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+----------------------------------------------------------------------------+ | Online Documentation for H2ASH | +----------------------------------------------------------------------------+ C/C++ modules within a program typically share definitions of types and data structures among themselves. They do this by including small files called header files, which contain type definitions and data structure definitions used by more than one module. A C/C++ header file usually has a name ending in H. Similarly, assembly modules use header files with names that end in .ASH (or .INC). Programs containing modules written in both C or C++ and modules written using Turbo Assembler must be able to share definitions of types and data structures. The H2ASH converter utility lets this happen. The converter has the following limitations: -- All executable statements are ignored; no code output is generated. -- #INCLUDEs are fully expanded in the output. -- Name conflicts can occur in the assembly output since C++ scoping rules differ greatly from assembly rules; using Ideal mode output can help. -- Multiple Inheritance, Virtual Base Classes, and Templates are not supported in this version of H2ASH. The H2ASH converter not only smooths the interface between C/C++ and assembly language, it also lets you write C++ base classes directly in assembly lang- uage (for maximum performance). H2ASH automatically converts base class declarations in C++ into equivalent assembly object definitions, and defines method names. We recommend that you use the following procedure for writing base classes in assembly language: 1) Write the class declaration in a C/C++ header file. 2) Include the C header file in all descendant classes, and in the C/C++ modules that use the base class. 3) Use the H2ASH converter on the header file to produce an assembly object header file; you can automate this by setting up a makefile. 4) Include the assembly object header file in the module where the assembly language methods are written. +----------------------------------------------------------------------------+ | Command Line Interface for H2ASH | +----------------------------------------------------------------------------+ You can invoke H2ASH by typing the following command on the command line: H2ASH [[switches] <filename> [<filename> ... ]] H2ASH triggers the printing of a help screen. By default, H2ASH accepts a C/C++ header file, and produces a Turbo Assembler (TASM) 3.0 compatible assembly include file with extension .ASH. The resulting file is not a self-contained assembly language program; rather, it contains TASM type declarations and EQU statements that correspond to declarations in the original C/C++ header file. H2ASH recognizes wild cards for filename matching. All H2ASH-specific command line switches are a submode of the -q switch, that is they all have the following form: -q[<character>] [-] H2ASH also recognizes a majority of the Borland C++ command-line switches. In particular, word-alignment (-a), force C++ compile (-P), set output file name (-o), define symbol (-D), and the compilation model directives (-mt, -ms, -ml, ...), are all supported. For a definitive description of the BCC command-line interface, see the Borland C++ User's Guide. H2ASH allows the following switches: -q- turn off the H2ASH converter <default is on> -qc pass c/c++ comments into the .ASH file <default is off> -qn enable name-mangling <default is on> -qf a 'strict' mode that strips out all untranslatable source code (as opposed to the default behavior of issuing a warning and partially translating the declaration in question) <default is off> -qi generate Ideal mode code, as opposed to Masm mode code <default is off> -qd generate EQUs for #DEFINE statements which appear on the command-line, in project configuration file, or in the original source program <default is on> -qb generate EQUs for #DEFINE statements which are normally generated automatically by the compiler <default is off> -qt generate Tasm directives as needed (H2ASH will emit .DATA and .MODEL directives whenever static declarations appear in the original C/C++ header file. The IDEAL directive is generated whenever Ideal mode is used) <default is on> -qs pass original source code