FBENCH

FBench is a hack of FastDoom for DOS, in order to benchmark it. Timings of the benchmarked functions are written to BENCH.CVS and can be exploited by plot.py which will display a stacked-bar graph.

The benchmark itself does not consume much time but requires around 1.2 MiB of memory.

How to build

Build tested with Watcom 1.9.

Run :

make clean bench

It will produced the executable fbench.exe. If the executable was produced on another OS with cross-compilation it ended with two errors: embedding the DPMI server can only be done under a DOS. Go then to DOS or DosBox and run

sb -r fbench.exe
ss fbench.exe dos32a.d32

How to bench

Run Fbench.exe in a folder where doom1.wad is available (the shareware data of doom). It will produce a bench.csv file containing the result off the bench.
The wile is written to disk when the game exits. It can take a long time.

To bench using one of the standard recorded demo:

fbench -timedemo demo2

In order to exploit and draw it, use the provided *plot.pyµ Python3 script.

About the code

Benched functions

• DrawMasked, masked element : sprites, partialy transparent walls, player's weapon.
• DrawFlat, flat visplanes : empty vertical space representing flors, ceils, sky...

ModeY vs Mode13h

• MODEY
  Rendering is done in RAM then VRAM is updated by small blocks
  • I_UpdateNoBlit() writes in VRAM after every major write sequence
  • I_UpdateBox() copies dirty boxes into the VRAM
  • I_FinishUpdate() modify the adress of the framebuffer to be displayed
• MODE13H
  Rendering is done in RAM then the screen is copied to VRAM as a single block.
  • I_UpdateNoBlit() does not exist
  • I_FinishUpdate() performs the copy of the whole screen.