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flat assembler > DOS > Pipes and Redirections

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smiddy



Joined: 31 Oct 2004
Posts: 562
Pipes and Redirections
Greetings DOS Gurus!

I am about to write a MORE command for DOS, such that I get the understanding on using STDIN, STDOUT, etcetera (please forgive my lack of knowledge here, my semantics may not be the vernacular used, so bear with me). I can recall using DOS' MORE command like this:

    type FILE.TXT|MORE
    MORE<FILE.TXT


If I were to build a MORE command, type, in my elementary understanding, simply sends the text to the screen or CON. MORE intercepts the data from the FILE.TXT and updates the screen or CON with a 'Press a key to continue...' or something like that.

So, some questions, and please don't hold back, because I am in the initial stages of understanding this, constructive feedback is great!

1. Where is CON? (I know that the screen RAM buffer gets updated, at the locales associated with the cursor locale for each character etcetera)
2. How do the pipes or redirects differ (ala > or < or | and are there more)?
2.1. Where do they get sent?
3. How does standard IN and standard OUT get used?

Thanks ahead of time for your comments and suggestions.

Smiddy
Post 23 Dec 2014, 14:13
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nop



Joined: 01 Sep 2008
Posts: 165
Location: right here left there
its been done Smile and old msdos source is publicly avalible now
source for dos v2.0 more paginate prog below with includes expanded but its masm Sad

| is pipe where output of first prog becomes input to second prog
< is stdin redirection from file
> is stdout redirection to file

Code:
        TITLE   MORE MS-DOS Paginate Filter
FALSE   EQU     0
TRUE    EQU     NOT FALSE

IBMVER  EQU     TRUE
KANJI   EQU     FALSE
MSVER   EQU     FALSE

;        INCLUDE DOSSYM.ASM
; DOSSYM.ASM
;include DOSMAC.ASM
; DOSMAC.ASM
; Macro file for MSDOS.
;

SUBTTL BREAK a listing into pages and give new subtitles
PAGE
BREAK   MACRO   subtitle
        SUBTTL  subtitle
        PAGE
ENDM

BREAK <I_NEEDdeclare a variable externalif necessaryand allocate a size>

;
; declare a variable external and allocate a size
;
I_NEED  MACRO   sym,len
    CODE    ENDS
    DATA    SEGMENT BYTE PUBLIC 'DATA'

    IFIDN   <len>,<WORD>
        EXTRN   &sym:WORD
    ELSE
        IFIDN   <len>,<DWORD>
            EXTRN   &sym:DWORD
        ELSE
           EXTRN   &sym:BYTE
        ENDIF
    ENDIF

    DATA    ENDS
    CODE    SEGMENT BYTE PUBLIC 'CODE'
ENDM

;
; call a procedure that may be external.  The call will be short.
;
invoke  MACRO   name
&.xcref
    add_ext name,near
&.cref
    CALL    name
ENDM

PAGE
;
; jump to a label that may be external.  The call will be near.
;
transfer    MACRO   name
&.xcref
    add_ext name,near
&.cref
    JUMP    name
ENDM

;
; get a short address in a word
;
short_addr  MACRO   name
    IFDIF   <name>,<?>
&.xcref
        add_ext name,near
&.cref
        DW  OFFSET DOSGROUP:name
    ELSE
        DW  ?
    ENDIF
ENDM

;
; get a long address in a dword
;
long_addr   MACRO   name
&.xcref
    add_ext name,far
&.cref
    DD  name
ENDM

;
; declare a PROC near or far but PUBLIC nonetheless
;
procedure   MACRO   name,distance
        PUBLIC  name
name    PROC    distance
ENDM

PAGE
;
; define a data item to be public and of an appropriate size/type
;
I_AM    MACRO   name,size
    PUBLIC  name

    IFIDN <size>,<WORD>
        name    DW  ?
    ELSE
        IFIDN <size>,<DWORD>
            name    DD  ?
        ELSE
            IFIDN <size>,<BYTE>
                name    DB  ?
            ELSE
                name    DB  size DUP (?)
            ENDIF
        ENDIF
    ENDIF
ENDM

PAGE
;
; play games with a possible external.  Create a new
; macro for the symbol and text, and string it together
; with a central invoker
;

.xcref
.xcref  ?i
.xcref def_mac
.xcref  ?z0
.xcref  add_ext
.cref

IF1
    ?i=0
ENDIF

?z0 macro
endm

;
; add an external declaration to s with type t if it is not defined
;
add_ext macro   s,t
&.xcref
&.xcref ?&s
&.cref
    IFNDEF   ?&s
        ?i = ?i + 1
        def_mac     ?z&%?i,?z&%(?i-1),s,t
    ENDIF
endm

;
; define a macro called that possibly externals s:t and then calls macro n
;
def_mac macro   m,n,s,t
&.xcref
&.xcref  ?&s
&.xcref  m
&.cref
m   macro
    ifndef s
        extrn s:&t
    endif
    purge m
    purge ?&s
    n
endm
?&s macro
&endm
endm

;
; call the macro chain
;
do_ext  macro
&.xcref
    expand_mac  ?z%?i
&.cref
endm

PAGE
expand_mac macro m
    m
endm

;
; define an entry in a procedure
;
entry macro name
    PUBLIC  name
name:
endm

BREAK <ERROR - print a message and then jump to a label>

error macro code
    local a
.xcref
    MOV AL,code
    transfer    SYS_RET_ERR
.cref
ENDM

BREAK <JUMP - real jump that links up shortwise>
;
; given a label <lbl> either 2 byte jump to another label <lbl>_J
; if it is near enough or 3 byte jump to <lbl>
;

jump    macro lbl
    local a
.xcref
    a:
    ifndef lbl&_J                       ; is this the first invocation
        JMP lbl
    ELSE
        IF lbl&_J GE $
            JMP lbl
        ELSE
            IF ($-lbl&_JGT 126            ; is the jump too far away?
                JMP lbl
            ELSE                            ; do the short one...
                JMP lbl&_J
            ENDIF
        ENDIF
    ENDIF
endm