into the .ASH file <default is off> +----------------------------------------------------------------------------+ | Processing #DEFINE directives and macros | +----------------------------------------------------------------------------+ H2ASH accepts C preprocessor #DEFINE direcives and generates a corres- ponding EQU directive containing the symbol name and its associated value. Hexidecimal and octal constants force H2ASH to append an 'h' or 'q' radix specifier onto the end of the constant value. Decimal constants are passed directly to the output stream, while floating point numbers are treated as text literals. Here's an example of input and output: ---- H2ASH input ---- #define ONE 1 #define NEG_ONE -1 #define OCTAL_ONE 01 #define HEX_ONE 0x1 #define FLOAT_ONE 1.000 ---- H2ASH output ---- ONE EQU 1 NEG_ONE EQU -1 OCTAL_ONE EQU 1q HEX_ONE EQU 1h FLOAT_ONE EQU <1.000> All other macro #DEFINEs generate text EQUs into the H2ASH output stream. However, if the #DEFINE contains any macro arguments, a warning is issued and the macro in question is not processed. For example, ---- H2ASH input ---- #define PI 22/7 #define LOOP_FOREVER while(1) { #define seq(s,t) strcmp(s,t) ---- H2ASH output ---- PI EQU <22/7> LOOP_FOREVER EQU <while(1) {> H2ASH does not directly translate C preprocessor conditional #IF/#ELSE/#ENDIF directives into their TASM equivalents. Rather, it evaluates the constant-expression that is the argument to the conditional directive, and then passes the appropriate clause of the conditional into the output stream, as follows: ---- H2ASH input ---- #if 0 #define PI 3.14159 #else #define PI 22/7 #endif ---- H2ASH output ---- ZOO PI <22/7> +----------------------------------------------------------------------------+ | Processing Simple Declarations | +----------------------------------------------------------------------------+ H2ASH does not process declarations that have storage class 'auto'; that is, any C/C++ declarations contained in compound-blocks are ignored. However, declarations that have static linkage are translated into TASM 'DB', 'DW', 'DD', .... statements, depending on the size or type of the variable. Further- more, declarations that have external linkage are translated into TASM 'GLOBAL' statements with an appropriate type specifier that is dependant on the size of the C/C++ variable. H2ASH ignores all initializers for declara- tions if the initializer expression is not a constant expression. If this situation occurs, H2ASH issues a warning message. For example, ---- H2ASH input ---- char char; unsigned char unsigned_char; signed char signed_char; int integer; unsigned int unsigned_integer; signed int signed_integer; long long; unsigned long unsigned_long; signed long signed_long; float float; double double; long double long_double; ---- H2ASH output ---- GLOBAL C char:BYTE GLOBAL C unsigned_char:BYTE GLOBAL C signed_char:BYTE GLOBAL C integer:WORD GLOBAL C unsigned_integer:WORD GLOBAL C signed_integer:WORD GLOBAL C long:DWORD GLOBAL C unsigned_long:DWORD GLOBAL C signed_long:DWORD GLOBAL C float:PWORD GLOBAL C double:QWORD GLOBAL C long_double:TBYTE H2ASH ignores the type modifiers 'const' and 'volatile'. However, the linkage specifiers 'pascal' and 'cdecl', do generate the corresponding TASM equivalents. Static variables, as required by the ANSI C standard, generate a default zero initializer expression of the appropriate width for the data type in question. ---- H2ASH input ---- const int const_int; volatile int volatile_int; static int static_int; static double static_double; extern int extern_int; int pascal int_pascal; int cdecl int_cdecl; ---- H2ASH output ---- GLOBAL C const_int :WORD GLOBAL C volatile_int:WORD .DATA static_int DW 0 static_double DQ 0.0 GLOBAL C extern_int :WORD GLOBAL PASCAL int_pascal :WORD GLOBAL C int_cdecl :WORD +----------------------------------------------------------------------------+ | Processing Reference/Pointer/Array Declarations | +----------------------------------------------------------------------------+ Reference and pointer declarations are handled in a similar manner to basic variable declarations, except that the 'PTR' type specifier is intro- duced for each level of pointer/reference indirection. Note that any init- ializer that requires the creation of a temporary