World of Shareware - Software Farm 2/wosw_2.zip/wosw_2/CPROG/CMDSRC.ZIP/CMDMACRO.ASM

Assembly Source File | 1990-06-24 | 43KB | 1,529 lines

; CMDMACRO.ASM
; (c) 1989, 1990 Ashok P. Nadkarni
;
; Module implementing macro and symbol feature for CMDEDIT.
;
; Symbols :
; CMDEDIT symbols can be defined either from the command line or read
; from a file during initialization. The syntax is given by
;    defs symbolname expansion
; When the defined symbol appears as the first word in the line, it is
; replaced by its expansion. The rest of the line is unchanged. The
; following line defines a symbol called 'ed' that runs my editor.
;
;    defs ed c:\util\editor
;
; Now if you type
;
;    ed newfile
;
; the command
;
;    c:\util\editor newfile
;
; will be executed.
;
; Symbols are expanded recursively.
;
; Macros :
;
; CMDEDIT macros can be defined either from the command line or read
; from a macro file when CMDEDIT is installed. In both cases, macros
; are defined using the same syntax. Macros may expand into multiple
; lines. In the latter case, each line of the expansion in passed to
; the calling application one at a time.
;
; Macros are defined using the CMDEDIT command 'defm' followed by the
; macro name. The macro name is separated from the 'defm' keyword by one
; or more spaces/tabs. Any characters after the name of the macro are ignored.
; Each line of the macro expansion is defined on a separate line. The
; expansion may contain any number of lines (limited by buffer space)
; and is terminated by a line that begins with the keyword 'endm'. For
; example, the following lines define a macro that will change the
; current directory from any disk:
;    defm gotc
;    c:
;    cd \TURBOC
;    endm
; Macro keywords are case-insensitive.
;
; Macro Parameters:
;    Similar to batch files, macros can be passed parameters. (Read
; your DOS manual to find out about parameters). Although the
; concept is similar to DOS batch files, CMDEDIT parameters behave a
; little differently. Upto 9 parameters can be defined. These are
; indicated in macro definitions as '%n' where n is a digit from 1 to 9.
; A parameter can appear anywhere in the definition and need
; not be surrounded by whitespace. Also, the character % itself can be
; placed anywhere in the definition as long as it is not followed by a
; digit. If you do want a '%n' sequence in the expansion, indicate the '%'
; character as '%%'.
; For example, consider
;    defm bf
;    copy %1 a:\%1\%%1
;    endm
; Then, when you type
;    "bf myfile"
; the macro will expand to
;    "copy myfile a:\myfile\%1"
; Note how %1 has been replaced by 'myfile' in two places but not the third.
;
; A macro cannot call another macro except if the call is the last
; line in the macro. Macros anywhere else are not expanded and the line
; is passed to the calling application without modification.
;
; Note that the macro name can be null as well. In this case, hitting
; carraige return on an blank line will result in that macro being run.

    INCLUDE common.inc
    INCLUDE general.inc
    INCLUDE ascii.inc
    INCLUDE dos.inc

    PUBLIC    macro_init
    PUBLIC    symbol_init
    PUBLIC    execute_defm
    PUBLIC    execute_defs
    PUBLIC    execute_delm
    PUBLIC    execute_dels
    PUBLIC    execute_rstsym
    PUBLIC    execute_rstmac
    PUBLIC    execute_cmdstat
    PUBLIC    get_macro_line
    PUBLIC    expand_macro
    PUBLIC    expand_symbol
    PUBLIC    expand_var
    PUBLIC    get_symbol
    PUBLIC    mac_stk
    PUBLIC    sym_stk
    PUBLIC    ismacsym

PLACEHOLDER equ PERCENT                ;Placeholder character

    INCLUDE buffers.inc

CSEG    SEGMENT    PARA PUBLIC 'CODE'
DGROUP    GROUP    CSEG

    EXTRN    endm_cmd:BYTE
    EXTRN    defm:BYTE
    EXTRN    defs:BYTE
    EXTRN    get_kbd_line:ABS
    EXTRN    source:WORD
    EXTRN    macro_level:WORD
    EXTRN    macro_ignore_char:BYTE
    EXTRN    lastchar:WORD
    EXTRN    linebuf:BYTE
    EXTRN    dot:WORD
    EXTRN    LINEBUF_END:ABS
    EXTRN    cur_macro:BYTE
    EXTRN    cur_macro_len:WORD

mac_stk $string_stack    <>        ;Descriptor for macro buffer
sym_stk    $string_stack    <>        ;Descriptor for sym buffer
separator db    13            ;Separator string between macros
sep_len    equ    $-separator        ;Length of separator string
macro_noroom_msg db 'Table full. Definition ignored.',CR,LF,DOLLAR
macro_prompt    db  CR,LF,'DEFM>',DOLLAR


    EXTRN    push_word:PROC
    EXTRN    push_string:PROC
    EXTRN    get_next_line:PROC
    EXTRN    reset_line:PROC
    EXTRN    abort_processing:PROC
    EXTRN    getargs:PROC
    EXTRN    stre_cmp:PROC
    EXTRN    set_disp_marks:PROC
    EXTRN    isspace:PROC
    EXTRN    isdelim:PROC
    EXTRN    skip_whitespace:PROC
    EXTRN    skip_nonwhite:PROC
    EXTRN    skip_nondelim:PROC
    EXTRN    makeroom:PROC
    EXTRN    remove_chars:PROC
    EXTRN    insert_chars:PROC
    EXTRN    output_counted_string:PROC
    EXTRN    output_newline:PROC
    EXTRN    locate_dosenv:PROC

    ASSUME    CS:DGROUP,DS:DGROUP,ES:DGROUP,SS:DGROUP


;+
; FUNCTION : macro_init,symbol_init
;
; Initializes the various data structures associated with the
; macro /symbol buffer. CALLER MUST ENSURE PASSED ADDRESSES ARE VALID
; AND BUFFER IS LARGE ENOUGH.
;
; Parameters:
;    AX     - length of buffer in bytes
;    BX    - address of buffer
;
; Returns:
;    Nothing.
; Registers destroyed :
;    BX
;-
macro_init proc    near
    push    bx
    mov    bx,offset DGROUP:mac_stk ;bx := address of buffer descriptors
    jmp    short @macsym_init
symbol_init LABEL near
    push    bx
    mov    bx,offset DGROUP:sym_stk ;bx := address of buffer descriptors
@macsym_init:
    xchg    ax,cx            ;CX = buffer size
    pop    ax            ;AX = Buffer address
                    ;BX points to appropriate descriptor
    call    near ptr strstk_init    ;Initialize buffer and descriptor