BREAK <RETURN - return from a function>

return  macro
    local a
.xcref
a:
    RET
ret_l = a
endm

BREAK <CONDRET - conditional return>

makelab macro l,cc,ncc
    j&ncc   a                           ; j<NCC> a:
    return                              ; return
    a:                                  ; a:
    ret_&cc = ret_l                     ; define ret_<CC> to be ret_l
endm

condret macro   cc,ncc
    local   a,b
    ifdef   ret_l                       ; if ret_l is defined
        if (($ - ret_lle 126and ($ gt ret_l)
                                        ;     if ret_l is near enough then
            a:  j&cc    ret_l           ;         a: j<CC> to ret_l
            ret_&cc = a                 ;         define ret_<CC> to be a:
        else
            makelab a,cc,ncc
        endif
    else
        ifdef   ret_&cc                     ; if ret_<CC> defined
            if (($ - ret_&ccle 126and ($ gt ret_&cc)
                                            ;     if ret_<CC> is near enough
                a:  j&cc    ret_&cc         ;         a: j<CC> to ret_<CC>
                ret_&cc = a                 ;         define ret_<CC> to be a:
            else
                makelab a,cc,ncc
            endif
        else
            makelab a,cc,ncc
        endif
    endif
endm
;condret macro   cc,ncc
;    local   a,b
;    ifdef   ret_l                       ; if ret_l is defined
;        if (($ - ret_l) le 126) and ($ gt ret_l)
;                                        ;     if ret_l is near enough then
;            a:  j&cc    ret_l           ;         a: j<CC> to ret_l
;            ret_&cc = a                 ;         define ret_<CC> to be a:
;            exitm
;        endif
;    endif
;    ifdef   ret_&cc                     ; if ret_<CC> defined
;        if (($ - ret_&cc) le 126) and ($ gt ret_&cc)
;                                        ;     if ret_<CC> is near enough
;            a:  j&cc    ret_&cc         ;         a: j<CC> to ret_<CC>
;            ret_&cc = a                 ;         define ret_<CC> to be a:
;            exitm
;        endif
;    endif
;    j&ncc   a                           ; j<NCC> a:
;    return                              ; return
;    a:                                  ; a:
;    ret_&cc = ret_l                     ; define ret_<CC> to be ret_l
;endm

BREAK <RETZ - return if zerolinks up shortwise if necessary>

retz    macro
    condret z,nz
endm

BREAK <RETNZ - return if not zerolinks up shortwise if necessary>

retnz   macro
    condret nz,z
endm

BREAK <RETC - return if carry setlinks up shortwise if necessary>

retc    macro
    condret c,nc
endm

BREAK <RETNC - return if not carrylinks up shortwise if necessary>

retnc   macro
    condret nc,c
endm
                                        
                                                         

; END OF DOSMAC.ASM
IF2
    %OUT    DOSSYM in Pass 2
ENDIF

IFNDEF  ALTVECT
ALTVECT EQU     0       ;FALSE
ENDIF

BREAK <Control character definitions>

c_DEL       EQU     7Fh         ;    ASCII rubout or delete previous char
c_BS        EQU     08h         ; ^H ASCII backspace
c_CR        EQU     0Dh         ; ^M ASCII carriage return
c_LF        EQU     0Ah         ; ^J ASCII linefeed
c_ETB       EQU     17h         ; ^W ASCII end of transmission
c_NAK       EQU     15h         ; ^U ASCII negative acknowledge
c_ETX       EQU     03h         ; ^C ASCII end of text
c_HT        EQU     09h         ; ^I ASCII tab

BREAK <BPB Definition>


;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
; Certain structures, constants and system  calls  below  are  private  to ;
; the DOS  and  are  extremely  version-dependent.  They may change at any ;
; time at  the  implementors'  whim.   As  a  result,  they  must  not  be ;
; documented to  the  general  public.   If  an  extreme case arises, they ;
; must be documented with this warning.                                    ;
;                                                                          ;
; Those structures and constants that are subject to  the  above  will  be ;
; marked and bracketed with the flag:                                      ;
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK  <Bios Parameter Block>
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;

; Bios Parameter Block definition
; This structure is used to build a full DPB

BPBLOCK STRUC
BPSECSZ DW      ?       ; Size in bytes of physical sector
BPCLUS  DB      ?       ; Sectors/Alloc unit
BPRES   DW      ?       ; Number of reserved sectors
BPFTCNT DB      ?       ; Number of FATs
BPDRCNT DW      ?       ; Number of directory entries
BPSCCNT DW      ?       ; Total number of sectors
BPMEDIA DB      ?       ; Media descriptor byte
BPFTSEC DW      ?       ; Number of sectors taken up by one FAT
BPBLOCK ENDS
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <Disk I/O Buffer Header>
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;

; Field definition for I/O buffer information

BUFFINFO        STRUC
NEXTBUF         DD      ?       ; Pointer to next buffer in list
; The next two items are often refed as a word
BUFDRV          DB      ?       ; Logical drive # assoc with buffer FF = free
BUFDIRTY        DB      ?       ; Dirty flag
BUFPRI          DB      ?       ; Buffer selection priority (see EQUs below)
VISIT           DB      ?       ; Visit flag for buffer pool scans
BUFSECNO        DW      ?       ; Sector number of buffer
; The next two items are often refed as a word
BUFWRTCNT       DB      ?       ; For FAT sectors, # times sector written out
BUFWRTINC       DB      ?       ; "   "     "   , # sectors between each write
BUFDRVDP        DD      ?       ; Pointer to drive parameters
BUFFINFO        ENDS

BUFINSIZ        EQU     SIZE BUFFINFO
                                ; Size of structure in bytes

