void setBit(int j) {
seg* segNum = whichseg(j);
int rownum = whichint(j);
int posinrow = whichbit(j);
seg *p = segNum;
unsigned int flag = 1;
flag = flag << posinrow;
p->bits[rownum] = p->bits[rownum] | flag;
}
int testBitIs0( int j ) {
seg* segNum = whichseg(j);
int rownum = whichint(j);
int posinrow = whichbit(j);
int a = 0;
seg *p = segNum;
unsigned int flag = 1;
flag = flag << posinrow;
int r = p->bits[rownum] & flag;
if ( r == 0 )
return 1;
else
return 0;
}
int testbit (int n, seg* head){
int q = (n-3)/2;
seg* thisseg = whichseg(q, head);
int thisint = whichint(q);
int thisbit = whichbit(q);
if(thisseg->bits[thisint] & 1 << thisbit)
return 1;
else
return 0;
}
void setbit (int n, seg* head){
int q = (n-3)/2;
seg* thisseg = whichseg(q, head);
int thisint = whichint(q);
int thisbit = whichbit(q);
thisseg->bits[thisint] |= 1 << thisbit;
}
void goldbach(int n){
// finds the seg, int and bit for 3 and k-3 and passes them to methods that increment up and down in 2 different methods
int numCount = 0;
int k = 3;
int ktwo = n-3;
int goldCount = 0;
int targetNum1 = 0;
int targetNum2 = 0;
///////seg int and bit for 3
seg* segNum2 = whichseg(k);
int kintone = whichint(k);
int bit1 = whichbit(k);
///////seg in and bit for k-3
seg* segNum3 = whichseg(ktwo);
int kinttwo = whichint(ktwo);
int bit2 = whichbit(ktwo);
while (k <= n/2){
if(checkLower(segNum2, kintone, bit1) && checkHigher(segNum3, kinttwo, bit2) == 1){
goldCount += 1;
targetNum1 = k;
targetNum2 = ktwo;
}
//printf("%d %d\n", k, ktwo);
//////////////////////////////////LOWER END LOGIC
if(bit1 != 31){
bit1 +=1;}
else{
bit1 = 0;
kintone += 1;}
if(kintone > 255 && segNum2->next !=NULL){
kintone = 0;
segNum2 = segNum2->next;}
/////////////////////////////////////////////////
//////////////////////////////////UPPER END LOGIC
if(bit2 != 0){
bit2 -=1;}
else{
bit2 = 31;
kinttwo -= 1;}
if( kinttwo < 0 && segNum3->prev != NULL){
kinttwo = 255;
segNum3 = segNum3->prev;
}
/////////////////////////////////////////////////
k += 2;
ktwo -=2;
}
printf("\nThe last Goldbach decomposition is: %d + %d \n", targetNum1, targetNum2 );
printf("The amount of decompositions is: %d \n", goldCount);
}
void main(int argc, char *argv[]) {
seg *head,*pt;
int i;
int howmany, upto;
//goldbach sample from class only worked if arg was sent in with the ./goldbach
if (argc == 2) sscanf(argv[1],"%d",&howmany);
else return;
upto = howmany;
howmany = ((howmany/2) +BITSPERSEG -1)/BITSPERSEG;
head = ( seg * ) malloc(sizeof(seg));
pt=head;
//link the segments created
for (i=1;i<howmany;i++) {
pt->next = ( seg *) malloc(sizeof (seg));
pt->next->prev = pt;
pt=pt->next;
}
//printf("Done allocating %d nodes\n",i);
int j;
pt=head;
//clear int's at a time for each segment
for (i=1;i<=howmany;i++) {
for(j=0;j<255;j++) {
pt->bits[j] = 0;
}
pt=pt->next;
//printf("Done clearing node %d \n",i);
}
//find the primes
printf("Calculating odd primes up to %d...\n",upto);
//sqrt() wasnt working so used i^2
for(i = 3 ; (i*i)<=upto ; i+=2) {
seg* myPT = whichseg(i,head);
int myInt = whichint(i);
int myBit = whichbit(i);
//after or'ing with the bit pos set to one, if its unchanged that means the number was turned on
if((myPT->bits[myInt]|(1<<myBit)) == myPT->bits[myInt]) {
//the number isnt prime
continue;
} else {
//we have a prime so remove its multiples!!!