variable, or is not a constant expression is ignored. For example, ---- H2ASH input ---- char *v1; int **v2; char far *v3; char near *v4; int &v5 = 1; ---- H2ASH output ---- GLOBAL C v1: PTR BYTE GLOBAL C v2: PTR PTR WORD GLOBAL C v3: FAR PTR BYTE GLOBAL C v4: NEAR PTR BYTE GLOBAL C v5: PTR WORD Arrays are treated like basic variable declarations, where the type specifier consists of the element type of the array, followed by an optional repetition field that contains the dimension of the array. If the array is an incomplete declaration, (that is, if it's dimension is not fully specified) the repetition field is not passed into the output stream. For example, ---- H2ASH input ---- extern char a1[]; extern char a2[10]; extern char a3[][10]; extern char a4[10][20]; ---- H2ASH output ---- GLOBAL C a1: BYTE GLOBAL C a2: BYTE : 10 GLOBAL C a3: BYTE GLOBAL C a4: BYTE : 200 +----------------------------------------------------------------------------+ | Processing TYPEDEF Declarations | +----------------------------------------------------------------------------+ C/C++ TYPEDEF declarations are mapped directly onto their equivalent TASM counterpart. When the typedef alias (the name of the typedef) is used as the type specifier in another declaration, the actual type of the typedef, as op- posed to the typedef alias itself, is emitted into the output stream. For example, ---- H2ASH input ---- typedef unsigned long ul; typedef ul alias_ul; alias_ul ul_object; ---- H2ASH output ---- ul TYPEDEF DWORD alias_ul TYPEDEF DWORD GLOBAL C ul_object :DWORD +----------------------------------------------------------------------------+ | Processing ENUM Declarations | +----------------------------------------------------------------------------+ C/C++ enumeration types are converted directly into TASM 'ENUM' defini- tions. Each enumerator is given an explicit initializer if the value of the enumerator changes by more than one unit from the previously processed enum- erator, or if the enumerator already has an explicit initializer in the C/C++ source code. As usual, this initializer must contain a constant- expression. H2ASH automatically synthesizes a tag name if the enumeration does not contain a tag. This generated name is always unique within the compilation unit it occurs in, and can be in subsequent variable declarations. For example, ---- H2ASH input ---- enum FOO { a, b, c = -1, d = sizeof(enum FOO)}; enum { north, east, south, west }; ---- H2ASH output ---- FOO enum \ a = 0, \ b, \ c = -1, \ d = 2 \ tag$1 enum \ north, \ east, \ south, \ west \ Finally, if the enumeration is not representable within a declaration of size BYTE, H2ASH generates an extra enumerator (which has a unique name), and appends it to the end of the enumeration list. This enumerator is used to induce TASM to pack the enumeration within a datatype of size WORD. This situation can occur whenvever you use the -b option, or whenever the value of an enumerator exceeds a value representable within a BYTE. For example, ---- H2ASH input ---- enum direction { north, east = 254, south, west }; enum color { red, green = 256, blue }; ---- H2ASH output ---- direction enum \ north, \ east = 254, \ south, \ west, \ pad$0 = 256 direction enum \ red, \ green = 256, \ blue +----------------------------------------------------------------------------+ | Processing Simple Aggregate Declarations | +----------------------------------------------------------------------------+ Structures and unions are mapped by H2ASH onto their direct TASM STRUC and UNION counterparts. If a tag is not present in the aggregate declaration, H2ASH automatically generates one. The GLOBAL directive is used to represent an instance of the structure, where the type-field contains that tag name of the structure or union in question. For example, ---- H2ASH input ---- struct S1 { int field1; int field2; } S1_object; union U1 { int field1; int field2; int (*field3)(void); } U1_object; ---- H2ASH output ---- S1 STRUC S1@field1 DW ? S1@field2 DW ? S1 ENDS GLOBAL C S1_object:S1 tag$0 UNION ; tag name is synthesized tag$0@field1 DW ? tag$0@field2 DW ? tag$0@field3 DD FAR PTR ? ; or NEAR PTR, depending on the model tag$0 ENDS GLOBAL C U1_object:tag$0 Using the word-alignment (-a) option lets H2ASH explicitly output appropriate