一 MVC指令
1．移动字符串指令MVC
移动字符串指令MVC的格式为：
MVC D1(L,B1),D2(B2) (移动字符串)
功能：（D1+（B1）） ← （D2+（B2））
L个字符
指令的执行用开始于D2(B2)的L字节替换开始于D1(B1)的L字节的内容。L个字节的内容
每次改变一个，从左边开始。如果域不重叠的话，这一事实是不重要的，但当域重叠时就特
别重要。本指令的操作码为D2。指令执行不改变条件代码CC。
例如指令：
MVC 14(8,R12),0(R1)
产生编码D207 C00E 1000。
SS语句可以使用隐式地址。这里，正如RS和SI指令中的情形一样，隐式地址中不说明
变址寄存器。当用一个隐式地址说明第一个操作数时，通过将其放在第一个操作数括号中说
明长度。这是一个可能产生混淆的地方。例如，指令：
MVC FIELD1(15),FIRLD2
说明操作数的长度为15，第一个操作数的地址为FIELD1，而不是R15内容的偏移。SS指令
中的长度说明允许为0，如果这样做了，生成的长度代码为0
二 汇编EXAMPLE
data segmentorg 80hpsp dw 0ffh dup(?)ddd db 'diretory:$'head db 'name size type date time ',0dh,0ah,24hspace db ' ',24hdir db 'xxx <dir> ',24hfn db 200h dup(?)dta db 128 dup(?)msg db 'press any key to continue...',0dh,0ah,24hnewline db 0dh,0ah,24hcount db ?show db 0base_10 dw 10used_32bits_high dw 0used_32bits_low dw 0var_32bits_high dw 0var_32bits_low dw 0quotidient_32bits_high dw 0quotidient_32bits_low dw 0negate_mask equ 0FFFFhlowest_signed_32bits_high dw 8000hlowest_signed_32bits_low dw 0000hlowest_signed_32bits_string db '-2147483648$'qhigh dw 0rhigh dw 0qlow dw 0rlow dw 0qhigh_redundant dw 0rhigh_redundant dw 0q_0 dw 0qhigh0 equ 0hrhigh0 equ 0hqhigh1 equ 1999hrhigh1 equ 6hqhigh2 equ 3333hrhigh2 equ 2hqhigh3 equ 4CCChrhigh3 equ 8hqhigh4 equ 6666hrhigh4 equ 4hqhigh5 equ 8000hrhigh5 equ 0hqhigh6 equ 9999hrhigh6 equ 6hqhigh7 equ 0B333hrhigh7 equ 2hqhigh8 equ 0CCCChrhigh8 equ 8hqhigh9 equ 0E666hrhigh9 equ 4hfilenum db 0dirnum db 0filespace db ' File(s) $'dirspace db ' Dir(s) $'bytes db ' Bytes.',0dh,0ah,24hbytesfree db ' Bytes free.',0dh,0ah,24h
data endsstack1 segment stackdw 0ffh dup(0)
stack1 endsmain segmentassume cs:main,ds:data,ss:stack1org 100h
cmdln equ byte ptr es:[82h] ;command line data;-------------------------------------------------------------------------------
p1 proc nearpush dsmov ax,datamov ds,axpop pspmov es,pspmov ax,stack1mov ss,axmov cl,byte ptr es:[80h]cmp cl,0 ;command line?jne l4 ;yes
no_dir:mov ah,19h ;noint 21hadd al,'a'mov byte ptr[fn],almov word ptr[fn+1],5c3ahmov ah,47h ;current directory but no driver,so have tolea si,fn[3] ;use 19h to add myselfsub al,'a'mov dl,alint 21hlea di,fn[3] ;to point di to the end of the diretoryl7:mov al,[di]cmp al,0je l6inc dijmp l7l4:lea si,cmdln lea di,fncldxor ch,chdec cl;rep movsblea di,fnlea bx,cmdlnlea bp,fnrepeat:mov al,es:[bx]mov ds:[bp],alinc bxinc bpinc didec cljnz repeatl6:mov cl,[di-1] ;end by '\' ?cmp cl,92 ;92-->'\'je l8 ;yes;mov byte ptr[di],92 ;no;inc dicmp byte ptr[di-1],'W'jne notWmov al,1mov [show],al
notW:cmp byte ptr[di-1],92 ;'\'je l8dec dijz no_dirjmp notWl8:mov word ptr[di],0a0dh ;end by $ for printingmov byte ptr[di+2],24hmov ah,09h ;print "directory:*:\*\*\";lea dx,dddmov dx,offset dddint 21hmov ah,09hlea dx,fnint 21hmov ah,09hmov al,[show]cmp al,1je w_headlea dx,headint 21h
w_head:mov word ptr[di],2e2ah ;add '*.* ' at the endmov word ptr[di+2],002ahl5:lea dx,dtamov ah,1ahint 21hmov ah,4eh ;first fdt matchedmov cx,16h ;all filelea dx,fnint 21hcall outp ;print first file imformationmov cl,1mov count,cl;-------------;mov ah,4ch;int 21h ;-----------
