I have a general programming challenge for you all. I've been scratching my head trying to figure out the best way to do this...
I'm working in C and I've got a "speed" value that is passed to my program. It ranges from 0-255. This speed value needs to correspond to a millisecond time delay built into the program.
unsigned char currentSpeed; //this is passed into my function, range 0-255
unsigned long SlowestSpeedMillis = 3000; //in milliseconds
if (currentSpeed > 0)
{
unsigned long Interval = ((256 - currentSpeed)*SlowestSpeedMillis)/255;
}else{ //currentSpeed = 0
//When Interval is zero, the program will freeze
Interval = 0;
}
Here's some sample results:
currentSpeed of 1 results in 3000 milliseconds (slowest)
currentSpeed of 128 results in ~1500 milliseconds (exactly half)
currentSpeed of 255 results in ~11 milliseconds (fastest)
The problem is that I would like it to be a curved result where it stays in the lower numbers and then quickly goes to 3000 at the end... I want the user to have the choice to make the program go as slow as 3000, but most values leading up to it aren't as important. Such as this:
currentSpeed of 1 results in 3000 milliseconds (slowest)
currentSpeed of 128 results in ~750 milliseconds (1/4th of potential)
currentSpeed of 255 results in ~11 milliseconds (fastest, anything close to zero)
Any ideas how to do this programmatically? Perhaps with some kind of equation?
Normally in math you might do something like:
(currentSpeed / 255) * 3000
for linear, and to get a bit of a curve use a power:
((currentSpeed / 255) * (currentSpeed / 255)) * 3000
But, in integer math that doesn't work because (currentSpeed / 255) will almost always be zero.
To do this without floating point you have to scale up first before division.
((3000 * currentSpeed) * currentSpeed) / (255 * 255)
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