title	CERI Compiler
subtitle	A simple Pascal compiler
author	Johanny Titouan
institution	Avignon Université
date	05/2025
description	A compiler from Pascal-like imperative LL(k) language to 64-bit x86 assembly language (AT&T syntax)
keywords	compiler pascal assembly version x86 x64

CERI Compiler

Overview

Please view this repository on github.

A simple Pascal compiler developed at the University of Avignon during the an assembly class given by Mr. Pierre Jourlin. You can see his reference git repository here.

• Author: Johanny Titouan
• Class: Assembly and Compiler
  • Teacher: Pierre Jourlin
  • University: Avignon (France)
• Purpose: Translates a Pascal-like imperative LL(k) language into 64-bit x86 assembly language (AT&T syntax).

For this assignment, I developed the compiler myself from the start (I didn't use my teacher's framagit). For the last part of the assignment "free coding", I implemented the following features :

• Case Of (Switch)
• Arrays
• Functions and Procedures
• Strings

I tried to follow as much as possible the standard Pascal Grammar even though I had to adjust a bit considering time and level constraints.

The display statement was made thanks to the internet, considering that my teacher's reference git repository only considered Ubuntu.

Language Grammar

The grammar is defined as follows:

$$ \begin{aligned} \langle\text{Program}\rangle; &::=; \textbf{[}; \langle\text{VarDeclarationPart}\rangle; \textbf{]}; \textbf{[}; \langle\text{FuncProcDeclarationPart}\rangle; \textbf{]}; \langle\text{StatementPart}\rangle; \textbf{.} \[16pt] \langle\text{VarDeclarationPart}\rangle; &::=; \textbf{VAR}; \langle\text{VarDeclaration}\rangle; \text{{}; \textbf{;}; \langle\text{VarDeclaration}\rangle; \text{}}; \textbf{.} \[4pt] \langle\text{VarDeclaration}\rangle; &::=; \langle\text{Ident}\rangle; \text{{};\textbf{,}; \langle\text{Ident}\rangle; \text{}}; \textbf{:}; \langle\text{Type}\rangle; \[4pt] \langle\text{Type}\rangle; &::=; \textbf{INTEGER}; \text{|}; \textbf{BOOLEAN}; \text{|}; \textbf{DOUBLE}; \text{|}; \textbf{CHAR}; \text{|}; \textbf{STRING}; \text{|}; \textbf{ARRAY}; \[16pt] \langle\text{FuncProcDeclarationPart}\rangle; &::=; \text{{};\langle\text{FuncProcDeclaration}\rangle\text{}}; \textbf{;} \[4pt] \langle\text{FuncProcDeclaration}\rangle; &::=; \langle\text{FunctionDeclaration}\rangle; \text{|}; \langle\text{ProcedureDeclaration}\rangle; \[4pt] \langle\text{ProcedureDeclaration}\rangle; &::=; \langle\text{ProcedureHeading}\rangle; \langle\text{BlockStmt}\rangle; \[4pt] \langle\text{ProcedureHeading}\rangle; &::=; \textbf{PROCEDURE}; \langle\text{Ident}\rangle; \text{[}; \textbf{(}; \langle\text{ParameterGroup}\rangle; \text{{}; \textbf{;}; \langle\text{ParameterGroup}\rangle; \text{}}; \textbf{)}; \text{]}; \textbf{;} \[4pt] \langle\text{ParameterGroup}\rangle; &::=; \langle\text{Ident}\rangle; \text{{}; \textbf{,}; \langle\text{Ident}\rangle; \text{}}; \textbf{:}; \langle\text{Type}\rangle; \[4pt] \langle\text{FunctionDeclaration}\rangle; &::=; \langle\text{FunctionHeading}\rangle; \langle\text{BlockStmt}\rangle; \[4pt] \langle\text{FunctionHeading}\rangle; &::=; \textbf{FUNCTION}; \langle\text{Ident}\rangle; \text{[}; \textbf{(}; \langle\text{ParameterGroup}\rangle; \text{{}; \textbf{;}; \langle\text{ParameterGroup}\rangle; \text{}}; \textbf{)}; \text{]}; \textbf{:}; \langle\text{Type}\rangle; \textbf{;} \[16pt] \langle\text{StatementPart}\rangle; &::=; \langle\text{Statement}\rangle; \text{{}; \textbf{;}; \langle\text{Statement}\rangle; \text{}}; \textbf{.} \[4pt] \langle\text{Statement}\rangle; &::=; \langle\text{AssignmentStmt}\rangle \text{|}; \langle\text{IfStatement}\rangle \text{|}; \langle\text{WhileStmt}\rangle \text{|}; \langle\text{ForStmt}\rangle \text{|}; \langle\text{CaseStmt}\rangle \text{|}; \langle\text{DisplayStmt}\rangle \text{|}; \langle\text{ReturnStmt}\rangle \text{|}; \langle\text{BlockStmt}\rangle; \[4pt] \langle\text{AssignmentStmt}\rangle; &::=; \langle\text{Ident}\rangle; \text{[}; \langle\text{ArrayAccess}\langle; \text{]}; \textbf{:=}; \langle\text{Expression}\rangle; \[4pt] \langle\text{IfStmt}\rangle; &::=; \textbf{IF}; \langle\text{Expression}\rangle; \textbf{THEN}; \langle\text{Statement}\rangle; \text{[}; \textbf{ELSE}; \langle\text{Statement}\rangle; \text{]};\[4pt] \langle\text{WhileStmt}\rangle; &::=; \textbf{WHILE}; \langle\text{Expression}\rangle; \textbf{DO}; \langle\text{Statement}\rangle; \[4pt] \langle\text{ForStmt}\rangle; &::=; \textbf{FOR}; \langle\text{AssignmentStmt}\rangle; \langle\text{ForEnd}\rangle; \text{[}; \textbf{STEP}; \langle\text{Number}\rangle; \text{]}; \textbf{DO}; \langle\text{Expression}\rangle; \[4pt] \langle\text{ForEnd}\rangle; &::=; \textbf{TO}; \langle\text{Expression}\rangle; \text{|}; \textbf{DOWNTO}; \langle\text{Expression}\rangle; \[4pt] \langle\text{CaseStmt}\rangle; &::=; \textbf{CASE}; \langle\text{Expression}\rangle; \textbf{OF}; \langle\text{CaseListElement}\rangle; \text{{}; \textbf{;}; \langle\text{CaseListElement}\rangle; \text{}}; \textbf{END} \[4pt] \langle\text{CaseListElement}\rangle; &::=; \langle\text{CaseLabelList}\rangle; \textbf{:}; \text{[}; Statement; \text{]};\[4pt] \langle\text{CaseLabelList}\rangle; &::=; \langle\text{Number}\rangle; \text{{}; \textbf{,}; \langle\text{Number}\rangle; \text{}}; \[4pt] \langle\text{BlockStmt}\rangle; &::=; \textbf{BEGIN}; \langle\text{Statement}\rangle; \text{{}; \textbf{;}; \langle\text{Statement}\rangle; \text{}}; \textbf{END} \[4pt] \langle\text{ReturnStmt}\rangle; &::=; \textbf{RETURN}; \text{[}; \langle\text{Expression}\rangle; \text{]};\[4pt] \langle\text{DisplayStmt}\rangle; &::=; \textbf{DISPLAY}; \langle\text{Expression}\rangle; \[16pt] \langle\text{Expression}\rangle; &::=; \langle\text{SimpleExpression}\rangle; \text{[}; \langle\text{RelationalOperator}\rangle; \langle\text{SimpleExpression}\rangle; \text{]};\[4pt] \langle\text{SimpleExpression}\rangle; &::=; \langle\text{Term}\rangle; \text{{}; \langle\text{AdditiveOperator}\rangle; \langle\text{Term}\rangle; \text{}}; \[4pt] \langle\text{Term}\rangle; &::=; \langle\text{Factor}\rangle; \text{{}; \langle\text{MultiplicativeOperator}\rangle; \langle\text{Factor}\rangle; \text{}}; \[4pt] \langle\text{Factor}\rangle; &::=; \langle\text{Identifier}\rangle; \text{|}; \langle\text{Number}\rangle; \text{|}; \langle\text{Double}\rangle; \text{|}; \langle\text{Character}\rangle; \text{|}; \langle\text{String}\rangle; \text{|}; \textbf{(}; \langle\text{Expression}\rangle; \textbf{)}; \text{|}; \textbf{!} \langle\text{Factor}\rangle; \[16pt] \langle\text{RelationalOperator}\rangle; &::=; \textbf{==}; \text{|}; \textbf{!=}; \text{|}; \textbf{>}; \text{|}; \textbf{<}; \text{|}; \textbf{>=}; \text{|}; \textbf{<=} \[4pt] \langle\text{AdditiveOperator}\rangle; &::=; \textbf{+}; \text{|}; \textbf{-}; \text{|}; \textbf{||} \[4pt] \langle\text{MultiplicativeOperator}\rangle; &::=; \textbf{*}; \text{|}; \textbf{/}; \text{|}; \textbf{%}; \text{|}; \textbf{&&} \[16pt] \langle\text{Number}\rangle; &::=; \langle\text{Digit}\rangle; \text{{}; \langle\text{Digit}\rangle; \text{}}; \[4pt] \langle\text{Digit}\rangle; &::=; \textbf{0}; \text{|}; \textbf{1}; \text{|}; \textbf{...}; \text{|}; \textbf{9} \[4pt] \langle\text{Double}\rangle; &::=; \langle\text{Number}\rangle \textbf{.} \langle\text{Number}\rangle; \[4pt] \langle\text{Character}\rangle; &::=; \textbf{'}; \text{[}; \textit{ASCII_Value}; \text{]};\textbf{'} \[4pt] \langle\text{String}\rangle; &::=; \textbf{"}; \text{{}; \textit{ASCII_Value}; \text{}}; \textbf{"} \[16pt] \langle\text{Identifier}\rangle; &::=; \langle\text{Letter}\rangle; \text{{}; \langle\text{LetterOrDigit}\rangle; \text{}}; \text{[}; \langle\text{Accessors}\rangle; \text{]} \[4pt] \langle\text{Accessors}\rangle; &::=; \langle\text{ArrayAccess}\rangle; \text{|}; \langle\text{FunctionAccess}\rangle; \[4pt] \langle\text{ArrayAccess}\rangle; &::=; \pmb{[}; \langle\text{Expression}\rangle; \pmb{]}; \[4pt] \langle\text{FunctionAccess}\rangle; &::=; \textbf{(}; \langle\text{Expression}\rangle; \text{{}; \textbf{,}; \langle\text{Expression}\rangle; \text{}}; \textbf{)}; \[4pt] \langle\text{Letter}\rangle; &::=; \textbf{a}; \text{|}; \textbf{...}; \text{|}; \textbf{z}; \text{|}; \textbf{A}; \text{|}; \textbf{...}; \text{|}; \textbf{Z} \[4pt] \langle\text{LetterOrDigit}\rangle; &::=; \langle\text{Letter}\rangle; \text{|}; \langle\text{Digit}\rangle; \[4pt] \end{aligned} $$

