1.重定向

以下a.asm,用含't'及回车13的txt,仿command.com,依masm命令行的arg符号值N,(如masm/Darg=0a;),重定向5个DOS开启文件(STD_):

N=0:是STDIN句柄,先bin方式读1符,再从txt输't'到char
N=1:是STDOUT句柄,输出char的'1'到txt
N=2:是STDERR句柄,输出char的'2'到txt

N=30,31:
3是STDAUX句柄,N=30,从txt输't'到char;N=31,输出char的'3'到txt

N=41:
4是STDPRN句柄,输出char的'4'到txt

调用功能:

N=0时,44,读/写设备info,敲键符值入100h,其ascii/scan对,入106h,遇扩展码时,首对,入104h,次值,入101h.如1,得(31,31,2),ctl_c,得(3,3,2e),F1,得(0,0,3bh),(3bh,0,3bh)

3d,依读写方式,打开txt,保存句柄到si
45,保存STD_句柄的复制值到di
46,将来访问(cx)句柄,重定向为访问(bx)=(si)句柄
3f/40,用STD_输入/出,字符数1,偏置char
3e,关闭txt

DEBUG做完a.com,对输入,见103h的char,变't',对输出,typetxt,见1~4.

ACT=2
IFDEFarg
IFargGT2

IFargEQ30
ACT=30
ENDIF

IFargEQ31
ACT=31
ENDIF

IFargEQ41
ACT=41
ENDIF

STD_=arg/10
ELSE
IFargGE0
ACT=1
STD_=arg

IFargEQ0
ACT=0
ENDIF
ENDIF
ENDIF
ENDIF

IFACTEQ2无效
%OUT/Darg=0|1|2|30|31|41
.ERR
ENDIF

justmacro
localj

movdi,es:[26]敲键,i9写低asc,高scan到[1Ch尾引字],i16读[1Ah首引字]到3f功能的ax
subdi,2

cmpdi,1ch未重划键区,现在回头
jaj

movdi,3ch刚才入尾

j:movax,es:[di]
endm

csegment
assumecs:c,ds:c

org100h

@:jmp@1

chardb'0'STD_
txtdb'txt',0

@1:movah,3dhopen
moval,ACTand1
leadx,txt
int21h

movsi,axhan

movbx,ACTstdin
testbx,63>41
jnz@4

movax,4400hI/O,从/到fil\nul定向,dx=42h\80c4,否则80d3
int21h

xordh,dh
pushdx

movax,4401h
ordl,32bin
int21h

movax,64bios数据区seg,1E~3D是键区
moves,ax

movah,3fh不等回车读
movcx,11符
leadx,@入256
int21h

cmpbyteptrcs:[256],224测扩展
jz@2

testbyteptrcs:[256],255再测
jnz@3

@2:just
movwordptrtxt,ax

movah,3fh取真
incdx
int21h

@3:just
movwordptrtxt[2],ax

popdx

movax,4401h复原
int21h

@4:movah,45hduplica
movbx,STD_
int21h

movdi,axhan

movah,46hforcehan
movbx,si
movcx,STD_
int21h

movah,3fhACTr/w=3f/40
movbx,STD_
movcx,1
leadx,char
int21h

movah,46h
movbx,di
movcx,STD_
int21h

movah,3ehclose
movbx,si
int21h

ret

cends
end@

2.管道及文件引用计数

反汇编DOS版3.31,得[100,1e9]/[1ea,219]是代码/数据,初值为18/50的1ea/leb,记录屏幕配置行/列数,初值1/1的1ec/1ed,记录已处理行/列数.

流程:

(2.1)100处,用功能30,取主/次版号al/ah,若非3/1f,就显1fc处"MORE:IncorrectDOSversion",再于110,用int20,退出

(2.2)置1ea=19,用int10,ah=0f,得屏幕列数到1eb,如50

(2.3)用功能45,复制stdin(bx=0)句柄到bp,如5,用功能3e,关闭stdin句柄

(2.4)用功能45,复制stderr(bx=2)句柄(也可复制运行时打开的si),必得已关句柄0,
为看完满屏而读键盘1符时,从stderr或si读,而不移管道stdin指针.

(2.5)139处,用功能3f,打开bp句柄,字节数cx=1000,目的地21a,读stdin

用|接入管道时,more不创建新进程.

未接入时,将读键盘行,如读"135",此串及回车0d,换行0a,被存目的地,被存长度5返到ax,键入符数多于cx时,前面cx个符被存目的地.对^Z单行,ax返回0.

