Free Pascal
Programmer’s Guide


_____________________________________________________________________
Programmer’s Guide for Free Pascal, Version 2.6.4
Document version 2.6
March 2014

Michaėl Van Canneyt

____________________________________________________________________________
Contents
List of Tables
 About this document
1 Compiler directives
 1.1 Introduction
 1.2 Local directives
  1.2.1 $A or $ALIGN : Align Data
  1.2.2 $A1, $A2,$A4 and $A8
  1.2.3 $ASMMODE : Assembler mode (Intel 80x86 only)
  1.2.4 $B or $BOOLEVAL : Complete boolean evaluation
  1.2.5 $C or $ASSERTIONS : Assertion support
  1.2.6 $BITPACKING : Enable bitsize packing
  1.2.7 $CALLING : Specify calling convention
  1.2.8 $CHECKPOINTER : Check pointer values
  1.2.9 $CODEALIGN : Set the code alignment
  1.2.10 $COPERATORS : Allow C like operators
  1.2.11 $DEFINE or $DEFINEC : Define a symbol
  1.2.12 $ELSE : Switch conditional compilation
  1.2.13 $ELSEC : Switch conditional compilation
  1.2.14 $ELSEIF or $ELIFC : Switch conditional compilation
  1.2.15 $ENDC : End conditional compilation
  1.2.16 $ENDIF : End conditional compilation
  1.2.17 $ERROR or $ERRORC : Generate error message
  1.2.18 $ENDREGION: End of a collapsible region
  1.2.19 $EXTENDEDSYM: Ignored
  1.2.20 $EXTERNALSYM: Ignored
  1.2.21 $F : Far or near functions
  1.2.22 $FATAL : Generate fatal error message
  1.2.23 $FPUTYPE : Select coprocessor type
  1.2.24 $GOTO : Support Goto and Label
  1.2.25 $H or $LONGSTRINGS : Use AnsiStrings
  1.2.26 $HINT : Generate hint message
  1.2.27 $HINTS : Emit hints
  1.2.28 $HPPEMIT: Ignored
  1.2.29 $IF : Start conditional compilation
  1.2.30 $IFC : Start conditional compilation
  1.2.31 $IFDEF Name : Start conditional compilation
  1.2.32 $IFNDEF : Start conditional compilation
  1.2.33 $IFOPT : Start conditional compilation
  1.2.34 $IMPLICITEXCEPTIONS : Implicit finalization code generation
  1.2.35 $INFO : Generate info message
  1.2.36 $INLINE : Allow inline code.
  1.2.37 $INTERFACES : Specify Interface type.
  1.2.38 $I or $IOCHECKS : Input/Output checking
  1.2.39 $IEEEERRORS : Enable IEEE error checking for constants
  1.2.40 $I or $INCLUDE : Include file
  1.2.41 $I or $INCLUDE : Include compiler info
  1.2.42 $J or $WRITEABLECONST : Allow assignments to typed consts
  1.2.43 $L or $LINK : Link object file
  1.2.44 $LIBEXPORT : Ignored
  1.2.45 $LINKFRAMEWORK : Link to a framework
  1.2.46 $LINKLIB : Link to a library
  1.2.47 $M or $TYPEINFO : Generate type info
  1.2.48 $MACRO : Allow use of macros.
  1.2.49 $MAXFPUREGISTERS : Maximum number of FPU registers for variables
  1.2.50 $MESSAGE : Generate info message
  1.2.51 $MINENUMSIZE : Specify minimum enumeration size
  1.2.52 $MINFPCONSTPREC : Specify floating point constant precision
  1.2.53 $MMX : Intel MMX support (Intel 80x86 only)
  1.2.54 $NODEFINE : Ignored
  1.2.55 $NOTE : Generate note message
  1.2.56 $NOTES : Emit notes
  1.2.57 $OBJECTCHECKS : Check Object
  1.2.58 $OPTIMIZATION : Enable Optimizations
  1.2.59 $PACKENUM or $Z : Minimum enumeration type size
  1.2.60 $PACKRECORDS : Alignment of record elements
  1.2.61 $PACKSET : Specify set size
  1.2.62 $POP : Restore compiler settings
  1.2.63 $PUSH : Save compiler settings
  1.2.64 $Q or $OV or $OVERFLOWCHECKS: Overflow checking
  1.2.65 $R or $RANGECHECKS : Range checking
  1.2.66 $REGION : Mark start of collapsible region
  1.2.67 $R or $RESOURCE : Include resource
  1.2.68 $SATURATION : Saturation operations (Intel 80x86 only)
  1.2.69 $SAFEFPUEXCEPTIONS Wait when storing FPU values on Intel x86
  1.2.70 $SCOPEDENUMS Control use of scoped enumeration types
  1.2.71 $SETC : Define and assign a value to a symbol
  1.2.72 $STATIC : Allow use of Static keyword.
