m730053b training

5/19/2018 M730053b Training

1/81SV P ED T DA 1 Khosrau Heidary C Coding Guidelines

Training on

C Coding Rules

M730053b

Welcome to the

Duration: approx. 4h (initial) / 2h (update)

Trainer: Khosrau Heidary

SV P ED T D

Tel.: !"#$##

e"%ail: &hosrau.heidary'sie%ens.o%

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Background

Break

C Coding Guidelines - Overview

General Rules

Comments

ata and ata t!"es O"erators and #$"ressions

%tatements and Control %tructures

&unctions

're"rocessor irectives

&orm and (""earance

)ames"aces

Tec*nical %olution

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Background

General Rules

Comments

ata and ata t!"es

O"erators and #$"ressions


&unctions


&orm and (""earance

)ames"aces

Tec*nical %olution

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while (*p>=1?1:0) f*=*p--;

while (*p>=1) f*=(*p)--;

/* calculate faculty of p */

Background +,

/* calculate faculty of p */

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Background +.

ode should *e porta*le *et+een people

ode should *e orret and understanda*le

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Background +3

ode should *e porta*le *et+een

pro,ets

#C/, #C/.

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flag lv_status; flag *pt = !lv_status;

u" status;

u" *pt = !status;

Background +

'lag could (e

de'ined as )*T

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#ea u1$ *pt1;

fa u1$ *pt%;

u1$ *pt1;

u1$ *pt%;

Background +5

near,'ar not

de'ined

(y *S-

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&'efi#e _+, (u%).0000 &if _+, = .0000

u% = _+,;

&'efi#e _+, .0000 &if _+, = .0000

u% = (u%)_+,;

Background +1

Cast in /i'

not allo0ed

)y *S-

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Background +7


o%pilers

*c *h files

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s1$ = -%000; u1$ y = %; if (( / y) 2 0)

s1$ = -%000; u1$ y = %;

if (( / (s1$)y) 2 0)

Background +2

2 , y 3 1%&%+

on 1% (it systems

-3.000 ,000 00,, 0000 0000

$ is "romoted to u,1

4,000 00,, 0000 0000 33531

4 33531 . 6 ,1712

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Background +


tar-ets

*c *h files

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u" 'iv(u" val_1 u" val_%) 3 etu# = val_1 / val_%; 4

u" 'iv(u" val_1 u" val_%) 3 if (val_% > 0)

3 etu# = val_1 / val_%; 4 else 3 4 4

Background +,0

di4ision (y

5ossi(le

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5o'_ah ----------- &'efi#e _678_989 %

5o'_

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Background +,.

ode should *e sae and ro*ust

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Background +,3

T*ere8ore9

(ctivities initiated b! %: (rc*itecture grou" 8or 3.-bit %:9

7Memor! (llocation conce"t

7(ggregate conce"t

7Con8iguration conce"t

7'artitioning

7Basic ata T!"es

7Coding Guidelines

7()%; %tandard

7;%O;#C 2 +1990< ,

7M;%R( guidelines 8or t*e C language in ve*icle based %:

7+ M00,< M00.0

%tandards 8or C-Coding9

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Background +,

Roadma"9

=7=0,

;nitial version ,=3

ela(orated and re4ie0ed

(y Wor8ing Grou59

Giron Patricia :T;S*S6A

Team9

Giron Patricia :T;Seri8ication Code re4ie0

#$am"le )ad Good

toto = lamb; #define SET_TOTO(a) {toto=(a); }

)ad

*n the (ad e2am5le code is generated (y the header 'ile The good e2am5le

e25orts a macro Code 0ill only (e generated 0hen the macro 0ill (e called 0ithin a

c'ileRe8erence

Background

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Background

General Rules

Comments

ata and ata t!"es



&unctions


&orm and (""earance

)ames"aces

Tec*nical %olution

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Comments

%ummar!%ummar!

. Explain eah P";int o%%ent

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Comments +.