FREEPRI EQU     0
LBRPRI  EQU     2               ; Last byte of buffer read
LBWPRI  EQU     4               ; Last byte written
RPRI    EQU     6               ; Read but not last byte
WPRI    EQU     8               ; Written but not last byte
DIRPRI  EQU     15              ; Directory Sector
FATPRI  EQU     30              ; FAT sector
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <User stack inside of system call>
; Location of user registers relative user stack pointer

user_environ    STRUC
user_AX     DW      ?
user_BX     DW      ?
user_CX     DW      ?
user_DX     DW      ?
user_SI     DW      ?
user_DI     DW      ?
user_BP     DW      ?
user_DS     DW      ?
user_ES     DW      ?
user_IP     DW      ?
user_CS     DW      ?
user_F      DW      ?
user_environ    ENDS

BREAK <interrupt definitions>

INTTAB          EQU     20H
INTBASE         EQU     4 * inttab
ENTRYPOINT      EQU     INTBASE+40H

        IF      ALTVECT
ALTTAB  EQU     0F0H
ALTBASE EQU     4 * ALTTAB
        ENDIF

;
; interrupt assignments
;
        IF      NOT ALTVECT
int_abort           EQU     INTTAB          ; abort process
int_command         EQU     int_abort+1     ; call MSDOS
int_terminate       EQU     int_abort+2     ; int to terminate address
int_ctrl_c          EQU     int_abort+3     ; ^c trapper
int_fatal_abort     EQU     int_abort+4     ; hard disk error
int_disk_read       EQU     int_abort+5     ; logical sector disk read
int_disk_write      EQU     int_abort+6     ; logical sector disk write
int_keep_process    EQU     int_abort+7     ; terminate program and stay resident
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
int_spooler         EQU     int_abort+8     ; spooler call
int_fastcon         EQU     int_abort+9     ; fast CON interrupt
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
        ELSE
int_abort           EQU     INTTAB          ; abort process
int_command         EQU     int_abort+1     ; call MSDOS
int_terminate       EQU     ALTTAB          ; int to terminate address
int_ctrl_c          EQU     int_terminate+1 ; ^c trapper
int_fatal_abort     EQU     int_terminate+2 ; hard disk error
int_disk_read       EQU     int_abort+5     ; logical sector disk read
int_disk_write      EQU     int_abort+6     ; logical sector disk write
int_keep_process    EQU     int_abort+7     ; terminate program and stay resident
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
int_spooler         EQU     int_terminate+3 ; spooler call
int_fastcon         EQU     int_abort+9     ; fast CON interrupt
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
        ENDIF

addr_int_abort          EQU    4 * int_abort
addr_int_command        EQU    4 * int_command
addr_int_terminate      EQU    4 * int_terminate
addr_int_ctrl_c         EQU    4 * int_ctrl_c
addr_int_fatal_abort    EQU    4 * int_fatal_abort
addr_int_disk_read      EQU    4 * int_disk_read
addr_int_disk_write     EQU    4 * int_disk_write
addr_int_keep_process   EQU    4 * int_keep_process
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
addr_int_spooler        EQU    4 * int_spooler
addr_int_fastcon        EQU    4 * int_fastcon
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <Disk map>
;  MSDOS partitions the disk into 4 sections:
;
;  phys sector 0:   +-------------------+
;       |           | boot/reserved     |
;       |           +-------------------+
;       |           |  File allocation  |
;       v           |      table(s)     |
;                   |  (multiple copies |
;                   |     are kept)     |
;                   +-------------------+
;                   |     Directory     |
;                   +-------------------+
;                   |     File space    |
;                   +-------------------+
;                   |   Unaddressable   |
;                   |  (to end of disk) |
;                   +-------------------+
;
; All partition boundaries are sector boundaries.  The size of the FAT is
; adjusted to maximize the file space addressable.

BREAK <Directory entry>

;
;       +---------------------------+
;       |  (12 BYTE) filename/ext   |       0       0
;       +---------------------------+
;       |     (BYTE) attributes     |       11      B
;       +---------------------------+
;       |    (10 BYTE) reserved     |       12      C
;       +---------------------------+
;       | (WORD) time of last write |       22      16
;       +---------------------------+
;       | (WORD) date of last write |       24      18
;       +---------------------------+
;       |   (WORD) First cluster    |       26      1A
;       +---------------------------+
;       |     (DWORD) file size     |       28      1C
;       +---------------------------+
;
;   First byte of filename  = E5 -> free directory entry
;                           = 00 -> end of allocated directory
;   Time:   Bits 0-4=seconds/2, bits 5-10=minute, 11-15=hour
;   Date:   Bits 0-4=day, bits 5-8=month, bits 9-15=year-1980
;
dir_entry   STRUC
dir_name    DB      11 DUP (?)          ; file name
dir_attr    DB      ?                   ; attribute bits
dir_pad     DB      10 DUP (?)          ; reserved for expansion
dir_time    DW      ?                   ; time of last write
dir_date    DW      ?                   ; date of last write
dir_first   DW      ?                   ; first allocation unit of file
dir_size_l  DW      ?                   ; low 16 bits of file size
dir_size_h  DW      ?                   ; high 16 bits of file size
dir_entry   ENDS

attr_read_only      EQU      1h
attr_hidden         EQU      2h
attr_system         EQU      4h
attr_volume_id      EQU      8h
attr_directory      EQU     10h
attr_archive        EQU     20h

attr_all            EQU     attr_hidden+attr_system+attr_directory
                                        ; OR of hard attributes for FINDENTRY

attr_ignore         EQU     attr_read_only+attr_archive
                                        ; ignore this(ese) attribute(s)
                                        ; during search first/next

attr_changeable     EQU     attr_read_only+attr_hidden+attr_system+attr_archive
                                        ; changeable via CHMOD

