Unprototyped Functions

The new home for Visual Studio documentation is Visual Studio 2017 Documentation on docs.microsoft.com.

The latest version of this topic can be found at Unprototyped Functions.

For functions not fully prototyped, the caller will pass integer values as integers and floating-point values as double precision. For floating-point values only, both the integer register and the floating-point register will contain the float value in case the callee expects the value in the integer registers.

func1();  
func2() {   // RCX = 2, RDX = XMM1 = 1.0, and R8 = 7  
   func1(2, 1.0, 7);  
}  

Calling Convention