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Assembly Source File | 1991-08-09 | 82KB | 2,202 lines

page 66,132 ;============================================================================ ; STRINGS.COM - a set of string handling functions for batch files. ; ; Syntax: ; STRINGS [/H][/M][/Pc ][var = ] function arg1 [, arg2] [, arg3] ; ; /? - Print help message ; /M - Use master environment block ; /Pc - Use c as parse character instead of ',' ; ; Revision History: ; ; Version 1.0 Initial Release ; ;============================================================================ code segment assume cs:code org 2ch local_environment dw ? ;Word containing the segment ; of the program's env. block. org 80h command_tail db ? ;Offset of the command tail. org 100h main: jmp initialize program db 13,10,"STRINGS 1.0 " copyright db "(c) 1991 Douglas Boling",10,13 db "First published in PC Magazine, September 10, 1991" db 10,13,10,"$",1Ah VAR_SIZE equ 128 ;Max size of variables DATABUFF_SIZE equ 16384 ;Size of file data buffer command_table db "LEFT",0 ;String functions db "RIGHT",0 db "MID",0 db "LENGTH",0 db "FIND",0 db "FINDC",0 db "LOWER",0 db "UPPER",0 db "CHAR",0 db "VAL",0 db "FILENAME",0 db "FILEEXT",0 db "READ",0 ;File functions db "WRITE",0 db "FILESIZE",0 db "LINESIZE",0 db "TRUENAME",0 db "VER",0 ;System functions db "ASK",0 db "ENVFREE",0 db "ENVSIZE",0 db "MASTERVAR",0 db "ADD",0 ;Math functions db "SUB",0 db "MUL",0 db "DIV",0 db 0 ;End of list flag jump_table dw offset left_str dw offset right_str dw offset mid_str dw offset length_str dw offset find_str dw offset findc_str dw offset lower_str dw offset upper_str dw offset char_str dw offset val_str dw offset filename_str dw offset fileext_str dw offset readrec_file dw offset writerec_file dw offset filesize_file dw offset numrec_file dw offset truename_file dw offset ver_sys dw offset ask_sys dw offset envfree_sys dw offset envsize_sys dw offset mastervar_sys dw offset add_num dw offset sub_num dw offset mul_num dw offset div_num jump_table_end = $ parse_char db "," ;Char used to parse command fill_char db " " ;Char used to fill zeros equalsub_char db 0cdh databuff_ptr dw 0 ;Ptr to file data buffer environment_seg dw 0 ;Segment of master env dos_version dw 0 shell_name db "COMMAND" console_out db 1 ;Flag for con out. use_mastenv db 0 ;Flag to use master env parse_literal db 0 ;Flag to respect lead spaces dest_var_val dw 0 dest_var_name dw 0 ;Buffer pointers to parsed cmd_value dw 0 ; command line variables. var1_value dw 0 ; These pointers must be var2_value dw 0 ; kept in this order for the var3_value dw 0 ; cmdline parse routine. hlpmsg db 13,10,"Usage: STRINGS [/H][/M][/Pc][environment var =]" db " FUNCTION [str1][, str2][, str3]",13,10,13,10 db " /? - Print this help message",13,10 db " /M - Use master environment as destination",13,10 db " /Pc - Use char c instead of ',' as the parse " db "character",13,10,10 db " LEFT Returns left n chars " db "String, Num of chars",13,10 db " RIGHT Returns right n chars " db "String, Num of chars",13,10 db " MID Returns middle n chars " db "String, Start char, Length",13,10 db " LENGTH Returns string length " db "String",13,10 db " FIND Finds position of findstring " db "String, findstring",13,10 db " FINDC Finds position of findstring. Case sen " db "String, findstring",13,10,0 hlpmsga db " LOWER Returns string all lowercase " db "String",13,10 db " UPPER Returns string all uppercase " db "String",13,10 db " CHAR Returns ASCII number of character " db "Character",13,10 db " VAL Returns ASCII char for a number " db "Number",13,10,10 db " READ Returns a line from a file " db "Filename, line number",13,10 db " WRITE Writes a string to the end of a file " db "Filename, String",13,10 db " FILESIZE Returns the size of a file " db "Filename",13,10 db " LINESIZE Returns the number of lines " db "Filename",13,10,0 hlpmsgb db " FILENAME Returns the file name " db "Filename",13,10 db " FILEEXT Returns the file extension " db "Filename",13,10 db " TRUENAME Returns the complete filename " db "Filename",13,10,10 db " ASK Returns a response from a user " db "[Prompt string]",13,10 db " VER Returns the DOS version number",13,10 db " ENVFREE Returns the bytes free in the environment",13,10 db " ENVSIZE Returns the size of the environment",13,10 db " MASTERVAR Returns a variable from the Master env ",13,10,10 db " ADD Returns the sum of two numbers " db "Number, Number",13,10 db " SUB Returns the difference of two numbers " db "Number, Number",13,10 db " MUL Returns the product of two numbers " db "Number, Number",13,10 db " DIV Returns the quotient of two numbers " db "Number, Number",13,10 db 0 errmsg0 db "Need DOS 2.0 or greater",0 errmsg1 db "For help type STRINGS /?",0 errmsg2 db "Not enought memory",0 errmsg3 db "Unknown command line switch",0 errmsg6 db "Illegal filename",0 errmsg7 db "Line numbers must be greater than 0",0 errmsg8 db "Line not found",0 errmsg9 db "DOS error",0 errmsg10 db "Multiply overflow error",0 errmsg11 db "Divide by zero error",0 errmsg12 db "Addition overflow",0 errmsg13 db "Subtraction underflow",0 errmsg14 db "Number too large",0 errmsg15 db "Out of environment space",0 errmsg16 db "Can't find environment",0 errmsg17 db "Variable not found",0 pausemsg db "Press any key to continue",13,10,0 endmsg db 13,10,0 ;---------------------------------------------------------------------------- ; Start of code. ;---------------------------------------------------------------------------- initialize proc near assume cs:code,ds:code,es:code cld ;Set string operations 'up.' mov ah,30h ;Get DOS version, run only int 21h ; if 2.0 or greater. xchg al,ah ;Swap major, minor numbers mov dos_version,ax mov si,offset errmsg0 ;Bad DOS version cmp ah,2 jae main_1 jmp disp_error main_1: mov di,offset end_of_code + 512 ;Set up data buffers mov sp,di ;Set stack mov si,offset dest_var_val mov cx,6 ;Set buffer pointers xor ax,ax main_2: mov [si],di ;Save ptr to buffer push cx mov cx,VAR_SIZE ;Initialize buffer to zero rep stosb pop cx inc si inc si loop main_2 mov databuff_ptr,di ;Save data buffer ptr mov bx,DATABUFF_SIZE add bx,di mov cl,4 shr bx,cl inc bx mov ah,4ah ;Reduce memory allocation int 21h call parse_cmdline ;Parse command line jc disp_error mov si,dest_var_name ;Point to dest env var name call caps_string mov si,cmd_value ;Point to command buffer call caps_string mov di,offset command_table call findstr mov si,offset errmsg1 jc disp_error shl bx,1 ;Compute offset of routine to add bx,offset jump_table ; call. call [bx] ;Call routine to compile