;Store a separator into the macro buffer
    call    near ptr separate

    ret
macro_init    endp





;+
; FUNCTION : execute_rstmac, execute_rstsym
;
; Resets the various data structures associated with the
; macro /symbol buffer.
;
; Parameters:
;    None.
;
; Returns:
;    Nothing.
;
; Registers destroyed :
;    AX,CX,BX,DX
;-
rst_macsym proc near
execute_rstmac LABEL near
;    mov    macro_level,0
    mov    bx,offset DGROUP:mac_stk ;bx := address of buffer descriptors
    jmp    short @rst_macsym
execute_rstsym LABEL near
    mov    bx,offset DGROUP:sym_stk ;bx := address of buffer descriptors
@rst_macsym:
    call    near ptr strstk_reset    ;Re-initialize buffer and descriptor

;Store a separator into the macro buffer
    call    near ptr separate
    ret
rst_macsym    endp




;+
; FUNCTION : ismacsym
;
;    Called to check if the passed string is a valid symbol or macro
;    name. If found, the symbol/macro string stack pointer is set to the
;    first line of the expansion of the symbol/macro.
;
; Parameters:
;    AX    - length of symbol name to be checked
;    BX    - address of the string stack descriptor (symbol or macro)
;    SI    - pointer to the symbol to be checked.
;
; Returns:
;    CF    - 1 if symbol not found, the string stack current pointer
;          is undefined
;          0 if symbol found. The string stack pointer points to the
;          first line of the expansion of the found symbol/macro.
; Register(s) destroyed:
;    AX,CX,DX
;-
ismacsym proc near
    @save    si,di

    mov    di,ax            ;DI<-length of symbol
    call    near ptr strstk_settop    ;Reset macro stack pointer

@ismacsym_20:
; Loop start, DI = num chars in word, SI->start of word

    mov    ax,si            ;AX->word
    mov    cx,di            ;CX<-length of word
    call    near ptr strstk_bck_find ;Look backward for string
;                     Params AX,BX,CX
;                     BX unchanged
    jc    @ismacsym_98        ;Not found so return with CF set
;    The name matched. Now make sure it is a macro name by ensuring
;    previous string is a separator.
    xor    cx,cx            ;cx<-length of pattern
    call    near ptr strstk_bck_match ;Set current to previous string
;                     BX unchanged
    jc    @ismacsym_98        ;start of buffer so return
;                     with CF set
    push    bx
    call    near ptr check_separator
    pop    bx
    je    @ismacsym_50        ;This is the one
;    Wasn't a separator. Move back over it to start the hunt again.
    xor    cx,cx
    call    near ptr strstk_fwd_match
    jmp    short @ismacsym_20

@ismacsym_50:
; The macro/symbol has been found.
    xor    cx,cx            ;CX<-match length
    call    near ptr strstk_fwd_match ;Skip over separator
    xor    cx,cx            ;CX<-match length
    call    near ptr strstk_fwd_match ;Skip over macro/symbol name
    clc                ;Clear return flag
@ismacsym_98:
    @restore
    ret
ismacsym endp



;+
; FUNCTION : execute_dels, execute_delm
;
;    execute_dels and execute_delm respectively delete symbols and
;    macros from the appropriate stack. All symbols/macros listed on the
;    line are deleted. If a particular symbol/macro is not defined, no
;    error is generated.
;
; Parameters:
;    SI    -> first char in linebuf following this command
;    CX    == remaining num chars in the line
;
; Returns:
;    Nothing.
;
; Register(s) destroyed:
;    AX,BX,CX,DX
del_macsym proc near
execute_dels LABEL near
    mov    bx,offset DGROUP:sym_stk
    jmp    short @del_macsym_5
execute_delm LABEL near
    cmp    macro_level,1
    jne    @execute_delm_1
    mov    ax,E_NESTED_DELM
    jmp    near ptr abort_processing
@execute_delm_1:
    mov    bx,offset DGROUP:mac_stk
@del_macsym_5:
    @save    si,di
    push    bp
    mov    bp,sp
    sub    sp,2
num_remain equ <word ptr [bp-2]>
;
@del_macsym_10:
; At this point, SI->remaining chars in line, CX is number of chars
    jcxz    @del_macsym_99            ;No more chars in line
;    Find first word
    push    bx                ;Save buffer descriptor addr
    call    near ptr skip_whitespace    ;SI->first non blank
    mov    di,si                ;DI->start of word
    call    near ptr skip_nondelim        ;SI->char after word
    mov    ax,si                ;
    xchg    si,di                ;SI->word, DI->rest of line
    sub    ax,si                ;AX<-num chars in word
    pop    bx                ;BX->buffer descriptor
    push    cx                ;Save remaining count
    call    near ptr ismacsym        ;Is it in macro/symbol stack ?
    pop    cx                ;Restore remaining count
    mov    si,di                ;SI->rest of line
    jc    @del_macsym_10            ;Not found so go onto next
;                         symbol
; The macro or symbol has been found. The current stack pointer is the
; first line of the expansion. Move it down to the separator just before
; the macro or symbol name itself. Then keep deleting strings from the
; stack until we hit another separator.
    push    cx                ;Save remaining count
    xor    cx,cx
    call    near ptr strstk_bck_match    ;Point to name
    xor    cx,cx
    call    near ptr strstk_bck_match    ;Point to separator
@del_macsym_20:
    call    near ptr strstk_kill        ;Delete the string
;    Check if separator
    call    near ptr check_separator    ;Is new 'current' a
;                         separator ?
    jne    @del_macsym_20            ;No, so keep deleting
;    Reached a separator.
    pop    cx                ;Restore count
    jmp    short @del_macsym_10        ;Keep looping for rest of line

@del_macsym_99:
    mov    sp,bp
    pop    bp
    @restore
    ret
del_macsym endp



