bitset in c++ related issues

[mohi@608]

i am trying to use bit set in one of my code but when i am using to_ulong command i am unable to get a desired result...
the code is given below......

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#include <iostream>
#include <string>
#include <bitset>
using namespace std;
 
class add
{
    int r0,r1;
public:
    int add_opcode(bitset<8> r0,bitset<8> r1);
};
int add::add_opcode(bitset<8> r0,bitset<8> r1)
{
    bitset<1> c,z,v;
    bitset<9> sum;
    int a,b;
    a=r0.to_ulong();
    b=r1.to_ulong();
cout<<a<<"\n"<<b<<"\n";
sum=a+b;
//r0=sum;
cout<<r0<<"\n";
if(sum[8]==1)
cout<<"c=1"<<"\n"<<" v=1"<<" \n";
else
cout<<"c=0 "<<"\n"<<" v=0"<<"\n";
if(sum==0)
    cout<<" z="<<0<<"\n";
else
    cout<<" z="<<1<<"\n";
 
cout<<"sum= "<<sum<<endl;
return 0;
}
int main()
 {
     add d1,d2,d3,d4;
     d1.add_opcode(00001111,00000000);
     d2.add_opcode(10001000,11111111);
     d3.add_opcode(0000,00000);
     d4.add_opcode(11111111,11111111);
 }

---

pls check....

 

[horace1]

in the statement

     d1.add_opcode(00001111,00000000);

the parameters are integers

should the parameters be bitset<>

    d1.add_opcode(bitset<8> (string("00001111")), bitset<8> (string("00000000")));

 

[mohi@608]

well thanks for the help ...is it type casting what u are suggesting here???
and

int r0,r1;

in the above code can i use

bitset<8> r0,r1;

do we still require type casting ????

 

[horace1]

well thanks for the help ...is it type casting what u are suggesting here???
and

int r0,r1;

in the above code can i use

bitset<8> r0,r1;

do we still require type casting ????

the bitset<> constructor
https://www.cplusplus.com/reference/stl/bitset/bitset/
is used in the statement

    d1.add_opcode(bitset<8> (string("00001111")), bitset<8> (string("00000000")));

you could use decimals, e.g.

    d1.add_opcode(15, 0);

 

[mohi@608]

ok and i have another ques can i store the

cout<<"sum= "<<r0=sum<<endl;

??
as i am using the 8th bit for only checking and i want the result to be stored back in register r0.........

 

[horace1]

ok and i have another ques can i store the

cout<<"sum= "<<r0=sum<<endl;

??
as i am using the 8th bit for only checking and i want the result to be stored back in register r0.........

bitset<> does not have an overloaded = operator
however, there is a member function to_ulong(), e.g.

cout<<"sum= "<<(r0=sum.to_ulong())<<endl;

 

[mohi@608]

thanks man....

 

[mohi@608]

i have another question can we use pointers on bits and if yes is there any specific syntax for it ??

 

[horace1]

i have another question can we use pointers on bits and if yes is there any specific syntax for it ??

have a look at bitset::reference
https://www.cplusplus.com/reference/stl/bitset/

 

[mohi@608]

well i have gone through the link but i am still not clear with it....i wish to give values by using pointers can i do that.....

- - - Updated - - -

well i have another doubt i wish to store a 16 bit num into 8 bit no. by selecting only last 8 bits .....

 

[horace1]

as far as I am aware you cannot access bits in a bitset<> using pointers
however, bitset::reference enables access to bits using the [] operator
https://msdn.microsoft.com/en-us/library/xf3ah8t3.aspx

e.g.

    bitset<8> x(string("00001111")), y(string("00000000"));
     cout << "x " << x << endl;
     x[1]=~x[1];
     cout << "x " << x << endl;

when run gives

x 00001111
x 00001101

 

[mohi@608]

well i have another doubt i wish to store a 16 bit num into 8 bit no. by selecting only last 8 bits .....

 

[horace1]

use the >> operator?

    bitset<16> x(string("1010111100001111"));
     bitset<16> y(string("00000000"));
     cout << "x " << x << endl;
     y=x>>8;
     cout << "y " << y << endl;

when run gives

x 1010111100001111
y 0000000010101111

 

[mohi@608]

well for pointer i was doing this

bitset<8> acc;
	int *ptr_acc=&acc;

and rest of the arithmetic was done on acc but it is still nt working......

- - - Updated - - -

can we use signed representation in bit form and how ???.........

 

[horace1]

well for pointer i was doing this

bitset<8> acc;
	int *ptr_acc=&acc;

and rest of the arithmetic was done on acc but it is still nt working......

not sure what you are trying to do?

can we use signed representation in bit form and how ???.........

bitset<> stores bits what they represent is up to you
e.g.

     bitset<16> z(string("0"));
     cout << "z " << z << endl;
     short int a=-1;
     z=a;
     cout << "z " << z << endl;

stored a 16-bit signed int in a bitset<>
when run it gives

z 0000000000000000
z 1111111111111111