c39
TITLE EXEC.ASM
;==== executes a program and show the errorlevel afterwards
;----------------------------------------------------------------------

        INCLUDE SCREEN.MAC
        INCLUDE KEYB.MAC

        B EQU BYTE PTR 0
        W EQU WORD PTR 0


CSEG    SEGMENT
        ASSUME CS:CSEG,DS:CSEG
        ORG 100h
;---------------------------------------------------------------------
Start:  jmp Begin


fcb1	 db 40 dup (0)
fcb2	 db 40 dup (0)

parmblk  dw 0                 ; Segment address of environment string
         dd 0                 ; Pointer to command line
	 dd 0		      ; Pointer to default FCB to be passed at PSP+5CH
	 dd 0                 ; Pointer to default FCB to be passed at PSP+6CH

buffer db 70
       db 75 dup (0)

cmdline db 50 dup (0)


stacksp db 32 dup ('STACK           ')
newstack dw 0
oldstack dw 0

Mshrink PROC NEAR

	mov ah,04aH              ;Mshrink
	mov bx,5000/16          ;Bytes left for program
	int 21H
        ret

Mshrink ENDP


get_input PROC NEAR

        Print 'Enter full pathname + filename and optional parameters: ' 
        cr_lf
        readstr buffer
        cr_lf

        mov si,OFFSET buffer+1
        mov cx,00h

spc_lp:
        inc si
        cmp b[si],20h
        jz spc_lp        

        push si                        ;Save start of filename
        
fn_lp:                                 ;Loop as long as "real" characters
        inc si
        cmp b[si],20h
        jz go_on
        inc cx
        jmp fn_lp

go_on:
        cmp cx,0        
        jz error
        mov al,[si]
        mov b[si],0                    ;Mark end of filename in buffer
        cmp al,0dh
        jz no_params

spc_lp2:
        inc si
        cmp b[si],020h
        jz spc_lp2

        cmp b[si],0dh
        jz no_params

        mov cx,00h
        mov di,OFFSET cmdline+1
par_lp:
        movsb 
        inc cx
        cmp b[si],0dh
        jz ready
        jmp par_lp
ready:
        mov b[cmdline],cl


error:
        stc
        jmp ret
no_params:
        clc
        pop si
        ret


get_input ENDP


Exec PROC NEAR

	mov bp,OFFSET parmblk
	mov [bp+2],OFFSET cmdline
	mov [bp+4],CS

	mov [bp+6],OFFSET fcb1
	mov [bp+8],CS
	mov [bp+10],OFFSET fcb2
	mov [bp+12],CS


	mov ah,4BH            ; EXEC
	mov al,00H            ; Load and Execute
	mov dx,si
        mov bx,OFFSET parmblk
	int 21H     	

        ret

Exec    ENDP

Errlvl_Chk PROC NEAR

        mov ah,04dh
        int 21h

        cr_lf
        Print 'ERRORLEVEL = '
        mov dl,al
        Wr_Byte

        ret

Errlvl_Chk ENDP

;---------------------------------------------------------------
Begin:          
        mov oldstack,sp
        mov sp,OFFSET newstack  ;New stack pointer

        call Mshrink
        call get_input
        jc err_end
        call Exec
        call Errlvl_chk
err_end:
        mov sp,oldstack
        ret
;---------------------------------------------------------------

CSEG    ENDS
        END Start        

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