;+
; FUNCTION : expand_macro, expand_symbol
;
;    expand_macro and expand_symbol attempt expand the first word in
;    linebuf as a macro name and symbol respectively. If no macro
;    expansion is going on, the expand_macro routine will attempt to
;    expand the first word in the line buffer as a macro (leading
;    whitespace is ignored). If an expansion is found, it is stored
;    in the line buffer with the parameters (if any) filled in. If
;    there is already a macro expansion going on or no macro is
;    found, the line buffer is unchanged.
;
;    In contrast, the expand_symbol routine always tries to
;    expand the first word as a symbol.
;
;    If the first character of the line is a macro_ignore_char, the
;    character is removed, the rest of the line moved up and no
;    expansions are done.
;
; Parameters:
;
; Returns:
;    CF =    0 if line buffer changed
;        1 otherwise (no macro/symbol or ongoing macro expansion)
;
; Register(s) destroyed:
; AX,BX,CX,DX
;-
expand_macro proc near
    mov    bx,offset DGROUP:mac_stk ;BX->macro descriptor
    jmp    short @expand
expand_symbol LABEL near
    mov    bx,offset DGROUP:sym_stk ;BX->symbol descriptor
@expand:
    push    si
    push    di
    push    bp
    mov    bp,sp
    sub    sp,2
num_remain  equ <word ptr [bp-2]>

    cmp    bx,offset DGROUP:mac_stk
    jne    @expand_10        ;If symbol, don't worry about
;                     whether any macro expansions
;                     are ongoing
    cmp    macro_level,0        ;Already expanding a macro?
    je    @expand_10        ;No macro expansion currently ongoing
    stc                ;set CF to indicate no expansion
    jmp    @expand_98        ;Yes, exit with carry flag set

@expand_10:
; Look back through the macro/symbol stack buffer for a macro definition.

;    Find first word of line.
    push    bx            ;Save buffer descriptor addr
    mov    cx,lastchar        ;End of line
    mov    si,offset DGROUP:linebuf ;SI->line buffer
    sub    cx,si            ;CX<-length of line
    call    near ptr skip_whitespace ;SI->first non blank
    mov    di,si            ;DI->start of word
    call    near ptr skip_nondelim    ;SI->char after word
    mov    num_remain,cx        ;Remember num chars remaining
;                     in line
    mov    ax,si            ;
    mov    si,di            ;SI->word
    sub    ax,si            ;AX<-num chars in word
    pop    bx            ;BX->buffer descriptor
    call    near ptr ismacsym    ;Is it in macro/symbol stack ?
    jc    @expand_98        ;Not found so return with CF set
; The macro or symbol has been found.

; CHeck if it is the macro/symbol string stack
    cmp    bx,offset DGROUP:mac_stk  ;Expanding a macro ?
    jne    @expand_50        ;No, expanding symbol

    mov    macro_level,1        ;Indicate expansion going on
;    Copy linebuf into cur_macro (to remember arguments)
    mov    di,offset DGROUP:cur_macro
    mov    si,offset DGROUP:linebuf
    mov    cx,lastchar
    sub    cx,si            ;CX<-length of linebuf
    mov    cur_macro_len,cx    ;Store length of invocation line
    rep    movsb            ;Remember macro invocation line
; The current stack string is the first expansion line of the macro
    mov    sp,bp            ;clean up stack
    pop    bp            ;restore registers
    pop    di
    pop    si
    jmp    short get_macro_line    ;Yes, copy it into the linebuf buffer
;    get_macro_line will return to caller with  the appropriate value
;    of the carry flag.

@expand_50:
; We are expanding a symbol.
; num_remain = num chars in linebuf after symbol
; First we move these characters to the end of the buffer

    mov    cx,num_remain        ;CX<-number of chars to move back

    call    near ptr makeroom    ;Make room in buffer
    mov    si,di            ;SI->chars copied to the back
;    Now copy the string
    mov    ax,offset DGROUP:linebuf ;AX->line buffer
    mov    cx,LINEBUF_SIZE        ;CX<-size of line buffer
    call    near ptr strstk_copy    ;Copy line. Never mind if end
;                     string overwritten.
;                     AX<-length of expanded string
    mov    di,offset DGROUP:linebuf
    add    di,ax            ;DI->location after expansion
    mov    cx,num_remain        ;CX<-num chars to copy after expansion
    add    ax,cx            ;ax<-total length of line
    cmp    ax,LINEBUF_SIZE        ;End chars overwritten ?
    jbe    @expand_60
    mov    ax,E_TRUNCATE        ;Truncation error
    jmp    near ptr abort_processing
@expand_60:
; Copy trailing chars to end of expansion
    rep    movsb
    mov    lastchar,di
    mov    dot,di
    clc                ;Indicate expansion took place
@expand_98:
; MUST NOT CHANGE CARRY FLAG AFTER THIS POINT.
    mov    sp,bp            ;clean up stack
    pop    bp            ;restore registers
    pop    di
    pop    si
    ret
expand_macro    endp




;+
; FUNCTION : get_macro_line
;
;    Copies a line from the macro stack to linebuf. All parameters
;    codes (%1, %2 etc.) are replaced with their corresponding
;    parameters. If this line is the last in the macro definition,
;    the macro_level flag is reset. This allows the last line in a
;    macro definition to be treated as a macro itself. In case of
;    any errors( eg. expansion too long), the macro expansion is
;    aborted and the input is directed to the keyboard.
;
; Parameters:
;    None.
;
; Returns:
;    CF    = 0 if a line copied to linebuf
;          1 if no more lines in expansion or no ongoing expansion
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
get_macro_line    proc near
    cmp    macro_level,0        ;Expanding a macro ?
    jne    @get_macro_line_1    ;Yes
    stc                ;CF = 1 for no expansion
    ret
@get_macro_line_1:
    push    si
    push    di
    push    bp
    mov    bp,sp
    sub    sp,LINEBUF_SIZE
tempbuf    equ    <byte ptr [bp-LINEBUF_SIZE]>