line. jc disp_error mov si,dest_var_val cmp console_out,0 ;See how to return result je main_3 call print_strcr ;Print result string to screen jmp short main_6 main_3: mov di,dest_var_name xchg di,si cmp use_mastenv,0 ;Find environment block jne main_4 call findenv ;Use parent's env by default. jnc main_5 main_4: call findmaster ;Find master env jc disp_error main_5: mov environment_seg,ax call setenv ;Set environemnt variable. jc main_7 main_6: xor al,al ;Return code = 0 exit: mov ah,4Ch ;Terminate int 21h ; ;Display error message. ; main_7: mov si,offset errmsg15 ;Out of environment space disp_error: push cs pop ds assume ds:code mov ah,9 ;Print copyright message mov dx,offset program int 21h push si call print_strcr ;print string pop si cmp si,offset hlpmsg jne main_9 mov ax,40h mov es,ax mov al,es:[84h] cmp al,42 ja main_8 call pause_scr mov si,offset hlpmsga call print_strcr call pause_scr mov si,offset hlpmsgb call print_strcr jmp short main_9 main_8: mov si,offset hlpmsga call print_strcr mov si,offset hlpmsgb call print_strcr main_9: mov al,01 ;Terminate with RC = 1 jmp short exit ;============================================================================= ; String Functions ;============================================================================= ;----------------------------------------------------------------------------- ; RIGHT STR returns the right n characters of the source string ;----------------------------------------------------------------------------- right_str proc near assume cs:code,ds:code,es:code mov si,var2_value ;Convert 2nd parameter to hex call asc2hex call truncnum ;Truncate number to string len push ax mov di,var1_value ;Scan to end of string call find_end pop ax right_str_2: sub di,ax dec di cmp di,var1_value ja right_str_3 mov di,var1_value right_str_3: mov si,dest_var_val xchg di,si call copy_string ;Copy string to dest buffer clc ret right_str endp ;----------------------------------------------------------------------------- ; LEFT STR Returns the left n characters of the source string ;----------------------------------------------------------------------------- left_str proc near assume cs:code,ds:code,es:code mov si,var2_value ;Convert 2nd parameter to hex call asc2hex call truncnum ;Truncate number to string len mov si,var1_value mov bx,ax mov byte ptr [si+bx],0 mov di,dest_var_val call copy_string ;Copy string to dest buffer clc ret left_str endp ;----------------------------------------------------------------------------- ; MID STR Returns a string of n characters starting m characters from the ; left of the source string ;----------------------------------------------------------------------------- mid_str proc near assume cs:code,ds:code,es:code mov si,var2_value ;Convert 2nd parameter to hex call asc2hex dec ax call truncnum ;Truncate number to string len mov cx,ax ;Copy second parameter mov si,var3_value ;Convert 3rd parameter to hex cmp byte ptr [si],0 ;See if no parameter je mid_str_0 call asc2hex ;If no number, return max jnc mid_str_1 ; value to insure remainder mid_str_0: mov ax,VAR_SIZE ; of string returned. mid_str_1: call truncnum ;Truncate number to string len push ax ;Save length of substring xor ax,ax cmp al,1 ;Clear zero flag mov di,var1_value ;Scan to new start of string jcxz mid_str_11 repne scasb mid_str_11: pop cx ;Pop length of substring mov si,di ;Copy ptr to start of substr je mid_str_2 ;If end of str found, end repne scasb ;Scan until end of substring mov byte ptr [di],0 mid_str_2: mov di,dest_var_val call copy_string ;Copy string to dest buffer clc ret mid_str endp ;----------------------------------------------------------------------------- ; LENGTH STR Computes the length of the source string ;----------------------------------------------------------------------------- length_str proc near assume cs:code,ds:code,es:code mov di,var1_value ;Find_end also returns the call find_end ; length of the string in mov ax,cx ; CX. xor dx,dx mov di,dest_var_val ;Convert value to ASCII call hex2asc clc ret length_str endp ;----------------------------------------------------------------------------- ; UPPER STR Convert the source string to upper case ;----------------------------------------------------------------------------- upper_str proc near assume cs:code,ds:code,es:code mov di,dest_var_val mov si,var1_value push di call copy_string ;Copy string to dest buffer pop si call caps_string ;Convert to upper case. clc ret upper_str endp ;----------------------------------------------------------------------------- ; LOWER STR Convert the source string to lower case ;----------------------------------------------------------------------------- lower_str proc near assume cs:code,ds:code,es:code mov di,dest_var_val mov si,var1_value push di call copy_string ;Copy string to dest buffer pop si call lc_string ;Convert to lower case. clc ret lower_str endp ;----------------------------------------------------------------------------- ; CHAR STR Convert the source number to a ASCII character ;----------------------------------------------------------------------------- char_str proc near assume cs:code,ds:code,es:code mov si,var1_value ;Convert ASCII number to hex call asc2hex mov di,dest_var_val xor ah,ah ;Write number directly to stosw ; dest string. Include clc ; zero for termination. ret char_str endp ;----------------------------------------------------------------------------- ; VAL STR Convert the source character to its HEX equivalent ;----------------------------------------------------------------------------- val_str proc near assume cs:code,ds:code,es:code mov si,var1_value ;Get ASCII character, then lodsb ; write its hex equivalent xor ah,ah ; to the output var. xor dx,dx mov di,dest_var_val call hex2asc clc ret val_str endp ;----------------------------------------------------------------------------- ; FILENAME STR Return only the filename from a filename string ;----------------------------------------------------------------------------- filename_str proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,var2_value ;Use 2nd buff as temp buff call parse_filename mov si,di mov bx,di filename_1: lodsb cmp al,'\' ;Mark start of filename or jne filename_2 ; directory. mov bx,si filename_2: or al,al je filename_3 cmp al,'.' jne filename_1 dec si filename_3: mov cx,si sub cx,bx ;Compute length mov di,dest_var_val mov si,bx rep movsb clc ret filename_str endp ;----------------------------------------------------------------------------- ; FILEEXT STR Return only the filename extension