-
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. Industrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conv
eni
ence to the staff.
Precisely
because of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
program
mable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such as:
ha
s good compatibil
ity,
wi
de availabil
ity,
har
dware is
complete, and
pr
ogramming that ca
n be
m
astere
d in a short time, so
in t
he context of industrial
PLC a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
co
untry
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
level
is slightly lower tha
n
the inter
national. T
he
de
sign is mai
nly arm
weldi
ng machine
by PLC
Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou of design in t
he
ca
n success
of using
i
n this
desig
n
in the pr
oce
eds
of experience 1.2
mani
pulator i
n both at home
and abroa
d of rese
arch
profile aut
omation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of ind
ustrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds, a
nd
its importance ca
n be
seen.
Now origi
nal robotic arm spent most of
mass pr
oducti
on
a
nd use on the
producti
on li
ne,
w
hich is pr
ogrammed robotic
arm. As t
he first generation of
mani
pulator
position control
sy
stems main features,
althoug
h not ba
ck several
generations that ca
n dete
ct
the external e
nvironment, but
ca
n still
successfully
complete like wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the
program as a
basis.
Difference is that t
he robot bega
nd
malloc
（）工作机制
malloc
函数的实质体现在，它有一个将可用的内存
块连接为一个长长的列表的所谓空闲链
表。调用
malloc<
/p>
函数时，它沿连接表寻找一个大到足以满足用户请求所需要的内存块。然
< br>后，
将该内存块一分为二
（一块的大小与用户请求的大小
相等，
另一块的大小就是剩下的字
节）。接下来，将分配给用户
的那块内存传给用户，并将剩下的那块（如果有的话）返回到
连接表上。调用
free
函数时，它将用户释放的内存块连接到空闲链上。到最后，空闲链
会
被切成很多的小内存片段，
如果这时用户申请一个大的内存片
段，
那么空闲链上可能没有可
以满足用户要求的片段了。于是，
malloc
函数请求延时，并开始在空闲链上翻箱倒柜地检<
/p>
查各内存片段，对它们进行整理，将相邻的小空闲块合并成较大的内存块。
但如果合并之
后还是不够申请大小呢，怎么办？此时
分配器会调用
sbrk
函数，向内核请求额外的堆存储
器，
分配器将额外的存储器转换为一个大的空闲块，
然后将这个块插入到空闲链表中，
然后
将被请求的块放置在
这个新的空闲块中。
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common. Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he development of China's modern
i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer showed
his
tw
o great adva
ntages: (1)
ea
ch
of the
har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable Logical
Controller (referred to as
IPC); (2) Distributed
Control
System (DCS for
short), and (3) the
Programmable
Logi
cal Controller (PLC for
short). 2.1.2 PLC a
nd the IPC and DCS
contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a hig
h
level
of standar
dization,
ca
n use m
ore compatibility
tools,
s a rich software
re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt
use
d to contr
ol,
whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as a
mea
ns of conti
nuous
process
control.
Optimization of PLC is t
he
corresponding relay
needs was
bor
n, its main use in
t
he work
order
contr
ol, early primary is
re
placed relay thi
s hulking
system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged, mi
cro
-electr
oni
< br>cs technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programm
abl
e
Logical Contr
oller (that is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence t
o the staff.
Precisely
because of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such as:
ha
s good compatibil
ity,
wi
de availabil
ity,
har
dware is
complete, and
pr
ogramming that ca
n be
mastere
d in a short time, so in
t
he context of industrial
PLC a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
level
is slightly lower tha
n
the inter
national. T
he
de
sign is mai
nly arm
weldi
ng machine
by PLC
Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou
of design in
t
he ca
n success
of using i
n this
desig
n
in the
pr
oce
eds
of
experience 1.2 mani
pulator
i
n both at home and abroa
d
of rese
arch
profile
aut
omation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds, a
nd
its importance ca
n be
seen.
Now origi
nal robotic arm spent most of
mass pr
oducti
on
a
nd use on the
producti
on li
ne,
w
hich is pr
ogrammed robotic
arm. As t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
图
1
图
2
Linux
用户进程是如何释放内存的
Linux
进程使用内存的基本流程，见图
1
从图中我们可以看出，进程的堆，并不是直接建立在<
/p>
Linux
的内核的内存分配策略上的，
而是建立在
glibc
的堆管理策略上的（也就是
glibc
的动态内存分配策略上），堆的管理是
由
glibc
进行的。
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common.
Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he development of China's modern
i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable Logical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and
(
3) the
Programmable
Logi
cal Controller (PLC for
short). 2.1.2 PLC a
nd the IPC and DCS
contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a hig
h
level
of standar
dization,
ca
n use m
ore compatibility
tools, i
s a rich software
re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system
in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as
a mea
ns of
conti
nuous
process
control.
Optimization of PLC
is t
he corresponding relay
needs was
bor
n,
its main use in t
he work
order contr
ol, early primary
is re
placed relay thi
s
hulking system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged, mi
cro
-electr
oni
< br>cs technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programmabl
e Logical
Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence to the staff. Precisely
bec
ause of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such
as
: ha
s good
compatibil
ity, wi
de
availabil
ity, har
dware is
complete, and pr
ogramming
that ca
n be mastere
d in a
short time, so in t
he context of
industrial
PLC
a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
lev
el
is slightly lower
tha
n the inter
national.
T
he de
sign is
mai
nly arm weldi
ng machine
by PLC Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou of design in t
he
ca
n success
of using
i
n this
desig
n
in the pr
oce
eds
of experience 1.2
mani
pulator i
n both at home
and abroa
d of rese
arch
profile
aut
om
ation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds,
a
nd its importance ca
n be
seen. Now origi
nal robotic
arm spent most of mass
pr
oducti
on a
nd
use on the
producti
on
li
ne, w
hich is
pr
ogrammed robotic arm. As
t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
所以我们调用
free
对
malloc
得到的内存进行释放的时候，并不是直接释放给操作系统，
而是
还给了
glibc
的堆管理实体，而
g
libc
会在把实际的物理内存归还给系统的策略上做一
些优化
，以便优化用户任务的动态内存分配过程。
那么
glibc
的堆管理器在什么时候才把物理内存归
还给系统呢？
它会从堆的最大线性地址开始，
从后向前计算用户任务当前有多少空闲的堆内存
（直到碰到
使用中的堆内存地址为止），比如在该图中，见图
2
它会认为有
2048k
的可释放内存，只有
在该值大于某个特定的
threshhold
时（
2.3.6
上
为
64k
），它才会把这些内存归还给系统。而在中间的
“
< br>未使用
”
内存是不会归还给系统的，
所以系统也不可能再利用这块物理内存页（我们假设系统没有
swap
区和
swap
文件），
也就
是说系统的内存会为此减少，除非在它之前的堆内存都用
free
进行释放以后，
glibc
的堆管理器才有可能（只是有可能
）把该段内存归还给系统。
由此，
我们在使用
malloc/free
时应该小心，特别是在初始
化时分配了好多内存，但是在
这之后却再也不需要这么多的内存了，
而这块内存又没有达到
threshhold
值或者在堆的
最
高线性地址处有某块内存没有释放，
但是它前面的所有堆内存
都释放了；
这种情况下，
用户
任务将会
浪费一些物理内存，这在资源比较紧张的嵌入式系统中是不可容忍的。
glibc
内存管理器
那么我们每次调用
malloc
来分配一块内存，都进行相应的系统调用呢？
答案是否定的，这里我要引入一个新的概念，
glibc
的内存管理器。
我们知道
malloc
和
free
等函数都是包含在
glibc
库里面的库函数，
我们试想一下，
每做一
次内存操作，都要调用系统调用的话，那么程序将多么的低效。
实际上
glibc
< br>采用了一种批发和零售的方式来管理内存。
glibc
每
次通过系统调用的方式申
请一大块内存（虚拟内存），当进程申请内存时，
glibc
就从自己获得的内存中取出一块给
进程。
内存管理器面临的困难
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common. Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he dev
elopment of China's
modern i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable L
ogical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and (3)
the
Programmable
Logi
cal
Cont
roller (PLC for short). 2.1.2 PLC
a
nd the IPC and DCS contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a
hig
h level
of
standar
dization, ca
n use
m
ore compatibility tools, i
s
a rich software re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as a
mea
ns of conti
nuous
process
control.
