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#ifndef _M68K_SHM_H

#define _M68K_SHM_H

#include <linux/config.h>

/* format of page table entries that correspond to shared memory pages

   currently out in swap space (see also mm/swap.c):

   bits 0-1 (PAGE_PRESENT) is  = 0

   bits 8..2 (SWP_TYPE) are = SHM_SWP_TYPE

   bits 31..9 are used like this:

   bits 15..9 (SHM_ID) the id of the shared memory segment

   bits 30..16 (SHM_IDX) the index of the page within the shared memory segment

                    (actually only bits 25..16 get used since SHMMAX is so low)

   bit 31 (SHM_READ_ONLY) flag whether the page belongs to a read-only attach

*/

/* on the m68k both bits 0 and 1 must be zero */

/* format on the sun3 is similar, but bits 30, 31 are set to zero and all

   others are reduced by 2. --m */

#ifndef CONFIG_SUN3

#define SHM_ID_SHIFT    9

#else

#define SHM_ID_SHIFT    7

#endif

#define _SHM_ID_BITS    7

#define SHM_ID_MASK     ((1<<_SHM_ID_BITS)-1)

#define SHM_IDX_SHIFT   (SHM_ID_SHIFT+_SHM_ID_BITS)

#define _SHM_IDX_BITS   15

#define SHM_IDX_MASK    ((1<<_SHM_IDX_BITS)-1)

#endif /* _M68K_SHM_H */