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Annotation of researchv9/sys/h/map.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Resource Allocation Maps.
        !             3:  *
        !             4:  * Associated routines manage sub-allocation of an address space using
        !             5:  * an array of segment descriptors.  The first element of this array
        !             6:  * is a map structure, describing the arrays extent and the name
        !             7:  * of the controlled object.  Each additional structure represents
        !             8:  * a free segment of the address space.
        !             9:  *
        !            10:  * A call to rminit initializes a resource map and may also be used
        !            11:  * to free some address space for the map.  Subsequent calls to rmalloc
        !            12:  * and rmfree allocate and free space in the resource map.  If the resource
        !            13:  * map becomes too fragmented to be described in the available space,
        !            14:  * then some of the resource is discarded.  This may lead to critical
        !            15:  * shortages, but is better than not checking (as the previous versions
        !            16:  * of these routines did) or giving up and calling panic().  The routines
        !            17:  * could use linked lists and call a memory allocator when they run
        !            18:  * out of space, but that would not solve the out of space problem when
        !            19:  * called at interrupt time.
        !            20:  *
        !            21:  * N.B.: The address 0 in the resource address space is not available
        !            22:  * as it is used internally by the resource map routines.
        !            23:  */
        !            24: struct map {
        !            25:        struct  mapent *m_limit;        /* address of last slot in map */
        !            26:        char    *m_name;                /* name of resource */
        !            27: /* we use m_name when the map overflows, in warning messages */
        !            28: };
        !            29: struct mapent
        !            30: {
        !            31:        int     m_size;         /* size of this segment of the map */
        !            32:        int     m_addr;         /* resource-space addr of start of segment */
        !            33: };
        !            34: 
        !            35: #ifdef KERNEL
        !            36: struct map *swapmap;
        !            37: int    nswapmap;
        !            38: struct map *argmap;
        !            39: #define        ARGMAPSIZE      16
        !            40: struct map *kernelmap;
        !            41: #endif

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