.TITLE  GCML
        .IDENT  /M0008/
        .ENABL  LC
;
;     Title:            FORTRAN callable version of GCML
;
;     Routine Name:     GCML
;
;     File  Name:       [377,2]GCML.MAC
;
;     Author:           M.J.McCombe
;                       Documentation and mods : B.Hillam
;
;     Description:
;               This routine allows the FORTRAN programmer to use the
;       facilities of the GCML subroutine to get a command line.
;       By default, GCML converts any lower case characters found
;       in the command line to upper case, but this can be
;       overridden by the optional IMODE parameter : see below.
;       The command may come from a terminal or from a command
;       file, and the source of the command is transparent
;       to the calling program : GCML decides where to interrogate
;       according to the rules below.
;       On entry, the user should have a LUN assigned to the terminal.
;       1) On its first attempt, GCML tries to obtain a command line
;       buffer from MCR. If this fails, it prompts the terminal,
;       using a user supplied prompt.
;       2) On subsequent calls, GCML continues to prompt the
;       terminal until it receives an indirect command filename,
;       indicated by @<filespec>. The default file extension is .CMD.
;       3) Having opened the specified file, GCML retrieves subsequent
;       lines from it each time it is called until end-of-file
;       is encountered. Further indirect command files may be
;       specified in a command file, to a current maximum nesting depth of 3.
;       4) Command lines beginning with ; are usually treated as comment lines
;       and are not returned to the calling program.
;               Control-Z from the terminal, in response to a prompt,
;       gives an error return from GCML. The possible error
;       returns are listed below.
;
;       Type HELP ADD GCML STATUS for details of modifications to GCML.
;       Type HELP ADD GCML PARAMETERS for parameter list details.
;       Type HELP ADD GCML ERRORS for details of error returns.
;       Type HELP ADD GCML MODE for details of the mode control parameter.
;
;3      MODE
;               Using the optional IMODE parameter, the user may modify
;       the default actions of GCML, as shown below. Particular bits
;       need to be set/cleared in IMODE for given actions. The
;       default conditions are marked with an asterisk (*). Note
;       that, since the entire IMODE parameter is copied to
;       the internal GCML mode control location, not simply
;       OR-ed with it, the user must ensure that all
;       of the bits have their correct default values if no change
;       is required.
;
;  *    Bit 0 set.   Command lines beginning with ; are treated
;                    as comments, and are not returned to the caller.
;       Bit 0 clear. Command lines beginning with ; are returned to
;                    the caller.
;  *    Bit 1 set.   Command lines beginning with @ are treated as indirect
;                    command file specifiers.
;       Bit 1 clear. Command lines beginning with @ are passed back to the
;                    calling program without being treated as indirect command
;                    file specifiers.
;  *    Bit 2 set.   The command file being read is to be closed after each
;                    call to GCML.
;       Bit 2 clear. The command file being read is not closed. In this case,
;                    the user must provide an additional file buffer
;                    using the task-builder ACTFIL command. The number
;                    of buffers required will be one greater than the number
;                    of logical units in use.
;       Bit 3 set.   Pass the command line to the caller without
;                    lower to upper case comversion.
;  *    Bit 3 clear. Convert any lower case characters in the command
;                    line to upper case before returning the line to
;                    the caller.
;       Bit 4 set.   Continuation lines allowed.
;                    This option should not be enabled since there is
;                    insufficient buffer space allocated within the
;                    routine to allow command lines of total length
;                    greater than 82 characters.
;  *    Bit 4 clear. Continuation lines not allowed.
;
;
;3    STATUS
;     Modification List:
;     M0003  Date: 12-AUG-81 B.Hillam
;       Indirect command file nesting depth increased to 3 (from 1).
;
;BH   M0004 13-AUG-81 Add optional mode control parameter.
;EDW  M0005 24-AUG-81 Use PURE.I and IMPURE PSECT's
;BH   M0006  1-SEP-81 Change PSECT IMPURE to PSECT GCMLID.
;BH   M0007 23-FEB-83 Change PSECT attributes on GCMLID : RW,GBL,OVR,D
;                     Correct embedded command file
;EDW  M0008 18-MAY-84 Change PSECT attributes on GCMLID : RW,GBL,OVR,D,SAV
;                       to remove overlay restriction
;
;     Restrictions:
;       Continuation mode is not allowed.
;       When using GCML in an overlaid program, force the PSECT GCMLID
;       into the root segment to avoid resetting of GCML workspace.
;       This is done by ODL commands of the form
;               .PSECT  GCMLID,RW,D,GBL,OVR
;               .ROOT   MAIN-GCMLID-*(OVLAY1,OVLAY2 ...
;       On M+ 2.1 or M 4.1 or greater this is done automatically
;
;
;3    PARAMETERS
;     Calling Sequence:
;
;       CALL GCML(ILUN,IPRMPT,ILEN,IBUF,ISIZ,IERR [,IMODE])
;
;     External Routines called:
;
;     Parameter List:
;     Inputs :
;       ILUN    INTEGER*2 parameter specifying LUN for use by GCML.
;               This LUN must initially be assigned to TI:, and must
;               not be used elsewhere, since GCML may re-assign it to
;               indirect command files.
;
;       IPRMPT  LOGICAL*1 array or Hollerith string containing
;               a prompt string for use when prompting the terminal.