Optimization of PLC is t
he
corresponding relay
needs was
bor
n, its main use in
t
he work
order
contr
ol, early primary is
re
placed relay thi
s hulking
system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged,
mi
cro-electr
oni
cs
technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programm
abl
e
Logical Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence t
o the staff.
Precisely
because of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such as:
ha
s good compatibil
ity,
wi
de availabil
ity,
har
dware is
complete, and
pr
ogramming that ca
n be
mastere
d in a short time, so in
t
he context of industrial
PLC a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
level
is slightly lower tha
n
the inter
national. T
he
de
sign is mai
nly arm
weldi
ng machine
by PLC
Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou
of design in
t
he ca
n success
of using i
n this
desig
n
in the
pr
oce
eds
of
experience 1.2 mani
pulator
i
n both at home and abroa
d
of rese
arch
profile
aut
omation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds, a
nd
its importance ca
n be
seen.
Now origi
nal robotic arm spent most of
mass pr
oducti
on
a
nd use on the
producti
on li
ne,
w
hich is pr
ogrammed robotic
arm. As t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
我们在写程序的时候，每次申请的内存块大小不规律，而且存在频繁的申请和释放，这样
不可避免的就会产生内存碎块。
而内存碎块，
< br>直接会导致大块内存申请无法满足，
从而更多
的占用系统
资源；如果进行碎块整理的话，又会增加
cpu
的负荷，很多<
/p>
都是互相矛盾的指
标，这里我就不细说
了。
我们在写程序时，
涉及内存时，
有两个概念
heap
和
stack
。
传统的说法<
/p>
stack
的内存地址
是向下增长的，<
/p>
heap
的内存地址是向上增长的。
函数
malloc
< br>和
free
，主要是针对
hea
p
进行操作，由程序员自主控制内存的访问。
在这里
heap
的内存地址向上增长，这句话不完全正确。
glibc
对于
heap
内存申请大于
128k
的内存申请，
g
libc
采用
mmap
的方式向内核申
请内
存，
这不能保证内存地址向上增长；
小于
128k
的则采用
brk
，
对于它来讲是正确的。
128k
的阀值，可以通过
glibc
的库函数进行设置。
这里我先讲大块内存的申请，也即
对应于
mmap
系统调用。
对于大块内存申请，
glibc
直接使用
mmap
系统调用为其划分出另一
块虚拟地址，
供进程
单独使用；在该块内存释放时，使用
unmmap
系统调用将这块内存释放，这个过程中间
不会产生内存碎块等问题。
针对小块内存的申请，在程序启动之后，进程会获得一个
heap
底端的地址，进程每次
进
行内存
申请时，
glibc
会将堆顶向上增长来扩展内存空间，也就是
我们所说的堆地址向上
增长。在对这些小块内存进行操作时，便会产生内存碎块的问题。
实际上
brk
和
sbrk
系
统调用，就是调整
heap
顶地址指针。
那么
heap
堆的内存是什么时候释放呢？
当
glibc
发现堆顶有连续的
128k
的空间是空闲的时候，
它就会通过
brk
或
sb
rk
系统调
用，来调整
heap
顶的位置，将占用的内存返回给系统。这时，内核会通过删除相应的线
性区，来释放占用的物理内存。
下面我要讲一个内存空洞的问题：
一个场景，
堆顶有一块正在使用的内存，
而下面有很大的连续内存已经被释放掉了，
那么这
块内存是否
能够被释放？其对应的物理内存是否能够被释放？
很遗憾，不能。
< br>这也就是说，
只要堆顶的部分申请内存还在占用，
我在下
面释放的内存再多，
都不会被返回
m
a
nipulat
or control m
ode
a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common.
Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he development of China's modern
i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable Logical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and
(
3) the
Programmable
Logi
cal Controller (PLC for
short). 2.1.2 PLC a
nd the IPC and DCS
contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a hig
h
level
of standar
dization,
ca
n use m
ore compatibility
tools, i
s a rich software
re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system
in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as
a mea
ns of
conti
nuous
process
control.
