Re: subobj-rmap

[Chuck Ebbert <76306.1226@compuserve.com>]

Davide Libenzi wrote:

1) |----------------------|
2)     |-----------|
3) |--------------------------|
4)         |-----------|

R) |---|---|-------|---|--|---|

    1   1   1       1   1  3
    3   2   2       3   3
        3   3       4
            4


 How's this for an alogorithm for finding which
chunk of 'R' you have hit with a given memory reference:

 o  Use a bitmap to represent the whole address range.
 o  Set the bits that correspond the the first page
    of each subregion.

 To search:

 o  Look up the bit for the page you are interested in.
 o  Scan backwards for a 1.
 o  Convert bit position to address, this is the
    base of the subregion.

 Since this is i386-only you can play neat assembler
tricks with this code to make it fast.

 (OS/2 did/does it that way.)

--
 Chuck
 I am not a number!