C=7 #ac* su""ression o8 'C-?int messages s*all be e$"lainedC=7 #ac* su""ression o8 'C-?int messages s*all be e$"lainedescri"tion To5 5riority is to a4oid su55ressing any PC;int 0arning A comment that su55resses

a PC;*T message must (e 0ell e25lained The sco5e o' the ;*T comment should

(e as small as 5ossi(le ;int 0arnings ha4e to (e su55ressed at the cause :eg atmacro or stu( de'inition< and not 0here they a55ear

#$am"le )ad Good

u16 c_xxx(u16 x) { u16 i = 0;

wile (i != x) i"";

etun = (x $ i);}

u16 c_xxx(u16 x) { u16 i = 0;

wile (i != x) i"";

etun = (x $ i); $%lint &e'*i alwa+, - 0 .- no di/ b+ eo %$

}

)ad

The (ad e2am5le generates the PC;int 0arning &.$ Concei4a(le di4ision (y

The good e2am5le su55resses this 0arning and descri(es the reason 0hy The

su55ression is only e''ecti4e 'or the 5articular code line

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Background

General Rules

Comments

ata and ata t!"es



&unctions


&orm and (""earance

)ames"aces

Tec*nical %olution

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ata and ata T!"es

%ummar!%ummar!

D.53 ast i%%ediate 7alues (exept 0..#2$) expliitly

D.8 t use the enumtype to deine 7aria*les

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ata and ata T!"es +.

=5 &lags s*all contain 0 and , onl!=5 &lags s*all contain 0 and , onl!escri"tion The data ty5e flagis de'ined to descri(e a (oolean in'ormation only Store only or 1

in a 4aria(le o' this ty5e *' more in'ormation needs to (e stored in a 4aria(le then

(it'ields or data ty5es :u+B F< shall (e used

#$am"le , )ad Goodfla l/_x;u16 m+_data;

l/_x = T23E;

l/_x = 0x4E;

l/_x = m+_data;

fla l/_x;u16 m+_data;

l/_x = 1;

l/_x = 1;

l/_x = (m+_data &= 0);

)ad

*n the (ad e2am5le you dont 8no0 i' T6E and =A;SE is eIual to 1 and *n the

good e2am5le the 4alues are de'ined e2actly The 4alue 2=E is assigned to a 'lag

This re5resents logical JT6EJ tooB (ut does not 0or8 on e4ery im5lementation The

right side o' an assignment to 'lags should al0ays (e a )oolean e25ression

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ata and ata T!"es +3

=5 &lags s*all contain 0 and , onl!=5 &lags s*all contain 0 and , onl!

#$am"le . )ad Good

$% 5oce,,o 1* fla a, int %$t+edef int fla;

$% 5oce,,o 7* fla a, bit %$

t+edef bit fla;

$% won u,ae of fla* %$fla l/_,tatu, = 0x10;

if (l/_,tatu, 8 0x10)9

$% don:t u,e fla in ti, ca,e* %$u ,tatu, = 0x10;

if (,tatu, 8 0x10)

)ad

The (ad e2am5le 0ill not 0or8 i' 'lag is really only a (it

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ata and ata T!"es +.

=1 o not use a "ointer to a 8lag=1 o not use a "ointer to a 8lagescri"tion Do not use a 5ointer to a 4aria(le o' data ty5e 'lag se a di''erent data ty5eB i' indirect

access is reIuired

#$am"le )ad Good

fla l/_,tatu,;

fla %t = 8l/_,tatu,;

u ,tatu,;

u %t = 8,tatu,;

)ad

The (ad e2am5le 0ill not 0or8 :or e4en get com5iled< i' 'lag is really a :non

addressa(le< (it

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ata and ata T!"es +

=7 o not initialiAe global and static variables wit* initial value 0=7 o not initialiAe global and static variables wit* initial value 0escri"tion Any glo(al or static 4aria(leB 0hich should (e initiali@ed 0ith during startu5B shall not

(e initiali@ed e25licitly

Background The initiali@ation o' these storage ty5es 0ith 0ill (e done at startu5 time (y the 6A>

test An e25licit initiali@ation 0ould result in additional startu5 time The 6A> test has

to (e con'igured accordingly

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#$am"le )ad Good

u% v1 = 0;static u% v% = 0;u

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R(M

v,

v.

