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| #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
typedef struct _TAddress
{ char IPclass;
int a[4];
int freeBits;
int Nbits;
int Mbits;
} TAddress;
void FillPow2 (int pow2[])
{ int i = 0;
pow2[0] = 1;
while (++i<25)
pow2[i] = pow2[i-1]*2;
}
int IsClass (char c)
{ char *alphabet = "ABC";
int i = strlen(alphabet);
while (--i >-1)
if (c == alphabet[i])
return 1;
return 0;
}
TAddress *CreateAddress (char cl)
{ TAddress *address = (TAddress*) malloc (sizeof(TAddress));
address->IPclass = cl;
address->a[0] = 255;
address->a[1] = address->a[2] = address->a[3] = 0;
if (cl == 'A')
address->freeBits = 24;
else
{ address->a[1] = 255;
if (cl == 'B')
address->freeBits = 16;
else
{ address->a[2] = 255;
address->freeBits = 8;
}
}
address->Mbits = address->Nbits = -1;
return address;
}
void DeleteAddress (TAddress *address)
{ free (address);
}
void PrintAddress (TAddress *address)
{ int i;
for (i = 0; i<4; i++)
printf("%3d.", address->a[i]);
printf("\n");
}
void FillBits (TAddress *address, int N, int M, int pow2[])
{ int i;
if (N)
{ for (i = 0; i<25; i++)
if (N <= pow2[i]-2)
{ address->Nbits = i;
break;
}
for (i = 0; i<25; i++)
if (M <= pow2[i]-2)
{ address->Mbits = i;
break;
}
}
else
{ address->Nbits = 0;
address->Mbits = address->freeBits;
}
}
int CheckBits (TAddress *address)
{ return address->Nbits + address->Mbits <= address->freeBits && address->Nbits>=0 && address->Mbits>0;
}
int ai (int pow2[], int bits)
{ int i = 0, sum = pow2[7];
while (++i < bits)
sum += pow2[7-i];
return sum;
}
void CreateMask (TAddress *address, int pow2[])
{ if (!address->Nbits)
return;
if (address->IPclass == 'C')
{ address->a[3] = ai(pow2, address->Nbits);
return;
}
if (address->IPclass == 'B')
{ if (address->Nbits <= 8)
{ address->a[2] = ai(pow2, address->Nbits);
return;
}
else
{ address->a[2] = 255;
address->a[3] = ai(pow2, address->Nbits-8);
return;
}
}
if (address->Nbits <= 8)
{ address->a[1] = ai(pow2, address->Nbits);
return;
}
else if (address->Nbits <= 16)
{ address->a[1] = 255;
address->a[2] = ai(pow2, address->Nbits-8);
return;
}
else
{ address->a[1] = address->a[2] = 255;
address->a[3] = ai(pow2, address->Nbits-16);
return;
}
}
int main()
{ int pow2[25], N, M;
FillPow2 (pow2);
char cl;
do
{ printf("Zadayte class seti:\t");
cl = toupper (getc(stdin));
getc(stdin);
} while (!IsClass (cl));
TAddress *address = CreateAddress (cl);
printf("Class standartnoy maski:\t");
PrintAddress (address);
printf("\n\nVvedite kolichestvo podsetey N = ");
scanf ("%d", &N);
printf("Maximal'noe kolichestvo computerov M = ");
scanf ("%d", &M);
getc(stdin);
FillBits (address, N, M, pow2);
printf("Free bits: %d\tBits for subs: %d\tBits for comps: %d", address->freeBits, address->Nbits, address->Mbits);
if (CheckBits (address))
{ CreateMask (address, pow2);
printf("\n\nIP-adresa:\t");
PrintAddress (address);
}
else
printf("\n\nRazbienie na podseti nevozmozhno\n");
DeleteAddress (address);
getchar();
return 0;
} |
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