CS5031: System Software

This is now out-of-date, as the syllabus for CS5031 changed for Autumn 2000

CS5031 was half-and-half Operating Systems and Compilers.

Compilers part of CS5031

Each session will consist of: a lab practical on unix workstations (using lex, yacc & gcc) or: a lecture followed by paper-and-pencil exercises. The exercises & lab practicals will be used both for reinforcement and for further exploration.
Activity & Handouts Extra information
C1 - lec1Introduction and Assemblers & Compilers answers to exercises
C2 - lec2Lexical analysis - Lex and example run of lex calculator answers to exercises
C3 - lab1Lex practical flex manual
hints: strings and comments
ANSI C: characters, pre-processing, syntax
C4 - lec3Syntactic analysis - Yacc & Parse Trees and example run of yacc calculator answers to exercises
(and see answers to lab2 below)
C5 - lab2Yacc practical byacc manual, including %left etc. & examples

Answers: (a) multiple expressions
1: c & results
2,3,5: data & results
(and see answers to lec3 above)

C6 - lec4Semantic analysis - Dictionaries and example snapshots of dictionary answers to exercises
C7 - lab3Syntax-directed Translation practical  
C8 - lec5Syntax-directed Translation [exercises?]
C9 - labcatch-up you can complete labs 1-3 (above) and start to think about the assessment exercise (below).
C10 - lab
2nd week
The deadline may be the end of term (17th/Dec) but you are strongly advised to finish by the end of the fortnight (3rd/Dec).
25% Compiler:
Lex, Yacc and C practical
if you require help mail pjj@cs.man.ac.uk
hints: grammar, strings and comments, bonus work
Get the basic exercise (worth 70%) marked as soon as you have completed it - preferably by the end of the week. I am happy to mark any bonus work separately.
25% Operating Systems:
written report
January Exam
(17th-28th 2000)
50%Answer 3 questions from 4 in 2 hours 2 questions on Operating Systems
In 1997/8, these were similar to those set in 1996/7.
2 questions on Compilers
The 1996/7 compiler questions are only partly relevant owing to syllabus changes. The 1997/8 & 1998/9 questions are in this form:
A question about using lex and yacc (and a dictionary or parse trees or similar) to recognise a simple grammar - similar to the lab exercises & examples sheets.
A question about compiler phases and code generation - e.g. describe what happens in the phases, give ARM code for some C, etc. The syllabus has changed, so we are not going to cover code generation for the ARM. I will have to think of something a little different to ask instead of that part
Here are the 1997/8 questions and answers and marking scheme.

what happened last year

Here are some hints about exam technique

Extra information about the practical exercises will appear here.
Handout: Debugging flex, byacc and make
If your program crashes at run-time, making a "core" file, and you want to find out what line it went wrong at etc., on Suns do:
	dbx program_name
or on Linux do:
	gdb program_name core
(This relies on using gcc -g, as with the makefiles I provide.)
Lab exercise 1 In the example output, I have picked up adjacent white-space characters to be a single lexeme using
	[ \t\n]+
but in the problem description and in the starting code I only pick up single white space characters using
	[ \t\n]
I would prefer to do the former, but I have to do the latter to be able to recognise preprocessor commands properly - can you see why? If not, try changing the rule for white space to see what happens - you should get lots of messages from the checker.
When you "make test" for the first time, you should see something like this:
echo your output is being redirected to "out1"
your output is being redirected to out1
./c_lexemes <data.c >out1

echo here are any error messages - look at "out1" for more details
here are any error messages - look at out1 for more details
grep OOPS out1
4       OOPS -  #include <stdio.h> is a preprocessor_command (not white_space etc. - see following list)
4       OOPS -  #define a(nasty)\

echo here is the final report, counting characters and lexemes
here is the final report, counting characters and lexemes
wc -c <data.c ; tail -20 out1

numbers of lexemes & characters - 22/9/99 10:17 GMT
  380 ignore(s)                         in   960 characters
    0 float_number(s)                   in     0 characters
    0 octal_int_number(s)               in     0 characters
    0 decimal_int_number(s)             in     0 characters
    0 hex_int_number(s)                 in     0 characters
    0 preprocessor_command(s)           in     0 characters
    0 comment(s)                        in     0 characters
    0 character(s)                      in     0 characters
    0 keyword(s)                        in     0 characters
    0 built_in_type(s)                  in     0 characters
    0 identifier(s)                     in     0 characters
    0 punctuation_or_operator(s)        in     0 characters
    0 punctuation(s)                    in     0 characters
    0 operator(s)                       in     0 characters
    0 string(s)                         in     0 characters
    0 unknown(s)                        in     0 characters
  237 white_space(s)                    in   237 characters
total:   617 lexemes                    in  1197 characters
As you can see, the checker is over-enthusiastic about pre-processor commands.
There is a second, rather larger set of test-data: bigdata.c
You are welcome to try your program on this - remove the leading "#" characters from these 3 lines in the makefile to do so:
#       ./c_lexemes <bigdata.c >out2
#       -grep OOPS out2
#       wc -c <bigdata.c ; tail -20 out2
Don't get bogged down trying to deal with some of the wierd things in this file before you have dealt with the simpler problems in the first data-file.


I teach a related undergraduate course CS2111: Design, Use and Implementation of Programming Languages, which you may find useful, including pointers to information about lex, yacc and C.

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