u% v1 = 0;static u% v% = 0;u

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=, Cast immediate values +e$ce"t 0==3.717 e$"licitl!=, Cast immediate values +e$ce"t 0==3.717 e$"licitl!escri"tion Each immediate 4alue :e2ce5t "!&%&< has to (e casted to a 5rede'ined data ty5e

:u1%B F

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=.0 'er8orm t!"e casts e$"licitl! i8 needed=.0 'er8orm t!"e casts e$"licitl! i8 neededescri"tion A4oid unnecessary e25licit ty5e casts Per'orm ty5e casts in the 'ollo0ing cases9

1 )oth o5erands o' a (inary o5erator :eg LB MB 33< ha4e to (e either unsigned or

signedB (ut not mi2ed *' not 5er'orm the reIuired ty5ecast

! The le'thand o5erand o' a (inary nonrelational o5erator has to (e casted i' its

si@e is smaller than the e25ected si@e o' the o5eration

" An e25licit ty5e cast is necessary to reduce the data si@e

# An e25licit ty5e cast is necessary 'or con4erting 'rom signed to unsigned or

(ac8

#$am"le ,

+not mi$ed

unsigned

signed o"er-

ands

)ad Good

,16 x = .

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ata and ata T!"es +

=.0 'er8orm t!"e casts e$"licitl! i8 needed=.0 'er8orm t!"e casts e$"licitl! i8 needed

#$am"le .

+le8t-*ando"erand de-

termines siAe o8

o"eration

)ad Good

,16 /a1;,16 /a7;,

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ata and ata T!"es +,0


escri"tion A4oid unnecessary e25licit ty5e casts Per'orm ty5e casts in the 'ollo0ing cases9





" An e25licit ty5e cast is necessary to reduce the data si@e

# An e25licit ty5e cast is necessary 'or con4erting 'rom signed to unsigned or

(ac8

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ata and ata T!"es +,,

#$am"le 3

+reduce data

siAe

)ad Good

u16 /a1;u /a7;9

if (/a1 ! 76){

/a7 = /a1;}el,e{ /a7 = 0x44;}

u16 /a1;u /a7;9

if (/a1 ! 76){

/a7 = (u)/a1;}el,e{ /a7 = 0x44;}

*n the J(adJ e2am5le it is unclear 0hether data si@e is reduced intentionally or (y mista8e ;*T 0ill

issue a 0arning *n the JgoodJ e2am5le the intention is documented

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ata and ata T!"es +,.


#$am"le

+converting

unsigned to

signed

)ad Good

,16 a;u16 b;

9a = u16_min_u16_u16(bA 0x'444);

,16 a;u16 b;

9a = (,16)u16_min_u16_u16(bA 0x'444);

*n the J(adJ e2am5le it is unclear 0hether the con4ersion to signed is done intentionally or (y

mista8e ;*T 0ill issue a 0arning *n the JgoodJ e2am5le the intention is documented

escri"tion A4oid unnecessary e25licit ty5e casts Per'orm ty5e casts in the 'ollo0ing cases9





" An e25licit ty5e cast is necessary to reduce the data si@e# An e25licit ty5e cast is necessary 'or con4erting 'rom signed to unsigned or

(ac8

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=. onDt use t*e enumt!"e to de8ine variables=. onDt use t*e enumt!"e to de8ine variablesescri"tion Varia(les o' enumty5e are not usa(le due to high 6A>consum5tion So use #define

or enumeration sets together 0ith the smallest 5ossi(le data ty5e :mostly u+< 'or state

4aria(les *n the latter case use only tagless enums

#$am"le , +R(M

consum"tion

)ad Good

enum {>?_STBTE1A >?_STBTE7} ,tate; #define >?_STBTE1 0x00

#define >?_STBTE7 0x01u ,tate;

,tate = (u)>?_STBTE1;

The (ad e2am5le is good in terms o' codeB (ut the state 4alue 0ill use the integer data ty5eB 0hich

needs more 6A>

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ata and ata T!"es +,

=. onDt use t*e enum t!"e to de8ine state variables=. onDt use t*e enum t!"e to de8ine state variables

#$am"le .

