🚀 go-pugleaf

Hi,

I am writing an application which analyses video data from a monochrome
camera. I am using Delphi 5 and 7 but use the built-in assembler to do
time-critical stuff. I try to do my calculations in less than 1 frame
period, so that the application can keep up with the camera frame rate.

In one mode I am having  problems - in this mode the calculations are
heavily dependant on one procedure, which calculates the integral of
intensity along a line joining two points in the image. This procedure uses
bilinear interpolation to calculate the intensities along the line based on
the values of neighbouring pixels. In other words, it is floating-point
intensive. The problem is that this procedure seems to run at two different 
speeds, depending on the time of day, the weather, and whether the stock 
market is rising or falling. I have a test loop that calls the procedure 100 
times, which is triggered by a button on a form. I get two very different 
times depending on whether I click the button, or activate it using the 
spacebar (if it has focus). In one case the execution time is about 1/2 the 
other case. I use a standard video image to do the benchmarking.

I have two versions of this procedure, a high level version and one
hand-coded in 80387 code (yes - I have been told that so last-century and
SSE is the way to go ...) Both show the timing variations, but the asm one
has the largest % difference..

You guys here seem to be experts in timing code - so I wondered if you have
any suggestions !!

BTW, I am using Windows XP running on a Dell Latitude D830 laptop with Intel
Core 2 Duo 2MHz processor (T7300) and 2GB RAM.

Thanks in advance for any help !