5E Starting At Higher Level: Calculating HP

Howdy, I'm fairly new to creating the whole macro thing a I'm trying to write a macro that automatically calculates HP for starting characters at higher levels, and here's what I have so far: HP at level ?{Level|1} = [[(?{Base HP at 1st Level|0}+?{CON at 1st|0})+(@{hit_dice}-1)d(@{hitdieroll})+(@{hit_dice}-1)*?{CON at 1st|0})]] The Base HP at 1st is whatever your class starts with + their CON mod and the -1 on dice roll takes away the roll for 1st level. This, however, doesn't take into account any Ability Score Improvements that might be applied to CON . Is there any way I could calculate  ASI after a certain amount of rolls up to the point of the  ASI and repeat the process for any extras improvements that a player might add to CON ?

The HP increase from a CON bump is retroactive, so you can just add it at the end - you just need to know the character's final CON mod. Same for the Tough feat, if they take that. So @{lvl1_hp} + [[@{level}-1]]d@{hit_die} + @{final_con_mod}*@{level} should be just about the ticket. I think. The Attribute names are made up. And obviously the second bit can be changed to average HP instead of rolling with a [[@{hit_die}/2+1]].