CS 3113: Project 1

Objectives

The objectives of this project are for you to:

Gain experience in the representation of chars, ints, floats and strings at the byte level, including translation between these representations.
Implement low-level file reading and writing, as well as positioning of the file offset at a specified location.

Overview

Your program will create a 112-byte buffer that it stores in memory. This buffer should be declared as an unsigned char array.
Through a text interface, the user is able to:
- Store characters, strings, ints, floats into specified locations in the buffer
- Read characters, strings, ints, floats from specified locations in the buffer
File storage:
- A file, specified at the command line, will store data in blocks of 112 bytes (the blocks are contiguous, meaning that block 0 corresponds to bytes 0..111 in the file, block 1 corresponds to bytes 112..223, ...)
- The user can request that a specific block is read from the file and into the buffer
- The user can request that the buffer be written to a specific block
- If the file does not exist, then it is created
- You may assume that user requests will never be beyond the available bytes in the file (except possibly to write a block just beyond the end of the file). The implication is that you don't need specific logic in your code to reason about file length vs which block you are reading from or writing to.

Proper Academic Conduct

The code solution to this project must be done individually. Do not copy solutions to this problem from the network and do not look at or copy solutions from others. However, you may use the net for inspiration and you may discuss your general approach with others.

Specification

Your main program maintains a 112-byte buffer in memory. The user can interact with this buffer by placing integer, floating point, character, and string values at a specified locations in the buffer. The user may request that integers be incremented/decremented and that strings be appended to. In addition, the user may request that the contents of the buffer be written to a specified block in a binary file, or that the buffer values be read from a specific block in the file.

The command-line interface to your program is as follows (note that you must respect the casing):

./project1 [FNAME]

This program does the following:

Opens the file specified using argument one. If no argument is specified, then use the file "data.bin".
Sitting in a loop, it accepts one of several commands from the user and executes these commands. The loop will continue until the end-of-file marker is received from stdin
Each command is exactly one input line, terminated by a newline character.
The commands manipulate or read the contents of the buffer, or they transfer values between the buffer and the file.
It is an error if a command has an incorrect number of arguments or incorrect arguments.
When there are no more commands (EOF), then the program closes the file and exits.
All errors are written to STDERR.

Parsing Lines

Use the same technique to tokenize the individual lines as you did in project 0.

Commands

There will be exactly one command per line of input from STDIN.

Dump the contents of the buffer.
```
d
```
Print each byte in hexadecimal format. There are 16 bytes per output line, for a total of 7 lines. Each byte has exactly two characters, and bytes are separated by a space.
Zero out the contents of the buffer.
```
0
```
Set all of the byte values in the buffer to zero.
Write a hexadecimal byte value to a buffer location.
```
H LOC VAL
```
LOC is the location in the buffer to write to (expressed in decimal). VAL is the byte value (in hexadecimal) to be written
Read a byte value from a buffer location.
```
h LOC
```
LOC is the location in the buffer to read from. Prints the value of the byte (in hexadecimal)
Write a character to a buffer location.
```
C LOC VAL
```
LOC is the location in the buffer to write to. VAL is the character to be written
Read a character value from a buffer location.
```
c LOC
```
LOC is the location in the buffer to read from. Prints the value of the character (i.e., the glyph)
Write an integer value to a buffer location.
```
I LOC VAL
```
LOC is the location in the buffer to write to (remember that integers require multiple bytes to store). VAL is the integer value (in decimal) to be written
Read an integer value from a buffer location.
```
i LOC
```
LOC is the location in the buffer to read from. Prints the value of the integer (in decimal)
Write a floating point value to a buffer location.
```
F LOC VAL
```
LOC is the location in the buffer to write to. VAL is the floating point value to be written
Read a floating point value from a buffer location and print it out.
```
f LOC
```
LOC is the location in the buffer to read from. Prints the value of the floating point value (use default floating point formatting ("%f")).
Write a string to a buffer location (may be multiple characters).
```
S LOC VAL
```
LOC is the location in the buffer to write to. VAL is the string value to be written. Note that it will contain no spaces (due to the tokenization process). Make sure that the NULL terminator is also written to the buffer.
Read a string from a buffer location.
```
s LOC
```
LOC is the location in the buffer to read from. Prints the value of the string.
Append a string to a string at a buffer location (may be multiple characters).
```
A LOC VAL
```
LOC is the location in the buffer of the original string. VAL is the string value to be be appended. Note that it will contain no spaces (due to the tokenization process). Make sure that the NULL terminator is also written to the buffer.
Write the contents of the buffer to the specified file block.
```
w BLOCK
```
BLOCK is the block number to write to.
Read the contents of the specified block in the file into the buffer.
```
r BLOCK
```
BLOCK is the block number to read from.
Increment the integer at a buffer location
```
+ LOC
```
LOC is the starting location in the buffer that contains the integer.
Decrement the integer at a buffer location
```
- LOC
```
LOC is the starting location in the buffer that contains the integer.