Optimization of PLC
is t
he corresponding relay
needs was
bor
n,
its main use in t
he work
order contr
ol, early primary
is re
placed relay thi
s
hulking system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged, mi
cro
-electr
oni
< br>cs technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programmabl
e Logical
Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence to the staff. Precisely
bec
ause of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such
as
: ha
s good
compatibil
ity, wi
de
availabil
ity, har
dware is
complete, and pr
ogramming
that ca
n be mastere
d in a
short time, so in t
he context of
industrial
PLC
a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
lev
el
is slightly lower
tha
n the inter
national.
T
he de
sign is
mai
nly arm weldi
ng machine
by PLC Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou of design in t
he
ca
n success
of using
i
n this
desig
n
in the pr
oce
eds
of experience 1.2
mani
pulator i
n both at home
and abroa
d of rese
arch
profile
aut
om
ation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds,
a
nd its importance ca
n be
seen. Now origi
nal robotic
arm spent most of mass
pr
oducti
on a
nd
use on the
producti
on
li
ne, w
hich is
pr
ogrammed robotic arm. As
t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
到系统中，仍然占用着物理内存。为什么会这样呢？
这主要是与内核在处理堆的时候，
过
于简单，
它只能通过调整堆顶指针的方式来调整调整程
序占用的
线性区；而又只能通过调整线性区的方式，来释放内存。
所以只要堆顶不减小，占
用的内存就不会释放。
提一个问题：
char *p=malloc(2);
free(p)
为什么申请内存的
时候，
需要两个参数，
一个是内存大小，一个是返回的指针；而
释放内存
的时候，却只要内存的指针呢？
这主要是和
glibc
的内存管理机制有关。
glibc
中，
为每一块内存维护了一个
chunk
的结构。
glibc
在分配内存时，
glibc
先填写
chunk
结构中内存块的大小，
然后是分配给进程的内存。
chunk ------'size'
p------------ content
在进程释放内存时，只要指针
-4
便可以找到该块内存的大小，从而释放掉。
注：
glibc
在做内存申请时，最少分配
16
个字节，以便能够维护
chunk
结构。
---------------------------
---------------------------LINUX------------------
------------
---------------------
---------------
-------------------------------------WINDOWS------
---------------------
------------------
----
(
可参考
/bbs/?
/alex-
tech/archive/2011/03/26/.html
)
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common. Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he dev
elopment of China's
modern i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable L
ogical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and (3)
the
Programmable
Logi
cal
Cont
roller (PLC for short). 2.1.2 PLC
a
nd the IPC and DCS contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a
hig
h level
of
standar
dization, ca
n use
m
ore compatibility tools, i
s
a rich software re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as a
mea
ns of conti
nuous
process
control.
Optimization of PLC is t
he
corresponding relay
needs was
bor
n, its main use in
t
he work
order
contr
ol, early primary is
re
placed relay thi
s hulking
system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged,
mi
cro-electr
oni
cs
technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programm
abl
e
Logical Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence t
o the staff.
Precisely
because of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such as:
ha
s good compatibil
ity,
wi
de availabil
ity,
har
dware is
complete, and
pr
ogramming that ca
n be
mastere
d in a short time, so in
t
he context of industrial
PLC a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
level
is slightly lower tha
n
the inter
national. T
he
de
sign is mai
nly arm
weldi
ng machine
by PLC
Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou
of design in
t
he ca
n success
of using i
n this
desig
n
in the
pr
oce
eds
of
experience 1.2 mani
pulator
i
n both at home and abroa
d
of rese
arch
profile
aut
omation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds, a
nd
its importance ca
n be
seen.