BREAK <File allocation Table information>
;
; The File Allocation Table uses a 12-bit entry for each allocation unit on the
; disk.  These entries are packed, two for every three bytes.  The contents of
; entry number N is found by 1) multiplying N by 1.5; 2) adding the result to
; the base address of the Allocation Table; 3) fetching the 16-bit word at this
; address; 4) If N was odd (so that N*1.5 was not an integer), shift the word
; right four bits; 5) mask to 12 bits (AND with 0FFF hex).  Entry number zero
; is used as an end-of-file trap in the OS and is passed to the BIOS to help
; determine disk format.  Entry 1 is reserved for future use.  The first
; available allocation unit is assigned entry number two, and even though it is
; the first, is called cluster 2.  Entries greater than 0FF8H are end of file
; marks; entries of zero are unallocated.  Otherwise, the contents of a FAT
; entry is the number of the next cluster in the file.
;
; Clusters with bad sectors are tagged with FF7H.  Any non-zero number would do
; because these clusters show as allocated, but are not part of any allocation
; chain and thus will never be allocated to a file.  A particular number is
; selected so that disk checking programs know what to do (ie.  a cluster with
; entry FF7H which is not in a chain is not an error).

BREAK <DPB structure>
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;

DIRSTRLEN       EQU     64      ; Max length in bytes of directory strings

dpb     STRUC
dpb_drive           DB      ?   ; Logical drive # assoc with DPB (A=0,B=1,...)
dpb_UNIT            DB      ?   ; Driver unit number of DPB
dpb_sector_size     DW      ?   ; Size of physical sector in bytes
dpb_cluster_mask    DB      ?   ; Sectors/cluster - 1
dpb_cluster_shift   DB      ?   ; Log2 of sectors/cluster
dpb_first_FAT       DW      ?   ; Starting record of FATs
dpb_FAT_count       DB      ?   ; Number of FATs for this drive
dpb_root_entries    DW      ?   ; Number of directory entries
dpb_first_sector    DW      ?   ; First sector of first cluster
dpb_max_cluster     DW      ?   ; Number of clusters on drive + 1
dpb_FAT_size        DB      ?   ; Number of records occupied by FAT
dpb_dir_sector      DW      ?   ; Starting record of directory
dpb_driver_addr     DD      ?   ; Pointer to driver
dpb_media           DB      ?   ; Media byte
dpb_first_access    DB      ?   ; This is initialized to -1 to force a media
                                ; check the first time this DPB is used
dpb_next_dpb        DD      ?   ; Pointer to next Drive parameter block
dpb_current_dir     DW      ?   ; Cluster number of start of current directory
                                ; 0 indicates root, -1 indicates invalid
                                ; (disk ? changed)
dpb_dir_text        DB      DIRSTRLEN DUP(?)
                                ; ASCIZ string of current directory
dpb     ENDS

DPBSIZ  EQU     SIZE dpb        ; Size of the structure in bytes

DSKSIZ  =       dpb_max_cluster ; Size of disk (temp used during init only)
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <File Control Block definition>
;
; Field definition for FCBs
; The FCB has the following structure:
;
;       +---------------------------+
;       |   Drive indicator(byte)   |
;       +---------------------------+
;       |    Filename (8 chars)     |
;       +---------------------------+
;       |    Extension (3 chars)    |
;       +---------------------------+
;       |   Current Extent(word)    |
;       +---------------------------+
;       |    Record size (word)     |
;       +---------------------------+
;       |    File Size (2 words)    |
;       +---------------------------+
;       |       Date of write       |
;       +---------------------------+
;       |       Time of write       |
;       +---------------------------+
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
;       | Flags:                    |
;       |  bit 7=0 file/1 device    |
;       |  bit 6=0 if dirty         |
;       |  bits 0-5 deviceid        |
;       +---------------------------+
;       |   first cluster in file   |
;       +---------------------------+
;       | position of last cluster  |
;       +---------------------------+
;       |   last cluster accessed   |   12 bit-+--- packed in 3 bytes
;       +---------------------------+          |
;       |     parent directory      |   <------+
;       +---------------------------+
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;       |    next record number     |
;       +---------------------------+
;       |   random record number    |
;       +---------------------------+
;

sys_fcb     STRUC
fcb_drive   DB      ?
fcb_name    DB      8 DUP (?)
fcb_ext     DB      3 DUP (?)
fcb_EXTENT  DW      ?
fcb_RECSIZ  DW      ?       ; Size of record (user settable)
fcb_FILSIZ  DW      ?       ; Size of file in bytes; used with the following
                            ; word
fcb_DRVBP   DW      ?       ; BP for SEARCH FIRST and SEARCH NEXT
fcb_FDATE   DW      ?       ; Date of last writing
fcb_FTIME   DW      ?       ; Time of last writing
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
fcb_DEVID   DB      ?       ; Device ID number, bits 0-5 if file.
                            ; bit 7=0 for file, bit 7=1 for I/O device
                            ; If file, bit 6=0 if dirty
                            ; If I/O device, bit 6=0 if EOF (input)
                            ;               Bit 5=1 if Raw mode
                            ;               Bit 0=1 if console input device
                            ;               Bit 1=1 if console output device
                            ;               Bit 2=1 if null device
                            ;               Bit 3=1 if clock device
fcb_FIRCLUS DW      ?       ; First cluster of file
fcb_CLUSPOS DW      ?       ; Position of last cluster accessed
fcb_LSTCLUS DW      ?       ; Last cluster accessed and directory
            DB      ?       ; pack 2 12 bit numbers into 24 bits...
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
fcb_NR      DB      ?       ; Next record
fcb_RR      DB      4 DUP (?)               ; Random record
sys_fcb     ENDS

FILDIRENT       = fcb_FILSIZ            ; Used only by SEARCH FIRST and
                                        ; SEARCH NEXT

;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
devid_file_clean        EQU     40h     ; true if file and not written
devid_file_mask_drive   EQU     3Fh     ; mask for drive number

devid_device            EQU     80h     ; true if a device
devid_device_EOF        EQU     40h     ; true if end of file reached
devid_device_raw        EQU     20h     ; true if in raw mode
devid_device_special    EQU     10h     ; true if special device
devid_device_clock      EQU     08h     ; true if clock device
devid_device_null       EQU     04h     ; true if null device
devid_device_con_out    EQU     02h     ; true if console output
devid_device_con_in     EQU     01h     ; true if consle input

