ProfitPress Mega CDROM2 Shareware Freeware (MSDOS)(1992)(Eng)

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/ ProfitPress Mega CDROM2 …eeware (MSDOS)(1992)(Eng) / ProfitPress-MegaCDROM2.B6I / MAGAZINE / MISC / PCR8905.ZIP / SHELL.ASM next >

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Assembly Source File | 1989-01-21 | 19.5 KB | 684 lines

comment | This is the control program of the menu system. Its job is to alternately execute the user-interface program and whatever programs the user wants to run. It communicates with the user-interface program' via the inter-application communications area (IACA) Written for MASM 5.1 and TASM 1.0 | ;---------------------------------------------------------- ; Order of segments ;---------------------------------------------------------- .MODEL SMALL,C .STACK .DATA .CODE end_seg segment end_seg ends ;---------------------------------------------------------- ; Data and buffers ;---------------------------------------------------------- .DATA IACA equ 4f0h ;Offset of IACA STDERR equ 2 ;Handle for STDERR CR equ 0dh ;Carriage return UI_BUFSIZE equ 800h ;Allow 2K bytes for U_I data ENV_SIZE equ 800h ;Allow 2K bytes for environ. EPB equ $ ;EXEC parameter block EPB_environ dw 0 ;Use inherited environment EPB_cmd_tail dw offset cmd_tail ;Address of command tail dw seg cmd_tail EPB_fcb1 dw offset fcb1 ;Pointers to FCBs dw seg fcb1 EPB_fcb2 dw offset fcb2 dw seg fcb2 model_fcb db 0 db 11 dup ('?') db 25 dup (0) fcb_len equ $-model_fcb fcb1 db fcb_len dup(0) fcb2 db fcb_len dup(0) ;---------- ; Execution codes returned ; from user-interface (U-I) ; (add 80H or 128 to each to ; force a pause after program ends) ;---------- call_table dw offset exit ;Code 0: EXIT to DOS dw offset reset ;Code 1: EXIT to DOS - ; & restore orig. directory dw offset cmd_exec ;Code 2: Exec via Command.Com dw offset dir_exec ;Code 3: Execute .EXE or .COM dw offset shell_exec ;Code 4: Shell to DOS dw offset change_env ;Code 5: Alter environment LAST_CODE equ 5 INVALID_CODE equ 07fh ;----------- ; Buffer space ;----------- EVEN exec_path db 128 dup (?) ;Program path from U-I exec_tail db 128 dup (?) ;Command tail from U-I ui_buf db UI_BUFSIZE dup (?) ;U-I's memory buffer exec_code dw ? ;Return code from U-I cmd_path dw ? ;Ptr to Command.Com path ui_path dw ? ;Ptr to user interface path cur_drive db ? cur_directory db 66 dup (0) prog_path db 128 dup (0) ;Program to execute cmd_tail db 128 dup (0) ;Line to execute sp_save dw ? ;To save stack pointer ss_save dw ? ;To save stack segment our_psp dw ? ;Segment of our PSP env_seg dw ? ;Segment of environment copy env_end dw ? ;Offset of end of environment pause_flag dw 0 ;----------- ; Literal strings ; and messages ;----------- comspec db "COMSPEC=",0 ;Environment string ui_spec db "PCRSHELL=",0 ;Environment string no_var db "Cannot find COMSPEC or PCRSHELL environment variable" no_var_len dw $-no_var bad_code db "Unknown execution code" bad_code_len dw $-bad_code bad_mem db "Memory allocation error" bad_mem_len dw $-bad_mem no_env db "Cannot allocate memory for new environment" no_env_len dw $-no_env long_env db "Inherited environment is too long" long_env_len dw $-long_env stop db " -- Program stopping" stop_len dw $-stop ;---------------------------------------------------------- ; Program code ;---------------------------------------------------------- .CODE error macro msg mov cx,&msg&_len lea dx,&msg call errorout endm ;----------- ; Program begins here ;----------- begin: mov ax,@data ;Set up registers mov ds,ax mov our_psp,es ;Save PSP mov ss_save,ss ; and stack segment cld call save_dir ;Save current default dir. call release_mem ;Release unneeded RAM call new_envr ;Make copy of environment push ds ;Copy data segment pop es ; to ES lea di,ui_buf ;ES:DI ==> U-I's memory buff. mov cx,UI_BUFSIZE/2 ;Words to fill sub ax,ax ;AX = 0 rep stosw ;Clear buffer call find_paths ;Find paths to Command.Com ;------------ ; Main program loop ;------------ lp: call run_ui ;Exec user_interface push ds ;Copy data segment pop es ; to ES lea si,model_fcb ;Clear FCB1 lea di,fcb1 ; by copying the mov cx,fcb_len ; model FCB into it rep movsb lea si,model_fcb ;Clear FCB2 lea di,fcb2 ; in the same way mov cx,fcb_len rep movsb lea di,prog_path ;Clear prog_path & mov ax,0 ; cmd_tail mov cx,128 rep stosw mov bx,[exec_code] ;Get execution code and bx,80h ;Isolate Pause bit mov pause_flag,bx ; and save it mov bx,[exec_code] ;Get return code again and bx,7fh ;Clear pause bit cmp bx,LAST_CODE ;Is code okay? jbe lp2 ;Yes -- go error bad_code ;Else report error lp2: add bx,bx ;BX * 2 for call table call [call_table+bx] ;Call requested routine jmp lp ;Loop back to U-I again ;---------------------------------------------------------- ; Utility Routines ;---------------------------------------------------------- ;----------- ; Find length of a string ; Offset and segment are received ; on the stack. Length is returned ; in AX ;----------- strlen proc uses es di cx, str_off:word, str_seg:word mov es,str_seg ;Put string address mov di,str_off ; in ES:DI sub al,al ;AL = 0 (end marker) mov cx,-1 ;Maximum possible length repne scasb ;Search for end dec di ;DI ==> last character mov ax,di ;Offset in AX sub ax,str_off ;AX = string length ret strlen endp ;----------- ; Copy a string from DS:SI to ES:DI ; Maximum length to copy received on stack ; Returns number of bytes moved in AX (including 0 byte) ;----------- strcpy proc uses di si bx cx, max_len:word mov cx,max_len ;Length in CX sub bx,bx ;BX will count bytes cpy1: or cx,cx ;Test for end jz cpy2 ;Go if at end lodsb ;Else get a byte stosb ;Move it inc bx ;Count it dec cx ;Reduce maximum left or al,al ;Was it end of string? jnz cpy1 ;No -- move another cpy2: mov ax,bx ;Return count of bytes ret strcpy endp ;----------- ; Save the default drive ; and subdirectory. ;----------- save_dir proc uses dx si mov ah,19h ;DOS Service: Get cur. disk int 21h ;Call DOS mov [cur_drive],al ;Save default drive mov dl,al ;Drive in DL inc dl ;A=1, B=2, etc. lea si,cur_directory ;SI ==> buffer add al,'A' ;AL has drive letter mov [si],al ;Save it mov byte ptr [si+1],':' ; and a colon add si,2 ;Move pointer past drive mov ah,47h ;DOS Service: Get cur. dir. int 21h ;Call DOS ret save_dir endp ;----------- ; Restore default drive ; and directory ;----------- restore_dir proc uses dx mov dl,[cur_drive] ;Get original drive mov ah,0eh ;DOS Service: set cur. disk int 21h ;Call DOS lea dx,cur_directory ;DX ==> directory mov ah,3bh ;DOS Service: Change dir. int 21h ;Call DOS ret restore_dir endp ;----------- ; Release unneeded memory ; to make room for child ; programs ;----------- release_mem proc uses bx mov ax,our_psp ;Get seg. of this program mov es,ax ;ES==> our PSP mov bx,seg end_seg ;BX = end of our program sub bx,ax ;BX = paragraphs to keep mov ah,4ah ;DOS Service: set block size int 21h ;Call DOS jc rel_mem1 ;Go if error ret ;Else return rel_mem1: error bad_mem ;Abort if error release_mem endp ;----------- ; Report error and ; abort program. Receives ; pointer to message in DX ; and message length in CX ;----------- errorout proc mov bx,STDERR ;Report to screen mov ah,40h ;DOS Service: write to handle int 21h ;Call DOS lea dx,stop ;DS:DX==> halting