What is meaning of those suffixes?

gelmişken...gitmişken...yapmışken...oynamışken...?

some more examples when to use them?

gelmişken... while you´re came  gitmişken... while you´re going   yapmışken...  while you´re did    oynamışken...while you´re played

examples:  while you went to home say to hi from me to your family: Evine gitmişken benden selam söyle senin evdekilere.

-mIşken [mIş + ken ]

Verb stem + mişken [mışken]

This form denotes the secondary [extra] future actions of  an already planned actions.

1. There is a planned action. ---> Bakkala gidiyorsun. [ You are going to the shop]

2.  Secondary action --->  bana da bir sigara al. [ buy me a cigarette ]

3.  Person is identified from the second part, if we don´t use personal pronoun.

Bakkala gitmişken     bana da bir sigara alıver.

Planned action          secondary action

As you are already going to the shop. Buy me a cigarette.

 [ You already planned to go the shop, while you are in shop, buy me a cigarette]

*****************************

Ankara´ya gelmişken    okul arkadaşımı da ziyaret edeceğim.

 Planned action             secondary action 

- I came to Ankara,cus it was my plan to come to Ankara]

-  While I am in Ankara, I will also visit my school friend.

- Since I am in Ankara, I will also visit my school friend.

[Since I came to Ankara]

----------------------------------------

Mutfağa  gitmişken   bana bir bardak su getiriver.

Planned action          secondary action

As you´re going to kitchen , get me a glass of water.

You are going to kitchen anyway so bring me a glass of water from the kitchen.

------------------------------------------

It also denotes  the present action which creates the chance for perform the other action.

Seni görmüşken  söyleyeyim dedim.

As I got the chance of seeing you now,  I wanted to tell you [this].

Since  I see you [now] I wanted to tell you.

ikinize de teşekkür ediyorum.