Free paging

[ClapClapSnap]

Sorry, I have no idea how to add this or who needs it, but here is the code for free paging

var 4 start_pageList
var 4 hold_thisPage

---------------------------------Initialize Page List-------------------------

procedure 0 InitializePageList(4 fsp 4 pNum)
[4 iterator 4 fsp_next]{

fsp contains the address of the first free space

pNum is the number of pages total in the list

Page aligned, have to make some dead space

Add 1 to first twenty bits, then make last 12 bits 0

(= &fsp (>> fsp 12)) #push bits right
(= &fsp (+ fsp 1)) #increase the 13th bit
(= &fsp (<< fsp 12)) #push bits left

(= &start_pageList fsp) #Make page_head start where the free space pointer is

Loop through until we've reserved pNum pages

(= &iterator 1)
while((not(== iterator pNum))) {

            (= &fsp_next (+ fsp 4096))  #fsp_next holds the next free page
            (= fsp fsp_next)    #first entry in fsp now contains the address of the next page
            (= &fsp fsp_next)   #fsp now holds the next page


            (= &iterator (+ iterator 1))#Increment iterator/ We've added one more page
    }

(= fsp 0) #Pointer is now at the last page, so make the first thing in that page 0 to signify that it's the last page

}

procedure 4 NextPage()[4 current_pointer]{

need to give a free page to the kernel and take it off the linked list. before giving it to the kernel need to wipe it.

(= &current_pointer start_pageList) #current_pointer has page to be given
(= &hold_thisPage start_pageList) #hold the page to be given
(= &current_pointer *(4)current_pointer) #second page in list given to current
(= &start_pageList current_pointer) #update new head of linked list
(= &current_pointer hold_thisPage) #current has page to be given
while((not(== current_pointer (+ hold_thisPage 4096)))){ #wipes the page to be given clean,
(= current_pointer 0)
(= &current_pointer (+ current_pointer 4))
}

return hold_thisPage

}

procedure 0 ReturnPage(4 p_add)[]{

get an address and add it back to the front of the linked list.

(= p_add start_pageList) #old head now points to added page
(= &start_pageList p_add) #update the head

}