;
; structure of devid field as returned by IOCTL is:
;
;       BIT     7   6   5   4   3   2   1   0
;             |---|---|---|---|---|---|---|---|
;             | I | E | R | S | I | I | I | I |
;             | S | O | A | P | S | S | S | S |
;             | D | F | W | E | C | N | C | C |
;             | E |   |   | C | L | U | O | I |
;             | V |   |   | L | K | L | T | N |
;             |---|---|---|---|---|---|---|---|
;       ISDEV = 1 if this channel is a device
;             = 0 if this channel is a disk file
;
;       If ISDEV = 1
;
;             EOF = 0 if End Of File on input
;             RAW = 1 if this device is in Raw mode
;                 = 0 if this device is cooked
;             ISCLK = 1 if this device is the clock device
;             ISNUL = 1 if this device is the null device
;             ISCOT = 1 if this device is the console output
;             ISCIN = 1 if this device is the console input
;
;       If ISDEV = 0
;             EOF = 0 if channel has been written
;             Bits 0-5  are  the  block  device  number  for
;                 the channel (0 = A, 1 = B, ...)
;
devid_ISDEV     EQU     80h
devid_EOF       EQU     40h
devid_RAW       EQU     20h
devid_SPECIAL   EQU     10H
devid_ISCLK     EQU     08h
devid_ISNUL     EQU     04h
devid_ISCOT     EQU     02h
devid_ISCIN     EQU     01h

devid_block_dev EQU     1Fh             ; mask for block device number

;
; find first/next buffer
;
find_buf    STRUC
find_buf_sattr      DB  ?           ; attribute of search
find_buf_drive      DB  ?           ; drive of search
find_buf_name       DB  11 DUP (?)  ; formatted name
find_buf_LastEnt    DW  ?           ; LastEnt
find_buf_ThisDPB    DD  ?           ; This DPB
find_buf_DirStart   DW  ?           ; DirStart
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

find_buf_attr       DB  ?           ; attribute found
find_buf_time       DW  ?           ; time
find_buf_date       DW  ?           ; date
find_buf_size_l     DW  ?           ; low(size)
find_buf_size_h     DW  ?           ; high(size)
find_buf_pname      DB  13 DUP (?)  ; packed name
find_buf    ENDS

BREAK <Process data block>
;
; Process data block (otherwise known as program header)
;

FilPerProc          EQU     20

Process_data_block  STRUC
PDB_Exit_Call       DW      ?           ; INT int_abort system terminate
PDB_block_len       DW      ?           ; size of execution block
                    DB      ?
PDB_CPM_Call        DB  5 DUP (?)       ; ancient call to system
PDB_Exit            DD      ?           ; pointer to exit routine
PDB_Ctrl_C          DD      ?           ; pointer to ^C routine
PDB_Fatal_abort     DD      ?           ; pointer to fatal error
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
PDB_Parent_PID      DW      ?           ; PID of parent (terminate PID)
PDB_JFN_Table       DB  FilPerProc DUP (?)
                                        ; indices into system table
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
PDB_environ         DW      ?           ; seg addr of environment
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
PDB_User_stack      DD      ?           ; stack of self during system calls
PDB_PAD1            DB      1Eh DUP (?)
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
PDB_Call_system     DB      5 DUP (?)   ; portable method of system call
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
PDB_PAD2            DB      6h DUP (?)  ;
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
Process_data_block  ENDS

BREAK <EXEC and EXE file structures>
;
; EXEC arg block - load/go program
;

;
; The following get used as arguments to the EXEC system call.  They indicate
; whether or not the program is executed or whether or not a program header
; gets created.
;
exec_func_no_execute    EQU 1           ; no execute bit
exec_func_overlay       EQU 2           ; overlay bit

Exec0           STRUC
Exec0_environ   DW      ?               ; seg addr of environment
Exec0_com_line  DD      ?               ; pointer to asciz command line
Exec0_5C_FCB    DD      ?               ; default fcb at 5C
Exec0_6C_FCB    DD      ?               ; default fcb at 6C
Exec0           ENDS

Exec1           STRUC
Exec1_environ   DW      ?               ; seg addr of environment
Exec1_com_line  DD      ?               ; pointer to asciz command line
Exec1_5C_FCB    DD      ?               ; default fcb at 5C
Exec1_6C_FCB    DD      ?               ; default fcb at 6C
Exec1_SP        DW      ?               ; stack pointer of program
Exec1_SS        DW      ?               ; stack seg register of program
Exec1_IP        DW      ?               ; entry point IP
Exec1_CS        DW      ?               ; entry point CS
Exec1           ENDS

Exec3           STRUC
Exec3_load_addr DW      ?               ; seg address of load point
Exec3_reloc_fac DW      ?               ; relocation factor
Exec3           ENDS

;
; Exit codes in upper byte
;
Exit_terminate      EQU     0
Exit_abort          EQU     0
Exit_Ctrl_C         EQU     1
Exit_Hard_Error     EQU     2
Exit_Keep_process   EQU     3

;
; EXE file header
;

EXE_file    STRUC
exe_signature   DW  ?                   ; must contain 4D5A  (yay zibo!)
exe_len_mod_512 DW  ?                   ; low 9 bits of length
exe_pages       DW  ?                   ; number of 512b pages in file
exe_rle_count   DW  ?                   ; count of reloc entries
exe_par_dir     DW  ?                   ; number of paragraphs before image
exe_min_BSS     DW  ?                   ; minimum number of para of BSS
exe_max_BSS     DW  ?                   ; max number of para of BSS
exe_SS          DW  ?                   ; stack of image
exe_SP          DW  ?                   ; SP of image
exe_chksum      DW  ?                   ; checksum  of file (ignored)
exe_IP          DW  ?                   ; IP of entry
exe_CS          DW  ?                   ; CS of entry
exe_rle_table   DW  ?                   ; byte offset of reloc table
exe_iov         DW  ?                   ; overlay number (0 for root)
exe_sym_tab     DD  ?                   ; offset of symbol table in file
EXE_file    ENDS

exe_valid_signature     EQU 5A4Dh
exe_valid_old_signature EQU 4D5Ah

symbol_entry    STRUC
sym_value       DD  ?
sym_type        DW  ?
sym_len         DB  ?
sym_name        DB  255 dup (?)
symbol_entry    ENDS

