INTERFACE Ushm;

FROM Ctypes IMPORT char, short, int, void_star, unsigned_long, char_star;
FROM Utypes IMPORT time_t, key_t, size_t, ushort, swblk_t;
FROM Uipc   IMPORT struct_ipc_perm;

** IPC Shared Memory Facility.

** Implementation Constants.

CONST
                        (* segment low boundary address multiple *)
                        (* (SMLBA must be a power of 2) *)
  (* SMLBA = ctob(CLSIZE);   where does ctob come from ? - em *)

                        (* for SYSTEM V compatibility           *)
  (* SHMLBA = SMLBA;         see SMLBA - em *)

** Permission Definitions.

SM_R = 8_0400; (* read permission *)
  SM_W = 8_0200;  (* write permission *)

                        (* for SYSTEM V compatibility           *)
  SHM_R = SM_R;
  SHM_W = SM_W;

** ipc_perm Mode Definitions.

SM_CLEAR = 8_00000; (* clear segment on next attach *)
    (* Linux does not seem to have this (was 1000) - hayter *)
  SM_DEST  = 8_01000; (* destroy seg when # attached = 0 *)
    (* this was 2000 - hayter *)
  SM_LOCKED = 8_02000; (* Segment will not be swapped *)

                        (* for SYSTEM V compatibility           *)
  SHM_INIT = SM_CLEAR;
  SHM_DEST = SM_DEST;

** Message Operation Flags.

SM_RDONLY = 8_010000;        (* attach read-only (else read-write) *)
  SM_RND    = 8_020000;        (* round attach address to SHMLBA *)
  SM_REMAP  = 8_040000;        (* Take-over region on attach *)

                        (* for SYSTEM V compatibility           *)
  SHM_RDONLY = SM_RDONLY;
  SHM_RND    = SM_RND;
  SHM_REMAP  = SM_REMAP;

* sizing constant (the balance are in /sys/h/param.h and /sys/conf/param.c.

SMMNI = 128;        (* Max number SM segments in system *)

** Structure Definitions.

** There is a shared mem id struct for each segment in the system.

Doesn't seem to be present in glibc2/linux 2.0.32 - rrw

TYPE
  struct_shm_desc = RECORD
    task      : void_star;     (* really 'struct task_struct *',
                                  but they're horrible *)
    shm_sgn   : unsigned_long; (* Signature for this attach *)
    start     : unsigned_long; (* virt addr of attach, multiple of SHMLBA *)
    end       : unsigned_long; (* multiple of SHMLBA *)
    task_next : UNTRACED REF struct_shm_desc; (* next attach for task *)
    seg_next  : UNTRACED REF struct_shm_desc; (* next attach for segment *)
  END;

 (* The next two structs (one of which Linux does not seem to have)
    had their names swapped! -- hayter *)
  struct_shmid_ds = RECORD
                                (* SM_PERM must be the first    *)
                                (* element in the structure.    *)
    shm_perm:    struct_ipc_perm;          (* permission struct *)
    shm_segsz : int;				(* size of segment (bytes) *)
    shm_atime : time_t;		   (* last attach time *)
    shm_dtime : time_t;                  (* last detach time *)
    shm_ctime : time_t;                  (* last change time *)
    shm_cpid  : ushort;                  (* pid of creator *)
    shm_lpid  : ushort;                  (* pid of last operator *)
    shm_nattch : short;                  (* no. of current attaches *)
    (* The following are private *)
    shm_npages : ushort;                 (* Size of segment (pages) *)
    shm_pages : UNTRACED REF unsigned_long; (* array of ptrs to
                                                frames -> SHMMAX *)
    attaches : UNTRACED REF struct_shm_desc;    (* descriptors for attaches *)
  END;

                        (* for SYSTEM V compatibility           *)
  (*  key_t = long;     already defined in Utypes.i3 - em *)

 (* Linux doesn't appear to have this structure, so I can't check it -
    be cautious *)

  struct_smem = RECORD
                                (* SM_PERM must be the first    *)
                                (* element in the structure.    *)
    shm_perm:    struct_ipc_perm;          (* permission struct *)
    sm_daddr:   UNTRACED REF swblk_t;    (* disk addrs of DMTEXT page segs *)
    sm_ptdaddr: swblk_t;                  (* disk address of page table *)
    shm_segsz:  size_t ;                  (* segment size (bytes) *)

*)
    sm_caddr: ADDRESS;                    (* where is struct_proc ? - em *)

*)
    sm_ptaddr:  ADDRESS;                  (* where is struct_pte ? - em *)

    sm_rssize:  size_t;                   (* SM resource set size (pages) *)
    shm_lpidL:  ushort;                   (* pid of last smop *)
    shm_cpid:   ushort;                   (* pid of creator *)
    shm_nattch: char;                     (* reference count *)
    sm_ccount:  char;                     (* number of loaded references *)
    sm_lcount:  short;                  (* number of processes locking SMS *)
    sm_flag:    short;                    (* traced, written flags *)
    sm_poip:    short;                    (* page out in progress count *)
    shm_atime:  time_t;                   (* last smat time *)
    shm_dtime:  time_t;                   (* last smdt time *)
    shm_ctime:  time_t;                   (* last change time *)
  END;

  struct_shmid_ds_star = UNTRACED REF struct_shmid_ds;

CONST

SMLOCK =  8_0010;           (* Being swapped in or out *)
  SMWANT =  8_0020;           (* Wanted for swapping *)
  SMNOSW =  8_0100;           (* Lock segment in memory *)

SHM_LOCK   = 11;       (* Lock segment in memory *)
  SHM_UNLOCK = 12;       (* Unlock segment in memory *)

* sminfo structure is used by the system for bounds checking. All of * the elements in this structure are initialized in /sys/conf/param.c. * * Three of the elements are configurable via the config program * (smmax, smmin, smbrk). If they are not config'ed, then they all * have defaults.

TYPE
  (* Linux doesn't have this either, so use with care *)
  struct_sminfo = RECORD
    smmax: int;       (* max shared memory segment size *)
    smmin: int;       (* min shared memory segment size *)
    smmni: int;       (* # of shared memory identifiers *)
    smseg: int;       (* max attached shared memory segs per proc *)
    smbrk: int;       (* gap (in clicks) used between data and SM *)
    smsmat: int;      (* max shmem attach addr (clicks) *)
  END;

                        (* for SYSTEM V compatibility *)
  struct_shminfo = RECORD
    shmmax: int;       (* max shared memory segment size *)
    shmmin: int;       (* min shared memory segment size *)
    shmmni: int;       (* # of shared memory identifiers *)
    shmseg: int;       (* max attached shared memory segs per proc *)
    shmall: int;       (* God knows *)
  END;

<*EXTERNAL*>
PROCEDURE shmctl (shmid, cmd: int; buf: struct_shmid_ds_star): int;

<*EXTERNAL*>
PROCEDURE shmget (key: key_t; size, semflg: int): int;

<*EXTERNAL*>
PROCEDURE shmat (shmid: int; shmaddr: char_star; shmflg: int): char_star;

<*EXTERNAL*>
PROCEDURE shmdt (shmaddr: char_star): int;

END Ushm.