·汇编源码--BRK
·汇编源码--CLOCK
·汇编源码--BURNOUT
·汇编源码--DOSSYM
·汇编源码--circle
·汇编源码--DEV
·汇编源码--getspace
·汇编源码--CLEAR
·汇编源码--col
·汇编源码--gameport
extrn$$main:far
csegsegment para public 'code'
; This program is used to set the PSP address for a compiled BASIC program.
; The PSP segment is saved at 0:4F2H.
; It can also be used to limit the maximum memory available to a compiled
; BASIC program. The option '/M:nnn' is used on the command line, where
; nnn is the number of K-bytes the program is limited to. If no, /M option
; is specified, no memory limitation takes place. For example, '/M:64' would
; limit the program to 64*1024 bytes. The range for nnn is 64 to 1024.
; This routine gets control before BASIC, does its handiwork, and then
; passes control to the BASIC program. It must be linked as follows:
; LINK BASMAIN+yourprog,yourprog,NUL.MAP,BASCOM
; If BASMAIN is unable to limit memory as requested, a message is displayed
; and the execution of the program is continued.
publicbasmain
basmain proc far
assume cs:cseg,ds:cseg,ss:nothing,es:nothing
push ds ; save ds
xor ax,ax
mov ds,ax; ds=0
mov si,4f2h; dos communications area
mov ax,es; get psp seg
mov [si],ax; save psp in dos comm area
pop ds; restore ds
mov si,80h; point to command line
mov ch,0
mov cl,[si]; get length of command line
jcxz p025; it's zero
p010:inc si
mov al,[si]; get char from command line
cmp al,'/' ; is it a slash?
jnz p020; no
mov ax,[si+1]; get next 2 chars
cmp ax,':M' ; is it M: ?
jz p030 ; yes
cmp ax,':m' ; is it m: ?
jz p030 ; yes
p020:loop p010; check next char
p025:jmp p080; no /m: or /M: found
p030:; found /m: or /M:
add si,3; point to first number
mov ax,0
mov bx,0
mov cx,10
p040:mov bl,[si]; get character
cmp bl,'0' ; out of range?
jb p050 ; yes
cmp bl,'9' ; out of range?
ja p050 ; yes
sub bl,'0' ; convert to binary
mul cx; multiply ax by 10
add ax,bx; add new digit
inc si; point to next char
jmp p040; continue
p050:; got value in ax
cmp ax,64; less than 64K?
jb p060 ; yes - print msg
cmp ax,1024; greater than 1024K?
ja p060 ; yes - print msg
mov cl,6
sal ax,cl; convert from KB to paragraphs (*64)
mov bx,es; get psp
add bx,ax; new top of memory
mov si,2; point to top of memory in psp
mov ax,[si]; get current top of memory
cmp ax,bx; is new setting larger?
jae p055; no
mov dx,offset msg2; yes - print msg
jmp p065
p055:mov [si],bx; save new top of memory
jmp p080
p060:mov dx,offset msg1; print the message
p065:add dx,100h; fudge for the psp
mov ah,9
int 21h
p080:jmp $$main; jump to BASIC's start point
msg1db 'Memory specification must be from 64 to 1024',7,10,13,'$'
msg2db 'Unable to limit memory',7,10,13,'$'
basmain endp
csegends
endbasmain ; must be a main program!
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