CP/M/CPM_CDROM.iso/mbug/mbug141.arc/IF.LBR/IF.AQM/IF.ASM

Assembly Source File | 1979-12-31 | 11KB | 347 lines

;
;   IF   --  conditionally execute or skip commands witthin a submit file
;
;         Written by Marc C. Brooks 1/4/83
;
;         based on David Kirkland's version of SKIPIF as of 6/12/83
;
;         Usage:
;
;         IF A[mbig] fn      true if fn is ambigous
;         IF E[xists] fn     true if file fn exists
;         IF M[issing] fn    true if file fn does not exist
;         IF N[ull] (fn)     true if the fn is missing
;         IF Z[ero] fn       true if file fn is zero length or does not exist
;
;         If the condition is true, all commands up to the next ELSE or
;         ENDIF statement are executed.  If an ELSE is encountered before
;         the ENDIF statement is reached, commands are skipped until the
;         ENDIF is found.  If the condition is false, commands are skipped
;         until the matching ELSE or ENDIF is found.  Command execution then
;         resumes.  IF-ELSE-ENDIF groups may be nested to any depth.
;
;         Only the first character of the first keyword (the A of Ambig or
;         whatever) is checked.  If an invalid keyword is entered, all
;         commands between the IF and its matching ENDIF will be skipped
;         (after a suitable error message.)
;
cpm    equ    0000h
tpa    equ    0100h
ccpoff    equ    0806h        ; offset from (bdos+1) to bottom of ccp
bdos    equ    0005h
fcb1    equ    005ch        ;the first fcb prepared by the CCP
name1    equ    fcb1+1        ; start of the filename of fcb1 (AEMN or Z)
fcb2    equ    006ch
name2    equ    fcb2+1
fcb2CUR    equ    fcb2+32        ; current record for fcb2
;
drive    equ    'A'        ; the drive with the $$$.SUB file
bell    equ    07h        ; an ASCII bell character
;   BDOS codes used
;
PrtStr    equ    9        ; Print a string to console (terminated by $)
Open    equ    15        ; Open a file
Close    equ    16        ; Close a file
Srch1st    equ    17        ; Search for the first occurence of a file
Erase    equ    19        ; Erase a file
Read    equ    20        ; Read a sequential record from a file
SetDma    equ    26        ; Set the dma buffer address
;
    org    tpa
;
;  First set the Stack, Dma address and check for a $$$.SUB file
;
    lhld    bdos+1        ; get the address of the BDOS
    lxi    d,-ccpoff    ;  and add the CCP offset
    dad    d        ; set the stack below the CCP
    sphl

    mvi    c,SetDma    ; set the dma address to the buffer following
    lxi    d,dmabuf    ;  the variables.
    call    bdos

    mvi    c,Open        ; open $$$.SUB
    lxi    d,subfile
    call    bdos
    inr    a        ; check to see if the $$$.SUB exists
    jz    explain        ;  if not, explain the syntax and return
;
;  Everything is fine so execute the command the caller actually asked for
;
    lda    name1        ; first character of the AMBIG or EXISTS or ..

    cpi    'N'        ; Null?
    jz    null

        lda    name2        ; check the to see if the user gave
        cpi    020h        ;  a filespec as the second argument
    jnz    process

    mvi    c,PrtStr    ; fn is null, bitch to user and skip both the
    lxi    d,FnNulMsg    ;  IF and ELSE clauses
    call    bdos
    jmp    skipboth

process    lda    name1        ; okay, we have a filespec, branch to command
    cpi    'A'        ; Ambig?
    jz    ambig
    cpi    'E'        ; Exists?
    jz    exists
    cpi    'M'        ; Missing?
    jz    missing
    cpi    'Z'        ; Zero?
    jz    zero

    mvi    c,PrtStr    ; no match so print error message
    lxi    d,BadOptMsg
    call    bdos

    jmp    skipboth    ; skip both IF anf ELSE clauses

;  ambig - do the IF clause if the 2nd argument is ambiguous
ambig    mvi    b,11        ; 11 characters in filename & filetype
    lxi    h,name2        ; bypass the drive code

scanlp    mov    a,m        ; scan for '?' in parsed fcb
    cpi    '?'
    jz    cpm        ; fn is ambiguous, return to CP/M
    inx    h
    dcr    b        ; done ?
    jnz    scanlp        ;  no, loop back for next char

    jmp     false        ; no '?', so false

;  exists - do the IF clause if the file exists
exists    call    search
    jnz    cpm        ; file found, return to CP/M
    jmp     false