; Copy the current string from the macro buffer into temp buffer.
    mov    bx,offset DGROUP:mac_stk ;BX->address of buffer descriptors
    lea    ax,tempbuf        ;AX->destination address
    mov    cx,LINEBUF_SIZE        ;CX<-size of buffer
    call    near ptr strstk_copy    ;Copy macro into temp buffer
                    ;AX<-length of expansion
                    ; No error possible
; Replace any placeholders in the macro line by the corresponding paramters.
; copy all chars until first placeholder. Copy argument.
; Repeat for whole expansion. If at any time there is no place in
; buffer, then abort.
    xchg    cx,ax            ;CX<-length of expansion
    lea    si,tempbuf        ;SI->tempbuf (macro expansion)
    mov    di,offset DGROUP:linebuf ;DI->linebuf
@get_macro_line_38:
    jcxz    @get_macro_line_60    ;Jump if no more expansion

@get_macro_line_40:
; At the start of the loop, the following hold :
; DI->next empty location in the linebuf
; SI->next char of macro expansion to be examined (in tempbuf)
; CX = remaining number of chars in expansion (> 0)
    mov    al,PLACEHOLDER        ;Going to search for placeholder
    mov    dx,cx            ;DX<-length of remaining expansion
    push    di            ;Save DI
    mov    di,si            ;DI->start point for
;                     placeholder scan
    repne    scasb            ;Look for placeholder
                    ;assumes! (ES == SS)
;    CX is number of chars after placeholder
    sub    dx,cx            ;DX<-num chars to be copied
    xchg    dx,cx            ;CX<-num chars to be copied
                    ;DX<-num chars after placeholder
    pop    di            ;DI->destination in linebuf
    rep    movsb            ;Move chars from tempbuf to linebuf
                    ;assumes! (ES == SS)
;    Note we don't care if the characters at the end of the linebuf
;    are overwritten.
    mov    cx,dx            ;CX<-remaining number of chars
    jcxz    @get_macro_line_60    ;All chars copied (placeholder
                    ; not found or last char in line)
;    We have found a placeholder character in tempbuf. SI points to the
;    character AFTER the placeholder. Based on the JCXZ above, there
;    is at least one character after the placeholder. If it is a
;    char between '0' and '9' then it is a genuine placeholder. If
;    it is another placeholder character, then a single placeholder
;    is stored. Else both the placeholder as well as the character
;    will be stored into linebuf.
    mov    al,[si]            ;AL<-char after placeholder
    cmp    al,PLACEHOLDER        ;Is it a placeholder ?
    jne    @get_macro_line_45    ;No
;    Skip over second placeholder
    inc    si
    loop    @get_macro_line_40
    jmp    short @get_macro_line_60 ;No more chars in expansion
@get_macro_line_45:
    cmp    al,'9'
    ja    @get_macro_line_40    ;Not a digit
    sub    al,'0'-1        ;Compaer with '0'. At the same
;                     time translate '0'->1,'1'->2
;                     ..and so on to '9'->10 since
;                     getargs counts from 1, not 0.
    jbe    @get_macro_line_40    ;Not a digit
    dec    di            ;Cancel stored PLACEHOLDER char
    push    cx            ;Save CX
    mov    bx,di            ;BX->destination for argument
    mov    dx,LINEBUF_END
    sub    dx,bx            ;DX<-remaining space in buffer
    mov    di,si            ;Save SI in DI
    mov    si,offset DGROUP:cur_macro ;SI->current macro being expanded
    xor    ah,ah            ;AX<-arg number (AL already
;                     holds actual arg number)
    mov    cx,cur_macro_len    ;Length of original macro string
    call    near ptr getargs    ;Get the argument into linebuf
                    ;AX<-num chars copied, BX unchanged
                    ;CF indicates error condition
    pop    cx            ;Restore CX (num remaining
;                     chars in macro expansion)
    mov    si,di            ;Restore SI
;                    (SI->char AFTER placeholder char)
    mov    di,bx            ;Start of copied characters
    jc    @get_macro_line_101    ;Jump if getargs returned error
@get_macro_line_50:
    add    di,ax            ;DI->next destination char in linebuf
    inc    si            ;SI->next char of macro expansion
    loop    @get_macro_line_40    ;Decrement remaing characters

@get_macro_line_60:

    mov    lastchar,di            ;Update end of line
    mov    dot,di                ;Update cursor
; Set the lastchar and display end pointers
    IF    0
    Currently no need to set display pointers since macro lines are
    not displayed
    mov    ax,di                ;AX->Potential disp_end
    mov    dx,offset DGROUP:linebuf     ;Potential disp_begin
    call    near ptr set_disp_marks        ;Set the marks
    ENDIF

; Finally check to see if this line is the last in the macro expansion.
    mov    bx,offset DGROUP:mac_stk ;BX->macro stack descriptor
    xor    cx,cx            ;Move to next string in stack
    call    near ptr strstk_fwd_match
    call    near ptr check_separator ;Is this the last line of
;                      expansion ?
    jne    @get_macro_line_90    ;No

; This was the last line in the macro expansion. Reset macro flag
    mov    macro_level,0        ;Reset flag
@get_macro_line_90:
;    @unlink
    mov    sp,bp            ;clean up stack
    pop    bp            ;restore registers
    pop    di
    pop    si
    clc                ;Return macro expanded
    ret

@get_macro_line_101:
; truncation error
    mov    ax,E_TRUNCATE        ;Indicate truncation of line
    jmp    near ptr abort_processing

get_macro_line    endp




;+
; FUNCTION : check_separator
;
;    Checks to see if the current macro/symbol buffer line is a
;    separator.
;
; Parameters:
;    BX    = address of macro/symbol stack descriptor
;
; Returns:
;    ZF = 1 if current buffer line is the separator string
;         0 otherwise.
;
; Register(s) destroyed:
;    AX,CX
;-
check_separator proc near
    mov    ax,offset DGROUP:separator
    mov    cx,sep_len
    call    near ptr strstk_compare    ;Is it the separator ?
;    strstk_comapre sets ZF.
    ret
check_separator endp




;+
; FUNCTION : execute_defs
;
;    Called to define a symbol.
;
; Parameters:
;    SI    -> first char in linebuf following this command
;    CX    == remaining num chars in the line
;
; Returns:
;    Nothing.
;
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
execute_defs    proc near
    mov    bx,offset DGROUP:sym_stk    ;BX->stack descriptor
; Push macro name
    call    near ptr push_word        ;Push first word onto
;                         the stack. Params :
;                         SI->string
;                         CX=num chars
;                         Returns:
;                         AX<-status code
;                         SI->char after word
;                         CX<-num remaining chars
    cmp    ax,0                ;Check status
    jg    @execute_defs_99        ;No word on line,
;                         ignore command
    jl    @execute_defs_109        ;No room in stack

