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các lệnh cần thiết trong lập trình assembly
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!(G0.1&2$.,( $E+%E2+=(* ( System*services*used*for*input/output* ( J$=(&$(0,+(5X5 F7!!(,',&+B(,+%E21+,( 1.*Load*the*service*number*in*register*$v0 .* 2.*Load*argumen t*val ues,* if*an y,*in*$a0, *$a1, *or*$a2* 3.*Is sue*the*SYSCALL*instruction.* 4.*Retrieve*r etur n*values,*if*any,*from*resu lt*registers** ( Y"#C+($G(F$BB$.C'(Z ,+/(5+%E21+,(( Service $v0 Arguments Result print integer 1 $a0 = integer to print print string 4 $a0 = address of null- terminated string to print read integer 5 $v0 contains integer read read string 8 $a0=address of input buffer $a1=max. # of chars. to read exit (stop execution) 10 print character 11 $a0=character to print read character 12 $v0 contains character read open file 13 $a0=address of null-terminated string containing filename $a1=flags $a2=mode $a0 contains file descriptor (- if error) read from file 14 $a0 = file descriptor $a1=address of output buffer $a2=max. # of chars to read $a0 contains # of chars. read (0=EOF,- if error) write to file 15 $a0 = file descriptor $a1=address of output buffer $a2= # of chars to write $a0 contains # chars. written (- if error) close file 16 $a0 = file descriptor * * Examples of Simple I/O for lab today * * #*H%2.&(".(2.& +@+% (( ( C2(PESQ)* #*load*service*number*in to*$v0( ( ((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((( ( C2(P"SQR ( #* load*value*to*be*printed*i nto*$a0( ( ( (((((((((((((((((((((((( ( ,',1"CC* * ( * #H%2.&("(.0CC<&+%B2."& +/(,&%2. @** * C2(PESQ?(* #load*s ervice*number*in*$v0( ( ( ( ( ( ( C"(P"SQH%$BH&[ ,&%2.@( (( * * * #*load*a ddress*of*string*to*be*printe d*into*$a0* * ,',1"CC(( ( * #*the*null‐termi nated*string* must*be* defined*in*data*segment* * T/"&"( (((((H%$BH&[,&%2 .@\((T",122W(UO.&+% ( "(E"C0+\( U* ( ( ( ( ( #(%+"/(2.(".(2.&+@+%** * C2(PESQR( #load*s ervice*number*in*$v0( ( ( ( ( ( ( ,',1"CC* #the*value*entered*by*the*user*is*returned*in*$v0( ( ( ( ( B$E+(P&SQPES* #store*value*entered*into* another*register* * * #*%+"/(2.("(,&%2.@* * * C2(PESQ]((( * ***#load*service*number*in * $v0* C"(P"SQ".,=+%* ***#pu t*address* of*answe r*string*in* $a0* * * C=(P")Q"C+.@&9* ***#put*length*of * string*in*$ a1* * * * * ,',1"CC* **#*string*is*stored*in*memory*at*the*answer%*lo cation* * #answe r*and*ale ngth*mu st*be*defined*in*da ta*segme nt* *********T/"&" ( ".,=+%\((T,H"1+ ( RS**#*allocate*sp ace*for*str i ng*to*be* stored* * "C+.@&9\ ( ( T =$%/(RS***#length*of*string*to*be* entered( * #(&+%B2."&+(+K+10& 2$.($G(H%$@%"B * C2(PESQ)S( #load*s ervice*number*in*$v0( ( ( ( ( ,',1"CC* #should*alway s*be*the* f i nal*instructions*i n*your*pr ogram* * ( . ***#*store*value*of*word*in*$t1*to*address/* * * * * * *******location*in*m emory**specified *by*label% % * *(C=(and*,= (can* also*be*byte* or*halfword,*i.e.*C# ,*C 9Q(,#Q,9)* * * * * 4,+ 0/$<2.,&%01. s*your*/"&"(,+@B+.&*(data*de clarations)* * (text*segment *can* come*before*data*seg men t,*or* vice* versa)* * ( T",122((U, &%2.