from a filename string ;----------------------------------------------------------------------------- fileext_str proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,var2_value ;Use 2nd buff as temp buff call parse_filename mov si,di xor bx,bx fileext_1: lodsb cmp al,'.' ;Mark start of filename or jne fileext_2 ; directory. mov bx,si fileext_2: or al,al jne fileext_1 or bx,bx je fileext_3 mov cx,si sub cx,bx ;Compute length mov di,dest_var_val mov si,bx rep movsb fileext_3: clc ret fileext_str endp ;----------------------------------------------------------------------------- ; FIND STR finds a string within another string. ; Exit: AL - Return code if string not found ; CF - Set if string not found ;----------------------------------------------------------------------------- find_str proc near mov si,var1_value ;To ignore case, capitalize call caps_string ; both strings, then call mov si,var2_value ; the findc function. call caps_string call findc_str ret find_str endp ;----------------------------------------------------------------------------- ; FINDC STR finds a string within another string, respects case. ; Exit: AL - Return code if string not found ; CF - Set if string not found ;----------------------------------------------------------------------------- findc_str proc near mov di,var1_value ;Get ptr to 1st string push di call find_end ;Compute length pop si push cx ;Save length mov di,var2_value mov dx,di call find_end mov bx,cx ;Save length of search string pop cx ;Restore length of trg string sub cx,bx ;Sub length of search string. jb find_str_not_found inc cx find_str_1: push cx mov cx,bx ;Restore search str length mov di,dx ;Restore ptr to search str push si repe cmpsb ;Compare command pop si pop cx je find_str_found inc si ;Inc target string ptr loop find_str_1 find_str_not_found: xor ax,ax ;Set bad return code jmp short find_str_2 find_str_found: mov ax,si ;Copy offset sub ax,var1_value ;Sub starting offset inc ax find_str_2: xor dx,dx mov di,dest_var_val ;Convert value to ASCII call hex2asc clc find_str_exit: ret findc_str endp ;============================================================================= ; File Functions ;============================================================================= ;----------------------------------------------------------------------------- ; READ REC returns record n from a file. ;----------------------------------------------------------------------------- readrec_file proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,dest_var_val ;Use dest buff as temp buff call parse_filename mov dx,di ;Copy filename pointer call open_file jc readrec_error mov si,var2_value ;Convert 2nd param to record call asc2hex ; number. call findrec_file ;Find record. mov ax,si ;Copy end of file flag. mov si,offset errmsg8 ;Record not found. jc readrec_error1 ;Error if record not found. mov si,dest_var_val xchg di,si jcxz readrec_2 readrec_1: lodsb ;Copy record to destination cmp al,13 ; buffer. je readrec_3 stosb loop readrec_1 readrec_2: or ah,ah ;Check end of file flag jne readrec_3 mov dx,databuff_ptr ;If at end of data buffer. mov cx,VAR_SIZE ; read enough to complete call read_file ; record. jc readrec_error mov cx,ax ;Copy number of bytes read. mov di,dx jmp short readrec_1 readrec_3: xor al,al ;Append terminating zero stosb call close_file ;Close file jc readrec_error readrec_exit: ret readrec_error: mov si,offset errmsg9 ;Generic DOS error msg stc jmp short readrec_exit readrec_error1: call close_file stc jmp short readrec_exit readrec_file endp ;----------------------------------------------------------------------------- ; WRITE REC appends a string to the end of a file. ;----------------------------------------------------------------------------- writerec_file proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,dest_var_val ;Use dest buff as temp buff call parse_filename mov dx,di ;Copy filename pointer call open_file ;Open file. If file does not jnc writerec_0 ; exist, create the file. call create_file jc writerec_error mov si,1 jmp short writerec_1 writerec_0: xor ax,ax ;Move file ptr to end of file cwd mov cx,2 ;Move pointer from end. call move_fileptr ;Move file pointer jc writerec_error mov si,1 or dx,dx jne writerec_01 or ax,ax je writerec_1 writerec_01: mov ax,-1 ;Move file ptr to last byte cwd mov cx,2 ;Move pointer from end. call move_fileptr ;Move file pointer jc writerec_error dec si ;Clear EOF marker flag mov dx,dest_var_val ;Read last char to check for mov cx,1 ; EOF marker call read_file jc writerec_error mov di,dx cmp byte ptr [di],1Ah jne writerec_1 mov ax,-1 ;See if last byte 1A EOF mark cwd mov cx,2 ;Move pointer from end. call move_fileptr ;Move file pointer jc writerec_error inc si ;Set EOF marker flag writerec_1: mov di,var2_value ;Get length of string mov dx,di call find_end dec di ;Backup before zero mov ax,0a0dh stosw inc cx inc cx or si,si je writerec_2 mov al,1ah ;Append EOF marker stosb inc cx writerec_2: call write_file jc writerec_error call close_file ;Close file jc writerec_error writerec_exit: mov di,dest_var_val ;Clear dest value. mov byte ptr [di],0 ret writerec_error: mov si,offset errmsg9 ;Generic DOS error msg stc jmp short writerec_exit writerec_error1: call close_file stc jmp short writerec_exit writerec_file endp ;----------------------------------------------------------------------------- ; NUMREC FILE returns the number of records in a file. ;----------------------------------------------------------------------------- numrec_file proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,dest_var_val ;Use dest buff as temp buff call parse_filename mov dx,di ;Copy filename pointer call open_file jc numrec_error xor ax,ax ;Attempt to find large rec num mov dx,ax call findrec_file ;Find record. jnc numrec_error1 ;Error if record found. not ax ;Compliment line count. No not dx ; need to add 1 since count ; already 1 too many. mov di,dest_var_val ;Convert rec number to ASCII call hex2asc call close_file ;Close file jc numrec_error numrec_exit: ret numrec_error: mov si,offset errmsg9 ;Generic DOS error msg stc jmp short numrec_exit numrec_error1: call close_file jc numrec_error stc jmp short numrec_exit numrec_file endp ;----------------------------------------------------------------------------- ; FIND REC returns an offset to the Nth record of a file. ; Entry: DX,AX - Record to find ; BX - Source File handle ; Exit: DX,AX - Records remaing if end of file ; CF - Set if record not found. ; DI - Points to record. ; CX - Number of bytes to end of data buffer ; SI - Points to error message if CF set. ;----------------------------------------------------------------------------- findrec_numl equ word ptr [bp-2] findrec_numh equ word ptr [bp-4] findrec_eof equ byte ptr [bp-5] findrec_file proc near assume cs:code,ds:code,es:code push bp mov bp,sp sub sp,6 mov si,offset errmsg8 ;Record not found mov findrec_eof,0 ;Clear end of file flag. mov findrec_numl,ax ;Save record number. mov findrec_numh,dx findrec_1: mov cx,databuff_ptr xchg cx,dx mov cx,DATABUFF_SIZE ;Get size of data buffer call read_file ;Read data from file. jc findrec_error cmp ax,cx ;See if buffer filled. If je findrec_2 ; not, end of file. mov findrec_eof,1 ;Set end of file flag. findrec_2: mov cx,ax ;Copy num bytes read. mov di,dx ;Copy buffer ptr mov dx,ax ;Save size of buffer mov al,13 ;Scan for CR findrec_3: sub findrec_numl,1 ;Decriment record count sbb findrec_numh,0 jne findrec_4 ;See if record count = 0 cmp findrec_numl,0 je findrec_5 findrec_4: repne scasb je findrec_3 cmp findrec_eof,1 ;If end of buffer, see if jne findrec_1 ; end of file. Yes = exit stc jmp short findrec_exit findrec_5: cmp byte ptr [di],0ah ;discard Line feed jne findrec_6 inc di dec cx findrec_6: clc findrec_exit: mov ah,findrec_eof mov al,0 mov si,ax ;Save end of file flag mov ax,findrec_numl ;Get record number. mov dx,findrec_numh mov sp,bp pop bp ret findrec_error: mov si,offset errmsg9 ;Generic DOS error msg findrec_error1: stc jmp short findrec_exit findrec_file endp ;----------------------------------------------------------------------------- ; FILE SIZE returns the size of a file ;----------------------------------------------------------------------------- filesize_file proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,dest_var_val ;Use dest buff as temp buff call parse_filename mov dx,di ;Copy filename pointer call open_file mov di,dest_var_val ;Point DI to result buffer. jc filesize_exit xor ax,ax ;Zero offset. xor dx,dx mov cl,2 ;Move pointer from end. call move_fileptr ;Move file pointer jc filesize_exit call hex2asc ;Convert size to ASCII filesize_exit: ret filesize_file endp ;----------------------------------------------------------------------------- ; TRUENAME FILE returns the fully qualified name of a file. ;----------------------------------------------------------------------------- truename_file proc near assume cs:code,ds:code,es:code mov si,var1_value ;Fully qualify filename mov di,dest_var_val ;Use dest buff as temp buff call parse_filename jnc truename_1 mov si,offset errmsg6 ;Illegal filename msg truename_1: ret truename_file endp ;============================================================================= ; System Functions ;============================================================================= ;----------------------------------------------------------------------------- ; VER SYS returns the DOS version number ;----------------------------------------------------------------------------- ver_sys proc near mov ax,dos_version push ax mov al,100 xchg al,ah ;Copy major ver number mul ah pop bx xor bh,bh add ax,bx xor dx,dx mov di,dest_var_val call hex2asc clc ret ver_sys endp ;----------------------------------------------------------------------------- ; ASK SYS prints a string then returns the user response. ;----------------------------------------------------------------------------- ask_sys proc near mov si,var1_value cmp byte ptr [si],0 je ask_1 call print_strcr ;Print result string ask_1: mov bx,80h mov byte ptr [bx],127 mov dx,bx mov ah,0ah int 21h mov si,offset endmsg call print_str ;Insert a CR-LF xor cx,cx ;Append zero to string. inc bx mov cl,[bx] inc bx mov si,bx add bx,cx mov byte ptr [bx],0 inc cx mov di,dest_var_val ;Move string to result buff rep movsb clc ret ask_sys endp ;----------------------------------------------------------------------------- ; RC SYS returns the return code from the prev process ;----------------------------------------------------------------------------- rc_sys proc near mov ah,4dh ;Get return code int 21h xor ah,ah xor dx,dx mov di,dest_var_val call hex2asc clc ret rc_sys endp ;----------------------------------------------------------------------------- ; ENVFREE SYS returns the number of bytes free in the environment. ;----------------------------------------------------------------------------- envfree_sys proc near push es cmp use_mastenv,0 ;Find environment block jne envfree_0 call findenv ;Use parent's env by default. jnc envfree_01 envfree_0: call findmaster ;Find master env jc envfree_exit envfree_01: push ax dec ax mov es,ax mov dx,es:[3] ;Get size of env segment mov cl,4 ;Convert paragraphs to bytes shl dx,cl pop es mov cx,dx xor ax,ax xor di,di envfree_1: repne scasb ;Loop through the environment cmp byte ptr es:[di],al ; until the end of the loopne envfree_1 ; env strings is found. jcxz envfree_2 mov ax,dx sub ax,di dec ax ;Sub byte for extra zero envfree_2: xor dx,dx pop es mov di,dest_var_val call hex2asc clc envfree_exit: ret envfree_sys endp ;----------------------------------------------------------------------------- ; ENVSIZE SYS returns the size of the environment. ;----------------------------------------------------------------------------- envsize_sys proc near push es cmp use_mastenv,0 ;Find environment block jne envsize_1 call findenv ;Use parent's env by default. jnc envsize_2 envsize_1: call findmaster ;Find master env jc envfree_exit envsize_2: push ax dec ax mov es,ax mov ax,es:[3] ;Get size of env segment mov cl,4 ;Convert paragraphs to bytes shl ax,cl pop es xor dx,dx pop es mov di,dest_var_val call hex2asc clc ret envsize_sys endp ;----------------------------------------------------------------------------- ; MASTERVAR SYS returns the value from a variable in the master environment. ;----------------------------------------------------------------------------- mastervar_sys proc near push ds push es mov di,var1_value push di call find_end mov word ptr es:[di-1],003dh ;Append = sign pop si call caps_string push cx ;Save length of var name call findmaster pop cx jc mastervar_exit mov es,ax xor di,di ;Use find string routine to call findstr ; find the variable name. jnc mastervar_1 mov si,offset errmsg17 stc jmp short mastervar_exit mastervar_1: mov si,dest_var_val push es push ds ;Exchange DS:SI and ES:DI pop es ; pointers. pop ds xchg si,di mastervar_2: lodsb ;Find end of var name. cmp al,'=' jne mastervar_2 call copy_string clc mastervar_exit: pop ds pop es ret mastervar_sys endp ;============================================================================= ; Number