; Now push the rest of the string as is except that leading whitespace
; is compressed.
    call    near ptr skip_whitespace    ;Skip leading whitespace
                        ;Params SI, CX
                        ;Returns SI->first
;                         non-white space char
;                         CX<-remaining chars
;                         (maybe 0)
    call    near ptr push_string        ;Push string onto stack
;                         (maybe null string)
    jc    @execute_defs_109        ;No room in stack
    call    near ptr cmdsym_separate    ;Push separator onto stack
    jc    @execute_defs_109        ;No room in stack
@execute_defs_99:
    ret

@execute_defs_109:
; Error. No room in macro stack.
    call    near ptr cmdsym_cleanup        ;Clear out partial definition
    call    near ptr disp_noroom    ;Display error
    ret
execute_defs    endp


;+
; FUNCTION : execute_defm
;
;    Called to define a multiple line macro. This function will
;    keep reading from the current input source and storing it in
;    the macro buffer until an `endm' is seen. The ENDM directive
;    can be followed by any characters (eg. macro name)
;
; Parameters:
;    SI    -> first char in linebuf following this command
;    CX    == remaining num chars in the line
;
; Returns:
;    Nothing.
;
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
execute_defm    proc near
    mov    ax,E_NESTED_MACRO    ;Assume error
    cmp    macro_level,0        ;Expanding a macro ?
    je    @execute_defm_1        ;No, jump
    jmp    near ptr abort_processing ;Yes, nested macro error
@execute_defm_1:
    @save    si,di
    push    bp
    mov    bp,sp
    sub    sp,2
err_flag equ <word ptr [bp-2]>
    mov    bx,offset DGROUP:mac_stk    ;BX->stack descriptor
    mov    err_flag,0            ;Initially no errors

; If expanding a macro, ignore all lines until an endm
    cmp    macro_level,0
    jnz    @execute_defm_5            ;Go set error flag

; Push macro name
    call    near ptr push_word        ;Push first word onto
;                         the stack. Params :
;                         SI->string
;                         CX=num chars
;                         Returns:
;                         AX<-status code
;                         SI->char after word
;                         CX<-num remaining chars
    cmp    ax,0                ;Check status
    jb    @execute_defm_5            ;No room in stack
    je    @execute_defm_40        ;No errors
; No name for macro. Push a 0 length macro name. Macro can be called by
; a blank line
    xor    cx,cx                ;CX<-0 (length of string)
    call    near ptr push_string        ;Push onto stack
    jnc    @execute_defm_40        ;No errors

@execute_defm_5:
    mov    err_flag,1            ;Indicate error
    call    near ptr cmdmacro_cleanup    ;Cleanup macro fragments

@execute_defm_40:
; Keep reading lines from the input and store in macro buffer unless an error
; has been previously seen.

;     Prompt is displayed only if reading from the keyboard.
    cmp    source,offset DGROUP:get_kbd_line
    jne    @execute_defm_42
    @DispStr macro_prompt
    call    near ptr reset_line
@execute_defm_42:
    call    near ptr get_next_line
    mov    si,offset DGROUP:linebuf    ;SI->String to push
    mov    cx,lastchar
    sub    cx,si                ;CX<-length of line
    push    si                ;Remember SI and CX
    push    cx
    call    near ptr skip_whitespace    ;SI->first non-white
                        ;CX<-num remaining chars
    jcxz    @execute_defm_50        ;Blank line so go store it
    mov    di,si                ;DI->start of word
    call    near ptr skip_nonwhite
    mov    cx,si
    sub    cx,di                ;CX<-length of word
    xor    ah,ah
    mov    si,offset DGROUP:endm_cmd
    lodsb                    ;AX<-length of endm command
    cmp    cx,ax
    jne    @execute_defm_50        ;Not ENDM
    call    near ptr stre_cmp        ;Compare strings
    jnz    @execute_defm_50
; ENDM seen.
    cmp    err_flag,1            ;Had we seen an error ?
    jne    @execute_defm_45        ;No
    call    near ptr disp_noroom    ;Display error
    jmp    short @execute_defm_99
@execute_defm_45:
; End of macro seen. Store macro separator
    call    near ptr cmdmacro_separate
    jmp    short @execute_defm_99

@execute_defm_50:
; Store line in macro buffer
    pop    cx                ;CX<-length of line
    pop    si                ;SI->linebuf
    mov    bx,offset DGROUP:mac_stk    ;BX->stack descriptor
    call    near ptr push_string
    jnc    @execute_defm_40        ;No error
    jmp    short @execute_defm_5        ;Indicate error

@execute_defm_99:

    mov    sp,bp
    pop    bp
    @restore
    ret
execute_defm endp




;+
; FUNCTION : cmdmacro_separate,cmdsym_separate,separate
;
;    Pushes a separator string onto the stack.
;
; Parameters:
;    None for cmdmacro_separate and cmdsym_separate
;    BX->buffer descriptor for routine separate
; Returns:
;    CF    = 1 if no room in stack
;          0 otherwise
;
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
cmdmacro_separate proc near
    mov    bx,offset DGROUP:mac_stk    ;BX->stack descriptor
    jmp    short separate
cmdsym_separate LABEL near
    mov    bx,offset DGROUP:sym_stk    ;BX->stack descriptor
separate    LABEL near
    mov    ax,sep_len            ;AX<-length of separaot string
    mov    dx,offset DGROUP:separator    ;DX->separator string
    mov    cx,1                ;Force push onto stack
    call    near ptr strstk_push        ;Returns status in CF
    ret
cmdmacro_separate endp




