1. Anatomy of a C Header
Back to contents
## to do
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
Back to contents
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.
Back to contents
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;
Back to contents
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;
Back to contents
3. Data Types
3.1. Basic Data Types
Here is a list of C data types and the equivalents in Delphi:
C Delphi UNSIGNED LONG Dword (Longint) UNSIGNED SHORT word INT integer UNSIGNED CHAR byte, char (Depending on usage)
Back to contents
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:
API Type declaration Type used in Delphi Translation Type Specification ULONG ULong DWord PULONG PULong ^DWord USHORT UShort SmallInt PUSHORT PUShort ^SmallInt UCHAR UChar Byte PUCHAR PUChar ^Byte DWORD DWord DWord PDWORD, LPDWORD PDWord ^DWord BOOL Bool Bool PBOOL, LPBOOL PBool ^Bool BYTE Byte Byte PBYTE, LPBYTE PByte ^Byte WORD Word Word PWORD, LPWORD Pword ^Word INT Integer Integer PINT, LPINT PInteger ^Integer LPVOID Pointer Untyped Pointer UINT UInt Integer PUINT, LPUINT PUInt ^Integer WCHAR WChar WideChar PWCHAR, LPWCHAR, PCWCH, LPCWCH, NWPSTR, PWChar ^WideChar PWSTR, LPWSTR LPWStr ^WideChar PCWSTR, LPCWSTR LPCWStr ^WideChar PCH, LPCH PChar ^Char PSTR, LPSTR LPStr ^Char PCSTR, LPCSTR LPCStr ^Char HANDLE THandle DWord PHANDLE, LPHANDLE PHandle ^DWord
Back to contents
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 be
MyType = 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.
Back to contents
本文地址：http://com.8s8s.com/it/it6022.htm