Functions ;============================================================================= ;----------------------------------------------------------------------------- ; ADD NUM returns the sum of two numbers ;----------------------------------------------------------------------------- add_num proc near assume cs:code,ds:code,es:code call conv2num ;Convert first two parms to jc add_num_exit ; 32 bit numbers. Carry add ax,bx ; set, overflow. adc dx,cx mov si,offset errmsg12 ;Add overflow jc add_num_exit ;If overflow, error mov di,dest_var_val call hex2asc ;Convert result to ASCII add_num_exit: ret add_num endp ;----------------------------------------------------------------------------- ; SUB NUM returns the difference of two numbers ;----------------------------------------------------------------------------- sub_num proc near assume cs:code,ds:code,es:code call conv2num ;Convert first two parms to jc sub_num_exit ; 32 bit numbers. Carry sub ax,bx ; set, overflow. sbb dx,cx mov si,offset errmsg13 ;Sub underflow jc sub_num_exit mov di,dest_var_val call hex2asc ;Convert result to ASCII sub_num_exit: ret sub_num endp ;----------------------------------------------------------------------------- ; MUL NUM returns the product of two numbers ;----------------------------------------------------------------------------- mul_num proc near assume cs:code,ds:code,es:code push bp call conv2num ;Convert first two parms to jc mul_num_exit ; 32 bit numbers. Carry mov di,dx ; set, overflow. mov si,ax mul cx ;32 bit multiply. jc mul_num_error ;Param 1 in DI,SI mov bp,ax ;Param 2 in CX,BX mov ax,di mul cx ; DI SI or ax,dx ; CX BX jnz mul_num_error ; --------------------- mov ax,di ; (BX * SI) mul bx ; (BX * DI) jc mul_num_error ; (CX * SI) add bp,ax ; + (CX * DI) mov ax,si ; --------------------- mul bx ; DX AX add dx,bp jc mul_num_error mov di,dest_var_val call hex2asc ;Convert result to ASCII mul_num_exit: pop bp ret mul_num_error: stc mov si,offset errmsg10 ;Multiply overflow stc jmp short mul_num_exit mul_num endp ;----------------------------------------------------------------------------- ; DIV NUM returns the quotient of two numbers ;----------------------------------------------------------------------------- div_num proc near assume cs:code,ds:code,es:code call conv2num ;Convert first two parms to jc div_num_exit ; 32 bit numbers. push cx or cx,bx ;Prevent divide by zero pop cx jz div_num_error div_num_1: or cx,cx ;Divide both numbers by 2 je div_num_2 ; until high word of shr dx,1 ; divisor (CX) is zero. rcr ax,1 shr cx,1 rcr bx,1 jmp short div_num_1 div_num_2: push ax ;Save low word mov ax,dx xor dx,dx div bx ;Divide high word mov cx,ax ;Save high quotent pop ax div bx ;Divide low word mov dx,cx mov di,dest_var_val call hex2asc ;Convert result to ASCII div_num_exit: ret div_num_error: mov si,offset errmsg11 stc jmp short div_num_exit div_num endp ;============================================================================= ; Support Procedures ;============================================================================= ;----------------------------------------------------------------------------- ; CONV2NUM converts the first two parameters to hex numbers. ; Exit: DX AX - Number from 1st parameter ; CX BX - Number from 1st parameter ; CF - Set if either number too large ; SI - Set to error message if CF set ;----------------------------------------------------------------------------- conv2num proc near mov si,var2_value ;Convert 2nd parameter to hex call asc2hex jc conv2num_error mov bx,ax ;Copy second parameter mov cx,dx mov si,var1_value ;Convert 1st parameter to hex call asc2hex jc conv2num_error conv2num_exit: ret conv2num_error: mov si,offset errmsg14 ;Number too large jmp short conv2num_exit conv2num endp ;----------------------------------------------------------------------------- ; PARSE CMDLINE Parse the command line into seperate buffers for each word. ; Entry: SI - Pointer to string to parse. ; Exit: CF - Set if error. ; SI - Points to error message if CF set. ;----------------------------------------------------------------------------- parse_cmdline proc near mov si,offset command_tail cmp byte ptr [si],0 ;See if cmdline = 0 jne parse_cmdline_1 ;If zero, report error parse_error: mov si,offset errmsg1 ;Syntax error message stc jmp parse_cmdline_exit1 parse_cmdline_1: inc si xor cx,cx xor bx,bx call scan4char ;Find 1st char jc parse_error cmp al,'/' ;See if cmdline switch jne parse_cmdline_2 inc si ;Skip past '/'. lodsb ;Get cmdline switch cmp al,'?' je parse_cmdline13 or al,20h cmp al,'m' jne parse_cmdline_11 mov use_mastenv,1 ;Set use master env flag jmp short parse_cmdline_1 parse_cmdline_11: cmp al,'p' jne parse_cmdline_12 lodsb mov parse_char,al ;Set new parse character jmp short parse_cmdline_1 parse_cmdline_12: cmp al,'h' jne parse_error parse_cmdline13: mov si,offset hlpmsg stc jmp short parse_cmdline_exit1 parse_cmdline_2: mov di,cmd_value mov bx,203dh ;copy until = or space call copy_till jc parse_cmdline_exit cmp al,'=' je parse_cmdline_4 parse_cmdline_3: xor bl,bl call scan4char ;Find next char jc parse_cmdline_exit cmp byte ptr [si],'=' jne parse_cmdline_5 inc si ;Move src ptr past = parse_cmdline_4: mov console_out,0 ;Clear console out flag xor bl,bl ;Find next char call scan4char jc parse_error push si ;If = found, 1st parameter mov si,cmd_value ; was dest var name. Copy mov di,dest_var_name ; name, then get new cmd call copy_string ; string. pop si mov bx,2020h ;Copy until next space mov di,cmd_value call copy_till mov al,0 ;Terminate new cmd with 0 stosb jc parse_cmdline_exit parse_cmdline_5: mov bp,offset var1_value mov cx,3 ;Max 3 parameters parse_cmdline_6: xor bl,bl ;Find start of parameter call scan4char jc parse_cmdline_exit mov bl,parse_char ;If consecutive parse chars mov bh,bl ; lead a parameter, skip the cmp [si],bx ; characters. This is used jne parse_cmdline_7 ; to allow leading spaces in inc si ; parameters. inc si parse_cmdline_7: mov di,[bp] ;Get ptr to buffer xor bh,bh call copy_till ;Copy until parse char jc parse_cmdline_exit add bp,2 loop parse_cmdline_6 parse_cmdline_exit: clc parse_cmdline_exit1: ret parse_cmdline endp ;----------------------------------------------------------------------------- ; COPY TILL Copys a string until a specified character is found ; Entry: SI - Pointer to source string ; DI - Pointer to destination buffer ; BL - 1st end character ; BH - 2nd end character ;----------------------------------------------------------------------------- copy_till proc