;               GCML will prefix the string by <CR><LF> before using it.
;               Should be <= 80 characters.
;
;       ILEN    INTEGER*2 character count for IPRMPT.
;
;       IMODE   INTEGER*2 optional mode control parameter for GCML.
;               The default values shown above will be used if this
;               parameter is not present. Any attempt to set continuation
;               mode will be ignored.
;
;     Outputs:
;       IBUF    LOGICAL*1 array to receive the command line from GCML.
;               Must be dimensioned at least 82 in the calling program.
;
;       ISIZ    INTEGER*2 character count for IBUF.
;               0 if the command line was blank.
;
;       Type HELP ADD GCML ERROR for details of the error return parameter
;3      ERROR
;       IERR    INTEGER*2 error return.
;                 1 = Success
;                -1 = I/o error during command line input
;                -2 = GCML was unable to open/re-open specified command file.
;                -3 = Syntax error in indirect command file name
;                -5 = Attempt to exceed maximum allowed nesting depth (3).
;               -10 = End-of-file detected on first (un-nested) command file.
;               -16 = Command buffer too small for total number of characters.
;                     In this last case, the buffer contains as many
;                     characters as possible.
;
;               In addition, any valid FCS error return may be given
;               when using indirect command files.
;
;     Common Blocks:
;
;               NONE
;
;END
        .MCALL  GCML$,GCMLB$
;
;       Define parameter offsets
;
ILUN=2
IPRMPT=4
ILEN=6
IBUF=8.
ISIZ=10.
IERR=12.
IMODE=14.
NULARG=-1
;
        .PSECT  GCMLID,RW,D,GBL,OVR,SAV                                 ;M00008
CBLOCK: GCMLB$  3,,,,PDL        ;GCML CONTROL BLOCK
PDL:    .BLKB   80.             ;PUSH DOWN LIST
PROMPT: .BLKB   82.             ;PROMPT STRING
        .PSECT  PURE.I,RO,I                                             ;M00005
GCML::
        MOV     #CBLOCK,R0      ;GET CONTROL BLOCK ADDRESS
        MOVB    @ILUN(R5),F.LUN(R0) ;SET LUN.
        MOV     IPRMPT(R5),R2   ;SET PROMPT STRING
        MOV     @ILEN(R5),R3    ;GET LENGTH
        CMP     R3,#80.         ;LONGER THAN 80 BYTES ?
        BLT     2$              ;BR IF NOT
        MOV     #80.,R3         ;FORCE MAXLENGTH TO 80.
2$:     MOV     #PROMPT,R4      ;SET PROMPT
        MOVB    #15,(R4)+       ;Prefix prompt string by <CR><LF>
        MOVB    #12,(R4)+       ;
3$:     TST     R3              ;ANY PROMPT LEFT ?
        BEQ     4$              ;BR IF NOT
5$:     MOVB    (R2)+,(R4)+     ;MOVE IT
        BEQ     4$              ;BR IF END OF STRING
        SOB     R3,5$           ;DECREMENT CHARACTER COUNT
4$:     SUB     #PROMPT,R4      ;CALCULATE PROMPT LENGTH
        MOV     #CBLOCK,R0      ;GET CONTROL BLOCK ADDRESS.
        MOV     R4,G.PSDS(R0)   ;SET PROMPT LENGTH
        MOV     #PROMPT,G.PSDS+2(R0);SET PROMPT ADDRESS
        CMPB    (R5),#7         ;7 parameters ?
        BLT     41$             ;LT if no
        CMP     IMODE(R5),#NULARG ;Missing 7th argument ?
        BEQ     41$             ;EQ if yes
        MOV     @IMODE(R5),-(SP);Get the parameter
        BR      42$
41$:    MOV     #<GE.IND!GE.CLO!GE.COM>,-(SP)   ;Set default mode
42$:    BIC     #<^C<GE.IND!GE.CLO!GE.COM!GE.LC>!GE.CON>,(SP)
        BICB    #<GE.IND!GE.CLO!GE.COM!GE.LC>,G.MODE(R0)
        BISB    (SP)+,G.MODE(R0)
        JSR     PC,.GCML1       ;GET COMMAND LINE.
        BCS     ERR             ;ERROR.
        MOV     G.CMLD(R0),R1   ;GET REPLY LENGTH
        MOV     R1,@ISIZ(R5)    ;RETURN  SIZE
        BEQ     200$            ;BR IF ZERO
        MOV     G.CMLD+2(R0),R0 ;
        MOV     IBUF(R5),R3       ;
1$:     MOVB    (R0)+,(R3)+     ;COPY BUFFER BACK
        SOB     R1,1$           ;
200$:   MOV     #1,@IERR(R5)      ;RETURN SUCCESS CODE.
        RTS     PC              ;RETURN
ERR:
        MOVB    G.ERR(R0),R1    ;GET ERROR CODE
        CMPB    #GE.IOR,R1      ;I/O ERROR ?
        BEQ     1$              ;IF EQ YES
        CMPB    #GE.OPR,R1      ;
        BNE     2$              ;IF NE NO.
1$:     MOVB    F.ERR(R0),R1    ;RETURN FCS ERROR.
        MOV     R1,@IERR(R5)      ;
        RTS     PC              ;
2$:     MOV     R1,@IERR(R5)      ;RETURN GCML ERROR.
        RTS     PC
        .END