padding. For the exact structure-alignment rules, see the C++ Programmer's Guilde. For example, ---- H2ASH input ---- struct S2 { char field1; int field2; }; ---- H2ASH output ---- S2 STRUC S2@field1 DB ? DB ? ; force word alignment (only if -a is used) S2@field2 DW ? S2 ENDS H2ASH treats nested structures as separate TASM STRUC declarations, and gives the nested structures specially mangled names. This is done because nested structures are not true members; they are merely in the lexical scope of the structure in which they are contained. However, if a nested structure is instantiated (for example, an object of the type of that structure is declared), the appropriate space is reserved in the enclosing structure as in the following example: ---- H2ASH input ---- struct a { int i; struct b { int j; }; int k; struct c { int l; } c_instance; }; ---- H2ASH output ---- a@b STRUC a@b@j DW ? a@b ENDS a@c STRUC a@c@l DW ? a@c ENDS a STRUC a@i DW ? a@k DW ? a@c_instance C <> ;this is an actual member, so reserve space for it a ENDS +----------------------------------------------------------------------------+ | Processing Bitfield Declarations | +----------------------------------------------------------------------------+ Bitfields are represented by H2ASH as TASM RECORD declarations. In general, it generates two kinds of RECORDS. First, if a STRUCT contains only bitfield declarations and if each of the bitfields are of the same type, and if this type is sufficiently large to contain all of the fields, H2ASH generates a global RECORD declaration. H2ASH inserts a uniquely named padding field at the top of the RECORD so that proper alignment is achieved. For example, ---- H2ASH input ---- struct S1 { int field1: 1; int field2: 4; }; ---- H2ASH output ---- S1 RECORD { S1@pad_0 :11, ; 11+4+1 = sizeof(int); S1@field21 :4, S1@field11 :1 } If H2ASH is unable to generate a global RECORD declaration, a local one is emitted within the STRUC in which the original bitfield is declared. Furthermore, a member with the type of the tag of the local RECORD declaration is declared to reserve the appropriate amount of storage. H2ASH attempts to pack adjacent bitfields within a single record when adjacent bitfields are of the same type, and whenever the type of the bitfield is large enough to contain the adjacent fields. For example, ---- H2ASH input ---- struct S1 { int field1; char field2: 1; char field3: 8; // NOTE: cannot be packed with field2 }; ---- H2ASH output ---- S1 STRUC S1@field1 DW ? S1@REC_0 RECORD { S1@REC_0 :7 S1@field2 :1 } S1@BIT_0 S1@REC_0 <> ; create an instance of this record S1@REC_1 RECORD { S1@field2 :8 } S1@BIT_1 S1@REC_1 <> ; create an instance of this record S1 ENDS +----------------------------------------------------------------------------+ | Processing Function/Operator Declarations | +----------------------------------------------------------------------------+ File scope function declarations are emitted as GLOBAL declarations with type NEAR or FAR, depending on the model settings. Prototypes for func- tions are ignored, because TASM does not support typed CALLs or typed PROTO statements. However, the prototype is encrypted by the mangled name of the function. For example, ---- H2ASH input ---- void fvv(void); extern efvv(void); int fiii(int, int); ---- H2ASH output ---- GLOBAL C @fvv$qv :NEAR ;or far, depending on model GLOBAL C @efvv$qv :NEAR ;or far, depending on model GLOBAL C @fiii$qii :NEAR ;or far, depending on model H2ASH ignores default arguments, as well as all function bodies. In both cases, H2ASH issues a warning and processes that declaration as if the default arguments and function bodies were not present. H2ASH also ignores static function declarations. In this case, the declaration is not emitted into the output stream. Here's an example: ---- H2ASH input ---- static sfvv(void); void dfii(int i = 0, int = sizeof(foo)); int fvv(int i) { return ++i; } ---- H2ASH output ---- ; warning, declaration of static function 'sfvv(...)' ignored void C @dfii$qii :NEAR ; warning, default arguments ignored void C @fvv$qi :NEAR ; warning, function body ignored H2ASH supports function and operator overloading by encoding function prototypes and operator names. Otherwise, H2ASH treats these declarations in exactly the same manner as