Now origi
nal robotic arm spent most of
mass pr
oducti
on
a
nd use on the
producti
on li
ne,
w
hich is pr
ogrammed robotic
arm. As t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
C
语言标准定义了一系列的内存管理函数，
< br>如
malloc(), memcpy(),
free()
等。
Windows
系
统也支持标准
C
。在应用程序中，也可以使用标准
C
内存管理函数来对内存分配释放，
操作管理。
(crt : c
run time)
中包括了各种标准
C
库函数的实现，使用标准
C
库函数并不会
脱离
Windows
系统内存管理模式。事实上，在
Windows
上，和大多数标准
C
库函数一
样，像
malloc()
这种函数仍然是通过
API
函数实现的。
malloc()
在对
其参数进行了简单
的处理后就直接调用了
HeapAlloc()
函数。
调用关系为
: new ->
malloc -> HeapAlloc -> VirtualAlloc ->
驱动程序的
_PageAlloc
堆内存管理依赖于虚拟内存管理。
在创建堆时，
HeapCreate()
函数会向系统请求虚
拟内存
分页，
然后在这个堆上的内存分配实际上是从虚拟内存管
理中获取的内存分页上再分配大小
任意的内存块。
如果在建立堆
时指定了堆的大小是固定的，
那么在堆上分配内存块时，
其范<
/p>
围不能超过设置的堆大小，
堆大小一定是内存页大小的整数倍。<
/p>
如果在建立堆时不固定堆的
大小，那堆管理函数会根据分配的请求
数量，动态地向虚拟内存管理函数请求内存分页。
VirtualAlloc()
的
功能是对进程虚拟地址空间中内存分页的状态进行管理，属于虚拟内存管
理
(
以内存页为单位
)
的范围
。当然，内存的分配也是通过改变虚拟内存内存页面属性来实现
的，所以
VirtualAlloc()
间接达到了分配内存的目的。
堆管理器也是依赖于虚拟内存管理的，在收到
HeapAlloc()
的内存分配
的请求时，堆管理
器会根据情况决定是否使用虚拟内存管理机制分配新的页面，
以及如何在页面上分配内存块，
因此从这个层次上来讲，
VirtualAlloc()
更为底层。
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common.
Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he development of China's modern
i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable Logical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and
(
3) the
Programmable
Logi
cal Controller (PLC for
short). 2.1.2 PLC a
nd the IPC and DCS
contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a hig
h
level
of standar
dization,
ca
n use m
ore compatibility
tools, i
s a rich software
re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system
in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as
a mea
ns of
conti
nuous
process
control.
Optimization of PLC
is t
he corresponding relay
needs was
bor
n,
its main use in t
he work
order contr
ol, early primary
is re
placed relay thi
s
hulking system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged, mi
cro
-electr
oni
< br>cs technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programmabl
e Logical
Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence to the staff. Precisely
bec
ause of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such
as
: ha
s good
compatibil
ity, wi
de
availabil
ity, har
dware is
complete, and pr
ogramming
that ca
n be mastere
d in a
short time, so in t
he context of
industrial
PLC
a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
lev
el
is slightly lower
tha
n the inter
national.
T
he de
sign is
mai
nly arm weldi
ng machine
by PLC Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou of design in t
he
ca
n success
of using
i
n this
desig
n
in the pr
oce
eds
of experience 1.2
mani
pulator i
n both at home
and abroa
d of rese
arch
profile
aut
om
ation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds,
a
nd its importance ca
n be
seen. Now origi
nal robotic
arm spent most of mass
pr
oducti
on a
nd
use on the
producti
on
li
ne, w
hich is
pr
ogrammed robotic arm. As
t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
实际上，只要虚拟内存管理函数将页面属性设置为
“
已提交
”
后，就可以在
上面进行读写等
操作。
堆管理函数为应用程序提供了一种更灵活
，
更简单的方式来管理这些
“
已提交<
/p>
”
的内存，
其好处一就是分配更简单，<
/p>
二是可以分配任意大小的内存，
三是不用直接与复制的内存分页<
/p>
机制打交道。
如标准
C
中的
malloc()
函数实际上就是直接调用了
HeapAlloc()
，因此其效率也会比直
接使用
HeapAlloc()
来得低。
因为
HeapAlloc()
和
VirtualAlloc()
的层次和功能定位都不同，因
此在效率上没有可比性。
从原理上来讲，
HeapAlloc(
)
在分配内存时，如果堆管理器中有足够的已提交的页面可用，
那么它就不需要将内存分页从其他状态
(
空闲或保留的
)
改为已提交状态，
只需要在堆管理器
中进行相关管理即可。
如果在分配时没有足够的已提交页面可供使用，
那么还需要将虚拟内
存分页从其他状态改为已提交状态，
在有足够的可使用已提交页面时，
再由对管理器进行相
关管理。
虚拟地址空间内存页有
3
种状态，它们分别是：空闲的
(free)
，保
留的
(reserved)
，提交的
(
committed)
。大多数情况下，一个页的大小是
4KB
。
空闲的
对于空闲页面，
由于页面还未被分配，
因此进程不能访问。
对这属于
种页面的虚拟内存地址
访问都将引起访问异常。
保留的
被保留的页面为将来之备用。
这些页面已经分配，
但是还没被使用，
物理地址空间中的内存
不存在与其对应的物理内存分页。处理保留状态的内存分页也不能
被访问。
提交的
< br>内存已经被分配，并且已经被使用，具有与之对应的物理地址空间中的内存分页。
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common. Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he dev
elopment of China's
modern i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable L
ogical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and (3)
the
Programmable
Logi
cal
Cont
roller (PLC for short). 2.1.2 PLC
a
nd the IPC and DCS contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a
hig
h level
of
standar
dization, ca
n use
m
ore compatibility tools, i
s
a rich software re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as a
mea
ns of conti
nuous
process
control.
