## Presentation Device Driver Reference for OS/2

[prev][next][parent][TOC]

### Calling Conventions

Presentation drivers interact with both the external API and the internal interface to the graphics engine and dispatch table. Parameters are passed as 32-bit values on the stack by using the C convention. These parameters are pushed to the stack in reverse order of how they appear in the statement. The hardware architecture locates the conceptual top of the stack at the high-order address of the stack space. When data is pushed to the stack, the stack pointer is decremented so that upon completion, the pointer addresses the first item of data.

At entry to the handling routine, the stack contains a frame of 32-bit parameters and a return address as shown in the following figure. [Artwork not shown]