Motor drive function?

[Mike]

Lets say I want to have a function, that somehow modifies an inputted speed and sets an inputted motor to that speed. Instinct tells me it would be something similar to

void Drive(int motor, unsigned char speed)
{
	// modify inputted speed
	motor = speed;
}

Drive(pwm01, 100);

However, I've tried that and it doesn't seem to work. The motors just don't spin. I'm assuming it is because when you read pwm01, it gives you the current speed that pwm01 is running at. So Drive(pwm01, 100) is similar to, say, Drive(127, 100)

What is the cause of this problem? How can I fix it?