;  missing - do the IF clause if the file does not exist
missing    call    search
    jnz    false
    jmp    cpm        ; file not found, return to CP/M

;  null - do the IF clause if the second parameter is missing
null    lda    name2        ; Check the second FCB to see if the user
    cpi    020h        ;  gave a filespec as the second arg
    jnz    false
    jmp    cpm        ; fn is not present, return to CP/M

;  zero - do the IF clause if the 2nd argument is a zero length file
zero    call    search        ; does the file exist?
    jz    cpm        ;  nope, zero long then so return to CP/M

    mvi    c,Open        ;  yes, lets open it
    lxi    d,fcb2
    call    bdos

        xra    a        ; zero the current record byte
    sta    fcb2CUR
    mvi    c,Read        ; now try to read one record (will fail if
    lxi    d,fcb2        ;  the file is zero length)
    call    bdos
    ora    a
    jz    false        ; read was OK, so not zero length
    jmp    cpm        ; read failed, return to CP/M

;  search - search for the first (possibly) ambiguous file to match fcb
search    mvi    c,Srch1st
    lxi    d,fcb2
    call    bdos
    inr    a        ; adjust the flags
    ret

;  skipboth - tell the user and skip both clauses of the IF
skipboth mvi    c,PrtStr    ; tell the user that both the IF and the
    lxi    d,SkipMsg    ;  ELSE clauses are being skipped
    call    bdos

    mvi    c,Open        ; open $$$.SUB
    lxi    d,subfile
    call    bdos

    call    skipend        ; skip line till the ENDIF is encountered

    mvi    c,Close        ; close the $$$.SUB to rewrite the modified fcb
    lxi    d,subfile
    call    bdos

    jmp    cpm        ; return to CPM

;  false - skip all command up to and including the ELSE, then return
false    mvi    c,Open        ; open $$$.SUB
    lxi    d,subfile
    call    bdos

    call    skipelse    ; skip lines till ELSE or ENDIF

    mvi    c,Close        ; close the $$$.SUB to rewrite the modified fcb
    lxi    d,subfile
    call    bdos

    jmp    cpm        ; return to CP/M to execute else clause

;  skipend - skip lines in the $$$.SUB file till an ENDIF is found
skipend    call    nxtline        ; get the next line from the $$$.SUB file

    lxi    d,EndLit    ; point to the ENDIF literal
    call    compstr        ; and compare
    jnz    skipend        ;  not equal, loop till it is
    ret            ;  equal, return to caller

;  skipelse - skip lines in the $$$.SUB file till an ELSE or ENDIF is found
skipelse call    nxtline        ; get the next line from the $$$.SUB file

        lxi    d,ElseLit    ; point to the ELSE literal
    call    compstr        ; now compare the record just read to if equal
    rz            ;  yes, return to caller

    lxi    d,EndLit    ; point to the ENDIF literal
    call    compstr        ; and compare
    jnz    skipelse    ;  not equal, loop till found
    ret            ;  equal, return to caller

;  nxtline - get the next line from the $$$.SUB file (with recursion stuff)
nxtline    call    nxtcmd        ; get the next command line from the $$$.SUB

    lxi    d,IfLit        ; is it an IF statement?
    call    compstr
    rnz            ;  nope, okay, return the line to caller

    call    skipend        ;  yes, skip both clauses of this nested IF
    jmp    nxtline        ; and now get the next command line

;  nxtcmd - get the command line from the $$$.SUB file and chop it off the file
nxtcmd    lda    subCNT        ; get the current record count for $$$.SUB
    dcr    a        ;  decrement by one
    sta    subREC        ;  and set the current record
        mvi    c,Read        ; read the next command
        lxi    d,subfile
        call    bdos
    inr    a
    jz    killsub        ;  if error, kill $$$.SUB and exit

    lxi    h,dmabuf    ; load the address of the command buffer
    mov    e,m        ;  get the byte count
    mvi    d,0
    dad    d
    inx    h
    mvi    m,0        ; and terminate the command with a zero

    lxi    h,subs2        ; zero the S2 byte of the fcb to force the
    mvi    m,0        ;  BDOS to rewrite it
    inx    h        ; now point to the record count byte
    mov    a,m        ;  and see if it is a zero
    ora    a
    jz    erasub        ;  yes, erase the $$$.SUB and return to CP/M
    dcr    m        ;  no, decrement the record count and return
    ret