near copytill_1: lodsb cmp al,13 ;Check for carriage return. je copytill_eol copytill_2: cmp al,equalsub_char ;See if = sub char jne copytill_3 mov al,'=' copytill_3: cmp al,bl ;See if end character found je copytill_exit cmp al,bh ;See if any char at or below jbe copytill_exit ; 2nd end character. stosb jmp short copytill_1 copytill_exit: clc copytill_exit1: ret copytill_eol: stc jmp short copytill_exit1 copy_till endp ;----------------------------------------------------------------------------- ; PARSE FILENAME creates a proper pathname for a filename ; Entry: SI - Pointer to ASCIIZ filename ; DI - Pointer to buffer to hold resulting pathname ;----------------------------------------------------------------------------- parse_filename proc near assume cs:code,ds:code,es:code push di push si cmp dos_version,300h ;See if DOS 3.x or greater. jb parse_fname_0 ;If not, parse the old way. mov ah,60h ;DOS Resolve Path int 21h jmp short parse_fname_7 parse_fname_0: cmp byte ptr [SI+1],":" ;See if disk specified je parse_fname_1 ;Yes, skip disk assignment mov ah,19h ;Get default disk int 21h inc al mov dl,al ;Save default disk number add al,40h ;Make ASCII mov ah,":" jmp short parse_fname_2 parse_fname_1: lodsw ;Get disk specified and al,0DFh ;Convert to caps mov dl,al sub dl,40h ;Convert to hex parse_fname_2: stosw ;Load disk specification ;Look for directory specification. mov bx,di ;save start of path mov al,"\" cmp byte ptr [si],al ;See if starting from root je parse_fname_3 ;Yes, skip append of path stosb ;Start at root push si ;Save current pointer mov si,di ;Point to dest buffer mov ah,47h ;Get default path int 21h pop si cmp byte ptr [di],0 ;See if NULL path je parse_fname_3 call find_end ;Scan to end of path string dec di ;move back before zero mov al,"\" ;Append path string with stosb ; a \. CX = length of path parse_fname_3: add cx,2 ;Append filename to path. mov ax,VAR_SIZE ;Compute space remaining in sub ax,cx ; the destination buffer. xchg cx,ax xor ah,ah ;Clear last char holder parse_fname_4: lodsb ;Get filename character. If or al,al ; end of string, exit. jz parse_fname_6 ;Else, write char. stosb cmp ax,".." ;If last two chars are .., jne parse_fname_5 ; scan backwards to delete std ; last directory. sub di,4 ;First, backup past '\..' mov al,"\" ;Look for directory sep push cx mov cx,di ;Compute length of path sub cx,bx repne scasb ;Now, past last directory pop cx cld ;Scan forwards again inc di ;Move back past \ parse_fname_5: mov ah,al ;Save last character read. loop parse_fname_4 parse_fname_6: xor al,al ;Terminate string with 0 stosb parse_fname_7: pop si pop di ret parse_filename endp ;----------------------------------------------------------------------------- ; CREATE FILE Creates a new file. ; Entry: DX - Pointer to ASCIIZ filename. ; Exit: BX - File handle ; CF - Set if error ;----------------------------------------------------------------------------- create_file proc near push cx mov ah,3ch ;Create file xor cx,cx ;Normal attributes int 21h mov bx,ax ;Copy file handle pop cx ret create_file endp ;----------------------------------------------------------------------------- ; OPEN FILE Opens a file. ; Entry: DX - Pointer to ASCIIZ filename. ; Exit: BX - File handle ; CF - Set if error ;----------------------------------------------------------------------------- open_file proc near mov ax,3d02h ;Open file, read/write int 21h mov bx,ax ;Copy file handle ret open_file endp ;----------------------------------------------------------------------------- ; CLOSE FILE Closes a file. ; Entry: BX - File handle ; Exit: CF - Set if error ;----------------------------------------------------------------------------- close_file proc near mov ah,3eh ;Close file int 21h ret close_file endp ;----------------------------------------------------------------------------- ; READ FILE Reads data from a file ; Entry: BX - File handle ; CX - Number of bytes to read ; DX - Pointer to data buffer ; Exit: CF - Set if error ; AX - bytes read. ;----------------------------------------------------------------------------- read_file proc near mov ah,3fh ;Read file data int 21h ret read_file endp ;----------------------------------------------------------------------------- ; WRITE FILE Writes data to a file ; Entry: BX - File handle ; CX - Number of bytes to write ; DX - Pointer to data buffer ; Exit: CF - Set if error ;----------------------------------------------------------------------------- write_file proc near mov ah,40h ;Write file data int 21h ret write_file endp ;----------------------------------------------------------------------------- ; MOVE FILEPTR Moves the file read pointer of a file. ; Entry: AX,DX - Offset of file pointer ; BX - File handle ; CL - Move type, 0 = from start, 2 = from end. ; Exit: CF - Set if error ;----------------------------------------------------------------------------- move_fileptr proc near xchg cx,dx ;Copy most sig word xchg dx,ax ;Copy least sig word mov ah,42h ;Move file pointer int 21h ret move_fileptr endp ;----------------------------------------------------------------------------- ; TRUNCNUM truncates a number to the max length of a string ; Entry: AX - Number to truncate ; Exit: AX - Truncated number ;----------------------------------------------------------------------------- truncnum proc near cmp ax,VAR_SIZE ;VAR_SIZE = max string length jb trunc_1 mov ax,VAR_SIZE trunc_1: ret truncnum endp ;----------------------------------------------------------------------------- ; FINDSTR determines if a string is in a list. ; Entry: DS:SI - Pointer to ASCII string to find. ; ES:DI - Pointer to list of ASCIIZ strings. ; CX - Size of string ; Exit: DI - Pointer to entry in list ; CF - Clear if string found ; BX - If CF clear, index into list ;----------------------------------------------------------------------------- findstr proc near push cx push dx xor dx,dx or dx,cx ;Save length of string je finds_3 xor bx,bx ;Zero index counter finds_1: push di push si push cx repe cmpsb ;Compare command pop cx pop si pop di clc je findstr_exit inc bx ;Inc string count push cx call find_endl ;Find end of string. pop cx jne finds_3 cmp byte ptr es:[di],0 ;See if second zero. If so jne finds_1 ; end of list. finds_3: stc ;Indicate string not found findstr_exit: pop dx pop cx ret findstr endp ;----------------------------------------------------------------------------- ; FIND END scans to the end of an ASCIIZ string. ; Entry: ES:DI - Pointer to ASCII string ; Exit: ES:DI - Pointers to character after string. ; CX - Length of