## Display Device Driver Reference for OS/2

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### Deciphering File Names in the S3 Driver

Many of the files in the S3 driver are derived from the original XGA driver for OS/2.

Most of the modules in the XGA driver are named some variant of "edd*.*". The "edd" portion of the file name stands for Expressway Device Driver. This is based on numerous references to the "Expressway hardware" found throughout the driver.

The fourth letter of the filename conveys useful information. In addition, the last four letters in the filename are typically a kind of abbreviation describing what the module actually does. The following is a list of prefixes:

eddb*.* - bitmap creation modules
eddbcrea.c - bitmap creation code
eddbdelt.c - bitmap deletion code
eddbsubrs.c - bitmap creation subroutines
eddbimag.c - image data function (doesn't fit the pattern)

eddc*.* - driver color support functions
eddcdith.c - dithering code
eddcctab.c - color table manipulation functions

edde*.* - initialization code
eddefldb.c - FillLogicalDeviceBlock a primary initialization entry point
eddefpdb.c - FillPhysicalDeviceBlock - another key part of the initialization code
eddesres.c - obtain desired resolution and color depth for the driver

eddf*.*, and ff*.asm - bitmap rendering code, "The MESS."
eddffast.asm - eddf_MESS - the top level of the software drawing code
ffbltsd.asm - MESS support for bitblt's involving source and destination
ffbltpd.asm - MESS support for bitblt's involving pattern and destination
ffbltd.asm - MESS support for bitblt's involving only the destination

eddh*.asm - hardware dependent modules. These are the primary files to be altered.
eddhbblt.asm - driver bitblt support
eddhgchs.asm - driver text output support
eddhline.asm - hardware line drawing support

eddl*.* - polyline and poly shortline code
eddlpoly - eddl_Polyline - entry point for the polyline function

eddm*.* - cursor code, and death and resurrection related code
eddmccrs.c - color cursor setup code
eddmcurs.c - monochrome cursor setup code
eddmdead.c - driver support for death and resurrection

eddn*.* - high-level driver entry points, and caching code
eddnbblt.c - driver entry point for bitblt
eddngchs.c - driver entry point for text output
eddncach.c - font and bitmap caching support code

eddq*.* - query functions
eddqsres.c - query driver for available resolutions
eddqesc.c - multimedia escape functions

eddv*.* - AVIO text functions
eddvsrec.c - eddv_ScrollRect - scroll a rectangle in an AVIO window