COPYRT 
COMMON
SSOVL
          IDENT  SSOVL
          ENTRY  SSOVL
          ENTRY  SSOVL
          SYSCOM B1
 SSOVL    TITLE  SSOVL - LOAD *SSEXEC* OVERLAYS.
*COMMENT  LOAD *SSEXEC* OVERLAYS.
          COMMENT  COPYRIGHT CONTROL DATA SYSTEMS INC.  1992.

*CALL COMCMAC
          SPACE  4,30
***       SSOVL - LOAD *SSEXEC* OVERLAYS.
*
*         SSOVL(OVLLEV,XFRADR);        ( *SYMPL* CALL )
*
*         ENTRY  (OVLLEV) = OVERLAY LEVEL.  THE FORMAT IS -
*                           48/ 0, 6/ PRIMARY LEVEL, 6/ SECONDARY
*                           LEVEL.
*
*                (XFRADR) = TRANSFER ADDRESS, ENTRY TO OVERLAY.
*                           IF 0, ENTER OVERLAY AT ENTRY POINT ADDRESS.
*                           ELSE, ENTER OVERLAY AT SPECIFIED ABSOLUTE
*                           ADDRESS.
*
*         EXIT   THE RETURN ADDRESS IS PLACED IN THE OVERLAY.
*                CONTROL TRANSFERS TO THE OVERLAY.
*
*         USES   A - 1, 2, 5, 6.
*                B - 1, 6, 7.
*                X - 0, 1, 2, 5, 6, 7.
*
*         CALLS  FOL.LOV.
*
*         NOTES  IT IS ASSUMED THAT THE ENTRY POINT ADDRESS OF EACH
*                OVERLAY CONTAINS (IN BITS 47-30) THE ADDRESS OF THE
*                ROUTINE TO BE EXECUTED.  THIS MODIFICATION IN OVERLAY
*                DESIGN IS DONE TO HANDLE *SYMPL* PROCEDURES.
*
*         DAYFILE MESSAGE    * OVERLAY NOT FOUND.*


 SSOVL    SUBR               ENTRY/EXIT

 SSOVL0   BSS    0           ENTRY FROM *RCOVL*
          SB1    1
          SX6    A1          PARAMETER LIST ADDRESS
          SA2    A1+B1
          SA3    X2          GET *XFRADR* PARAMETER
          BX7    X3
          SA7    XFRADR      SAVE TRANSFER ADDRESS
          SA6    OVLPARAM

*         DETERMINE IF REQUESTED OVERLAY IS PRIMARY OR SECONDARY.
*         IF IT IS ALREADY LOADED, SKIP THE LOAD.

          SA1    X1          LEVEL OF REQUESTED OVERLAY
          MX7    -6
          BX0    -X7*X1      EXTRACT SECONDARY LEVEL NUMBER
          ZR     X0,OVL.1    IF PRIMARY OVERLAY REQUESTED
          SX0    B1
 OVL.1    BSS    0
          SA5    X0+OVLLEV   LEVEL OF CURRENT OVERLAY
          SA2    X0+OVLEPTA
          SB7    X2          CURRENT OVERLAY ENTRY POINT ADDRESS
          BX6    X1-X5
          ZR     X6,OVL1     IF OVERLAY IS ALREADY IN FL

          BX6    X1
          SA6    A5          SAVE OVERLAY LEVEL
          NZ     X0,OVL.2    IF SECONDARY LOAD
          MX6    0
          SA6    OVLLEV+1    CLEAR SECONDARY LEVEL NUMBER
 OVL.2    BSS    0

*         LOAD THE OVERLAY.

          RJ     =XFOL.LOV   CALL OVERLAY LOADER
          NG     B7,OVL3     IF OVERLAY NOT FOUND
          SA2    OVLC        INCREMENT OVERLAY COUNTER
          SX6    X2+B1
          SA6    A2
          SX6    B7          ENTRY POINT ADDRESS
          SA6    X0+OVLEPTA  SAVE ENTRY POINT ADDRESS

*         SET UP RETURN ADDRESS AND ENTER THE OVERLAY.

 OVL1     BSS    0
          SA2    SSOVL       GET RETURN ADDRESS
          BX6    X2
          SA5    B7          GET ADDRESS TO PROCEDURE
          LX5    30
          SB7    X5          ENTRY POINT ADDRESS TO PROCEDURE
          SA6    B7          PLACE RETURN ADDRESS
          SB7    B7+B1       ADVANCE TO TRANSFER ADDRESS
          SA1    OVLPARAM    PARAMETER LIST ADDRESS
          SA2    XFRADR
          ZR     X2,OVL2     IF TRANSFER TO ENTRY POINT


          SB7    X2          TRANSFER ADDRESS

 OVL2     SA1    X1+2        ADVANCE PARAMETER POINTER

          JP     B7          SIMULATED CALL TO PROGRAM


 OVL3     MESSAGE MADDR      ISSUE ERROR MESSAGE
          ABORT              ABORT
*CALL COMXOVL

 MADDR    DATA   40C OVERLAY NOT FOUND.
 XFRADR   BSSZ   1           SAVED TRANSFER ADDRESS
 OVLEPTA  BSSZ   2           ENTRY POINT ADDRESS OF CURRENT OVERLAY
 OVLLEV   BSSZ   2           LEVEL NUMBER OF CURRENT OVERLAY
 OVLPARAM BSSZ   1           ADDRESS TO CALLER PARAMETER LIST


 RSOVL    TITLE  RSOVL - REPLACE CURRENT OVERLAY.

**        RSOVL - REPLACE CURRENT OVERLAY.
*
*         RSOVL(OVLLEV,XFRADR);              ( *SYMPL* CALL )
*
*         ENTRY  (OVLLEV) = OVERLAY LEVEL.  THE FORMAT IS -
*                           48/ 0, 6/ PRIMARY LEVEL, 6/ SECONDARY
*                           LEVEL.
*
*                (XFRADR) = TRANSFER ADDRESS, ENTRY TO OVERLAY.
*                           IF 0, ENTER OVERLAY AT ENTRY POINT ADDRESS.
*                           ELSE, ENTER OVERLAY AT SPECIFIED ABSOLUTE
*                           ADDRESS.
*                *SSOVL* MUST HAVE BEEN CALLED PREVIOUSLY TO LOAD
*                THE PRIMARY OVERLAY.
*
*         EXIT   (A1)     = *FWA* OF PARAMETER LIST.
*
*         CALLS  SSOVL
*
*         NOTES  *RSOVL* CAN BE CALLED ONLY TO GO FROM ONE SECONDARY
*                OVERLAY TO ANOTHER SECONDARY OVERLAY.  THE CURRENT
*                SECONDARY OVERLAY IS REPLACED BY THE REQUESTED
*                SECONDARY OVERLAY.  *RSOVL* CANNOT BE USED TO GO
*                FROM ONE PRIMARY OVERLAY TO ANOTHER PRIMARY OVERLAY.


 RSOVL    SUBR               ENTRY/EXIT
          EQ     SSOVL0      ALTERNATE ENTRY TO *SSOVL*

          END