汇编源码系列之basload
2008-04-29 09:34:36 来源:WEB开发网这个都是过去DOS时代的汇编源码,虽然已经过去了,但是对于学习汇编还是有帮助的,汇编语言只是程序员一门基础语言,大多人掌握即可,不一定要深入研究.......
;BASLOAD.ASM 07/09/84 - DKeels
;----------------------------------------------------------------------------
;This program provides BASIC programs with access to the program loader (LOAD)
;by passing parameters via the system parameter area (SYSPARM).
;
;Inputs:
; FILE SPEC 1 - A string (len <= 80) with the complete name, including
; path, of the file to be loaded and executed.
; Example: 'MAINMENU.EXE' or 'C:FORMAT.COM'
; PARAMETER 1 - A string (len <= 80) with the command line parameters
; to be passed to the program specified in FILE SPEC 1.
; Example: '' or 'A:'
; FILE SPEC 2 - Same as 1.
; PARAMETER 2 - Same as 1.
;
;Outputs:
; This program gives control to LOAD.
;----------------------------------------------------------------------------
CODE SEGMENT 'CODE'
ASSUME CS:CODE
PUBLIC BASLOAD ;make known to BASIC at link time
BASLOAD PROC FAR
;prologue
PUSH BP ;save BP
MOV BP,SP ;set base for parm list
PUSH DS ;DS -> basic work area
PUSH ES ;ES -> basic work area
MOV DX,'dk' ;interrupt verification switch
INT 77H ;get seg address of sysparm area in AX
MOV ES,AX ;ES -> sysparm area
CLD ;set direction for all moves
;move file spec 1 to sysparm
MOV BX,SS:[BP+12] ;get addr of string descriptor
MOV CX,DS:[BX] ;get length of string into CX
MOV SI,DS:[BX+2] ;get addr of string into SI
MOV DI,0 ;offset into sysparm
REP MOVSB ;move string
MOV BYTE PTR ES:[DI],0 ;make it asciiz string
;move parameter 1 to sysparm
MOV BX,SS:[BP+10] ;get addr of string descriptor
MOV CX,DS:[BX] ;get length of string into CX
MOV SI,DS:[BX+2] ;get addr of string into SI
MOV DI,81 ;offset into sysparm
INC CL ;adjust for cr to be added at end
MOV BYTE PTR ES:[DI],CL ;1st byte is length of string
DEC CL ;re-adjust for move operation
INC DI
REP MOVSB ;move string
MOV BYTE PTR ES:[DI],13 ;add cr to end
;move file spec 2 to sysparm
MOV BX,SS:[BP+8] ;get addr of string descriptor
MOV CX,DS:[BX] ;get length of string into CX
MOV SI,DS:[BX+2] ;get addr of string into SI
MOV DI,163 ;offset into sysparm
REP MOVSB ;move string
MOV BYTE PTR ES:[DI],0 ;make it asciiz string
;move parameter 2 to sysparm
MOV BX,SS:[BP+6] ;get addr of string descriptor
MOV CX,DS:[BX] ;get length of string into CX
MOV SI,DS:[BX+2] ;get addr of string into SI
MOV DI,244 ;offset into sysparm
INC CL ;adjust for cr to be added at end
MOV BYTE PTR ES:[DI],CL ;1st byte is length of string
DEC CL ;re-adjust for move operation
INC DI
REP MOVSB ;move string
MOV BYTE PTR ES:[DI],13 ;add cr to end
;exit to BASIC
POP ES
POP DS
POP BP
RET 8
BASLOAD ENDP
CODE ENDS
END BASLOAD
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