+enumusage

)ad Good

enum STBTES {>?_STBTE1A>?_STBTE7};u ,tate;

,tate = >?_STBTE1;

enum {>?_STBTE1A >?_STBTE7};u ,tate;

,tate = (u)>?_STBTE1;

*n the (ad e2am5le the enumhas the tag STATES This de'ines a ne0 data ty5e An e25licit ty5e

cast 0ould (e necessary 0hen assigning the state CNSTATE1 to the 4aria(le state

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=. onDt use t*e enum t!"e to de8ine state variables=. onDt use t*e enum t!"e to de8ine state variables

#$am"le 3

+enumusage)ad Good

enum { >?_CDB = 0x?_TOTO =0xBB};

u /a;

/a = >?_CDB;

#define >?_CDB 0x?_TOTO 0xBBu /a;

/a = (u)>?_CDB;

*n the (ad e2am5le an enum mem(er is used to initiali@e a u+ 4aria(le Enumsare a s5ecial data

ty5e to contain enumerations only They ha4e nothing to do 0ith the integer data ty5es *n this case

use #define

*' you need to de'ine state 4alues its more use'ul to use enumty5e 'or de'inition o' data sets

together 0ith u+ ty5e :see e2am5le !

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#$ercise +,

#$ercises on

7General Rules

7Comments

7ata and ata T!"es

#$ercises on

7General Rules7Comments

7ata and ata T!"es

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Background

General Rules

Comments

ata and ata t!"es



&unctions


&orm and (""earance )ames"aces

Tec*nical %olution

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%ummar!%ummar!

.# Do not use state%ents +hih depend on the order o e7aluation or on lo-ial shortuts

.4 6se the ?operator only in speial ases

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O"erators and #$"ressions +.

O=3 o not use statements w*ic* de"end on t*e order o8 evaluation or on logical s*ortcuts O=3 o not use statements w*ic* de"end on t*e order o8 evaluation or on logical s*ortcutsescri"tion E4ery statement has to (e 0ritten in a 0ay that does not de5end on the order o'

e4aluation se only 'unctions in an e25ressionB 0hich dont modi'y glo(al resources

=unctionsB 0hich 5er'orm an actionB are not allo0ed to (e used in e25ressions 0ith a

shortcut

#$am"le , )ad Good

x = biF " i""; x = biF " i;

i"";

*n the J(adJ e2am5le it is not clearB 0hat the 4alue o' i isB 0hen accessing (Oi *t de5ends on the

order o' e4aluation There'ore in the good e2am5le i is incremented 0ithin a se5arate statement

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O"erators and #$"ressions +3

O=3 o not use statements w*ic* de"end on t*e order o8 evaluation or on logical s*ortcuts O=3 o not use statements w*ic* de"end on t*e order o8 evaluation or on logical s*ortcuts#$am"le . )ad Good

u a10F = {0A1A7A

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O"erators and #$"ressions +

O= /se t*e ?o"erator onl! in s"ecial casesO= /se t*e ?o"erator onl! in s"ecial casesescri"tion se the ? o5erator only i' the 5rogram (ecomes 'aster and,or smaller The used

e25ressions should (e less com5le2 in that case

*n standard cases and 'or more com5le2 e25ressionsB use the ifinstructioninstead

#$am"le , )ad Good

e=(d 88 (a - (b%c))) G a " c * b; if (d 88 ( a - (b % c))){

e = a " c;}el,e{ e = b;}

*n the (ad e2am5le the reada(ility is not acce5ta(le =urthermore the use o' Q has no ad4antageThe i'instruction should (e used in such cases

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O"erators and #$"ressions +5

#$am"le . )ad Good

u16 tm_n_min;

if (l/_at) tm_n_min = c_n_min_at;el,e tm_n_min = c_n_min_mt;

if (l/_ena

88 (n - tm_n_min))

HHH

if (l/_ena 88 (n - (l/_at G c_n_min_at * c_n_min_mt))

HHH

*n J(adJ e2am5leB the im5lementation is Iuite ine''ecti4e *n this case it ma8es sense to use the Q

o5erator

O= /se t*e ?o"erator onl! in s"ecial casesO= /se t*e ?o"erator onl! in s"ecial cases

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Background

General Rules

Comments

ata and ata t!"es

O"erators and #$"ressions %tatements and Control %tructures

&unctions



Tec*nical %olution

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%ummar!%ummar!