ordinary functions. For example, ---- H2ASH input ---- int abs(int, int); int abs(int); struct alpha; int operator+(alpha, int); int operator+(int, alpha); ---- H2ASH output ---- GLOBAL C @abs$qii :NEAR GLOBAL C @abs$qi :NEAR GLOBAL C @$badd$q5alphai :NEAR GLOBAL C @$badd$iq5alpha :NEAR +----------------------------------------------------------------------------+ | Processing Classes | +----------------------------------------------------------------------------+ C++ classes are mapped onto TASM STRUC declarations, just as C STRUCTS are. Nonstatic class data members are treated as ordinary STRUCT fields. Static class data members are treated as GLOBAL declarations, and are emitted after the class declaration in whcih they are declared. Nonvirtual function members are treated exactly like ordinary function definitions, except, that they recieve a mangled name that encodes the tagname of class in which they are contained. Virtual function members are treated exactly like nonvirtual functions, except that they force H2ASH to allocate space for a virtual- function-table-pointer. This pointer has a mangled name containing the suffix 'vptr$', which is always unique throughout a single compilation unit. Finally, all 'special' member functions (constructors, copy constructors, assignment operators), are treated as ordinary function declarations. However, if they are compiler-synthesized members, H2ASH does not emit them. For example, ---- H2ASH input ---- class c { static int static_member; int normal_member; public: virtual void f1_virtual(void); virtual void f2_virtual(void); void f3_normal(void); void *operator ++(); c(); c(int&); ~c(); }; ---- H2ASH output ---- c STRUC @c@normal_member DW ? @c@vptr$0 DW NEAR PTR ? c ENDS GLOBAL C @c@static_member :WORD GLOBAL C @c@f1_virtual$qv :FAR GLOBAL C @c@f2_virtual$qv :FAR GLOBAL C @c@f3_normal$qv :FAR GLOBAL C @c@$binc$qv :FAR GLOBAL C @c@$bctr$qv :FAR GLOBAL C @c@$bctr$qmi :FAR GLOBAL C @c@$bdtr$qv :FAR H2ASH supports single inheritance. If a program using multiple inheri- tance is presented as input, or if virtual bases are present, H2ASH terminates and gives an appropriate error message. Within a derived class, a base class is represented as a member subobject, and is treated by H2ASH as if it were an ordinary member with a specially synthesized name: 'subobject$' which has the type of the base class in question. Again, this name is always unique. Virtual function table pointers are shared between the base and derived class; hence, no further space is allocated for the virtual-pointer within the derived class. For example, ---- H2ASH input ---- class d : c { int derived_member; virtual void f1_virtual(void); // virtual override of c::f1_virtual() d(); ~d(); }; ---- H2ASH output ---- d STRUC d@subobject$0 c <> d@derived_member DW ? d ENDS GLOBAL C @d@f1_virtual$qv :FAR GLOBAL C @d@$bctr$qv :FAR GLOBAL C @d@$bdtr$qv :FAR There are two kinds of pointer to data members: SI/MI members, or VB members, represented as a single WORD or as a STRUC of width two WORD's, respectively. Pointers to function members are either a single WORD, for SI, a double WORD STRUC, for MI, or a triple WORD STRUC, for VB. In each case, a separate TASM TYPEDEF or STRUC name is used as an alias for the type of the appropriate width. For a further discussion of pointers to data members, see the Borland C++ Programmer's Guilde. Here's another example: ---- H2ASH input ---- int f::*pointer_to_data_member; int (f::*pointer_to_function)(char *); ---- H2ASH output ---- ; if a SI/MI data member is generated SIMIdataPtr$ TYPEDEF WORD GLOBAL C pointer_to_data_member:SIMIdataPtr$ ; if a SI function member pointer is generated SIfuncFPtr$ TYPEDEF FAR PTR WORD GLOBAL C pointer_to_function_member:SIfuncFPtr$ ; if a VB data member is generated VBdataPtr$ STRUC VBdataPtr@memberOffset WORD VBdataPtr@vbcptrOffset WORD VBdataPtr$ ENDS GLOBAL C pointer_to_data_member:VBdataPtr$ ; if a SI function member pointer is generated VBFuncFPtr$ STRUC VBFuncFPtr@funcAddr FAR PTR WORD VBFuncFPtr@memberOffset WORD VBFuncFPtr@vbcptrOffset WORD VBdataFPtr$ ENDS GLOBAL C pointer_to_function_member:VBFuncFPtr$ C++ Templates are not supported in this version of H2ASH. If a program containing templates is given as input, H2ASH outputs an error and terminates execution.