stem/CS/Calling Conventions.md

---
tags:
  - low-level
---
- The order in which atomic (scalar) parameters, or individual parts of a complex parameter, are allocated
- How parameters are passed
	- Pushed on the stack, placed in registers, or a mix of both
- Which registers the called function must preserve for the caller
	- Also known as: callee-saved registers or non-volatile registers
- How the task of preparing the stack for, and restoring after, a function call is divided between the caller and the callee

Subtle differences between [Compilers](Compilers.md), can be difficult to interface codes from different [compilers](Compilers.md)

Calling conventions, type representations, and name mangling are all part of what is known as an [application binary interface](https://en.wikipedia.org/wiki/Application_binary_interface) ([ABI](ABI.md))

# cdecl
C declaration

- Originally from Microsoft's C [compiler](Compilers.md)
	- Used by many C [compilers](Compilers.md) for x86
- Subroutine arguments passed on the stack
- Function arguments pushed right-to-left
	- Last pushed first
- Caller cleans stack after function call returns

# stdcall

- Variation on Pascal calling convention
- Callee cleans stack
- Params pushed onto stack right-to-left
	- Same as _cdecl_
- Standard for Microsoft Win32 API