l2:mov ah,4fh ;next fdtint 21hjc l0 ;end when no file any morecall outp ;print next file imformationmov cl,countinc clmov count,clcmp cl,14hja pause
pause_end:jmp l2pause:mov dl,[show]cmp dl,1je pause_endmov ah,9h;move 9 into ah (9 is the interrupt for output)lea dx,msg;move the message into dxint 21h ;call dos functionmov ah,7h;move 7 into ah (7 is the interrupt for input)mov dx,00h;get the actual inputint 21h ;dos interruptmov cl,0mov count,cljmp pause_endl0: ;int 20h ;endmov dl,[show]cmp dl,0je not_newlinemov ah,2 ;new linemov dl,0dhint 21hmov ah,2mov dl,0ahint 21hnot_newline:lea dx,[space]mov ah,09hint 21hmov al,[filenum]xor ah,ahmov [var_32bits_low],axxor al,almov [var_32bits_high],axcall showspacelea dx,filespacemov ah,09hint 21hmov ax,[used_32bits_high]mov [var_32bits_high],axmov ax,[used_32bits_low]mov [var_32bits_low],axcall showspacelea dx,bytesmov ah,09hint 21hlea dx,[space]mov ah,09hint 21hmov al,[dirnum]xor ah,ahmov [var_32bits_low],axxor al,almov [var_32bits_high],axcall showspacelea dx,[dirspace]mov ah,09hint 21h;-----------------------get free spacemov dl,fn[0]sub dl,'a'mov ah,36hint 21hmul bxmov bx,cxxor cx,cxcall mymul32mov var_32bits_high,cxmov [var_32bits_low],bxcall showspacelea dx,bytesfreemov ah,09hint 21hmov ah,4chint 21hp1 endppspace proc nearpush dxpush axmov dl, ' 'mov ah, 2hint 21hpop axpop dx
pspace endpprintax proc nearcmp ax,0je pretpush bxpush cxpush axpush dxxor cx,cx;jmp lable1
b11: xor dx,dx
lable1: mov si,10div sipush dxinc cxcmp ax,0jne b11b22: pop dxadd dl,30hmov ah,2int 21hloop b22pop dxpop axpop cxpop bx
pret: ret
printax endpprintax_hex proc nearmov cx,4 ; print 4 hex digits (= 16 bits)
.print_digit:rol ax,4 ; move the currently left-most digit into the least significant 4 bitsmov dl,aland dl,0Fh ; isolate the hex digit we want to printadd dl,'0' ; and convert it into a character..cmp dl,'9' ; ...jbe .ok ; ...add dl,7 ; ... (for 'A'..'F')
.ok: ; ...push ax ; save EAX on the stack temporarilymov ah,2 ; INT 21H / AH=2: write character to stdoutint 21hpop ax ; restore EAXloop .print_digitret
printax_hex endp;----------------------------print the file imfomation--------------------
outp proc nearpush bxpush dxpush axpush cxmov cx,16lea bx,dta[1eh] ;print name
o0:mov dl,[bx]cmp dl,0je o1mov ah,2int 21hdec cxinc bxjmp o0o1:mov ah,02h ;print space between name and sizemov dl,20hint 21hloop o1call b2d ;print size and dir type;----judge is Wmov dl,[show]cmp dl,1je w_filecall datm ;print date and timemov ah,2 ;new linemov dl,0dhint 21hmov ah,2mov dl,0ahint 21h
w_file:pop cxpop axpop dxpop bxret
outp endp
;------------------------------print size-------------------------------------
b2d proc nearpush cxpush axpush dxpush sixor cx,cxlea si,dta[1ah]mov ax,[si]call add_used_spacecall add_filenumcmp ax,0je b4;----judge is Wmov dl,[show]cmp dl,1je b5xor cx,cx
b1:xor dx,dxmov si,10div sipush dxinc cxcmp ax,0jne b1mov si,cxb2:pop dxadd dl,30hmov ah,2int 21hloop b2mov cx,10sub cx,si