message mov cx,stop_len ;CX has length mov ah,40h ;Write to handle again int 21h ;Call DOS call restore_dir ;Restore original dir. mov ax,4cffh ;Exit with error int 21h ;Return to DOS errorout endp ;---------------------------------------------------------- ; EXEC functions -- These routines run child programs ;---------------------------------------------------------- ;---------- ; Execute a ; child program ;---------- execute proc uses bx cx dx di si push ds pop es ;ES ==> our data segment lea dx,prog_path ;DS:DX ==> prog. to execute lea bx,epb ;ES:BX ==> EPB push bp ;Save stack frame pointer mov [sp_save],sp ;Save stack pointer mov ax,4b00h ;Func. 4b: execute program int 21h ;Call DOS mov ax,@data ;Restore data segment mov ds,ax mov ss,[ss_save] ;Restore stack mov sp,[sp_save] pop bp ;Restore frame pointer cld ;Avoid possible bug in 2.x test pause_flag,-1 ;Should we pause? jz ex1 ;No -- go mov ah,8 ;Else wait for keystroke int 21h cmp al,0 ;Extended key? jne ex1 ;No -- go mov ah,8 ;Yes -- call again int 21h ; for rest of key code ex1: ret execute endp ;---------- ; Run the user-interface program ; after setting up the appropriate ; values in the inter-application ; communications area (IACA) ;---------- run_ui proc uses cx di si mov exec_code,INVALID_CODE ;Make sure of valid return mov pause_flag,0 ;No pause on return sub ax,ax ;AX = 0 mov es,ax ;ES ==> BIOS area mov di,IACA ;ES:DI ==> IACA mov ax,ds ;Get data segment stosw ;Save it lea ax,exec_path ;Get offset of path buffer stosw ;Save it lea ax,exec_tail ;Get offset of tail buffer stosw ;Save it lea ax,ui_buf ;Get offset of memory buffer stosw ;Save it lea ax,exec_code ;Get offset of code word stosw ;Save it push ds ;Copy data segment pop es ; to ES lea di,cmd_tail ;ES:DI==> command tail sub ax,ax ;AX = 0 stosw ;Clear command tail lea di,prog_path ;ES:DI ==> program path mov si,[ui_path] push ds ;Save DS mov ds,[env_seg] ;DS:SI ==> U-I path name mov ax,128 ;Maximum bytes to move push ax call strcpy ;Move the string add sp,2 ;Clear the stack pop ds ;Recover data segment call execute ;Execute U-I ret run_ui endp ;---------------------------------------------------------- ; Routines to service commands from User Interface ;---------------------------------------------------------- ;---------- ; Execution code 0 ; Exit to DOS ;---------- exit proc mov ax,4c00h ;Return to DOS -- no error int 21h exit endp ;---------- ; Execution code 1 ; Reset original default ; drive & directory and ; exit to DOS ;---------- reset proc call restore_dir ;Restore default dir. jmp exit ;Now exit reset endp ;---------- ; Execution code 2 ; Execute a program ; or DOS command ; via Command.Com ;---------- cmd_exec proc push ds pop es ;ES==> data segment push ds ;Save DS lea di,prog_path ;ES:DI==> program name buffer mov si,[cmd_path] mov ds,[env_seg] ;DS:SI==> Command.Com path mov ax,128 ;Bytes to move push ax call strcpy ;Move path name add sp,2 ;Clear the stack pop ds ;Recover data segment lea di,cmd_tail+1 ;ES:DI==> tail buffer push di ;Save the address mov al,'/' ;Start tail with stosb ; "/c " mov al,'c' stosb mov al,' ' stosb lea si,exec_tail ;DS:SI==> command to run mov ax,124 ;Maximum bytes push ax call strcpy ;Move the string add sp,2 pop di ;DS:DI ==> cmd_tail + 1 push ds ;Push segment of cmd_tail push di ; and offset of cmd_tail text call strlen ;Find length of tail add sp,4 ;Clear the stack mov bx,ax ;Length in BX cmp byte ptr [di+bx-1],CR ;Does it end with a CR? jne ce1 ;No -- go dec ax ;Else reduce count jmp short ce2 ;And go ce1: mov byte ptr [di+bx],CR ;Put carriage return at end ce2: mov [cmd_tail],al ;Put count in place call execute ;Run the program ret cmd_exec endp ;----------- ; Execution code 3 ; Execute an .EXE or .COM ; program directly ;----------- dir_exec proc push ds ;Copy data segment pop es ; to ES lea si,exec_path ;DS:SI==> program to run lea di,prog_path ;ES:DI==> execution buffer mov ax,128 ;Maximum bytes push ax call strcpy ;Copy the string add sp,2 ;Clear the stack lea si,exec_tail ;Program tail lea di,cmd_tail+1 ;Execution tail mov ax,127 ;Maximum tail bytes push ax call strcpy ;Move the tail add sp,2 ;Clear the stack dec ax ;Don't count 0 byte mov bx,ax ;Length of string in BX cmp [cmd_tail+bx],CR ;Is last byte a CR? jne de1 ;No -- go dec ax ;Else reduce count jmp short de2 ;And go de1: mov [cmd_tail+bx+1],CR ;Terminate with a CR de2: mov [cmd_tail],al ;Store the count or al,al ;Was there a tail? jz dir_exec1 ;No -- go lea si,cmd_tail+1 ;DS:SI==> tail text lea di,fcb1 ;ES:DI==> 1st FCB mov ax,2901h ;DOS Service: Parse fname int 21h ;Call DOS lea di,fcb2 ;ES:DI==> 2nd FCB mov ax,2901h ;DOS Service: Parse fname int 21h ;Call DOS dir_exec1: call execute ;Run the program ret dir_exec endp ;----------- ; Execution code 4 ; Shell to Command.Com ; and give user control ;----------- shell_exec proc push ds ;Copy data segment pop es ; to ES lea di,prog_path ;ES:DI==>execution buffer push ds ;Save data segment mov si,[cmd_path] mov ds,[env_seg] ;DS:SI==>Command.Com path mov ax,128 ;Maximum bytes push ax call strcpy ;Copy path name add sp,2 ;Clear the stack pop ds ;Recover data segment call execute ret shell_exec endp ;----------- ; Execution code 5 ; Add, delete or change ; environment string ;----------- change_env proc call del_env_string ;Delete old value push ds ;Copy data segment pop es ; to ES lea di,exec_tail ;ES:DI==>new value mov cx,128 ;Maximum bytes mov al,"=" ;Look for "=" repne scasb cmp byte ptr es:[di],0 ;Is there new text? je change_env1 ;No -- go call add_env_string ;Else add this string change_env1: call find_paths ;Readjust path pointers ret change_env endp ;---------------------------------------------------------- ; Environment routines -- These routines handle our copy ; of the environment, which is passed to both the user-interface ; and to every application ;---------------------------------------------------------- ;----------- ; Create a new environment that ; we can manipulate and send to ; child programs ;----------- new_envr proc uses bx cx si di mov bx,ENV_SIZE/16 ;BX = # of paragraphs for environ. mov ah,48h ;DOS Service: Allocate block int 21h ;Get memory block jnc env1 ;Go if okay error no_env ;Else report error and stop env1: mov [EPB_environ],ax ;Save new segment in EPB mov [env_seg],ax ; and for us mov es,ax ;ES==> new segment push ds ;Save DS mov bx,our_psp ;Get PSP address mov ds,bx ;DS==> PSP mov ds,ds:[2ch] ;DS==> inherited environment sub si,si ;DS:SI==> current environment mov di,si ;ES:DI==> new environment sub cx,cx ;CX will count bytes env2: test byte ptr ds:[si],-1 ;Are we done? jz env4 ;Yes -- go env3: lodsb ;Get a byte stosb ;Store it inc cx ;And count it or al,al ;End of string? jz env2 ;Yes -- start next string cmp cx,ENV_SIZE ;Past the end? jae env_err ;Yes -- report error jmp env3 ;Else do next byte env4: lodsb ;Get last 0 stosb ;Store it pop ds ;Clear stack dec di ;DI ==> last 0 mov [env_end],di ;Save address of end of env. ret env_err: pop ds ;Clear the stack error long_env ;Report error and end new_envr endp ;---------- ; Find environment variable in ; our copy of the environment. ; Return a pointer to beginning ; of environment string in ES:AX ; Receives a pointer requested name in