AttackSpeed is capped at 2.5 Attacks per Second for each Hero.
AttackSpeed = (1 /Base Attack Time)*AttackSpeed Modifier
Ex(Murdock with 100 of attack speed):AttackSpeed=(1/1.35)*2.196(cause at lvl 15 he got 119.6 attack speed)=1.626666 of attack speed.
A simpler way to look at it --> P/AtkSpd P=Character Basic Attack Speed without modifiers x100 AtkSpd= The number of the Attack Speed Modifier (Ex. 149.6)
Example: Kallari's Basic Attack Speed is 1.00. Multiply that by 100 = 100. Now divide that by your AtkSpd (149.6) and you would have an Attack every .66 Seconds.