b3:mov ah,02hmov dl,20hint 21hloop b3;----judge is Wmov dl,[show]cmp dl,1je b5mov ah,9lea dx,spaceint 21hjmp b5b4:call add_dirnumcall sub_filenum;----judge is Wmov dl,[show]cmp dl,1je b5mov ah,09hlea dx,dirint 21hb5:pop sipop dxpop axpop cxret
b2d endpadd_filenum proc nearpush axmov al,[filenum]inc almov [filenum],alpop axret
add_filenum endpadd_dirnum proc nearpush axmov al,[dirnum]inc almov [dirnum],alpop axret
add_dirnum endpsub_filenum proc nearpush axmov al,[filenum]dec almov [filenum],alpop axret
sub_filenum endp;------------------------------print date and time-----------------------------------------------
datm proc nearpush axpush bxpush cxpush dxpush dilea bx,dta[18h];datamov di,[bx]mov cx,7;yearxor bx,bx
d1:shl di,1rcl bx,1loop d1add bx,1980call bi2demov ah,2mov dl,"."int 21hmov cx,4;monthxor bx,bx
d2:shl di,1rcl bx,1loop d2call bi2demov ah,2mov dl,"."int 21hmov cx,5;dayxor bx,bx
d3:shl di,1rcl bx,1loop d3call bi2demov cx,3
d7:mov ah,2mov dl," "int 21hloop d7;timelea bx,dta[16h]mov di,[bx]mov cx,5;hourxor bx,bx
d5:shl di,1rcl bx,1loop d5call bi2demov ah,2mov dl,":"int 21hmov cx,6;minxor bx,bx
d6:shl di,1rcl bx,1loop d6call bi2depop dipop dxpop cxpop bxpop axret
datm endp;---------------------------------binary2decimal-----------------------------
bi2de proc nearpush axcmp bx,9ja bi0mov ah,2mov dl,'0'int 21h
bi0:xor cx,cxmov ax,bx
bi1:xor dx,dxmov si,10div sipush dxinc cxcmp ax,0jne bi1bi2:pop dxadd dl,30hmov ah,2int 21hloop bi2pop axret
bi2de endp;----------------multiplies dx:ax x cx:bx return dx:ax:cx:bx
mymul32 proc nearpush sipush dimov si,dx ;save op1hi in simov di,ax ;save op1lo in dimul bx ;op1l0 x op2lopush ax ;save 1st (32 bit) pp. on stackpush dx
;mov ax,si ;op1hi in axmul bx ;op1hi x op2l0pop bx ;add 2nd (48 bit) pp. to pp1add ax,bxadc dx,0push axmov bx,dx ;pp1 + pp2 in bx:tos:tos+2
;mov ax,di ;op1lo in axmul cx ;op1lo x op2hipop di ;add 3rd (48 bit) pp. to pp1 + pp2add di,axpush dimov di,0adc bx,dxadc di,0 ;pp1+pp2+pp3 in di:bx:tos:tos+2
;mov ax,si ;op1hi in axmul cx ;op1hi x op2hiadd ax,bx ;add 4th (64 bit) pp. to pp1+pp2+pp3adc dx,dipop cxpop bx ;final product in dx:ax:cx:bx
;pop dipop siret
mymul32 endpshowspace proc nearpush axpush bxpush dxpush cxmov ax,0mov bx,0 ;bx: quotidient_32bits_highmov dx,0 ;dx: quotidient_32bits_lowmov cx,0 ;counter = 0
;16bits or 32bits ?mov ax,var_32bits_highcmp ax,0jne _32bits_routinejmp _16bits_routine;;;
_32bits_routine:mov cx,0
;if == -2147483648 (-2^31)mov ax,var_32bits_highcmp ax,lowest_signed_32bits_highjne check_if_negmov ax,var_32bits_lowcmp ax,lowest_signed_32bits_lowjne check_if_neg
;thenlea dx,lowest_signed_32bits_stringmov ah,9int 21hjmp return_to_dos
;if < 0
check_if_neg:mov ax,var_32bits_highcmp ax,0jnl preparations
;then print "-" ...mov ah,2mov dl,'-'int 21h
;... and negate number;---------xor 0ffffffff , + 1----------mov ax,var_32bits_highxor ax,negate_maskmov var_32bits_high,axmov ax,var_32bits_lowxor ax,negate_maskinc axmov var_32bits_low,axjnc preparationsmov ax,var_32bits_highinc axmov var_32bits_high,ax