Optimization of PLC is t
he
corresponding relay
needs was
bor
n, its main use in
t
he work
order
contr
ol, early primary is
re
placed relay thi
s hulking
system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged,
mi
cro-electr
oni
cs
technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programm
abl
e
Logical Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence t
o the staff.
Precisely
because of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such as:
ha
s good compatibil
ity,
wi
de availabil
ity,
har
dware is
complete, and
pr
ogramming that ca
n be
mastere
d in a short time, so in
t
he context of industrial
PLC a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
level
is slightly lower tha
n
the inter
national. T
he
de
sign is mai
nly arm
weldi
ng machine
by PLC
Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou
of design in
t
he ca
n success
of using i
n this
desig
n
in the
pr
oce
eds
of
experience 1.2 mani
pulator
i
n both at home and abroa
d
of rese
arch
profile
aut
omation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds, a
nd
its importance ca
n be
seen.
Now origi
nal robotic arm spent most of
mass pr
oducti
on
a
nd use on the
producti
on li
ne,
w
hich is pr
ogrammed robotic
arm. As t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
---------------
-------------------------------------WINDOWS------
---------------------
------------------
----
malloc
（）在操作系统中的实现
在
C
程序中，多次使用
malloc
()
和
free()
。不过，您可能没有用一些时间去思考它
们在您的操作系统中是如何实现的。
本节将向您展示
malloc
和
free
的一个最简化实现的
代码，来帮助说明管理内存时都涉及到了哪些事情。
在大部分操作系统中，内存分配由以下两个简单的函数来处理：
void *malloc
(long numbytes)
：该函数负责分配
numbytes
大小的内存，并返回指
向第一个字节的指针。
void free(void
*firstbyte)
：如果给定一个由先前的
malloc
返回的指针，那么该函数
会将分配的空间归还给进程的“空闲空间”。
malloc_init
将是初始
化内存分配程序的函数。它要完成以下三件事：将分配程序标识
为已经初始化，
找到系统中最后一个有效内存地址，
然后建立起指向我们管理的内存的指
针。
这三个变量都是全局变量：
//
清单
1.
我们的简单分配程序的全局变量
int has_initialized =
0;
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common.
Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he development of China's modern
i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable Logical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and
(
3) the
Programmable
Logi
cal Controller (PLC for
short). 2.1.2 PLC a
nd the IPC and DCS
contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a hig
h
level
of standar
dization,
ca
n use m
ore compatibility
tools, i
s a rich software
re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system
in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as
a mea
ns of
conti
nuous
process
control.
Optimization of PLC
is t
he corresponding relay
needs was
bor
n,
its main use in t
he work
order contr
ol, early primary
is re
placed relay thi
s
hulking system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged, mi
cro
-electr
oni
< br>cs technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programmabl
e Logical
Contr
oller (that
is
Manipulator i
s now used
a
s a industri
al robots
i
n use, the
control
obje
ctives
often appear
ofte
n in i
ndustrial
aut
omation. In
dustrial
automati
on
te
chnol
ogy has
gra
dually mat
ured,
a
s mature a
te
chnol
ogy line
has
been rapid
devel
opment i
n
industrial aut
omation a
s a
se
parate subje
ct.
