C-to-LC3 Compiler
• Over the course of the next two weeks, you will
build a program that will compile C code to LC-3
assembly language
• Don't panic! You can do this!
• The compiler will only allow for a (very small)
subset of the C programming language
• You will be given a lot of skeleton code to help
you get started
int fun (int a, int b) {
int x = a + b;
return x + 8;
}
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LDR
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AND
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R7,
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FP,
SP,
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R1,
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SP,
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SP,
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FP,
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FP,
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4
5
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Lab #5 (last week)
• Input: a string containing up to 10 white-space
separated tokens (substrings)
• Output: a 10-element string array, each holding
one of the substrings
• This is known as “tokenizing” a string
Lab #6 (today)
• Use the solution to Lab #5 (we'll give you one if
you didn't do the lab) to find variables that are
being declared in a C program
• Part 1: find parameters
int fun2 (int dog, int cat) {
• Part 2: find variable declarations
int a = x + 5;
int c = a + x, d, e = b;
Homework #7 (due next Monday)
• Implement a data structure called a Linked List
to represent the symbol table
– We will see Linked Lists in class tomorrow
• Modify solution to today's lab to populate the
symbol table with variable names and offsets
• Look for basic compiler errors:
– variable declared multiple times
– undeclared variables
Homework #8 (due Monday 12/10)
• Generate prologue in LC-3
• Compile each line of code to LC-3
• Generate epilogue in LC-3
Today
• Go to course website, then Schedule, then follow
the link for today's Lab Assignment
• Download solution to Lab #5 if you need it
• Download skeleton code and test code and make
sure it all compiles
• Start coding! You may work with other people
• This is Part 1 of Homework #7