BREAK <Internal system file table format>
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
;
; system file table
;

sft             STRUC
sft_link        DD      ?
sft_count       DW      ?               ; number of entries
sft_table       DW      ?               ; beginning of array of the following
sft             ENDS

;
; system file table entry
;

sf_entry        STRUC
sf_ref_count    DB      ?               ; number of processes sharing fcb
sf_mode         DB      ?               ; mode of access
sf_attr         DB      ?               ; attribute of file
sf_fcb          DB      (SIZE sys_fcbDUP (?)
                                        ; actual FCB
sf_entry        ENDS

sf_default_number   EQU     5h
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <Memory arena structure>
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
;
; arena item
;
arena   STRUC
arena_signature     DB  ?               ; 4D for valid item, 5A for last item
arena_owner         DW  ?               ; owner of arena item
arena_size          DW  ?               ; size in paragraphs of item
arena   ENDS

arena_owner_system  EQU 0               ; free block indication

arena_signature_normal  EQU 4Dh         ; valid signature, not end of arena
arena_signature_end     EQU 5Ah         ; valid signature, last block in arena
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;

BREAK <Machine instruction definitions>

mi_INT          EQU     0CDh
mi_Long_JMP     EQU     0EAh
mi_Long_CALL    EQU     09Ah
mi_Long_RET     EQU     0CBh

BREAK <Standard I/O assignments>

stdin       EQU     0
stdout      EQU     1
stderr      EQU     2
stdaux      EQU     3
stdprn      EQU     4

BREAK <Xenix subfunction assignments>

open_for_read   EQU 0
open_for_write  EQU 1
open_for_both   EQU 2

BREAK <Xenix error codes>

;
; XENIX calls all return error codes through AX.  If an error occurred then the
; carry bit will be set and the error code is in AX.  If no error occurred then
; the carry bit is reset and AX contains returned info.
;

no_error_occurred               EQU     0                                                         

     ?

error_invalid_function          EQU     1
error_file_not_found            EQU     2
error_path_not_found            EQU     3
error_too_many_open_files       EQU     4
error_access_denied             EQU     5
error_invalid_handle            EQU     6
error_arena_trashed             EQU     7
error_not_enough_memory         EQU     8
error_invalid_block             EQU     9
error_bad_environment           EQU     10
error_bad_format                EQU     11
error_invalid_access            EQU     12
error_invalid_data              EQU     13
;**** unused                    EQU     14
error_invalid_drive             EQU     15
error_current_directory         EQU     16
error_not_same_device           EQU     17
error_no_more_files             EQU     18

alloc_not_enough_memory         EQU     error_not_enough_memory
alloc_arena_trashed             EQU     error_arena_trashed

close_invalid_handle            EQU     error_invalid_handle
close_invalid_function          EQU     error_invalid_function

chdir_path_not_found            EQU     error_path_not_found

chmod_path_not_found            EQU     error_path_not_found
chmod_access_denied             EQU     error_access_denied
chmod_invalid_function          EQU     error_invalid_function

creat_access_denied             EQU     error_access_denied
creat_path_not_found            EQU     error_path_not_found
creat_too_many_open_files       EQU     error_too_many_open_files

curdir_invalid_drive            EQU     error_invalid_drive

dealloc_invalid_block           EQU     error_invalid_block
dealloc_arena_trashed           EQU     error_arena_trashed

dup_invalid_handle              EQU     error_invalid_handle
dup_too_many_open_files         EQU     error_too_many_open_files

dup2_invalid_handle             EQU     error_invalid_handle

exec_invalid_function           EQU     error_invalid_function
exec_bad_environment            EQU     error_bad_environment
exec_bad_format                 EQU     error_bad_format
exec_not_enough_memory          EQU     error_not_enough_memory
exec_file_not_found             EQU     error_file_not_found

filetimes_invalid_function      EQU     error_invalid_function
filetimes_invalid_handle        EQU     error_invalid_handle

findfirst_file_not_found        EQU     error_file_not_found
findfirst_no_more_files         EQU     error_no_more_files
findnext_no_more_files          EQU     error_no_more_files

international_invalid_function  EQU     error_invalid_function

ioctl_invalid_handle            EQU     error_invalid_handle
ioctl_invalid_function          EQU     error_invalid_function
ioctl_invalid_data              EQU     error_invalid_data

lseek_invalid_handle            EQU     error_invalid_handle
lseek_invalid_function          EQU     error_invalid_function

mkdir_path_not_found            EQU     error_path_not_found
mkdir_access_denied             EQU     error_access_denied

open_invalid_access             EQU     error_invalid_access
open_file_not_found             EQU     error_file_not_found
open_access_denied              EQU     error_access_denied
open_too_many_open_files        EQU     error_too_many_open_files

read_invalid_handle             EQU     error_invalid_handle
read_access_denied              EQU     error_access_denied

rename_file_not_found           EQU     error_file_not_found
rename_not_same_device          EQU     error_not_same_device
rename_access_denied            EQU     error_access_denied

rmdir_path_not_found            EQU     error_path_not_found
rmdir_access_denied             EQU     error_access_denied
rmdir_current_directory         EQU     error_current_directory

setblock_invalid_block          EQU     error_invalid_block
setblock_arena_trashed          EQU     error_arena_trashed
setblock_not_enough_memory      EQU     error_not_enough_memory
setblock_invalid_function       EQU     error_invalid_function

unlink_file_not_found           EQU     error_file_not_found
unlink_access_denied            EQU     error_access_denied

write_invalid_handle            EQU     error_invalid_handle
write_access_denied             EQU     error_access_denied