int j;
for( j = i+i; j<=upto; j+=i) {
if((j%2)!=0) {
seg* nonprimePT = whichseg(j,head);
int nonprimeInt = whichint(j);
int nonprimeBit = whichbit(j);
nonprimePT->bits[nonprimeInt] = nonprimePT->bits[nonprimeInt]|(1<<nonprimeBit);
}
}
}
}
//count the primes
int countPrimes =0;
pt=head;
int finalInt = whichint(upto);
int finalBit = whichbit(upto);
int segment =1;
int num = 3;
for(segment=1; segment<=howmany; segment++) {
for(i = 0 ; i<=255 ; i++) {
for(j = 0 ; j<32;j++) {
if (((pt->bits[i]|(1<<j))) == pt->bits[i]) {
//printf(" number not prime: %d: data:i- %d and j- %d \n", num,i,j);
num+=2;
continue;
} else {
if(num>upto) {
//done counting
break;
} else {
//found a prime!
countPrimes++;
}
}
num+=2;
}
}
pt= pt->next;
}
printf("The number of odd primes less than or equal to %d is: %d \n",upto,countPrimes);
//now from prime numbers calc the possible pair sums
printf("Enter Even Numbers >5 for Goldbach Tests\n");
int even;
scanf("%d",&even);
int lasteven = 0;
while(even) {
int sumCounter = 0;
int lasti = 0;
//when a non-int was entered, my program would freakout.
if(even == lasteven) {break;}
//end on EOF
if(even == EOF) { break;}
//must be even number and greater than 5 and less than that to which i calc primes for
if(even >= 6 & even <= upto & even%2==0) {
int lowerNum = 3;
seg* lowerPT = whichseg(lowerNum,head);
int lowerInt = whichint(lowerNum);
int lowerBit = whichbit(lowerNum);
int higherNum = even-3;
seg* higherPT = whichseg(higherNum,head);
int higherInt = whichint(higherNum);
int higherBit = whichbit(higherNum);
//while statement
while(lowerNum <= higherNum) {
if((lowerPT->bits[lowerInt]|(1<<lowerBit)) == lowerPT->bits[lowerInt]) {
//lower is not prime
//rise lowerbit/ lower higherbit
if(lowerBit==31) {
lowerBit=0;
lowerInt++;
if(lowerInt==256) {
lowerInt =0;
lowerPT=lowerPT->next;
}
lowerNum+=2;
} else {
lowerBit++;
lowerNum+=2;
}
if(higherBit==0) {
higherBit=31;
higherInt--;
if(higherInt==-1) {
higherInt =255;
higherPT=higherPT->prev;
}
higherNum-=2;
} else {
higherNum-=2;
higherBit--;
}
/////// end of bit manipulation
continue;
} else {
if((higherPT->bits[higherInt]|(1<<higherBit)) == higherPT->bits[higherInt]) {
//higher is not prime
//rise lowerbit/ lower higherbit
if(lowerBit==31) {
lowerBit=0;
lowerInt++;
if(lowerInt==256) {
lowerInt =0;
lowerPT=lowerPT->next;
}
lowerNum+=2;
} else {
lowerBit++;
lowerNum+=2;
}
if(higherBit==0) {
higherBit=31;
higherInt--;
if(higherInt==-1) {
higherInt =255;
higherPT=higherPT->prev;
}
higherNum-=2;
} else {
higherNum-=2;
higherBit--;
}
/////// end of bit manipulation
continue;
} else {
sumCounter++;
lasti = lowerNum;
//printf("solution %d: lowerNum- %d, higherNum %d \n",sumCounter,lowerNum, higherNum);
//rise lowerbit /lower higherbit
if(lowerBit==31) {
lowerBit=0;
lowerInt++;
if(lowerInt==256) {
lowerInt =0;
lowerPT=lowerPT->next;
}
lowerNum+=2;
} else {
lowerBit++;
lowerNum+=2;
}
if(higherBit==0) {
higherBit=31;
higherInt--;
if(higherInt==-1) {
higherInt =255;
higherPT=higherPT->prev;
}
higherNum-=2;
} else {
higherNum-=2;
higherBit--;
}
/////// end of bit manipulation
}
}
} //end while
//calc the middle term using the value
printf("Largest %d = %d + %d out of %d solutions \n", even ,lasti, even-lasti,sumCounter);
}
lasteven = even;
scanf("%d",&even);
} // outer while
}
