; EXECSUB - execute program from compiled BASIC - requires DOS 2.00 ; This version allows one BASIC program to call another ; ; CALL EXECSUB(PROG$,PARM$,FCB1$,FCB2$,RETCD%) ; PROG$ is the program name (e.g. 'command.com') ; PARM$ is the parameter to be passed to the program (e.g. '/c dir *.bas') ; FCB1$ is the first file control block (required by some programs) ; FCB2$ is the second file control block (required by some programs) ; RETCD% is the error return code skip equ 2 ; 1 for intERPretive, 2 for compiled cseg segment para public 'code' public execsub execsub proc far assume cs:cseg,ds:cseg,ss:nothing,es:nothing basicds equ 510h i24ip equ 90h i24cs equ 92h i1bip equ 6ch i1bcs equ 6eh i1cip equ 70h i1ccs equ 72h b24ip equ 51ah b24cs equ 51ch b1bip equ 516h b1bcs equ 518h b1cip equ 512h b1ccs equ 514h push bp mov bp,sp jmp p010 stak equ this byte dw 0 ; save sp dw 0 ; save ss prm1 equ this byte dw 0 ; environment prm2 equ this word dw 0 ; command line - ip & cs dw 0 prm3 equ this byte dw 0 ; default FCB - ip & cs dw 0 prm4 equ this byte dw 0 ; second default FCB - ip & cs dw 0 p010: xor ax,ax ; get psp mov es,ax ; es=0 mov bx,ds ; save ds mov ds,ax ; ds=0 cli push ds:[basicds] ; save basic's ds push ds:[i24ip] ; save int 24h and shadow push ds:[b24ip] push ds:[b24ip] pop ds:[i24ip] push ds:[i24cs] push ds:[b24cs] push ds:[b24cs] pop ds:[i24cs] push ds:[i1bip] ; save int 1bh and shadow push ds:[b1bip] push ds:[b1bip] pop ds:[i1bip] push ds:[i1bcs] push ds:[b1bcs] push ds:[b1bcs] pop ds:[i1bcs] push ds:[i1cip] ; save int 1ch and shadow push ds:[b1cip] push ds:[b1cip] pop ds:[i1cip] push ds:[i1ccs] push ds:[b1ccs] push ds:[b1ccs] pop ds:[i1ccs] sti mov ds,bx ; restore ds mov di,4f2h ; point to dos comm. area mov ax,es:[di] ; get psp segment mov es,ax mov di,2 mov bx,es:[di] ; get top of memory sub bx,ax ; subtract psp mov ah,4ah int 21h ; free memory jnc p020 ; no error mov ah,0 ; memory error jmp p090 ; to error control p020: mov si,[bp+12] ; point to parm$ add si,skip mov ax,[si] mov si,offset prm2 ; establish command line mov cs:[si],ax mov ax,ds mov cs:[si+2],ax mov si,[bp+10] ; point to fcb1$ add si,skip mov ax,[si] mov si,offset prm3 mov cs:[si],ax mov ax,ds mov cs:[si+2],ax mov si,[bp+8] ; point to fcb2$ add si,skip mov ax,[si] mov si,offset prm4 ; establish second fcb mov cs:[si],ax mov ax,ds mov cs:[si+2],ax push bp ; save reGISters push ds push es pushf mov si,offset stak ; save stack mov cs:[si],sp mov cs:[si+2],ss mov ah,4bh ; load prog mov al,0 ; load & execute mov si,[bp+14] ; point to prog$ add si,skip mov dx,[si] push cs pop es mov bx,offset prm1 ; point to parameter int 21h ; load & execute program jnc p050 ; no error mov ah,1 ; set error code jmp p060 p050: mov ax,0 ; clear error p060: mov bx,cs ; restore stack mov ds,bx mov si,offset stak cli ; no interrupts mov sp,cs:[si] mov ss,cs:[si+2] sti ; allow interrupts popf ; restore registers pop es pop ds pop bp mov cx,ds ; save ds xor bx,bx mov ds,bx ; ds=0 cli pop ds:[b1ccs] ; restore int 1ch pop ds:[i1ccs] pop ds:[b1cip] pop ds:[i1cip] pop ds:[b1bcs] ; restore int 1bh pop ds:[i1bcs] pop ds:[b1bip] pop ds:[i1bip] pop ds:[b24cs] ; restore int 24h pop ds:[i24cs] pop ds:[b24ip] pop ds:[i24ip] pop ds:[basicds] ; restore basic's ds sti mov ds,cx p090: mov si,[bp+6] ; point to RETCD% mov [si],ax ; return error, if any pop bp ; return to caller ret 10 execsub endp cseg ends end