S.55 he& array indexes

S.58 Ter%inate eah ase in a switchstate%ent +ith a break

S.5$ Put the %ost deisi7e riterion o a ondition at the *e-innin-

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%tatements and Control %tructures +.

%=,, C*eck arra! inde$es%=,, C*eck arra! inde$esescri"tion *nde2es on arrays must (e chec8ed during coding 5hase and re4ie0ing to ensure that

inde2 4alue 5oints do not e2ceed the array range *' it can not (e guaranteed (y any

other means :eg code re4ie0B static code chec8B integration re4ie0

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%tatements and Control %tructures +3

%=,5 Terminate eac* case in a switchstatement wit* a break%=,5 Terminate eac* case in a switchstatement wit* a breakescri"tion Each case :including the de'ault case< shall (e terminated 0ith a (rea8 statement *' it

is 0anted to omit the (rea8 statement then it needs to (e documented

#$am"le )ad Good

,witc(,tate){

ca,e 0* ca,e 1*

do_,ometin_fo_ca,e_0_and_1(); beaK; ca,e 7* do_,ometin_fo_ca,e_7(); beaK; default*}

,witc (,tate) {

ca,e 0* $%lint .falltou%$ ca,e 1*

do_,ometin_fo_ca,e_0_and_1(); beaK; ca,e 7* do_,ometin_fo_ca,e_7(); beaK; default* beaK;

}

The good e2am5le terminates each case 0ith a (rea8 or documents that it 0as intentionally

omitted ote9 ;int understands the comment ,lint 'allthrough, a'ter the last statement o' the

5receding case Please note that the case(loc8 in "! im5lies (racesU so the ;*Tcomment must(e outside the (ody o' the case(loc8

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%tatements and Control %tructures +

%=,1 'ut t*e most decisive criterion o8 a condition at t*e beginning%=,1 'ut t*e most decisive criterion o8 a condition at t*e beginning

#$am"le , )ad Good

fla x;

if (l/_iK 88 l/_,t) x = 1;if (l/_,t LL l/_iK) x = 1;

fla x;

if (l/_,t 88 l/_iK) x = 1;if (l/_iK LL l/_,t) x = 1;

AssumingB that it is more li8ely that l4Nig8 is set and l4Nst is not setB the order o' the criterions is

0rong in the (ad e2am5le

Put the least 5ro(a(le criterion 0ithin a condition and the most 5ro(a(le criterion

0ithin a condition at the (eginning o' the e25ression

Put the most 5ro(a(le case at the (eginning o' a s0itchstatement

escri"tion

#$am"le . )ad Good

fla f;

if((u_add_u_u(aA b) ! c) 88 f)9

fla f;

if (f 88 (u_add_u_u(aA b) ! c)) 9

*n the (ad e2am5le the 'unction 0ill (e called in any case

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#$ercise +.

#$ercises on

7O"erators and #$"ressions

7%tatements and Control %tructures

#$ercises on

7O"erators and #$"ressions

7%tatements and Control %tructures

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Break

Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

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Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

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&unctions

%ummar!%ummar!

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&unctions +.