  1.2.73 $STOP : Generate fatal error message
  1.2.74 $STRINGCHECKS : Ignored
  1.2.75 $T or $TYPEDADDRESS : Typed address operator (@)
  1.2.76 $UNDEF or $UNDEFC : Undefine a symbol
  1.2.77 $V or $VARSTRINGCHECKS : Var-string checking
  1.2.78 $W or $STACKFRAMES : Generate stackframes
  1.2.79 $WAIT : Wait for enter key press
  1.2.80 $WARN : Control emission of warnings
  1.2.81 $WARNING : Generate warning message
  1.2.82 $WARNINGS : Emit warnings
  1.2.83 $Z1, $Z2 and $Z4
 1.3 Global directives
  1.3.1 $APPID : Specify application ID.
  1.3.2 $APPNAME : Specify application name.
  1.3.3 $APPTYPE : Specify type of application.
  1.3.4 $CALLING : Default calling convention
  1.3.5 $CODEPAGE : Set the source codepage
  1.3.6 $COPYRIGHT specify copyright info
  1.3.7 $D or $DEBUGINFO : Debugging symbols
  1.3.8 $DESCRIPTION : Application description
  1.3.9 $E : Emulation of coprocessor
  1.3.10 $EXTENSION : Extension of generated binary.
  1.3.11 $FRAMEWORKPATH : Specify framework path.
  1.3.12 $G : Generate 80286 code
  1.3.13 $IMAGEBASE : Specify DLL image base location.
  1.3.14 $INCLUDEPATH : Specify include path.
  1.3.15 $L or $LOCALSYMBOLS : Local symbol information
  1.3.16 $LIBPREFIX : Specify library filename prefix.
  1.3.17 $LIBRARYPATH : Specify library path.
  1.3.18 $LIBSUFFIX : Set the library suffix
  1.3.19 $MAXSTACKSIZE : Set maximum stack size
  1.3.20 $M or $MEMORY : Memory sizes
  1.3.21 $MINSTACKSIZE : Set minimum stack size
  1.3.22 $MODE : Set compiler compatibility mode
  1.3.23 $MODESWITCH : Select mode features
  1.3.24 $N : Numeric processing
  1.3.25 $O : Level 2 Optimizations
  1.3.26 $OBJECTPATH : Specify object path.
  1.3.27 $P or $OPENSTRINGS : Use open strings
  1.3.28 $PASCALMAINNAME : Set entry point name
  1.3.29 $PIC : Generate PIC code or not
  1.3.30 $POINTERMATH : Allow use of pointer math
  1.3.31 $PROFILE : Profiling
  1.3.32 $S : Stack checking
  1.3.33 $SCREENNAME : Specify screen name
  1.3.34 $SETPEFLAGS : Specify PE Executable flags
  1.3.35 $SMARTLINK : Use smartlinking
  1.3.36 $SYSCALLS : Select system calling convention on Amiga/MorphOS
  1.3.37 $THREADNAME : Set thread name in Netware
  1.3.38 $UNITPATH : Specify unit path.
  1.3.39 $VARPROPSETTER : Enable use of var/out/const parameters for property setters.
  1.3.40 $VERSION : Specify DLL version.