DS:SI ;---------- find_env_var proc uses di si cx dx mov es,env_seg ;ES:DI ==> copy of environ. sub di,di push ds push si ;Pass string address call strlen ;Find length of string at DS:SI add sp,4 ;Clear stack mov dx,ax ;DX has length fen1: cmp byte ptr es:[di],0 ;End of environment? jz fen_err ;Yes -- error return mov cx,dx ;Length in CX push di ;Remember where we started push si repe cmpsb ;At variable name? pop si ;Recover start of strings pop di jz fen_found ;Found it! mov al,0 ;Else search for end of string mov cx,8000h ;Look for 32K repne scasb ;Move to end of string jmp fen1 ;And try again fen_err: mov ax,-1 ;Return impossible addr. jmp short fen_end fen_found: mov ax,di ;Move addr. to AX fen_end: ret ;Return to caller find_env_var endp ;----------- ; Find value of environment string ; Receives pointer to beginning of ; name, returns pointer to beginning ; of value ;----------- find_env_val proc uses es di cx, var_off:word mov es,env_seg mov di,var_off ;ES:DI ==> environ. variable mov al,"=" ;Look for "=" sign mov cx,-1 ;Maximum length repne scasb ;Look for "=" mov ax,di ;Pointer to val in AX ret find_env_val endp ;----------- ; Find paths to Command.Com and user-interface ; by looking in our copy of the environment. ; Abort with an error if either is missing. ;----------- find_paths proc uses si lea si,comspec ;DS:SI ==> "Command.Com" call find_env_var ;Get addr. in environment cmp ax,-1 ;Was it found? je fp_error ;No -- go push ax ;Else pass offset call find_env_val ;Find beginning of path add sp,2 ;Clear stack mov [cmd_path],ax ;Save address lea si,ui_spec ;DS:SI ==> "PCRSHELL" call find_env_var ;Get addr. in environment cmp ax,-1 ;Was it found? je fp_error ;No -- go push ax ;Else pass offset call find_env_val ;Find beginning of path add sp,2 ;Clear stack mov [ui_path],ax ;Save address ret fp_error: error no_var ;Report error and abort find_paths endp ;----------- ; Erase environment variable by ; copying all following strings over ; it. String to erase is in exec_tail buffer. ;----------- del_env_string proc uses di si cx push ds pop es lea di,exec_tail ;ES:DI ==> exec_tail mov cx,128 ;Maximum size mov al,'=' ;Look for "=" repne scasb ;Find end of variable name dec di ;ES:DI ==> "=" mov byte ptr es:[di],0 ;Terminate name lea si,exec_tail ;DS:SI ==> name call find_env_var ;Find name in environment mov byte ptr ds:[di],'=' ;Replace "=" cmp ax,-1 ;Did we find it? je del_env_end ;No -- go mov di,ax ;ES:DI ==> string to erase push di ;Save address mov al,0 ;Look for end of string mov cx,-1 ;Look until end repne scasb ;Move to 1st byte after end mov si,di ;SI ==> next string pop di ;ES:DI ==> beginning of string mov cx,[env_end] ;CX has address of end of env. push ds mov ds,env_seg ;DS:SI ==> next string del_env1: movsb ;Move a byte cmp si,cx ;Are we done? jbe del_env1 ;No -- loop back dec di ;ES:DI ==> last 0 pop ds ;Restore data segment mov [env_end],di ;Save end address del_env_end: ret del_env_string endp ;----------- ; Add a string to our copy of the ; environment table. The string is ; in the exec_tail buffer ;----------- add_env_string proc uses di si cx mov es,[env_seg] mov di,[env_end] ;ES:DI ==> end of environment lea si,exec_tail ;DS:SI ==> new string push ds push si ;Pass address of string call strlen ;Find length to add add sp,4 ;Clear the stack inc ax ;Length + final 0 mov cx,ax ;Save string length add ax,di ;Is there room for it? cmp ax,ENV_SIZE ja add_env_end ;No -- simply return rep movsb ;Move the string mov byte ptr es:[di],0 ;Terminate environment mov [env_end],di ;Save new end address add_env_end: ret add_env_string endp end begin