&=. (lwa!s declare 8unction "rotot!"es 8or e$"orted 8unctions&=. (lwa!s declare 8unction "rotot!"es 8or e$"orted 8unctionsescri"tion The de4elo5er o' an e25orted 'unction has to declare a 'unction 5rototy5e in the

res5ecti4e header 'ile When this 'unction is to (e used in another moduleB the header

has to (e included o e25licit e2terndeclaration shall (e done outside this header

The 5rototy5e must (e 8no0n 0hen calling the 'unction

)ote =or 5ri4ate 'unctions :'unctions that are only 4isi(le 0ithin the module< no e25licit

5rototy5e is needed in order to a4oid redundancy *nsteadB the de4elo5er can ta8ecare 'or the correct order o' the 'unctions de'initions to ensure that the 5rototy5e o' a

'unction is a4aila(le 0hen it is called

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&unctions +3

moduleE,=c

void 8Ee$t+void F

static void 8E"riv+void F

8E"riv+ H

void 8Eclient+void F

8Ee$t+ H

moduleE.=ce$tern void 8Ee$t+voidH

e$tern void 8Ee$t+voidHmoduleE,=*

static void 8E"riv+voidH

Iinclude JmoduleE,=*K

Take

care

o8correctorderL

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&unctions +

&=1 /se inline 8unctions w*ere reuired&=1 /se inline 8unctions w*ere reuiredescri"tion *nline 'unctions are a use'ul means to im5lement 'unctionli8e structures 0ithout the

o4erhead o' 'unction calls They shall (e used 0here4er this is suita(le

#$am"le )ad Good

,

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Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

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%ummar!%ummar!

P.4 Enlose %aros9 +hih don>t ha7e a return 7alue9 +hithin {}

P.8 @aros %ust not end +ith a ABC

' i ti +.

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're"rocessor irectives +.

'= #nclose macros< w*ic* donDt *ave a return value< wit*in {}'= #nclose macros< w*ic* donDt *ave a return value< wit*in {}

#$am"le )ad Good

#define MN_MB?2O() l/_,tate_1=1; l/_,tate_7=0

if (l/_,tate_0) MN_MB?2O();

i, exanded to*if (l/_,tate_0) l/_,tate_1 = 1;

l/_,tate_7 = 0;

#define MN_MB?2O() {l/_,tate_1 = 1; l/_,tate_7 = 0;}

if (l/_,tate_0) MN_MB?2O();

i, exanded to*if (l/_,tate_0) {l/_,tate_1 = 1;

l/_,tate_7 = 0;};

*n (oth e2am5les rule A& is 4iolated *n the (ad e2am5le only the 'irst statement :l4NstateN1 3 1< is5art o' the i'structureB the second statement :l4NstateN! 3 < is e2ecuted unconditionally )e a0are

that the JgoodJ e2am5le is still not con'orming to the coding guidelinesB ne4ertheless the 5ro(lem

does not occur anymore

Background This is necessaryB i' the macro is called 0ithin a (ranch The second statement 0ould

(e unconditional

' i ti +.

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're"rocessor irectives +.

'=5 Macros must not end wit* a ;'=5 Macros must not end wit* a ;

#$am"le )ad Good

#define >?_4OO 10;HHHx = >?_4OO P ?_4OO 10HHHx = >?_4OO P

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Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

&orm and (""earance

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&orm and (""earance

%ummar!%ummar!

.5 6se a proper representation o expressions

.2 6se o%%on or%attin- rules9 +here applia*le

.# ;i%it identiier len-ths to #5 si-ns.4 Do not use identiiers +ith leadin- undersores

.8 Keep the o%plexity o expressions s%all

.$ Preer dei%al representation or inte-er onstants. Do not use hexadei%al

representation or ne-ati7e onstants. Do not use otal representation.

. The state%ents or%in- the *ody o an i9 else i9 else9 +hile9 do +hile or or

state%ent %ust al+ays *e enlosed in *raes

&orm and (""earance +.

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&orm and (""earance +.

(=1 're8er decimal re"resentation 8or integer constants= o not use *e$adecimal re"resentation 8or negative constants= o not use octal re"resentation=


#$am"le , )ad Good

foo = 0xc';

ba = 017;

foo = 1;

ba = 17;

bla = 0xff;bla = 0;

The (ad e2am5le assigns an octal constant 1! :decimal 1< to (ar 0hich is 5ro(a(ly not 0hat 0as

intended

escri"tion Any integer constants must (e gi4en in decimalsB not in he2adecimalsB e2ce5t i' the

he2adecimal re5resentation im5ro4es the reada(ility and the 4alue is 5ositi4e :eg

2'''' or 2+

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&orm and (""earance +3



#$am"le .

