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如何将C/C++程序转译成Delphi(五)

2001-07-24 13:28 531 查看
1. Anatomy of a C Header

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2. Conversion Basics

2.1. Naming

The naming in converted header files should follow Borland's style as far as possible. This means, keep the original names, but make them more Delphi-like.

How should the C names be translated into Delphi?

The C-programmer usually uses upper case letters for type identifiers, e.g. MY_TYPE. In Delphi, a type identifier has a T-prefix followed by the name of the type in mixed (proper) case. Underscores are not used. The Delphi-like translation of the C type identifier MY_TYPE is TMyType.

In C older header files the pointer-type is named LPMY_TYPE. In translation to Delphi it should be PMyType to conform with Borland's style.

Constants are usually named identically to the original name, including upper case letters and underscores.

A few examples:

C
Delphi-Translation
typedef struct _IMAGE_FILE_HEADER {
  WORD Machine;
  WORD NumberOfSections;
  DWORD TimeDateStamp;
  DWORD PointerToSymbolTable;
  DWORD NumberOfSymbols;
  WORD SizeOfOptionalHeader;
  WORD Characteristics;
} IMAGE_FILE_HEADER,
*PIMAGE_FILE_HEADER; 		type
  PImageFileHeader = ^TImageFileHeader;
  TImageFileHeader = packed record
    Machine: Word;
    NumberOfSections: Word;
    TimeDateStamp: DWORD;
    PointerToSymbolTable: DWORD;
    NumberOfSymbols: DWORD;
    SizeOfOptionalHeader: Word;
    Characteristics: Word;
  end;

#define LANG_NEUTRAL 0x00
#define LANG_AFRIKAANS 0x36
#define LANG_ALBANIAN 0x1C
#define LANG_ARABIC 0x01
#define LANG_BASQUE 0x2D
#define LANG_BELARUSIAN 0x23
#define LANG_BULGARIAN 0x02
#define LANG_CATALAN 0x03
#define LANG_CHINESE 0x04 		CONST
  LANG_NEUTRAL = $00;
  LANG_AFRIKAANS = $36;
  LANG_ALBANIAN = $1C;
  LANG_ARABIC = $01;
  LANG_BASQUE = $2D;
  LANG_BELARUSIAN = $23;
  LANG_BULGARIAN = $02;
  LANG_CATALAN = $03;
  LANG_CHINESE = $04;
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2.2. Unit dependencies

C and C++ use #include to include header files in another header file or a source file. Delphi refers to units (in the USES clause) instead of header files.

For example

D3D.H includes D3DTYPES.H, D3DCAPS.H

D3DTYPES.H includes DDRAW.H

One unit contains one translation of a header file, so incorporation of D3DTYPES.H and D3DCAPS.H is required when translating D3D.H.
Thus the translation of D3D.H (D3D.PAS) needs D3DTYPES.PAS and D3DCAPS.PAS in uses.

In Windows.pas Borland has already done a lot of work for us. Borland's windows unit contains most of the basic Windows datatypes, so any translated unit needing Windows datatypes needs the Windows unit in its uses clause.

Note: In Delphi 1.0, substitute WinProcs.pas and WinTypes.pas for Windows.pas, since these two units include for Delphi 16-bit what Delphi 32-bit defines in Windows.pas. In Delphi 2 these two files are also aliased to Windows.pas in Delphi 32-bit versions for backward compatibility. Some header files contain source which is not directly translatable into Pascal, but the header file's impact on compilation must be incorporated into the translated code. For example, PSHPACK?.H contains compiler directives that are not directly translatable to Delphi; PSHPACK4.H directs the compiler to use 4-byte packing. More about this later.

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2.3. #defines as constants

C and C++ use #defines in several ways. In a C header file #define can be used

for declaring a constant

for declaring a symbol for conditional compilation

for macros
This chapter describes the translation of #define into Delphi constants.

The format for declaring constants in C is: #define NameOfConstant Value
For example:#define TIME_ZONE_ID_UNKNOWN 0

#define TIME_ZONE_ID_STANDARD 1

#define TIME_ZONE_ID_DAYLIGHT 2
The translation in Delphi is: CONST

TIME_ZONE_ID_UNKNOWN = 0;

TIME_ZONE_ID_STANDARD = 1;

TIME_ZONE_ID_DAYLIGHT = 2;

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2.3.1. Hexadecimal values

C uses the prefix 0x to specify a hexadecimal value. For example, the C declaration #define MY_CONSTANT 0xFF
translates to Delphi as CONST

MY_CONSTANT = $FF;

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3. Data Types

3.1. Basic Data Types

Here is a list of C data types and the equivalents in Delphi:

CDelphi
UNSIGNED LONGDword (Longint)
UNSIGNED SHORTword
INTinteger
UNSIGNED CHARbyte, char (Depending on usage)
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3.2. Windows API Common Types

The Windows API defines some common types for API usage. It is recommended that the same names be used in translations as far as possible. Windows.pas declares most of these types, some of which are listed below:


4000
API Type declaration		Type used in Delphi Translation Type Specification
ULONGULongDWord
PULONGPULong^DWord
USHORTUShortSmallInt
PUSHORTPUShort^SmallInt
UCHARUCharByte
PUCHARPUChar^Byte
DWORDDWordDWord
PDWORD, LPDWORDPDWord^DWord
　　　
BOOLBoolBool
PBOOL, LPBOOLPBool^Bool
BYTEByteByte
PBYTE, LPBYTEPByte^Byte
WORDWordWord
PWORD, LPWORDPword^Word
INTIntegerInteger
PINT, LPINTPInteger^Integer
LPVOIDPointerUntyped Pointer
UINTUIntInteger
PUINT, LPUINTPUInt^Integer
　　　
WCHARWCharWideChar
PWCHAR, LPWCHAR, PCWCH, LPCWCH, NWPSTR,PWChar^WideChar
PWSTR, LPWSTRLPWStr^WideChar
PCWSTR, LPCWSTRLPCWStr^WideChar
PCH, LPCHPChar^Char
PSTR, LPSTRLPStr^Char
PCSTR, LPCSTRLPCStr^Char
　　　
HANDLETHandleDWord
PHANDLE, LPHANDLEPHandle^DWord
　　　
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3.3. Arrays - Two Methods

Method 1:

In C the first index of an array (or vector) is 0 and the declaration specifies the number of elements (not the last index), e.g. DWORD MyType[4]
Delphi declares arrays as the range of elements, so the same declaration would beMyType = Array [0..3] of DWord;
Method 2:

Alternatively, the number of elements may be specified by a constant, e.g #define NumberOfElements 5

//...

typedef struct _MyRec {

DWORD MyArray[NumberOfElements]

} MyRec, *PMyRec
The same declaration in Delphi is Const

NumberOfElements = 5

//...

Type

TmyArray = Record

MyArray : Array [0..NumberOfElements-1] of DWord;

end;
Remember, the range of the array is 0..NumberOfElements-1, but not0..NumberOfElements.

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标签：  delphi translation header integer borland constants
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