若ax=0,就用14a处的int20退出,否则

(2.6)150处,读目的地每字符到al

读到^Z,则转14a退出

读到0d,置列数1ed=1,转1ac

读到0a,行数1ec加1,转1ac

读到回退08,当1ed=1,转1ac,否则列数减1后,转1ac

读到制表09,则1ed置为下个制表位置,转1ac

读到响铃07,则不占输出列,转1ac

读到其它,1ed加1,比较屏幕配置列数1eb,不大于则转1ac,否则 财,软联盟,fs119.net

1ec加1,再置1ed=1

(2.7)1ac处,

用功能2,显当前符于stdout,以再接管道

若1ec小于屏幕配置行数1ea,则转1e1处,否则用功能09,显出1f0处的"--More--",用功能0c,且al=08,清键盘输入调功能08,无回显,从stderr读键盘1符

输出2空行,再置1ed=1,1ec=1

(2.8)1e1处,

cx减1,结果为0,转139,否则转150

(2.9)用a.com实现:

typea.asm|a.com时,AT机,每秒响铃,或
a.coma.com时,fcb,han各打开a.com,1次dup,1次force_dup,执行子进程,显计数11231123

csegment
assumecs:c;ds:c

org100h
@:jmpinit

cfg_rdb25
cfg_cdb80
cur_rdb1
cur_cdb1

bufdb"a.com"
db1000h-($-buf)dup(0)
buf_=$

keydb'-KEY-$'
crdb13,10,36

old4add59V6

parablkdbparasz
paradb-1
parasz=$-para
db13

envdw0
paraoffdwparablk
parasegdw?
FCB0dw92,?
dd-1

adjmacror,u
locala
moval,r
incal
daa
cmpal,u
stc
jnea
xoral,al
a:movr,al
endm 财管家.园.fs119.net

harpmacro
localh

movah,2
int26

adjdh,96秒BCD
jch

adjcl,96
jch

adjch,36

h:movah,7clr
int26

movah,6set
int26

endm

alarm:pushax
pushcx
pushdx

moval,7
int29h
harp

popdx
popcx
popax

jmpcs:old4a

J2Smacroh
movdi,h
moval,cs:24[di]原JFT
pushsi
pushes
callref
popes
popsi
endm

refproc
cbw
grp:cmpax,es:4[si];cnt
jlSFT

subax,es:4[si]

lessi,es:[si];next_addr
jmpgrp

SFT:mulwordptrold4a
addsi,ax

moval,byteptres:6[si]
addal,48
int41
ret
refendp

openproc
movah,82
int21h
lessi,es:[bxdi]矢SFT

cmpdi,4
jzunix

movah,15
movdx,92
int21h
oral,al
jnzopen1
open0:ret

unix:movax,3d00h
leadx,buf
int21h
jncopen0
open1:int20h
openendp

init:cmpbyteptrcs:[129],-1参数,ALT数字,都无法键入
jeLST_LST

movax,4406h
xorbx,bx
int21h
oral,al 财软联 盟 fs119.net
jzheir
jmpbell已改向

heir:leasp,buf_宽栈

movah,4ah新mem,始es节,长bx节
leabx,bell
addbx,15

rept4
shrbx,1字节转节
endm

int21h

LST_LST:movdi,26
callopen

moval,cs:[116]
callref

movbp,sp为关闭

movdi,4
callopen
pushax

movbx,ax
J2Sbx

movah,45hdup
int21h
pushax
J2Sax

moval,cs:[24]stdin
movbyteptr@,al

movah,46hforce
xorcx,cx
int21h

pushcx
J2Scx

movah,16为exec,关fcb
movdx,92
int21h

cmpbyteptrcs:[129],-1
jeclose

movax,cs
moves,ax

movparaseg,ax
movFCB0[2],ax

leabx,env;es:bx矢参数块
leadx,bufds:dx矢执行名

movax,4b00h
int21h

close:movah,3eh

close0:cmpbp,sp
jzclose1
popbx
int21h释放24[bx]
jmpclose0

close1:moval,byteptr@
movcs:[24],al

int20h

bell:movax,354ah
int21h

movwordptrold4a,bx
movwordptr[old4a2],es

movah,37
leadx,alarm

财软联盟,fs119.net

int21h

harp

xorbx,bx
movah,45h
int21h

movbp,ax

movah,3eh
int21h

movbx,2
movah,45h
int21h

read:leadx,buf
movcx,sizebuf
movbx,bp
movah,3fh
int21h

orax,ax
jnzread1

quit:ldsdx,cs:old4a
movax,254ah
int21h

int20h

read1:movcx,ax
movsi,dx

next:lodsb

cmpal,1ah
jzquit

cmpal,13
jnzCTL_CR

movcur_c,1
jmpshow

CTL_CR:cmpal,10
jnz?back

inccur_r
jmpshow

?back:cmpal,8
jnz?tab

cmpcur_c,1
jzshow

deccur_c
jmpshow

?tab:cmpal,9
jnz?bell

movah,cur_c
addah,7
andah,248
incah
movcur_c,ah
jmpshow

?bell:cmpal,7
jzshow

inccur_c

movah,cur_c
cmpah,cfg_c
jbeshow

inccur_r
movcur_c,1

show:movdl,al
movah,2
int21h

movah,cur_r
cmpah,cfg_r
jbendblk

leadx,key
movah,9
int21h

movax,0c08h
int21h

leadx,cr
movah,9
int21h

movcur_c,1
movcur_r,1

endblk:deccx
jzread@
jmpnext

read@:jmpread

cends
end@

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