BREAK <system call definitions>

ABORT                           EQU 0   ;  0      0
STD_CON_INPUT                   EQU 1   ;  1      1
STD_CON_OUTPUT                  EQU 2   ;  2      2
STD_AUX_INPUT                   EQU 3   ;  3      3
STD_AUX_OUTPUT                  EQU 4   ;  4      4
STD_PRINTER_OUTPUT              EQU 5   ;  5      5
RAW_CON_IO                      EQU 6   ;  6      6
RAW_CON_INPUT                   EQU 7   ;  7      7
STD_CON_INPUT_NO_ECHO           EQU 8   ;  8      8
STD_CON_STRING_OUTPUT           EQU 9   ;  9      9
STD_CON_STRING_INPUT            EQU 10  ; 10      A
STD_CON_INPUT_STATUS            EQU 11  ; 11      B
STD_CON_INPUT_FLUSH             EQU 12  ; 12      C
DISK_RESET                      EQU 13  ; 13      D
SET_DEFAULT_DRIVE               EQU 14  ; 14      E
FCB_OPEN                        EQU 15  ; 15      F
FCB_CLOSE                       EQU 16  ; 16     10
DIR_SEARCH_FIRST                EQU 17  ; 17     11
DIR_SEARCH_NEXT                 EQU 18  ; 18     12
FCB_DELETE                      EQU 19  ; 19     13
FCB_SEQ_READ                    EQU 20  ; 20     14
FCB_SEQ_WRITE                   EQU 21  ; 21     15
FCB_CREATE                      EQU 22  ; 22     16
FCB_RENAME                      EQU 23  ; 23     17
GET_DEFAULT_DRIVE               EQU 25  ; 25     19
SET_DMA                         EQU 26  ; 26     1A
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
GET_DEFAULT_DPB                 EQU 31  ; 31     1F
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
FCB_RANDOM_READ                 EQU 33  ; 33     21
FCB_RANDOM_WRITE                EQU 34  ; 34     22
GET_FCB_FILE_LENGTH             EQU 35  ; 35     23
GET_FCB_POSITION                EQU 36  ; 36     24
SET_INTERRUPT_VECTOR            EQU 37  ; 37     25
CREATE_PROCESS_DATA_BLOCK       EQU 38  ; 38     26
FCB_RANDOM_READ_BLOCK           EQU 39  ; 39     27
FCB_RANDOM_WRITE_BLOCK          EQU 40  ; 40     28
PARSE_FILE_DESCRIPTOR           EQU 41  ; 41     29
GET_DATE                        EQU 42  ; 42     2A
SET_DATE                        EQU 43  ; 43     2B
GET_TIME                        EQU 44  ; 44     2C
SET_TIME                        EQU 45  ; 45     2D
SET_VERIFY_ON_WRITE             EQU 46  ; 46     2E
; Extended functionality group
GET_DMA                         EQU 47  ; 47     2F
GET_VERSION                     EQU 48  ; 48     30
KEEP_PROCESS                    EQU 49  ; 49     31
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
GET_DPB                         EQU 50  ; 50     32
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
SET_CTRL_C_TRAPPING             EQU 51  ; 51     33
GET_INDOS_FLAG                  EQU 52  ; 52     34
GET_INTERRUPT_VECTOR            EQU 53  ; 53     35
GET_DRIVE_FREESPACE             EQU 54  ; 54     36
CHAR_OPER                       EQU 55  ; 55     37
INTERNATIONAL                   EQU 56  ; 56     38
; XENIX CALLS
;   Directory Group
MKDIR                           EQU 57  ; 57     39
RMDIR                           EQU 58  ; 58     3A
CHDIR                           EQU 59  ; 59     3B
;   File Group
CREAT                           EQU 60  ; 60     3C
OPEN                            EQU 61  ; 61     3D
CLOSE                           EQU 62  ; 62     3E
READ                            EQU 63  ; 63     3F
WRITE                           EQU 64  ; 64     40
UNLINK                          EQU 65  ; 65     41
LSEEK                           EQU 66  ; 66     42
CHMOD                           EQU 67  ; 67     43
IOCTL                           EQU 68  ; 68     44
XDUP                            EQU 69  ; 69     45
XDUP2                           EQU 70  ; 70     46
CURRENT_DIR                     EQU 71  ; 71     47
;    Memory Group
ALLOC                           EQU 72  ; 72     48
DEALLOC                         EQU 73  ; 73     49
SETBLOCK                        EQU 74  ; 74     4A
;    Process Group
EXEC                            EQU 75  ; 75     4B
EXIT                            EQU 76  ; 76     4C
WAIT                            EQU 77  ; 77     4D
FIND_FIRST                      EQU 78  ; 78     4E
;   Special Group
FIND_NEXT                       EQU 79  ; 79     4F
; SPECIAL SYSTEM GROUP
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
SET_CURRENT_PDB                 EQU 80  ; 80     50
GET_CURRENT_PDB                 EQU 81  ; 81     51
GET_IN_VARS                     EQU 82  ; 82     52
SETDPB                          EQU 83  ; 83     53
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
GET_VERIFY_ON_WRITE             EQU 84  ; 84     54
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;                                                                          ;
DUP_PDB                         EQU 85  ; 85     55
;                                                                          ;
;            C  A  V  E  A  T     P  R  O  G  R  A  M  M  E  R             ;
;----+----+----+----+----+----+----+----+----+----+----+----+----+----+----;
RENAME                          EQU 86  ; 86     56
FILE_TIMES                      EQU 87  ; 87     57

