BSD 4_1_snap development

[unix-history] / sys / h / map.h

/*	map.h	4.5	81/02/28	*/

/*
 * Resource Allocation Maps.
 *
 * Associated routines manage sub-allocation of an address space using
 * an array of segment descriptors.  The first element of this array
 * is a map structure, describing the arrays extent and the name
 * of the controlled object.  Each additional structure represents
 * a free segment of the address space.
 *
 * A call to rminit initializes a resource map and may also be used
 * to free some address space for the map.  Subsequent calls to rmalloc
 * and rmfree allocate and free space in the resource map.  If the resource
 * map becomes too fragmented to be described in the available space,
 * then some of the resource is discarded.  This may lead to critical
 * shortages, but is better than not checking (as the previous versions
 * of these routines did) or giving up and calling panic().  The routines
 * could use linked lists and call a memory allocator when they run
 * out of space, but that would not solve the out of space problem when
 * called at interrupt time.
 *
 * N.B.: The address 0 in the resource address space is not available
 * as it is used internally by the resource map routines.
 */
struct map {
	struct	mapent *m_limit;	/* address of last slot in map */
	char	*m_name;		/* name of resource */
/* we use m_name when the map overflows, in warning messages */
};
struct mapent
{
	int	m_size;		/* size of this segment of the map */
	int	m_addr;		/* resource-space addr of start of segment */
};

#ifdef KERNEL
struct	map *swapmap;
int	nswapmap;
struct	map *argmap;
#define	ARGMAPSIZE	16
struct	map *kernelmap;
#endif