;  compstr - compare the command just read to the literal point to by DE
compstr lxi    h,dmabuf+1    ; get the address of the command and
                ;  skip the leading whitespace

skipblk    mov    a,m        ; end of command string ?
    ora    a
    jz    nomatch        ;  yes, signal no match

    cpi    021h        ; is it whitespace ?
    jnc    complp        ;  no, start comparing
    inx    h        ;  yes, next character
    jmp    skipblk

nomatch    ori    0ffh        ; clear the zero flag to signal no match
    ret            ;  and return to caller

complp    ldax    d
    ora    a        ; end of the comparison string ?
    rz            ;  yes, they must match
        mov    c,a
    mov    a,m        ;  not eos, get next byte
    cpi    061h        ;   is 'a' <= a <= 'z' ?
    jc    compit
    cpi    07ah
    jnc    compit
    ani    05fh        ;   yes, fold to upper case
compit    cmp    c        ;  match ?
    rnz            ;   no , return non zero
    inx    h
    inx    d
    jmp    complp

;  killsub - kill the submit file and return to CP/M
killsub    mvi    c,PrtStr
    lxi    d,TermMsg    ; tell the user
    call    bdos

erasub    mvi    c,Erase        ; now kill the $$$.SUB file
    lxi    d,subfile
    call    bdos

    jmp    cpm        ; return to CP/M

;  explain - give the syntax and an operational synopsis since the user
;            involked IF with no $$$.SUB file present (i.e. from console)
explain mvi    c,PrtStr
    lxi    d,HelpMsg
    call    bdos

    jmp    cpm        ; return to CP/M
;
;
IfLit    db    'IF',0
;
ElseLit    db    'ELSE',0
;
EndLit    db    'ENDIF',0
;
;
;
TermMsg    db    bell,bell,bell,'ERROR - Submit procedure terminated'
    db    13,10,'$'
;
FnNulMsg db    bell,bell,bell,'A filespec must be given with this command'
    db    13,10,'$'
;
BadOptMsg db    bell,bell,bell,'That is not a legal option (A,E,M,N or Z)'
    db    13,10,'$'
;
SkipMsg    db    bell,bell,bell,'ERROR - Skipping both IF and ELSE clauses'
        db    13,10,'$'
;
HelpMsg    db    bell,13,10,'IF and its companion programs (ELSE, ENDIF and GOTO) are',13,10
    db    'used within submit files to allow conditional execution of',13,10
    db    'commands.  See IF.DOC for examples.',13,10
    db    13,10
    db    'Usage:        IF A[mbig] fn      true if fn is ambigous',13,10
    db    '        IF E[xists] fn     true if file fn exists',13,10
    db    '        IF M[issing] fn    true if file fn does not exist',13,10
    db    '        IF N[ull] (fn)     true if the fn is missing',13,10
    db    '        IF Z[ero] fn       true if file fn is zero length or',13,10
    db    '                   does not exist',13,10
    db    13,10
    db    'If the condition is true, all commands up to the next ELSE or',13,10
    db    'ENDIF statement are executed.  If an ELSE is encountered before',13,10
    db    'the ENDIF statement is reached, commands are skipped until the',13,10
    db    'ENDIF is found.  If the condition is false, commands are skipped',13,10
    db    'until the matching ELSE or ENDIF is found.  Command execution',13,10
    db    'then resumes.  IF-ELSE-ENDIF groups may be nested to any depth.',13,10
    db    13,10
    db    'Only the first character of the first keyword (the A of Ambig or',13,10
    db    'whatever) is checked.',13,10
    db    '$'
;
;
subfile    db    drive+1-'A'    ; drive for the $$$.SUB file
    db    '$$$     SUB'    ;  and the parsed name
    db    0,0        ;  and extent and S1 bytes
subs2    ds    1        ;  and the S2 byte (0'ed to cause BDOS rewrite)
subCNT    ds    1        ;  and the record count
        ds    16        ;  room for the allocation map
subREC    ds    1        ;  room for the current record number
    ds    3        ;  and finally, room for the random rec num
;
dmabuf    ds    128        ; the dma buffer for all operations
;
    end