Computer Project #5 -- Twos Complement Representation

Computer Project #5 -- Twos Complement Representation

Assignment Overview:

This assignment develops familiarity with the C programming language, the
"gcc" compiler, number systems, and twos complement representation.

It is worth 40 points (4% of course grade).

Assignment Specifications:

1) You will develop a C module which supports the conversion of integer
values between external representation and internal representation. The
module will consist of function "convert" and any other supporting functions
you choose to develop. The interface to the module is:

int convert( const char[], int, int* );

The first argument is the address of an array that contains the external
representation of the value which is to be converted.

The second argument is the value of the base in which the first argument is
represented. Valid bases range from 2 to 36 (inclusive).

The third argument is the address of a scalar where the function will store
the equivalent internal representation of the first argument.

Function "convert" will return the integer value one if the conversion is
successful, and the integer value zero otherwise.

The external representation of the value to be converted (the first argument
to "convert") is a null-terminated sequence of ASCII characters. It is
composed of three disjoint substrings: a substring of zero or more white
space characters (blanks, tabs and newlines), a substring which represents
the specified value (called the subject substring), and a substring of one
or more unprocessed characters (including the terminating null).

The subject substring is defined as the longest possible substring which is
of the expected form. It begins immediately after any leading white space,
and terminates with the first invalid character. The subject substring may
not be empty.

The subject substring represents a signed value. A negative value is
indicated by the character '-'; a positive value is indicated by the
character '+' or no sign character. Negative zero is represented by the
subject substring "-0", and positive zero is represented by the subject
substring "+0" or "0".

In the subject substring, alphabetic characters are used to represent digits
for bases greater than 10. Both upper and lower case letters are valid.

2) You will develop a driver module to test your implementation of the
conversion module. The source code for the driver module must be in a
separate file. All output will be appropriately labeled.

Your driver module will not be interactive. If it accepts any input, you
will supply that input in a text file named "proj05.tests".



Assignment Deliverables:

The deliverables for this assignment are:

proj05.makefile -- the makefile which produces "proj05"
proj05.support.c -- the source code for your conversion module
proj05.driver.c -- the source code for your driver module
proj05.tests -- the input to your driver module, if needed

Be sure to use the specified file names, and to submit your files for
grading via the "handin" program.

Assignment Notes:

Please note that your source code must be translated by "gcc", which is a C
compiler and accepts C source statements (a subset of C++).

Please note that you must supply a "makefile" (named "proj05.makefile"), and
that your makefile must produce an executable program named "proj05".

Please note that your driver module may not be written as an interactive
program, where the user supplies input in response to prompts. Instead,
your test cases will either be included in the source code as literal
constants, or will be supplied as inputs to the driver module in a file
named "proj05.tests".

If your driver requires no inputs, your solution will be executed using:

proj05

If your driver does require inputs, your solution will be executed using:

proj05 < proj05.tests

You may not call any C library functions from your conversion module. That
is, you may not call functions such as "printf", "scanf", "atoi", or
"isspace" from "convert" or any other function in your conversion module.

Your conversion module must convert between integers and characters without
using any C library functions. The equivalent integer value of a character
from the set {0..9} representing a decimal digit may be obtained by:

char ch;
int value = ch - '0';

Similarly, the equivalent integer value of a character from the set {A..F}
representing a hexadecimal digit may be obtained by:

char ch;
int value = (ch - 'A') + 10;

Chapter 2 of the Murdocca and Heuring text contains relevant information
about number systems (particularly pages 22-24).