string ; ZF - Clear if end not found in MAX length of characters ;----------------------------------------------------------------------------- find_end proc near push ax mov cx,VAR_SIZE xor al,al repne scasb pushf mov ax,VAR_SIZE sub ax,cx xchg ax,cx dec cx popf pop ax ret find_end endp ;----------------------------------------------------------------------------- ; FIND ENDL scans to the end of an ASCIIZ string. String can be up to 32K ; Entry: ES:DI - Pointer to ASCII string ; Exit: ES:DI - Pointers to character after string. ; CX - Length of string ; ZF - Clear if end not found in MAX length of characters ;----------------------------------------------------------------------------- find_endl proc near push ax mov cx,8000h xor al,al repne scasb pushf mov ax,8000h sub ax,cx xchg ax,cx dec cx popf pop ax ret find_endl endp ;----------------------------------------------------------------------------- ; CAPS STRING capitalizes ASCIIZ string ; Entry: SI - Pointer to ASCII string to capitalize ; Exit: CX - Length of string ;----------------------------------------------------------------------------- caps_string proc near assume ds:code,es:code push bx push dx mov bx,"za" ;Set filter limits mov dx,0df00h ;Set character filter call filter_string pop dx pop bx ret caps_string endp ;----------------------------------------------------------------------------- ; LC STRING makes an ASCIIZ string lower case ; Entry: SI - Pointer to ASCII ; Exit: CX - Length of string ;----------------------------------------------------------------------------- lc_string proc near assume ds:code,es:code push bx push dx mov bx,"ZA" ;Set filter limits mov dx,0ff20h ;Set character filter call filter_string pop dx pop bx ret lc_string endp ;----------------------------------------------------------------------------- ; FILTER STRING filters an ASCIIZ string ; Entry: DS:SI - Pointer to ASCII string ; BL - Lower limit of char range ; BH - Upper limit of char range ; DL - OR filter ; DH - AND filter ; Exit: CX - Length of string ;----------------------------------------------------------------------------- filter_string proc near assume ds:code,es:code push si push di push es mov di,si push ds pop es xor cx,cx ;Clear byte counter. filter_1: lodsb ;Get character or al,al ;Allow any non-space character je filter_exit cmp al,bl ;If between lower and upper jb filter_2 ; char limit it. cmp al,bh ja filter_2 or al,dl ;Apply OR filter and al,dh ;Apply AND filter filter_2: stosb ;Save character inc cx ;Inc byte counter jmp short filter_1 filter_exit: pop es pop di pop si ret filter_string endp ;----------------------------------------------------------------------------- ; COPY STRING copies an ASCIIZ string ; Entry: DS:SI - Pointer to source ASCIIZ string ; ES:DI - Pointer to destination buffer ; Exit: CX - Length of string ;----------------------------------------------------------------------------- copy_string proc near assume ds:code,es:code xor cx,cx copy_string_1: lodsb ;Move character stosb or al,al ;See if end of string je copy_string_exit ;If so, exit inc cx ;Inc count jmp short copy_string_1 copy_string_exit: ret copy_string endp ;----------------------------------------------------------------------------- ; PRINT STRCR prints an ASCIIZ string then appends a CR LF to the end ; Entry: SI - pointer to ASCIIZ string. ;----------------------------------------------------------------------------- print_strcr proc near assume ds:nothing,es:nothing call print_str mov si,offset endmsg call print_str ret print_strcr endp ;----------------------------------------------------------------------------- ; PRINT STR prints an ASCIIZ string to the std output device ; Entry: SI - Pointer to ASCIIZ string. ;----------------------------------------------------------------------------- print_str proc near lodsb ;Get character or al,al ;See if end of string je print_str_exit mov ah,2 ;DOS print character mov dl,al int 21h ;Call DOS jmp short print_str print_str_exit: ret print_str endp ;----------------------------------------------------------------------------- ; HEX2ASC converts number in DX AX to ASCII ; Entry: DX AX - Number ; DI - Destination buffer ; CF - Clear ;----------------------------------------------------------------------------- hex2asc proc near assume ds:nothing,es:nothing push ax push bx push cx push dx push si mov si,10 ;Load number base mov bx,ax mov cx,dx mov dx,-1 ;Load end of number flag push dx hex_loop1: xchg ax,cx ;Get high word in AX xor dx,dx ;Clear high word div si ;Divide by base (10) xchg cx,ax ;Save result of high divide xchg ax,bx ;Get low word, leave remainder div si ; in DX. xchg bx,ax ;Save result of low divide add dl,30h ;Convert to ascii push dx ;Save digit on stack or bx,bx jne hex_loop1 ;See if number = 0. If not, or cx,cx ; continue divide loop. jne hex_loop1 mov bl,"0" ;Set leading zero flag hex_loop2: pop dx ;Get digit off stack cmp dx,-1 ;See if end flag je hex_2 or bl,dl ;Don't print leading zeros. cmp bl,"0" ;The first non zero will je hex_1 ; change bl to non-zero. mov al,dl ;Write to buffer stosb hex_1: jmp short hex_loop2 hex_2: cmp bl,"0" ;If number zero, write last jne hex_exit ; zero. mov al,bl stosb hex_exit: xor al,al ;Termainate with zero stosb pop si pop dx pop cx pop bx pop ax ret hex2asc endp ;----------------------------------------------------------------------------- ; ASC2HEX converts an ASCII number to hex ; Entry: SI - Pointer to ASCIIZ string, max 5 digits. ; Exit: DX,AX - Number ; CF - Set if overflow ;----------------------------------------------------------------------------- asc2hex proc near assume ds:nothing,es:nothing push bx push cx push bp xor cx,cx ;Zero result xor di,di xor bx,bx mov bp,10 ;Load number base asc_loop1: mov bl,[si] ;Get next digit inc si sub bl,"0" ;Convert digit from ASCII to jb asc_exit ; hex. If digit illegal cmp bl,9 ; character, exit. ja asc_exit xchg ax,di ;Shift result in DI CX by mul bp ; the base. jc asc_exit1 xchg di,ax xchg ax,cx mul bp xchg cx,ax add di,dx jc asc_exit1 add cx,bx ;Add new number to result. adc di,0 jnc short asc_loop1 asc_exit1: mov ax,cx ;Copy result mov dx,di pop bp pop cx pop bx ret asc_exit: clc jmp short asc_exit1 asc2hex endp ;----------------------------------------------------------------------------- ; SCAN4CHAR scans a string to find the first character. ; Entry: SI - pointer to ASCII string ; BL - 0 = find next char, ; 1 = find next space, ; 2 = find end of line, ; 3 = find next space or =. ; 4 = find character in DL. ; Exit: AL - matching character ; SI - pointer