+"roblems wit*

negative *e$a-decimal con-

stants

)ad

,

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Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

)ames"aces

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)ames"aces

%ummar!%ummar!

.5 6se an o+n na%e spae or not speiied ite%s

.2 Do not deine the sa%e identiier in inner and outer sope

.# Do not use the sa%e identiiers in dierent na%e spaes

.4 The delaration %ust exatly %ath the deinition

.8 6se delarations +ith external lin&a-e only on ile le7el

.$ Deine an identiier +ith external lin&a-e exatly one

)ames"aces +.

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)ames"aces +.

)=, /se an own name s"ace 8or not s"eci8ied items)=, /se an own name s"ace 8or not s"eci8ied itemsescri"tion =or internal data se5arate names5aces shall (e usedB i' these data are not en

ca5sulated (y standardCmechanism9 *nsert the name o' the 5roducing instance to

any SWinternal data 0hich is not enca5sulated (y standardCmechanism An

*nstance may (e an aggregateB an element'ileB a C'unction or any other sco5eB the

data is (elonging to The naming rule 'or this instance may (e instances5eci'icPre'i2

sym(ols 'or meanings 0ith an en4ironmental descri5tion li8e9

Men4ironmental descri5tionRNNMmeaningR

Backgroud )y the distri(uted de4elo5ment o' SW the ris8 o' con'licting sym(ols gro0s SW 5artsrunning correctly aloneB crash 0hen com5iled together Some 8ey0ords li8e -EB

WA*TB -B -==B -KB E66-6 0ere used multi5ly 'or di''erent 5ur5oses

)ames"aces +3

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)ames"aces +3

)=, /se an own name s"ace 8or not s"eci8ied items)=, /se an own name s"ace 8or not s"eci8ied items

#$am"le )ad Good

mod_aHc

.......fla l/_old_,tate; $%lobal data %$

mod_bHc.......fla l/_old_,tate; $%lobal data %$

mod_aHc

.......,tatic fla l/_old_,tate;

mod_bHc.......,tatic fla l/_old_,tate;__________________________________O2*

HHHfla l/_mod_a_old_,tate;

.......HHHfla l/_mod_b_old_,tate;

To store STATEn1 the local data ;VN-;DNSTATE is used con'licting in t0o modules To a4oid

con'licts the name s5ace can (e se5arated (y standardCmechanism :static< or i' not 5ossi(le (y

creating o0n names5aces manually

#$ercise +3

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#$ercise +3

#$ercises on

7&unctions

7're"rocessor irectives

7&orm and (""earance

7)ames"aces

#$ercises on

7&unctions

7're"rocessor irectives

7&orm and (""earance

7)ames"aces


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C Coding Guidelines Overview

Background

General Rules

Comments

ata and ata t!"es


&unctions



Tec*nical %olution

Tec*nical %olution M% :OR

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Tec*nical %olution M% :OR

Enter here a certain e25ression to go toY

Possi(le entries9

6uleB eg XD1.X or Xd1.X Page num(erB eg X"$X

6ule category :T-C

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+

Tec*nical %olution M% :OR +3

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Creates a >S W-6D document containing

the result :Heading )ody< o' the selection

This selection 'ilters all 6ules o' Class A

that are not function criticaland

not checked by C!"int

Clic8 a rule

to Zum5 to

that rule

0ithin the

document

()

+

Tec*nical %olution %> ;ntranet

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*tt"s9intranet=sba=siemensvdo=com'owertrainOrganiAation#lectronicsrivOrganiAation%o8twar

eevelo"guid"roc3.bitc-codingstart=as"

Related Rules

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ocuments9

7&unction inlining9

Conce"t to allow inlining o8 librar! 8unctions on c-level

7?ibrar! and ObNect building

Rules *ow to build libraries and obNects7O#M %: integration

Rules *ow to integrate O#M %:

&eedbacks Comments

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