lab03.md

Lab 3

In this lab, you will create a version of the byte calculator from Lab 2 that will allow you to step through commands one at a time.

In order to do this, you will need to store commands in memory, rather than reading them one at a time:

• Create a struct to hold a command, its argument, and its line number (the first command is line 1, the second is line 2, and so on).

• Create an array of structs to hold several statements as a calculator program.

• Use the C initializer syntax from Modern C, Level 1, Sections 2.3 and 6.3 to hard-code the array of structs to hold the calculator program from lab02.input, rather than reading commands with scanf().

Now, instead of using scanf() to read calculator commands, your program should use scanf() to read commands describing what to do with the calculator program you've created and stored:

Command	Action
step	Execute the next calculator command
continue	Execute the rest of the calculator commands
print	Print the current byte value
list	Print the current, previous, and next commands

Note that in order to keep track of which calculator command to execute next, you will need to keep track of the current location in the array.

Example

$ ./debug-calculator
list
 1 set 1
 2 shl 1
step
print
1
list
 1 set 1
 2 shl 1
 3 shl 1
step
print
2
list
 2 shl 1
 3 shl 1
 4 or 1
continue
print
e
list
12 set 1c
13 shr 1