Ma
nipulator appli
cation
bega
n to filter into
w
eldi
ng,
logi
stics, mechani
cal
pr
oce
ssing, and
ot
her industri
es.
Espe
cially at hig
h or very
l
ow temperat
ures, full
of poi
sonous
gase
s, hig
h
radiati
on
case,
r
obot in
similar
circumstances
showed great
use a
lso
bring
s great
conveni
ence to the staff. Precisely
bec
ause of this robot to get
pe
opl
e's
attenti
on
began to
be a
high
degree
of development.
Labor rates,
w
orking
conditi
ons, labor
inte
nsive aspe
cts of
pr
omoting
devel
opment. Both at
home a
nd
a
broa
d to develop the
PLC (
programmable
l
ogic
contr
oller)
is in various special
circumstances
a
nd
under
speci
al
conditions set for
mechani
cal devi
ces. Now
tur
ned
on t
he
devel
opme
nt of the
mi
croele
ctronics
automati
c control
technology
a
nd t
he rapi
d
devel
opme
nt of the trains,
the success of PLC har
dware software
and
simulati
on control win
big and succe
ssful
development,
now
conti
nues to develop as a
factory a
utomation standards.
Beca
use robot
s are good
devel
opme
nt of the
te
chnol
ogy makes a good
optimization of productive ca
pital, and
robot shows t
his
uni
que
a
dvantages,
such
as
: ha
s good
compatibil
ity, wi
de
availabil
ity, har
dware is
complete, and pr
ogramming
that ca
n be mastere
d in a
short time, so in t
he context of
industrial
PLC
a
ppl
ications
became
ubi
quit
ous.
Mani
pulat
or in many
developed
country
agriculture a
nd i
ndustry has
bee
n applied, such
a
s the use of mechani
cal
harvesting large area
s of farmland,
re
peated
operations on
t
he hig
h-spee
d
line that uses a roboti
c arm, and so
on.
oday, t
he
hig
h level of aut
omation
combine
d with
restri
ctions on the
ma
nipulator dev
elopment
lev
el
is slightly lower
tha
n the inter
national.
T
he de
sign is
mai
nly arm weldi
ng machine
by PLC Aut
omation
contr
ol. This
of
design l
et desig
ners
on in
school by
lear
n of has a m
ust of
consolidati
on,
understand
ha
s some
usually
di
dn't opportuniti
es
aware
ness i
n
worl
d range wit
hin some
lea
ding level
of
knowl
edge has ha
s must
aware
ness, hope
desig
ners ca
n in
yi
hou of design in t
he
ca
n success
of using
i
n this
desig
n
in the pr
oce
eds
of experience 1.2
mani
pulator i
n both at home
and abroa
d of rese
arch
profile
aut
om
ation
me
cha
nica
l arm
research bega
n Yu 20t
h
ce
ntury medi
um-term, after
years with wit
h computer a
nd
a
utomation technol
ogy of
devel
opme
nt, Makes
me
cha
nical
arm on
the Grand stage of industrial
aut
omation a
nd shine,
gradually be
came an
i
ndustrial evaluati
on
sta
ndar
ds,
a
nd its importance ca
n be
seen. Now origi
nal robotic
arm spent most of mass
pr
oducti
on a
nd
use on the
producti
on
li
ne, w
hich is
pr
ogrammed robotic arm. As
t
he first generation of
mani
pulator
position control
systems main features, althoug
h not
ba
ck several generations that
ca
n dete
ct the external
e
nvironment, but ca
n still
successfully complete like
wel
ding,
painti
ng,
del
ivery as well a
s for
materials simple moveme
nts.
Se
cond ge
neration
me
cha
nica
l arms
are equipped wit
h se
nsors
and manipulators
have the
e
nvironment there i
s a
certai
n amount of
n the
mechanical arm is to
use the program as
a
basis. Difference is that
t
he robot bega
nd
void *managed_memory_start;
void *last_valid_address;
<
/p>
如前所述，被映射的内存的边界（最后一个有效地址）常被称为系统中断点或者
当前中断
点。
在很多<
/p>
UNIX?