  1.3.41 $WEAKPACKAGEUNIT : ignored
  1.3.42 $X or $EXTENDEDSYNTAX : Extended syntax
  1.3.43 $Y or $REFERENCEINFO : Insert Browser information
2 Using conditionals, messages and macros
 2.1 Conditionals
  2.1.1 Predefined symbols
 2.2 Macros
 2.3 Compile time variables
 2.4 Compile time expressions
  2.4.1 Definition
  2.4.2 Usage
 2.5 Messages
3 Using Assembly language
 3.1 Using assembler in the sources
 3.2 Intel 80x86 Inline assembler
  3.2.1 Intel syntax
  3.2.2 AT&T Syntax
 3.3 Motorola 680x0 Inline assembler
 3.4 Signaling changed registers
4 Generated code
 4.1 Units
 4.2 Programs
5 Intel MMX support
 5.1 What is it about?
 5.2 Saturation support
 5.3 Restrictions of MMX support
 5.4 Supported MMX operations
 5.5 Optimizing MMX support
6 Code issues
 6.1 Register Conventions
  6.1.1 accumulator register
  6.1.2 accumulator 64-bit register
  6.1.3 float result register
  6.1.4 self register
  6.1.5 frame pointer register
  6.1.6 stack pointer register
  6.1.7 scratch registers
  6.1.8 Processor mapping of registers
 6.2 Name mangling
  6.2.1 Mangled names for data blocks
  6.2.2 Mangled names for code blocks
  6.2.3 Modifying the mangled names
 6.3 Calling mechanism
 6.4 Nested procedure and functions
 6.5 Constructor and Destructor calls
  6.5.1 objects
  6.5.2 classes
 6.6 Entry and exit code
  6.6.1 Intel 80x86 standard routine prologue / epilogue
  6.6.2 Motorola 680x0 standard routine prologue / epilogue
 6.7 Parameter passing
  6.7.1 Parameter alignment
 6.8 Stack limitations
7 Linking issues
 7.1 Using external code and variables
  7.1.1 Declaring external functions or procedures
  7.1.2 Declaring external variables
  7.1.3 Declaring the calling convention modifier
  7.1.4 Declaring the external object code
 7.2 Making libraries
  7.2.1 Exporting functions
  7.2.2 Exporting variables
  7.2.3 Compiling libraries
  7.2.4 Unit searching strategy
 7.3 Using smart linking
8 Memory issues
 8.1 The memory model.
 8.2 Data formats
  8.2.1 Integer types
  8.2.2 Char types
  8.2.3 Boolean types
  8.2.4 Enumeration types
  8.2.5 Floating point types
  8.2.6 Pointer types
  8.2.7 String types
  8.2.8 Set types
  8.2.9 Static array types
  8.2.10 Dynamic array types
  8.2.11 Record types
  8.2.12 Object types
  8.2.13 Class types
  8.2.14 File types
  8.2.15 Procedural types
 8.3 Data alignment
  8.3.1 Typed constants and variable alignment
  8.3.2 Structured types alignment
 8.4 The heap
  8.4.1 Heap allocation strategy
  8.4.2 The heap grows
  8.4.3 Debugging the heap
  8.4.4 Writing your own memory manager
 8.5 Using dos memory under the Go32 extender
 8.6 When porting Turbo Pascal code
 8.7 Memavail and Maxavail
9 Resource strings
 9.1 Introduction
 9.2 The resource string file
 9.3 Updating the string tables
 9.4 GNU gettext
 9.5 Caveat
10 Thread programming
 10.1 Introduction
 10.2 Programming threads
 10.3 Critical sections
 10.4 The Thread Manager
11 Optimizations
 11.1 Non processor specific
  11.1.1 Constant folding
  11.1.2 Constant merging
  11.1.3 Short cut evaluation
  11.1.4 Constant set inlining
  11.1.5 Small sets
  11.1.6 Range checking
  11.1.7 And instead of modulo
  11.1.8 Shifts instead of multiply or divide
  11.1.9 Automatic alignment
  11.1.10 Smart linking
  11.1.11 Inline routines
  11.1.12 Stack frame omission
  11.1.13 Register variables
 11.2 Processor specific
  11.2.1 Intel 80x86 specific
  11.2.2 Motorola 680x0 specific
 11.3 Optimization switches
 11.4 Tips to get faster code
 11.5 Tips to get smaller code
 11.6 Whole Program Optimization
  11.6.1 Overview
 11.7 General principles
  11.7.1 How to use
  11.7.2 Available WPO optimizations
  11.7.3 format of the WPO file
12 Programming shared libraries
 12.1 Introduction
 12.2 Creating a library
 12.3 Using a library in a pascal program
 12.4 Using a pascal library from a C program
 12.5 Some Windows issues
13 Using Windows resources
 13.1 The resource directive $R
 13.2 Creating resources
 13.3 Using string tables.
 13.4 Inserting version information
 13.5 Inserting an application icon
 13.6 Using a Pascal preprocessor
A Anatomy of a unit file
 A.1 Basics
 A.2 reading ppufiles
 A.3 The Header
 A.4 The sections
 A.5 Creating ppufiles
B Compiler and RTL source tree structure
 B.1 The compiler source tree
 B.2 The RTL source tree
C Compiler limits
D Compiler modes
 D.1 FPC mode
 D.2 TP mode
 D.3 Delphi mode
 D.4 OBJFPC mode
 D.5 MACPAS mode
E Using fpcmake
 E.1 Introduction
 E.2 Functionality
 E.3 Usage
 E.4 Format of the configuration file
  E.4.1 clean
  E.4.2 compiler
  E.4.3 Default
  E.4.4 Dist
  E.4.5 Install
  E.4.6 Package
  E.4.7 Prerules
  E.4.8 Requires
  E.4.9 Rules
  E.4.10 Target
 E.5 Programs needed to use the generated makefile
 E.6 Variables that affect the generated makefile
  E.6.1 Directory variables
  E.6.2 Compiler command line variables
 E.7 Variables set by fpcmake
  E.7.1 Directory variables
  E.7.2 Target variables
  E.7.3 Compiler command line variables
  E.7.4 Program names
  E.7.5 File extensions
  E.7.6 Target files
 E.8 Rules and targets created by fpcmake
  E.8.1 Pattern rules
  E.8.2 Build rules
  E.8.3 Cleaning rules
  E.8.4 Archiving rules
  E.8.5 Installation rules
  E.8.6 Informative rules
F Compiling the compiler
 F.1 Introduction
 F.2 Before starting
 F.3 Compiling using make
 F.4 Compiling by hand
  F.4.1 Compiling the RTL
  F.4.2 Compiling the compiler
G Compiler defines during compilation