Notes

You may assume that the user will not specify a buffer location that is outside the 112-byte buffer (and multi-byte values will not extend past the end of the buffer).
You may assume that the user will provide arguments in the correct numerical range.
All program input is from STDIN.
All normal program output is to be placed in STDOUT.
You must address the case of incorrect numbers of arguments or of parse errors by writing an error to STDERR.

Examples

Program Invocation (for all examples)

./project1

Input Text

0
d

Output Text

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Input Text

Output Text

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 43 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
67
43
C
C

Input Text

0
S 20 Hello,
s 20
d
c 24
i 24
h 24
H 26 20
A 20 World!
d
s 20

Output Text

Hello,
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 48 65 6c 6c 6f 2c 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
o
11375
6f
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 48 65 6c 6c 6f 2c 20 57 6f 72 6c 64 
21 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
Hello, World!

Input Text

Output Text

1138
4
0
72
4
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
73 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
1140
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
74 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Input Text

0
d
w 0
S 30 Baumwipfelpfad
i 0
d
w 1
w 2
r 0
i 0
d
I 20 1138
i 0
d
w 3
r 2
i 0
d
r 3
i 0
d

Output Text

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 42 61 
75 6d 77 69 70 66 65 6c 70 66 61 64 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 72 04 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 42 61 
75 6d 77 69 70 66 65 6c 70 66 61 64 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
0
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 72 04 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Submitting Your Program

The deadline for submission is Monday, Sept. 28th at 11:45:00 pm.
Bonus: if you have your d, 0, h, H, i and I commands working by Wednesday, Sept. 23rd (11:45:00 pm), then you can receive up to 5% additional points. To have this count, you must submit your project by the early deadline to the project1-bonus Gradescope area.
Your submission is composed of the following files, named exactly as shown (including casing):
- project1.c: your source file
  - Include your name and project number at the top of the file
- Makefile: the makefile that implements:
  1. all: compiles your program (this is the default behavior)
  2. clean: deletes the executable file (project1) and any intermediate files (.o, specifically)
- README.txt: documentation
  - Include your name and project number at the top of the file
  - Document any Internet resources that you consulted (URLs). If there are none, then explicitly state this. These must be specific URLs that we can use to see the same pages that you are using. If there are none, then explicitly state this.
  - Document any peer class members that you discussed your solution with. Note that you may not look at or share code that solves this specific problem. If there are none, then explicitly state this.
Documentation requirements: function-level and inline documentation are important components of writing code. They help you to organize your thoughts while programming and help to communicate the method and the intent of the code to your future self or to collaborators (of course, you will not have collaborators in this class). While we will not be specifically grading documentation in this class, we will not be able to comment on your code unless it is sufficiently documented. This will be true whether you are asking for help before the submission deadline or looking for feedback on your solution after the deadline. In short, you should take the time to properly document your code as you develop it.
Submit your files:
- Create a zip file named project1.zip containing your source code (c and h files), Makefile and README.txt file. The following Linux shell command will do this for you:
  zip project1.zip *.c *.h Makefile README.txt
  Note I: this is a good thing to add to your Makefile.
  Note II: do not include object files, executables or temporary files in your zip file.
- Submit your zip file to Gradescope (access via Canvas). Shortly after your submission, you will receive automated feedback and a grade for the correctness component of your grade.
- You may submit multiple times until the deadline.
To be counted as on time, your solution must be submitted to the Gradescope server by 11:45:00 pm on Monday, Sept. 28th. Grade penalties will be imposed for late submissions (see the syllabus for the details).

Grading Criteria

README.txt (10%): contains the required information
Makefile (10%): satisfies the make file requirements
Correctness (80%): passes all of the (hidden) unit tests

Downloads

The following file contains a number of example tests: project1_dist.tar

Testing

The testing procedure is the same as in Project 0.

Hints

Remember that characters use the ASCII encoding. You can take advantage of this to make your implementation simple.
Don't implement everything at once. Instead, get the first few commands written and tested before moving on to the more complicated commands.
Any debugging code should only print to STDERR. This way, it won't interfere with our testing procedures.
Useful C functions:
- fprintf()
  This function behaves like printf(), except you can specify which stream will receive the output (first parameter). stdout and stderr are valid choices here.
- memset()
- memcpy()
- read()
- write()
- lseek()
- open()
- strcmp()
- strcpy()
- strcat()
You can ask your VM about any of the above functions. For example, type the following into your shell:
```
man fgets
```
Useful libraries (which define the above functions):
- stdio
- ctype
- string
- stdlib
You can simulate an end-of-file marker (EOF) at the terminal by typing CTRL-d

Addenda

2020-09-17: The user interaction loop continues to process lines until the end-of-file marker is received from stdin.
2020-09-17: All locations (LOC) are expressed in decimal.
2020-09-17: Printing of floating point values should just use the default formatting ("%f").
2020-09-17: Bonus deadline has been extended by one day (to Wednesday the 23rd)
2020-09-21: Small change made to required elements in the README.txt file.

andrewhfagg at gmail.com

Last modified: Tue Sep 29 10:01:44 2020