;+
; FUNCTION : cmdmacro_cleanup,cmdsym_cleanup
;
;    This function is called to clean up the top of the macro or symbol
;    stacks when a complete definition cannot be pushed onto the
;    stack due to lack of space. The routine keeps deleting strings
;    from the top of the macro stack until it finds a separator string.
;
; Parameters:
;    None.
;
; Returns:
;    Nothing.
;
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
cmdmacro_cleanup proc near
    mov    bx,offset DGROUP:mac_stk    ;BX->stack descriptor
    jmp    short @cleanup_5
cmdsym_cleanup    LABEL near
    mov    bx,offset DGROUP:sym_stk    ;BX->stack descriptor
@cleanup_5:
    call    near ptr strstk_settop        ;Reset cur pointer
;                         BX unchanged
; While the top of stack is not a separator, keep killing strings.
@cleanup_10:
    call    near ptr check_separator
;    mov    ax,offset DGROUP:separator    ;AX->separator string
;    mov    cx,sep_len            ;CX<-length of separator
;    call    near ptr strstk_compare        ;Is this a separator ?
    je    @cleanup_99            ;Yes, then all done
    call    near ptr strstk_kill        ;Kill string
    jmp    short @cleanup_10        ;Keep going
@cleanup_99:
    ret
cmdmacro_cleanup endp




;+
; FUNCTION : disp_noroom
;
;    Displays a message saying there is no room in the macro buffer.
;
; Parameters:
;    None.
;
; Returns:
;    Nothing.
; Register(s) destroyed:
;    AX,DX
;-
disp_noroom proc near
    @DispStr macro_noroom_msg
    ret
disp_noroom endp







;+
; FUNCTION : search_variable
;
;    Called to search the passed string for a variable. A variable is a
;    sequence of characters starting with the VAR_MARKER character
;    followed by another VAR_MARKER character. Two marker characters in
;    succession are left untouched. (This is so that this routine can be
;    called again to check for more variables.)
;
; Parameters:
;    SI    - points to the string.
;    AX    - length of the string.
;
; Returns:
;    SI    - Points to first marker character of variable if AX is not 0
;          else points to end of string.
;    AX    - length of variable (including marker chars) if
;          variable is present, else 0
; Register(s) destroyed:
;    CX
;-
search_variable proc near
    @save    di
    mov    cx,ax

@search_variable_10:
    mov    di,si                ;DI->string to search
;                         CX is number of chars
; Note we are OK if length of line is already 0.
    mov    al,VAR_MARKER
    repne scasb                ;Search for marker
; If marker not found or found in last position, CX will be 0.
    jcxz    @search_variable_99
; DI->char after first marker, CX is remaining number of characters
    mov    si,di
@search_variable_20:
    lodsb                    ;AL<-next char
    dec    cx
    jcxz    @search_variable_99        ;If there was only one char
;                         after the marker, variable
;                         not possible
    cmp    al,VAR_MARKER            ;Is it a marker ?
    je    @search_variable_10        ;Yes, found a marker, just
;                         ignore the pair and keep
;                         looking
; We have found the start of a variable. Look for its end.
    inc    di                ;Move past first char of var
    mov    al,VAR_MARKER
    repne    scasb                ;Look for it
    jne    @search_variable_99        ;Not found (CX is 0)
; Found a variable
    dec    si
    dec    si                ;SI->start marker of var
    mov    cx,di
    sub    cx,si                ;CX<-length of var

@search_variable_99:
    xchg    ax,cx                ;AX<-length of var
    @restore
    ret
search_variable    endp




;+
; FUNCTION : get_symbol
;
;    Hunts through the symbol stack looking for a match for the passed
;    symbol. If found, it is returned in passed buffer.
;
; Parameters:
;    SI    - points to the symbol
;    AX    - length of symbol
;    DI    - points to the expansion buffer
;    DX    - size of buffer
;
; Returns:
;    CF    - 1 symbol not found (AX set to 0) or [DI] buffer to small
;          to hold expansion (AX contains actual length of expansion).
;          0 symbol found. Its expansion is stored in [DI] with
;          length in AX.
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
get_symbol proc near
    @save    si
    mov    bx,offset DGROUP:sym_stk    ;BX->symbol stack
    push    dx                ;Save DX
    call    near ptr ismacsym        ;Is it a symbol ?
    pop    cx                ;CX<-size of buffer
    jnc    @get_symbol_20            ;Yes, go on
    xor    ax,ax                ;No, not a symbol
    stc                    ;Set CF to indicate error
    jmp    short @get_symbol_99

@get_symbol_20:
; Symbol has been found. The current symbol stack pointer has been set to
; its expansion string.
    mov    ax,di                ;AX->buffer
    call    near ptr strstk_copy        ;Params
;                         BX->stack descriptor
;                         AX->buffer
;                         CX->size of buffer
;                         Returns CF set if
;                         truncation error.
;                         AX always set to length of
;                         actual expansion.
;    CF set/reset by strstk_copy

@get_symbol_99:
    @restore
    ret
get_symbol endp





;+
; FUNCTION : get_dosenv
;
;    Hunts through the DOS environment looking for a match for the passed
;    string. If found, it is returned in passed buffer.
;
;    Assumes passed string does NOT contain a NULL byte.
;
; Parameters:
;    SI    - points to the string
;    AX    - length of string
;    DI    - points to the expansion buffer
;    DX    - size of buffer
;
; Returns:
;    CF    - 1 string not found (AX set to 0) or [DI] buffer too small
;          to hold expansion (AX contains actual length of expansion).
;          0 symbol found. Its expansion is stored in [DI] with
;          length in AX.
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
get_dosenv proc near
    @save    si,di,es
    push    bp
    mov    bp,sp
    sub    sp,6
var_len equ <word ptr [bp-2]>
exp_buf equ <word ptr [bp-4]>
exp_buf_len equ <word ptr [bp-6]>
    mov    var_len,ax            ;Save length of string
    mov    exp_buf,di            ;Save expansion buf address
    mov    exp_buf_len,dx            ;Save expansion buf length

    call    near ptr locate_dosenv        ;AX->DOS environment segment
    or    ax,ax                ;Is it 0?
    je    @get_dosenv_90            ;Yes, we do not know DOS env

; We have the DOS segment
    mov    es,ax                ;ES->environment segment
    xor    di,di                ;ES:DI->base of environment
    mov    cx,8000h            ;Max possible environ size
;                         is 32K

@get_dosenv_10:
; Top of env search loop. DI contains offset into environment. SI points to
; string. DI actually points to start of an env var name if any. CX is
; remaining bytes in environment (> 0)
    cmp    byte ptr es:[di],0        ;End of environment?
    je    @get_dosenv_89            ;Yes

