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alu.cpp
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alu.cpp
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#include<iostream>
#include"class.h"
/* ALU function:
+=add
-=sub
&=and
|=or
^=xor
~=cmp
0=pass0
IMPORTANT NOTE: AR.l() will never be used! ALU function automatically writes the ans to AR where necessary!
*/
int ALU(char opr)
{
int ans;
switch(opr)
{
case '+':
{
ans=busval+OR.val;
AR.val=ans;
break;
}
case '-':
{
ans=busval-OR.val;
AR.val=ans;
break;
}
case '|':
{
ans=busval|OR.val;
AR.val=ans;
break;
}
case '&':
{
ans=busval&OR.val;
AR.val=ans;
break;
}
case '^':
{
ans=busval^OR.val;
AR.val=ans;
break;
}
case '~':
{
ans=busval-OR.val;
break;
}
case '0':
{
ans=busval;
AR.val=ans;
break;
}
default:
{
cerr<<"ALU error: Unknown opr\n";
return 1;
}
}
FLAG.flagupdate(ans);
return 0;
}
void flagr::flagupdate(int result) //Function to update flag register
{
if(result)
nz=1;
else nz=0;
z=1-nz;
if(result>=0)
p=1;
else
p=0;
m=1-p;
op=1;
while(result)
{
if(result&1)
op=1-op;
result=result>>1;
}
ep=1-op;
}