preparations:mov ax,var_32bits_highmov quotidient_32bits_high,axmov ax,var_32bits_lowmov quotidient_32bits_low,ax
while_32bits:
; while >0 domov ax,quotidient_32bits_highcmp ax,0jne div_high_partmov ax,quotidient_32bits_lowcmp ax,0jne div_high_partjmp print_char
div_high_part:
;divide high partmov dx,0mov ax,quotidient_32bits_highdiv base_10mov qhigh,axmov rhigh,dx
;case rhighmov ax,rhighcmp ax,0je _rhigh0cmp ax,1je _rhigh1cmp ax,2je _rhigh2cmp ax,3je _rhigh3cmp ax,4je _rhigh4cmp ax,5je _rhigh5cmp ax,6je _rhigh6cmp ax,7je _rhigh7cmp ax,8je __rhigh8cmp ax,9je __rhigh9
_rhigh0:mov ax,qhigh0mov qhigh_redundant,axmov ax,rhigh0mov rhigh_redundant,axjmp _aftercase_rhigh1:mov ax,qhigh1mov qhigh_redundant,axmov ax,rhigh1mov rhigh_redundant,axjmp _aftercase
__rhigh8:jmp _rhigh8
__rhigh9:jmp _rhigh9
_rhigh2:mov ax,qhigh2mov qhigh_redundant,axmov ax,rhigh2mov rhigh_redundant,axjmp _aftercase
_rhigh3:mov ax,qhigh3mov qhigh_redundant,axmov ax,rhigh3mov rhigh_redundant,axjmp _aftercase
_rhigh4:mov ax,qhigh4mov qhigh_redundant,axmov ax,rhigh4mov rhigh_redundant,axjmp _aftercase
_rhigh5:mov ax,qhigh5mov qhigh_redundant,axmov ax,rhigh5mov rhigh_redundant,axjmp _aftercase
_rhigh6:mov ax,qhigh6mov qhigh_redundant,axmov ax,rhigh6mov rhigh_redundant,axjmp _aftercase
_rhigh7:mov ax,qhigh7mov qhigh_redundant,axmov ax,rhigh7mov rhigh_redundant,axjmp _aftercase
_rhigh8:mov ax,qhigh8mov qhigh_redundant,axmov ax,rhigh8mov rhigh_redundant,axjmp _aftercase
_rhigh9:mov ax,qhigh9mov qhigh_redundant,axmov ax,rhigh9mov rhigh_redundant,axjmp _aftercase
_aftercase:
;divide low partmov ax,0mov q_0,axmov dx,0mov ax,quotidient_32bits_lowdiv base_10mov qlow,axmov rlow,dxmov ax,rlowadd ax,rhigh_redundant
;if remainder >= 10cmp ax,base_10jl after_ifsub ax,base_10mov dx,1mov q_0,dx
after_if:mov rlow,axmov ax,q_0add ax,qlowmov qlow,axjnc label1mov ax,qhighinc axmov qhigh,ax
label1:mov ax,qlowadd ax,qhigh_redundantmov qlow,axjnc label2mov ax,qhighinc axmov qhigh,ax
label2:
;push remainder to stackmov ax,rlowpush axinc cxmov ax,qhighmov quotidient_32bits_high,axmov ax,qlowmov quotidient_32bits_low,axjmp while_32bits;;;
_16bits_routine:mov ax,var_32bits_lowmov bx,0 ;bx: quotientmov cx,0
while_loop:cmp ax,0je print_charmov dx,0div base_10mov bx,ax ;ax stores quotidientmov ax,dx ;dx stores remainder
;push remainderpush ax
;counter = counter + 1inc cx
;numerator = quotidientmov ax,bxjmp while_loop
print_char:cmp cx,0je return_to_dospop ax
;because at this point 0 <= ax <= 9, setting ah = 2 does not change the resultsmov ah,2mov dl,aladd dl,30h ;0-> '0',1->'1',....int 21hdec cxjmp print_charreturn_to_dos:pop cxpop dxpop bxpop axret
showspace endp;--------input:ax----------
add_used_space proc nearpush axpush bxpush cxpush dxmov dx,[used_32bits_low]add dx,axjnc add_finishmov bx,[used_32bits_high]inc bxmov [used_32bits_high],bxadd_finish:mov [used_32bits_low],dxpop dxpop cxpop bxpop axret
add_used_space endpmain endsend p1
