0x10010010 0x6574726f 0x6e612064 0x79532064
  0x7861746e
• 0x10010000 0x65704f0a
• 0x10010004 0x69746172
• 0x10010008 0x20736e6f
• 0x1001000c 0x70707553
• 0x10010010 0x6574726f
• 0x10010014 0x6e612064
• 0x10010018 0x79532064
• 0x1001001c 0x7861746e

10
Console
11
Debugging

• Click the Hand button to add a breakpoint
• Add the instruction address to break on
• After breaking, can
• single step (F10)
• multiple step (F11)
• Set Value (Simulator-Set Value)
• Continue Executing (F5)

12
Input/Output in SPIM

• Place proper arguments (e.g. system call code) to
  corresponding registers and place a syscall
• Print string
• li v0, 4
• la a0, var
• syscall
• Print integer
• li v0, 1
• add a0, t0, 0
• syscall
• Read integer
• li v0, 5 result in v0
• syscall
• See Appendix A for more.