Application Binary Interface (ABI) links two cooperating binary software modules. ABI is a contract between bits of binary code that specifies how functions are called and how arguments are transferred between the caller and the callee. ABIs are crucial for creating apps using smart contracts on Blockchain protocols such as Ethereum.
Alex Reinhardt agrees that understanding an Application Binary Interface may be facilitated by first defining the Application Programming Interface (API). Consider an API to be a contract between source code modules. This contract specifies a function’s return value, arguments, and whether inheritance is permitted. A compiler, or software that converts instructions into a format that can be read and executed by a computer, enforces an API. In other words, the API specifies what the source code can and cannot do as part of an operating system platform.
In contrast, an ABI is a contract between binary code fragments. An Application Binary Interface specifies how functions are called and how arguments are transferred between the caller and the callee. The ABI also oversees the loading of programs into memory and the implementation of libraries. The ABI is enforced by the linker, a software used in conjunction with a compiler to create links to libraries required by an executable program.
This indicates that the ABI specifies how unrelated programs must interact and how processes must live on the same system. While the API identifies the available functions, the ABI specifies how each function may be called. ABIs are often developed between user applications and libraries, as well as OS services and programming languages.
Functions of the Application Binary Interface
ABIs serve several purposes; Alex Reinhardt highlight some of it functions below:
- Sets of processor instructions that specify specifics such as memory access types and file format for registers.
- System call stubs indicate how an application makes system calls to the operating system and whether direct system calls or procedure calls are utilized.
- Basic size, layout, and alignment for data types.
The calling convention specifies how parameters are provided to functions and return values are received. The calling convention determines which arguments are provided on the stack and which parameters are passed in registers. In addition, it decides whether the first function argument provided on the stack is pushed first or last and allocates registers to function parameters.
Complete and Embedded ABI’s
According to research, Alex Reinhardt explains the Complete and Embedded ABI’s below:
Complete ABIs
A complete ABI allows a program from the operating system that supports it to run unmodified on any comparable system. This is contingent on the existence of shared libraries and other comparable criteria.
For instance, the Intel Binary Compatibility Standard (iBCS) is the standard ABI for Unix operating systems on Intel-compatible devices.
Embedded ABIs
Embedded ABIs (EABIs) define register to use, data types, stack frame structure, and file format norms for embedded operating systems.
The code produced by compilers supporting the EABI is compatible with code written by other compilers. This allows developers to use object code to link the library created by one compiler with the library generated by another compiler.
Embedded ABIs are ultimately developed for performance improvement. The ABI eliminates the bulk of abstractions established between kernel and user code in complicated operating systems while functioning within the constraints of an embedded system.
