Homework

1
Homework

• Reading Assignment
• Professional Assembly Language, pp 39-59, 62-65
• MP1
• Get assignment file from my web page and study it
• Make and populate your UNIX mp1 subdirectory
• Study the source code for mp1
• Lab 1
• Load and Read Lab1 Write up
• GO TO LAB WITH YOUR SECTION!

2
The Big Picture

• To use embedded software development tools, a
  development host is attached to a target host
  via
• RS-232
• Ethernet
• USB
• Other?

Three metal prongs on the side of the diving
computer
Development Host
Special USB Cable
3
The Big Picture
SAPCs in S-3-142 (OS is Tutor not UNIX)
Sun Blade (OS is UNIX)
ulab (OS is UNIX)
COM2
Pico or vi
IBM Compatible
mtip
COM2
IBM Compatible
COM1
COM2
IBM Compatible
COM1
COM2
IBM Compatible
Putty/SFTP or SSH Communications via Internet
Reset Server
4
The Big Picture

• UNIX system is your development host
• SAPC is your target machine
• SAPC does not normally have its keyboard, video
  monitor, or mouse attached!
• SAPC COM1 and COM2 ports are cabled to a local
  terminal or to ports on the UNIX host ulab

5
The Big Picture

• You will use a UNIX system to edit your source
  files, compile and assemble them.
• You will use the UNIX system as a server for
  downloading code to an SAPC
• You may be using an SAPC
• Locally in the SAPC lab via a terminal attached
  to one of its COM ports
• Remotely via the UNIX system named ulab

6
Picture of mtip Session
SAPC
ulab
You
mtip
Tutor
Transparent Relaying of Tutor commands
d
r
file.lnx
Memory
Reset Server
7
System Build Processes

• The system build processes for C and assembly
  source courses are driven by our make files
• However, it is important to understand how the
  component build steps work with the SW tools
• Sun/UNIX Intel/SAPC
• gcc i386-gcc
• as i386-as (informally called gas)
• ld i386-ld
• nm i386-nm
• objdump i386-objdump (alias disas)

8
Build for gcc Compilation
C Source Code
Translation Unit
Assembly Code
Object Code
Executable File
prog.i
prog.c
prog.s
prog.o
prog
gcc -E gcc -S gcc -c gcc -o
9
Build for i386-gcc Compilation
C Source Code
Translation Unit
Assembly Code
Object Code
Executable File
prog.i
prog.c
prog.s
prog.opc
prog.lnx
i386-gcc -E i386-gcc -S i386-gcc -c i386-gcc -o
10
Build for i386-gcc and i386-as
Object Code
Executable File
C Source Code
Assembly Code
prog.s
prog.opc
prog.lnx
progc.c
i386-gcc -c
i386-as
i386-ld
11
Build - Symbol Table Generation

• The syms file shows the memory address assigned
  for each variable or source label

Symbol File
Object Code
Executable File
prog.opc
prog.lnx
syms
i386-nm
i386-nm
12
Example Test Program

• Login to UNIX host ulab instead of users
• We will compile and run a program named test.c on
  both Unix and an SAPC
• Produce UNIX executable
• Run it using ./test
• Produce SAPC executable (.lnx extension)
• Download to the SAPC
• Run it
• Exit from the SAPC

13
Setup Test files on Unix

• Make a subdirectory test on your cs341
• Copy these files to that directory
• pcex/makefile
• pcex/test.c
• Note the name pcex is defined by the ulab module
  in your .cshrc file. If you cant use pcex as a
  directory name, check your ulab module
  configuration in .cshrc

14
Running test program on UNIX

• Create the UNIX executable test
• ulab(60) gcc o test test.c
• Execute it (avoiding conflict with UNIX test)
• ulab(61) ./test
• Follow the programs directions. It should
  finish up quickly and hand control back to UNIX.
  You will see a UNIX prompt again. 

15
Running a program on SAPC

• Make the SAPC executable, test.lnx . 
• ulab(65) make Ctest test.lnx
• The suffix .lnx is short for Linux, since we
  are using a Linux-defined executable format
• Must be logged in on host ulab to use mtip
• Otherwise, we get an error message
• blade64(9) mtip -f test.lnx
• . . .
• Sorry, no board currently available
• blade64(10)

16
Running a program on SAPC

• Execute mtip to access an SAPC
• ulab(66) mtip -f test.lnx
• Obtains an SAPC for you and tells mtip the
  executable file you are planning to download
• When you get an SAPC assigned, hit CR to get its
  Tutor prompt.
• Its safest to use r to reboot the SAPC which
  takes about 12 seconds.  (If an SAPC ever starts
  working weirdly, you should reboot it.)

17
Running a program on SAPC

• Type d to download test.lnx
• To execute the program, when you see the Tutor
  prompt again, type
• Tutorgt go 100100
• Follow the programs directions. It should
  finish up quickly and hand control back to Tutor.
  You will see Tutor prompt again.
• You can run it again by command go 100100.
• Type q or two ctrl-Cs to quit out of mtip

18
Analysis of Example

• For UNIX or SAPCs, basic process to develop
  programs is the same - only different in the
  details
• Cross-compilation is defined as the compilation
  of a program on one computer (Sun development
  host) for execution on another computer (SAPC
  target machine)
• We used gcc to generate an executable file that
  will run on the Sun-based UNIX system
• We used i386-gcc to generate an executable file
  that would NOT run on UNIX but will run on an SAPC

19
Analysis of Example

• Portability
• Defined as ability to write source code so that
  it can run on two or more types of machines
• Requires use of a different compiler/loader and
  library for each type of machine
• Notice that the library functions called by the
  test program worked slightly differently on the
  two types of machines (as noted in the text
  produced by the test program)

20
Analysis of Example

• Another difference between the Unix system and
  the SAPC is the presence/ absence of an operating
  system
• UNIX is an operating system that runs programs in
  a protected environment. Our code can not do
  some things such as access hardware directly
• Tutor is a debug monitor only and does not run
  programs in a protected environment. Our code
  can access hardware directly as youll see later

21
Two Different Environments

• How is our program loaded into memory? Unix/Sun
  SAPC

0x00000000
0x00000000
Reserved
Reserved
0x00010000
Code
0x00020000
Data
0x00050000
Tutor
0x000A0000
Video Memory
Reserved
0x000F0000
BIOS (ROM)
0x00100000
code
data
stack
0x003FFFFF
Not Implemented
Stack
0xFFFFFFFF
0xFFFFFFFF
22
Machine Project 1

• In mp1, you will add commands to a program that
  is a simple version of the Tutor program that we
  just used on the SAPC
• The program is portable so that it can be run
  on both the UNIX system and an SAPC
• You will learn about some things about the
  differences between the UNIX environment and the
  SAPC environment

23
Machine Project 1

• Key to understanding tutor is a struct
• typedef struct
• char cmdtoken / char string to invoke
  cmd /
• int (cmdfn)() / function to call for
  this cmd /
• char help / helpstring for cmd /
• cmd

cmd
cmdtoken
m d \0
(cmdfn) ( )
Function to process command
help
h e l p t e x t \0
24
Machine Project 1

• Your job entails
• Replacing the stub for the md command to
• Convert the character string to an integer
• Use that integer as an address (a pointer to
  memory)
• Find the contents of that address
• Display the contents of that address to the
  terminal
• Adding commands to the command table and writing
  code to make both of them work
• Memory Set - ms
• Help - h