Lab 1b: Data Representation in C

Lab Format

This lab uses a custom data representation of aisles in a store. aisle_manager.c and store_client.c have skeleton functions for you to implement, each with a comment describing its desired behavior.

You will start by implementing functions that use bitwise operators, bitmasks, and C control structures to manage an individual aisle. After implementing these functions, you will move onto functions that use pointers, arrays, and your aisle functions to manage multiple aisles in a store. We have provided two test programs to help you check the correctness of your work (see Checking Your Work for more details).

Aisle Manager

Start by reading the description of an aisle's data representation at the top of aisle_manager.c. Make sure you fully understand the layout of the representation before continuing. If you have any questions, please post on the message board or come to office hours.

Once you understand the data representation, you can begin to implement the skeleton functions in aisle_manager.c:

• get_section
• get_spaces
• get_id
• set_section
• set_spaces
• set_id
• toggle_space
• num_items
• add_items
• remove_items
• rotate_items_left
• rotate_items_right

Do not be discouraged by the number of functions! They build gradually in level of difficulty, and many of them are similar to each other. Here's one recommended way of working through the file:

1. Start by filling in the macros at the top of the file with various bitmasks to be used later.
2. Continue by implementing the get_* and set_* functions.
3. Finish by implementing the rest of the functions related to manipulating the items in an aisle.

At this point you should be able to pass all tests in the aisle_test executable! Now you can move onto store_client.c.

Store Client

store_client.c has some functions for interacting with a group of aisles and a stockroom in the store. Pay particular attention to its use of global arrays: (1) of type unsigned long to represent multiple aisles and (2) of type int to represent a stockroom for the store (items stowed away that are not in the aisles).

Skeleton functions:

• refill_from_stockroom
• fulfill_order
• empty_section_with_id
• section_with_most_items

At this point you should be able to pass all tests in the store_test executable! This means you are done with the programming part of the assignment (don't forget about the synthesis questions!).

Checking Your Work

We have included the following tools to help you check the correctness of your work:

• The functions print_binary_long and print_binary_short take an unsigned long and unsigned short, respectively, and output its binary representation. These are optional to use but can be useful in debugging your code. All calls to these functions should be removed from your final submission. Here is an example usage of print_binary_long (print_binary_short works similarly except it takes an unsigned short as its argument):

  void print_binary_example(unsigned long* argument) {
    // Print out binary view of argument for debugging.
    // The type of argument is unsigned long*, so we
    // must pass its dereference to print_binary_long.
    print_binary_long(*argument);
  }

• You can also use printf to debug your functions, but you'll have to add #include <stdio.h> at the top of your file. All calls to printf should be removed from your final submission.
• aisle_test and store_test are programs that check the functional correctness of the code in aisle_manager.c and store_client.c, respectively.
  You will need to rebuild these executables before running them each time you modify your code using the make command.

  To test all of the functions, use the following commands:

  $ ./aisle_test
  $ ./store_test

  The test one function at a time, use the -f flag on the appropriate executable, e.g.:

  $ ./aisle_test -f set_id
  $ ./store_test -f section_with_most_items

  • aisle_test and store_test first test your solution on specific cases, and then on a wide range of inputs. As a manner of limiting the test output, for the range of inputs the testing program will only print out the first input that your solutions are incorrect for (or no input if you pass all cases).
  • There is some partial credit awarded if your function passes the specific cases but not the range of cases, and each function is tested separately to allow for the opportunity for partial credit should you only complete some of the functions.