SET_OEM_HANDLER                 EQU 248 ; 248    F8
OEM_C1                          EQU 249 ; 249    F9
OEM_C2                          EQU 250 ; 250    FA
OEM_C3                          EQU 251 ; 251    FB
OEM_C4                          EQU 252 ; 252    FC
OEM_C5                          EQU 253 ; 253    FD
OEM_C6                          EQU 254 ; 254    FE
OEM_C7                          EQU 255 ; 255    FF
SUBTTL
; END OF DOSSYM.ASM
                               
CODE    SEGMENT PUBLIC
        ORG     100H
ASSUME  CS:CODE,DS:CODE,ES:CODE,SS:CODE
START:

        MOV     AH,GET_VERSION
        INT     21H
        XCHG    AH,AL                   ; Turn it around to AH.AL
        CMP     AX,200H
        JAE     OKDOS
        MOV     DX,OFFSET BADVER
        MOV     AH,STD_CON_STRING_OUTPUT
        INT     21H
        INT     20H
OKDOS:

        IF      IBMVER
        IF      KANJI
        MOV     BYTE PTR MAXROW,24
        ELSE
        MOV     BYTE PTR MAXROW,25
        ENDIF
        MOV     AH,15
        INT     16
        MOV     MAXCOL,AH
        ENDIF

        MOV     DX,OFFSET CRLFTXT       ; INITIALIZE CURSOR
        MOV     AH,STD_CON_STRING_OUTPUT
        INT     21H

        XOR     BX,BX                   ; DUP FILE HANDLE 0
        MOV     AH,XDUP
        INT     21H
        MOV     BP,AX

        MOV     AH,CLOSE                ; CLOSE STANDARD IN
        INT     21H

        MOV     BX,2                    ; DUP STD ERR TO STANDARD IN
        MOV     AH,XDUP
        INT     21H

ALOOP:
        CLD
        MOV     DX,OFFSET BUFFER
        MOV     CX,4096
        MOV     BX,BP
        MOV     AH,READ
        INT     21H
        OR      AX,AX
        JNZ     SETCX
DONE:   INT     20H
SETCX:  MOV     CX,AX
        MOV     SI,DX

TLOOP:
        LODSB
        CMP     AL,1AH
        JZ      DONE
        CMP     AL,13
        JNZ     NOTCR
        MOV     BYTE PTR CURCOL,1
        JMP     SHORT ISCNTRL

NOTCR:  CMP     AL,10
        JNZ     NOTLF
        INC     BYTE PTR CURROW
        JMP     SHORT ISCNTRL

NOTLF:  CMP     AL,8
        JNZ     NOTBP
        CMP     BYTE PTR CURCOL,1
        JZ      ISCNTRL
        DEC     BYTE PTR CURCOL
        JMP     SHORT ISCNTRL

NOTBP:  CMP     AL,9
        JNZ     NOTTB
        MOV     AH,CURCOL
        ADD     AH,7
        AND     AH,11111000B
        INC     AH
        MOV     CURCOL,AH
        JMP     SHORT ISCNTRL

NOTTB:
        IF      MSVER                   ; IBM CONTROL CHARACTER PRINT
        CMP     AL,' '
        JB      ISCNTRL
        ENDIF

        IF      IBMVER
        CMP     AL,7                    ; ALL CHARACTERS PRINT BUT BELL
        JZ      ISCNTRL
        ENDIF

        INC     BYTE PTR CURCOL
        MOV     AH,CURCOL
        CMP     AH,MAXCOL
        JBE     ISCNTRL
        INC     BYTE PTR CURROW
        MOV     BYTE PTR CURCOL,1

ISCNTRL:
        MOV     DL,AL
        MOV     AH,STD_CON_OUTPUT
        INT     21H
        MOV     AH,CURROW
        CMP     AH,MAXROW
        JB      CHARLOOP

ASKMORE:
        MOV     DX,OFFSET MORETXT
        MOV     AH,STD_CON_STRING_OUTPUT
        INT     21H                     ; ASK MORE?

        MOV     AH,STD_CON_INPUT_FLUSH  ; WAIT FOR A KEY, NO ECHO
        MOV     AL,STD_CON_INPUT
        INT     21H

        MOV     DX,OFFSET CRLFTXT
        MOV     AH,STD_CON_STRING_OUTPUT
        INT     21H

        MOV     BYTE PTR CURCOL,1
        MOV     BYTE PTR CURROW,1

CHARLOOP:
        DEC     CX
        JZ      GOBIG
        JMP     TLOOP
GOBIG:  JMP     ALOOP

MAXROW  DB      24
MAXCOL  DB      80
CURROW  DB      1
CURCOL  DB      1
        EXTRN   MORETXT:BYTE,BADVER:BYTE,CRLFTXT:BYTE,BUFFER:BYTE

CODE    ENDS
        END     START








Post 24 Dec 2014, 03:51
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smiddy



Joined: 31 Oct 2004
Posts: 562
I was playing around with the executable this evening. But in reading it I'm totally lost. I'll keep reading it, perhaps something will stick.
Post 24 Dec 2014, 05:04
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baldr



Joined: 19 Mar 2008
Posts: 1651
smiddy,

You can start with simple identity filter (copy stdin to stdout), then modify it to pause on full page (you may assume 25-row display). Here is an example you may find useful:

Code:
        org     100h
; t.com - copy stdin to stdout and stderr
t:      mov     ah3Fh
        mov     cxbuffer.size
        mov     dxbuffer
        xor     bxbx
        int     21h
        jc      .done
        mov     cxax
        jcxz    .done
        mov     ah40h
        inc     bx
        int     21h
        jc      .done
        mov     cxax
        jcxz    .done
        mov     ah40h
        inc     bx
        int     21h
        jc      .done
        test    axax
        jnz     t
.done:  ret

buffer  rb      4096
.size = $-buffer

Post 24 Dec 2014, 14:11
View user's profile Send private message Reply with quote
smiddy



Joined: 31 Oct 2004
Posts: 562
Thanks man! I am deep into Christmas Eve with my kids, so it will be sometime before I get the opportunity to play with it.
Post 24 Dec 2014, 19:20
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