; We are just going to call stre_cmp to compare strings. Does not matter if
; the environment or environment var ends before then since the comparison
; will fail since we are assuming a null byte does not occur in the string
; that was passed to us.
    push    cx                ;Remember how much
;                         environment left
    mov    cx,var_len            ;CX<-length to compare
    call    near ptr stre_cmp        ;Params DS:SI, ES:DI, CX
    pop    cx                ;CX<-remaining environment size
    je    @get_dosenv_50            ;Match so far

; No match. Hunt for the next null byte or end of environment.
@get_dosenv_40:
    xor    al,al
    repne    scasb
    jcxz    @get_dosenv_89            ;If no match for null or
;                         match in last byte, exit
    jmp    short @get_dosenv_10        ;Keep looking

@get_dosenv_50:
; We have a match so far. The next char in the environ must be a '='.
    mov    ax,var_len
    add    di,ax
    sub    cx,ax
    cmp    byte ptr es:[di],'='
    jne    @get_dosenv_40            ;No match

; We have a match.
    inc    di                ;DI->start of env expansion
    push    di                ;Save DI
    dec    cx                ;CX<-remaining length of env
    xor    ax,ax
    repne    scasb                ;Hunt for expansion end
    mov    ax,di
    pop    di                ;DI->start of expansion
    sub    ax,di
    dec    ax                ;AX<-length of expansion
    mov    cx,exp_buf_len            ;CX<-size of expansion buffer
    cmp    cx,ax                ;Is it too small?
    pushf                    ;Remember flags
    jb    @get_dosenv_60            ;Copy only that many bytes
    mov    cx,ax                ;Copy all bytes of expansion
@get_dosenv_60:
; AX contains number of bytes so do not change it after this.
    push    ds                ;Save DS
    push    es
    pop    ds
    pop    es
    mov    si,di                ;DS:SI->expansion of env var
    mov    di,exp_buf            ;ES:DI->expansion buffer
    rep    movsb
    push    es
    pop    ds                ;Restore DS. ES is restored
;                         at end of routine.
    popf                    ;Restore status in CF.
;                         AX already contains
;                         expansion actual byte count
    jmp    short @get_dosenv_99
@get_dosenv_89:
; Not found in environment
    xor    ax,ax
@get_dosenv_90:
; Error. AX must have been already set appropriately.
    stc
@get_dosenv_99:
    mov    sp,bp
    pop    bp
    @restore
    ret
get_dosenv endp



;+
; FUNCTION: replace_var_markers
;
;    Replaces all double VAR_MARKER characters with single VAR_MARKERs.
;    Any solo VAR_MARKERs are deleted (as in DOS batch files).
;
; Parameters:
;    DI    - points to string
;    CX    - length of string
;
; Returns:
;    AX - new length of string
;
; Registers destroyed:
;    AX,CX,DX
;-
replace_var_markers proc near
    @save    si,di
    mov    dx,cx
    mov    al,VAR_MARKER
@replace_var_markers_9:
    jcxz    @replace_var_markers_99
@replace_var_markers_10:
; CX must not be 0 at this point! Else calculation of DX goes wrong.
    repne    scasb                ;Look for marker
    jne    @replace_var_markers_99        ;No more markers in string
; Found a marker. Move remaining characters up by 1.
; DI->first char to be moved up, CX is number of chars to move up
    dec    dx                ;Deleted one char
    jcxz    @replace_var_markers_99        ;No more bytes
    push    cx                ;Sace byte count
    push    di                ;Save di
    mov    si,di
    dec    di
    rep    movsb                ;Move chars up
    pop    di                ;DI->next pos to start hunt
    pop    cx                ;remaining bytes
    dec    cx                ;jump over character that
;                         now occupies the original
;                         marker position.
    jmp    short @replace_var_markers_9

@replace_var_markers_99:
    mov    ax,dx                ;AX<-new string length
    @restore
    ret
replace_var_markers endp





;+
; FUNCTION : expand_var
;
;    Expands the variables (if any) present in the current line. A
;    variable consists of a series of non-delimiter characters
;    between two 'VAR_MARKER' characters. The DOS environment block is
;    first checked for the presence of the first such variable in the
;    line and if it is present, it is replaced with its value. Otherwise
;    the CMDEDIT symbols are checked for match. If there is a match, it
;    is replaced with the value of the symbol else, it is replaced by a
;    null string. This procedure is repeated until there are no symbols
;    in the line. Note that the replacements may themselves contain
;    variables which will be replaced in turn.
;
; Parameters:
;    None.
;
; Returns:
;    CF = 0 if no errors.
;    CF = 1 if errors (line too long). AX contains error code.
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
expand_var proc near
    @save    si,di
    push    bp
    mov    bp,sp
    sub    sp,LINEBUF_SIZE
var_exp equ <byte ptr [bp-LINEBUF_SIZE]>

@expand_var_10:
    mov    si,offset DGROUP:linebuf    ;SI->current line
    mov    ax,lastchar
    sub    ax,si                ;AX<-length of line
    call    near ptr search_variable    ;Look for a var
;                         AX<-length of var
;                         SI-> var
    or    ax,ax                ;AX is length of var
    je    @expand_var_60            ;No more vars,
; First check the DOS environment for the presence of this variable.
    mov    var_len,ax            ;Store var len in var_len
    inc    si                ;Move SI past the VAR_MARKER
    dec    ax
    dec    ax                ;Do not count the two
;                         VAR_MARKER characters
    lea    di,var_exp            ;DI->buffer
    mov    dx,LINEBUF_SIZE            ;DX<-size of expansion buffer
    call    near ptr get_dosenv        ;Params     SI->var, AX length
;                             DI->var_exp
;                         Returns expansion in [DI]
;                         AX length of expansion
    or    ax,ax                ;Any expansion ?
    jne    @expand_var_50            ;Yes - go store in line
; DOS environment did not have the var, now try the CMDEDIT symbol stack.
    mov    ax,var_len
    dec    ax
    dec    ax                ;Do not count the two
    mov    dx,LINEBUF_SIZE            ;DX<-size of expansion buffer
    call    near ptr get_symbol        ;Params SI,AX,DI,DX
;                         Returns expansion in [DI],
;                         length in AX
;    Even if expansion was null, fall thru and replace var with the
;    expansion (possibly null)