to matching character ; CF - set if carriage return or EOF found ;----------------------------------------------------------------------------- scan4char proc near assume ds:nothing,es:nothing scan4loop: lodsb cmp al,13 ;Check for carriage return. jne scan4_1 scan4_eol: stc jmp short scan4_exit1 scan4_1: cmp bl,4 je scan4_dl cmp bl,3 je scan4_equal cmp bl,1 ;Check if searching for space, je scan4_space ; character, or end of line. ja scan4loop cmp al," " ;Check for space or other jbe scan4loop ; 'white' characters. jmp short scan4_exit scan4_dl: cmp al,dl ;Check for parse character je scan4_exit jmp short scan4loop scan4_equal: cmp al,"=" ;Check for exit je scan4_exit scan4_space: cmp al," " ;Check for characters. ja scan4loop scan4_exit: dec si ;Back up before character clc scan4_exit1: ret scan4char endp ;----------------------------------------------------------------------------- ; PAUSE SCR Prints a 'press key' message then waits for one. ;----------------------------------------------------------------------------- pause_scr proc near mov si,offset pausemsg call print_strcr pause_1: int 28h ;Call Idle interrupt cld mov ah,01 ;Check for key press int 16h jz pause_1 xor ax,ax ;Get key from buffer int 16h ret pause_scr endp ;----------------------------------------------------------------------------- ; FINDENV Finds the parent's environment block. ; Exit: AX - Segment of local command processor environment. ;----------------------------------------------------------------------------- findenv proc near assume cs:code,ds:code,es:code,ss:code push di push si push es findenv_1: mov ax,es:[16h] ;Get parent's PSP mov dx,ax ;Save PSP segment push ax dec ax ;Point to mcb mov es,ax cmp byte ptr es:[0],"M" ;check for mcb signature pop es jne findenv_error cmp dx,es:[16h] ;See if PSP is own parent jne findenv_1 ;No, keep looking mov cx,30 mov es,ax findenv_2: add ax,es:[3] ;Add size of memory block inc ax mov es,ax cmp byte ptr es:[0],"M" ;check for mcb signature jne findenv_error cmp dx,es:[1] ;See if this owned by cmd proc je findenv_3 loop findenv_2 jmp short findenv_error findenv_3: inc ax clc findenv_exit: pop es pop si pop di ret findenv_error: mov si,offset errmsg16 ;Environment not found stc jmp short findenv_exit findenv endp ;----------------------------------------------------------------------------- ; FINDMASTER Finds the master environment block. ; Exit: AX - Segment of Master environment block ;----------------------------------------------------------------------------- findmaster proc near assume cs:code,ds:code,es:code,ss:code push di push si push es mov ah,52h ;Get address of first MCB int 21h mov ax,es:[bx-2] ;point ES to MCB mov cx,30 ;Allow only 30 loops. findmaster_1: mov es,ax cmp byte ptr es:[0],"M" ;check for mcb signature jne findmaster_exit inc ax ;point AX to memory block cmp ax,es:[1] ;See if this is a PSP block je findmaster_4 findmaster_2: add ax,es:[3] ;Get size of memory block loop findmaster_1 jmp short findmaster_error findmaster_4: cmp dos_version,0a00h ;If OS/2, use DOS 3.3 method. jae findmaster_5 cmp dos_version,0400h ;If DOS 4.00 or greater, jb findmaster_5 ; COMMAND.COM may not be the push ds ; first program loaded. Look mov si,offset shell_name ; at the name of the program mov di,8 ; stored in the last 8 bytes mov cx,7 ; of the memory control repe cmpsb ; block. If the string pop ds ; "COMMAND" isn't found, keep jne findmaster_1 ; looking. findmaster_5: mov dx,ax ;Save PSP seg mov es,ax mov bx,es:[2ch] ;Get seg of prog environment mov ax,bx dec bx mov es,bx cmp byte ptr es:[0],"M" ;See if valid memory block je findmaster_found mov ax,dx ;Get back cmd.com segment dec ax ;Point back to mcb mov es,ax findmaster_6: add ax,es:[3] ;If master env segment not inc ax ; saved at 2Ch of the PSP, mov es,ax ; scan the memory blocks cmp es:[1],dx ; for first segment owned je findmaster_7 ; above the PSP. loop findmaster_6 findmaster_error: mov si,offset errmsg16 ;Master env not found msg stc jmp short findmaster_exit ;Master env not found. findmaster_7: inc ax ;Point AX to env segment findmaster_found: clc findmaster_exit: pop es pop si pop di ret findmaster endp ;----------------------------------------------------------------------------- ; SETENV Sets environment variables. ; ; Entry: DS:SI - pointer to env var name ; ES:DI - pointer to env var value ;----------------------------------------------------------------------------- setenv proc near push bp push ds push es push di ;Save ptr to var value push es call find_end ;Get length of var value mov dx,cx ;Copy length mov di,si push ds ;Add length of var name plus pop es ; room for the equals sign. call find_end mov word ptr es:[di-1],003dh ;Append = sign inc cx ;Add byte for = add dx,cx inc dx ;Add byte for terminating 0 mov ax,environment_seg push ax dec ax mov es,ax mov bp,es:[3] ;Get size of env segment push cx mov cl,4 ;Convert paragraphs to bytes shl bp,cl pop cx pop es xor di,di ;Use find string routine to call findstr ; find the variable name. push si push ds jc setenv_2 ;Var not found, skip erase push es pop ds mov si,di ;Erase current var value by call find_endl ; copying the next env var xchg si,di ; over the current one. setenv_1: cmp byte ptr [si],0 je setenv_2 setenv_11: lodsb stosb or al,al jne setenv_11 jmp short setenv_1 setenv_2: pop ax ;Get ptr to var name pop cx pop ds ;Get ptr to var value pop si cmp byte ptr ds:[si],0 ;See if NULL variable, If so, je setenv_31 ; don't add to env block mov bx,di ;Get offset of end of env add bx,dx ;Add length of value inc bx ;Add length of terminating byte cmp bp,bx ja setenv_3 push ax ;Save ptr to var name push cx mov dx,es dec dx mov es,dx push es:[1] ;Save current owner segment inc dx mov es,dx add bx,15 ;If no room in environemnt, mov cl,4 ; see if env segment can be shr bx,cl ; resized to make room for mov ah,4ah ; new variable. int 21h ;Reallocate memory pop bx ;Get old owner pop cx pop ax jc setenv_5 push es dec dx mov es,dx mov es:[1],bx ;Restore old owner pop es setenv_3: push si push ds mov si,cx mov ds,ax call copy_string ;Copy var name to env dec di ;Back up over last zero pop ds pop si mov bl,"=" ;Since env vars can't have mov bh,bl ; the char '=', filter mov dl,-1 ; string to change = to mov dh,equalsub_char ; graphic char that looks call filter_string ; similar. call copy_string ;Copy var value to env setenv_31: xor al,al stosb ;Add 2 zeros to end env. setenv_4: clc ;Set pass flag setenv_5: pop es pop ds pop bp ret setenv endp initialize endp even ;Set stack on word boundry end_of_code = $ code ends end main