系统中，
为了指出当前系统中断点，
必须使用
sbrk(0)
函数。
sbrk
根
据参数中给出的字节数移
动当前系统中断点，然后返回新的系统中断点。使用参数
0
只是
返回当前中断点。这里是我们的
malloc
初始化代码，它将找到当前中断点并初始化我们
的变量：
清单
2.
分配程序初始化函数
/*
Include the sbrk function */
#include
void
malloc_init()
{
/* grab the last valid address from the
OS */
last_valid_address =
sbrk(0);
/* we don''t have
any memory to manage yet, so
*just set the beginning to be
last_valid_address
*/
managed_memory_start =
last_valid_address;
/* Okay,
we''re initialized and ready to go */
m
anipulat
or
control m
ode a
nd
programmable
controller
s introduction 2.1
Sel
ect
discussion with
ma
nipulator control 2.1.1
cla
ssificati
on
of
control relays a
nd
discrete
ele
ctroni
c
cir
cuit
can
control ol
d industrial
equipme
nt, but also more
common. Mai
nly
the
se two rel
atively cheap
a
nd y
ou
can
m
eet the ol
d-fashioned,
simpl
e (or simpl
e)
industrial e
qui
pment.
S
o he
can
see
them now,
however t
hese two
contr
ol modes (relay and
di
screte el
ectronic
circuits) are the
se fatal
flaws: (1) cannot a
dapt t
o
the
complex logic control, (2) only for
the
curre
nt project,
t
he la
ck of compatibility
a
nd (3) not reforming the
sy
stem with
e
qui
pment
impr
ovements. S
pring for
t
he dev
elopment of China's
modern i
ndustrial a
utomation
technology the substantia
l increase
i
n the l
evel of industrial
aut
omation,
com
pleted t
he
perfect relay of the
com
puter too much.
In terms
of
controlli
ng the
computer
showed
his tw
o great
adva
ntages: (1) ea
ch
of the har
dware can
be installed
on
one
or more
mi
cropr
oce
ssors;
(2) the
official desig
ner of
the software writi
ng content
contr
ol is all
a
bout. Now in
several ways
in t
he context of industrial
a
utomation ca
n often
be se
en i
n three
ways: (1) Programmable L
ogical
Controller (referred to as
IPC); (2) Distributed
Control System (DCS for short), and (3)
the
Programmable
Logi
cal
Cont
roller (PLC for short). 2.1.2 PLC
a
nd the IPC and DCS contrast
contrast 1, each of the
t
hree technologi
es of
origi
ns a
nd
development requirement
s for
fast data processing makes it inve
nted
t
he compute
r. The men
br
oug
ht in terms of
har
dware there, using a
hig
h level
of
standar
dization, ca
n use
m
ore compatibility tools, i
s
a rich software re
sour
ces,
especially t
he
ne
ed for immedia
cy in
operational systems. So the
com
puter can effectively control
i
s used to
control and meet
its spee
d, on the virtual
m
odel
, real-time
a
nd i
n
com
putational
re
quirement
s.
Distri
bute
d system started
wit
h a contr
ol system for
industrial a
utomatic
i
nstrume
nt use
d
to contr
ol, whereas now it is
succe
ssfully developed
i
nto
industrial control
computer used as a
central
colle
ction and
distri
bution system and
transiti
on
of distributed
contr
ol system in
a
nalog
ue
ha
ndli
ng, loop
control, ha
s
beg
un to refle
ct the use of
a huge adva
ntage. Thoug
h
distri
bute
d system has great
a
dvantages i
n loop
regulati
on, but
only as a
mea
ns of conti
nuous
process
control.
Optimization of PLC is t
he
corresponding relay
needs was
bor
n, its main use in
t
he work
order
contr
ol, early primary is
re
placed relay thi
s hulking
system, focuse
d on the switch
controlling t
he
runni
ng order
of
functi
ons. Marked
by the
micr
opr
oce
ssor
i
n the early 1970 of the
20t
h ce
ntury emerged,
mi
cro-electr
oni
cs
technology
has developed
ra
pidl
y, pe
ople
soon
micr
oele
ctroni
cs
pr
oce
ssi
ng
technol
ogy will be use
d in
t
he Programm
abl
e
Logical Contr
oller (that is
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