@expand_var_50:
; Replace the var pointed to by SI of length var_len by the expansion given
; in var_exp (with length in AX).
    dec    si                ;SI->points to marker
    mov    di,ax                ;Store AX in DI
    mov    ax,var_len
    call    near ptr remove_chars        ;SI,AX parameters
    mov    ax,di                ;Restore length of expansion
    mov    di,si                ;DI->destination
    lea    si,var_exp
;    push    dot                ;Save position
    call    near ptr insert_chars        ;SI,DI,AX parameters
;    pop    dot
    jnc    @expand_var_10            ;No error
    mov    ax,E_TRUNCATE            ;Truncation error
    jmp    short @expand_var_99        ;Exit, CF already has status


@expand_var_60:
; All variables have been replaced. Now change all double marker characters
; to single and delete all solo markers (similar to DOS)
    mov    di,offset DGROUP:linebuf    ;DI->string
    mov    cx,lastchar
    sub    cx,di                ;CX<-length of string
    call    near ptr replace_var_markers
    add    ax,di
    mov    lastchar,ax
    cmp    dot,ax
    jb    @expand_var_80
    mov    dot,ax
@expand_var_80:
    mov    dx,offset DGROUP:linebuf
    call    near ptr set_disp_marks        ;Assume all chars changed.
    clc                    ;CF<-0 (no errors)

@expand_var_99:
;    CF has status
    mov    sp,bp
    pop    bp
    @restore
    ret
expand_var endp



;+
; FUNCTION: disp_until_sep
;
;    This function outputs the contents of the specified stack until the
;    separator is seen. Each element of the stack is followed by a
;    CR-LF. The current pointer is left pointing to the separator.
;
; Parameters:
;    BX    - pointer to stack descriptor
;-
disp_until_sep proc near
    @save    si,di
    push    bp
    mov    bp,sp
    sub    sp,LINEBUF_SIZE+2
display_buf equ <byte ptr [bp-LINEBUF_SIZE]>
sym_kluge equ    <byte ptr [bp-LINEBUF_SIZE-2]> ;Kluge to not output extra
;                        space after defs line
    mov    sym_kluge,1

@disp_until_sep_10:
; Start of loop. Check if the current entry is a separator. If so exit.
; Else display the line.
    call    near ptr check_separator
    je    @disp_until_sep_99        ;Yes, all done
; Copy the string into the display buffer and display it.
    lea    ax,display_buf
    mov    cx,LINEBUF_SIZE
    call    near ptr strstk_copy
    xchg    cx,ax                ;CX<-length of string
    push    bx                ;Save BX
    lea    dx,display_buf            ;DX->string, CX is count
    call    near ptr output_counted_string
    pop    bx
    cmp    bx,offset DGROUP:mac_stk
    jne    @disp_until_sep_30
    call    near ptr output_newline
    jmp    short @disp_until_sep_32
@disp_until_sep_30:
    cmp    sym_kluge,0
    je    @disp_until_sep_32
    @DispCh    ' '
@disp_until_sep_32:
    xor    cx,cx
    call    near ptr strstk_fwd_match
    mov    sym_kluge,0
    jmp    short @disp_until_sep_10

@disp_until_sep_99:
    mov    sp,bp
    pop    bp
    @restore
    ret
disp_until_sep endp



;+
; FUNCTION: output_symbols,output_macros
;
;    Outputs to standard output the current buffer contents of
;    the symbol/macro buffer.
;
; Parameters:
;    None.
;-
output_macsym proc near
output_symbols LABEL near
    mov    bx,offset DGROUP:sym_stk
    mov    ax,offset DGROUP:defs
    jmp    short @output_macsym_5
output_macros LABEL near
    mov    bx,offset DGROUP:mac_stk
    mov    ax,offset DGROUP:defm
@output_macsym_5:
    @save    si,di
    mov    di,ax                ;DI->'defs' or 'defm'
    call    near ptr strstk_save_cur    ;Save current pointer.
;                         Probably not necessary for
;                         symbols, but do anyway
    call    near ptr strstk_setbot        ;Go to bottom of stack

    call    near ptr output_newline

@output_macsym_10:
; Start of loop. One entire macro or symbol has been processed so far.
; The current stack pointer is at the separator. First skip over the separator.
    xor    cx,cx
    call    near ptr strstk_fwd_match
; Try to move one more to make sure there is another string
    xor    cx,cx
    call    near ptr strstk_fwd_match
    jc    @output_macsym_99        ;End of buffer
; OK move back to get the name of the symbol / macro.
    xor    cx,cx
    call    near ptr strstk_bck_match
; Now output either 'defs' or 'defm'
    mov    dx,di
    inc    dx                ;Point to string
    xor    cx,cx
    mov    cl,[di]                ;Length of string
    push    bx                ;Save BX
    call    near ptr output_counted_string    ;Show command string
    @DispCh    ' '                ;followed by a space
    pop    bx
;    Now display all strings until a separator is seen
    call    near ptr disp_until_sep

; Now if we are showing a macro, output the 'endm', else a newline
    cmp    bx,offset DGROUP:mac_stk    ;Macro ?
    jne    @output_macsym_70        ;No, repeat loop
;    Output the 'endm'
    push    bx
    mov    bx,offset DGROUP:endm_cmd
    xor    cx,cx
    mov    cl,[bx]
    mov    dx,bx
    inc    dx
    call    near ptr output_counted_string    ;AX,BX,CX,DX destroyed
    pop    bx
    call    near ptr output_newline        ;Separate each macro with a
;                         newline

@output_macsym_70:
    call    near ptr output_newline
    jmp    @output_macsym_10

@output_macsym_99:
    call    near ptr strstk_restore_cur    ;Restore the current pointer
    @restore
    ret
output_macsym endp



;+
; FUNCTION: execute_cmdstat
;
;    Displays the current macro and symbol buffer contents.
;
;
; Parameters:
;    SI    -> first char in linebuf following this command
;    CX    == remaining num chars in the line
;
; Returns:
;    Nothing.
;
; Register(s) destroyed:
;    AX,BX,CX,DX
;-
execute_cmdstat proc near
    call    near ptr output_symbols
    call    near ptr output_macros
    call    near ptr output_newline
    ret
execute_cmdstat endp


CSEG    ENDS

    END