Requirements

Please make sure you have the flex/flex++ package installed as it is essential for the compiler to parse lexemes. Flex might not be installed by default on your system.

For windows users, you can download the package from here, or via msys2 or vcpkg. Then please make sure the flex exe is in your PATH and/or FlexLexer.h is in your include path.

Required minimum versions :

• c++ : 23
  • compiler : GCC 13+, Clang 17+, MSVC 19.38+
• cmake : 3.20
• make : 4.4.1
• flex/flex++ : 2.6

Please note that the compiler have been made for windows, even though I tried to develop it with linux, I do not guarantee its functionality on linux, especially with the displays.

Project folders

Project tree

. # project root
├── bin/          # final compiler executable
├── lib/          # static libs produced by CMake/Make
├── build/        # out-of-source CMake builds
├── compiler/     # CLI front‑end (main.cpp)
├── parser/       # recursive‑descent parser
├── tokeniser/    # Flex lexer (.l -> tokeniser.cpp)
├── utils/        # small helper library
├── examples/     # sample Pascal programs
├── include/      # public headers (generated/copied)
└── CMakeLists.txt + per‑dir CMakeLists.txt

Installation and Build

To compile the Pascal compiler with cmake ( while in project root folder) :

# 1. Configure an out‑of‑tree build
cmake -B build -S . -DCMAKE_BUILD_TYPE=Release # Or Debug

# 2. Build everything with the default generator (Make)
cmake --build build -j$(nproc)

# 3. (Optional) Install to ./bin & ./lib inside the source tree
cmake --install build

You can also use all.run.xml in the .run folder to compile the project with cmake more easily.

Windows MSVC version if needed :

cmake -B build -S . -G "Ninja Multi-Config"
cmake --build build --config Release # Or Debug

With GNU make :

make
make clean

(Switching between the Makefile and CMake builds is safe—they share the same output directories.)

If the Parser Header file doesn't generate with cmake, please clean your build and bin, then try again. If the problem persists, try generating the Parser Header file manually or with make.

To compile with the pascal compiler, which only gives an assembly at&t file :

./bin/pascal <input.p> [-o output.s]

Example

cd examples
../bin/pascal factorial.p -o factorial.s
gcc -no-pie -o factorial factorial.s
./factorial 5   # => 120

You can also use make to compile all examples while in the examples directory, associated .s files will be in examples/build and exes in examples/bin.