D Application Binary Interface

A D implementation that conforms to the D ABI (Application Binary Interface) will be able to generate libraries, DLL's, etc., that can interoperate with D binaries built by other implementations.

Most of this specification remains TBD (To Be Defined).

C ABI

The C ABI referred to in this specification means the C Application Binary Interface of the target system. C and D code should be freely linkable together, in particular, D code shall have access to the entire C ABI runtime library.

Basic Types

TBD

Structs

Conforms to the target's C ABI struct layout.

Classes

An object consists of:

offset	contents
0	pointer to vtable
4	monitor
8...	non-static members

The vtable consists of:

offset	contents
0	pointer to instance of ClassInfo
4...	pointers to virtual member functions

The class definition:

class XXXX
{
    ....
};

Generates the following:

An instance of Class called ClassXXXX.
A type called StaticClassXXXX which defines all the static members.
An instance of StaticClassXXXX called StaticXXXX for the static members.

Interfaces

TBD

Arrays

A dynamic array consists of:

offset	contents
0	array dimension
4	pointer to array data

A dynamic array is declared as:

type array[];

whereas a static array is declared as:

type array[dimension];

Thus, a static array always has the dimension statically available as part of the type, and so it is implemented like in C. Static array's and Dynamic arrays can be easily converted back and forth to each other.

Associative Arrays

TBD

Reference Types

D has reference types, but they are implicit. For example, classes are always referred to by reference; this means that class instances can never reside on the stack or be passed as function parameters.

When passing a static array to a function, the result, although declared as a static array, will actually be a reference to a static array. For example:

int abc[3];

Passing abc to functions results in these implicit conversions:

void func(int array[3]); // actually <reference to><array[3] of><int>
void func(int *p);       // abc[3] is converted to a pointer
			 // to the first element
void func(int array[]);	 // abc[3] is converted to a dynamic array

Name Mangling

D accomplishes typesafe linking by mangling a D identifier to include scope and type information.

MangledName:
    _D QualifiedName Type

QualifiedName:
    SymbolName
    SymbolName QualifiedName

SymbolName:
    LName
    TemplateInstanceName

Template Instance Names have the types and values of its parameters encoded into it:

TemplateInstanceName:
     __T LName TemplateArgs Z

TemplateArgs:
    TemplateArg
    TemplateArg TemplateArgs

TemplateArg:
    T Type
    V Type Value
    S LName

Value:
    n
    Number
    N Number
    e 20HexDigits
    c 20HexDigits 20HexDigits

HexDigits:
    HexDigit
    HexDigit HexDigits

HexDigit:
    Digit
    a
    b
    c
    d
    e
    f

n is for null arguments.
Number is for positive numeric literals (including character literals).
N Number is for negative numeric literals.
e 20HexDigits is for real and imaginary floating point literals.
c 20HexDigits 20HexDigits is for complex floating point literals.
Width Number _ HexDigits: Width is whether the characters are 1 byte (a), 2 bytes (w) or 4 bytes (d) in size. Number is the number of characters in the string. The HexDigits are the hex data for the string.

Name:
    Namestart
    Namestart Namechars

Namestart:
    _
    Alpha

Namechar:
    Namestart
    Digit

Namechars:
    Namechar
    Namechar Namechars

Type:
	TBD

A Name is a standard D identifier.

LName:
    Number Name

Number:
    Digit
    Digit Number

Digit:
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9

An LName is a name preceded by a Number giving the number of characters in the Name.

Function Calling Conventions

TBD

Exception Handling

Windows

Conforms to the Microsoft Windows Structured Exception Handling conventions. TBD

Linux

Uses static address range/handler tables. TBD

Garbage Collection

TBD

Runtime Helper Functions

TBD

Module Initialization and Termination

TBD

Unit Testing

TBD