Lab 9 Complete

Labs/Lab09/Makefile

+CFLAGS = -Wall -g
+CC     = gcc
+
+all: ex1 ex2 ex3 ex4 ec
+ex1: bigint.o ex1.o
+ex2: bigint.o ex2.o
+ex3: bigint.o ex3.o
+ex4: bigint.o ex4.o
+ec: bigint.o ec.o
+
+clean:
+	/bin/rm -f core *.o $(EXE) *~

Labs/Lab09/bigint.c

+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include "bigint.h"
+
+struct bigint* bigint_init(char* value, int N){
+  int i;
+  int k = strlen(value);
+  struct bigint* r;
+
+  // ensure N is divisible by 4
+  if (N%4 > 0){
+    N += (4-(N%4));
+  }
+
+  if (k > N){
+    printf("ERROR: too many digits\n");
+    exit(1);
+  }
+
+  r = malloc(sizeof(struct bigint) + N);
+  r->N = N;
+  bigint_zero(r);
+
+  // copy digits from the C string value into the digits
+  for(i = 0; i < k; i++){
+	int index = k-i-1;
+  	r->digit[i] = (int)value[index];
+  }
+  return r;
+}
+
+void bigint_zero(struct bigint* bn){
+  memset(bn->digit, '0', bn->N);
+}
+
+void bigint_str(char* dst, struct bigint* bn){
+  int i;
+  for(i = bn->N; i > 0; i--){
+    *dst++ = bn->digit[i-1];
+    if ( (i-1)%4 == 0){
+      *dst++ = ' ';
+    }
+  }
+  *dst = '\0';
+}
+void bigint_hexstr(char* dst, struct bigint* bn){
+  *dst= '\0';
+}
+
+// this might be useful
+void full_add(char carry_in, char a, char b, char* sum, char* carry_out){
+  int i =0;
+  if (a == '1') i++;
+  if (b == '1') i++;
+  if (carry_in == '1') i++;
+  switch(i){
+    case 0: *sum = '0'; *carry_out = '0'; break;
+    case 1: *sum = '1'; *carry_out = '0'; break;
+    case 2: *sum = '0'; *carry_out = '1'; break;
+    case 3: *sum = '1'; *carry_out = '1'; break;
+    default: printf("Impossible error!\n"); exit(255);
+  }
+}
+
+void bigint_add(struct bigint* c, struct bigint* a, struct bigint* b){
+	int carry_out = 0;
+	int carry_in = 0;
+	int sum = 0;
+	int i;
+	for(i = 0; i < a->N; i++){
+		char digitA = a->digit[i];
+		char digitB = b->digit[i];
+		full_add(carry_in, digitA, digitB, &sum, &carry_out);
+		c->digit[i] = sum;
+		carry_in = carry_out;	
+		if (i == 7 && carry_in == 1){
+			printf("Error: Overflow");
+			exit(255);
+		}
+	}
+}
+
+void bigint_inv(struct bigint* out, struct bigint* in){
+}
+
+void bigint_sub(struct bigint* c, struct bigint* a, struct bigint* b){
+}
+
+void bigint_rshift(struct bigint *bn, int bits){
+	int i;
+	int n = bn->N;
+	int temp = bn->digit[n-1];
+	for(i = n-1; i>0; i--){
+		bn->digit[i] = bn->digit[i-bits];
+	}
+	bn->digit[0] = temp;	
+}
+
+void bigint_lshift(struct bigint *bn, int bits){
+	int i;
+	int n = bn->N;
+	int temp = bn->digit[0];
+	for (i = 0; i < n-1; i++){
+		bn->digit[i] = bn->digit[i+bits];
+	}
+	bn->digit[n-1] = temp;
+}
+
+void bigint_mult(
+  struct bigint* prod,
+  struct bigint* mcand,
+  struct bigint* mplier){
+	int i;
+	for (i = 0; i < prod->N; i++){
+		if (mplier->digit[0] == '1'){
+			bigint_add(prod, prod, mcand);
+		}
+		bigint_rshift(mplier, 1);
+		bigint_lshift(mcand, 1);
+	}
+}
+
+void bigint_div(
+  struct bigint* quotient,
+  struct bigint* remainder,
+  struct bigint* dividend,
+  struct bigint* divisor){
+
+}
+int bigint_iszero(struct bigint* in){
+  return 1;
+}
+struct bigint* bigint_copy(struct bigint* in){
+}
+void bigint_fact(
+  struct bigint* result,
+  struct bigint* in){
+}

Labs/Lab09/bigint.h

+#ifndef bigint_h_
+#define bigint_h_
+
+struct bigint {
+  int N;
+  char digit[];
+};
+
+// INIT, create a bigint with value (given in binary)
+struct bigint*  bigint_init(char* value, int N);
+
+// set the value to zero
+void bigint_zero(struct bigint* bn);
+
+// OUTPUT a bigint to a pre-allocated C string
+void bigint_str(char* dst, struct bigint* bn);
+
+// needed for extra credit
+void bigint_hexstr(char* dst, struct bigint* bn);
+struct bigint* bigint_copy(struct bigint* in);
+
+// BITWISE OPERATIONS
+void bigint_inv(struct bigint* out, struct bigint* in);
+void bigint_rshift(struct bigint *bn, int bits);
+void bigint_lshift(struct bigint *bn, int bits);
+
+// LOGICAL operations
+int bigint_iszero(struct bigint* in);
+
+// ARITHMETIC
+void bigint_add(struct bigint* c, struct bigint* a, struct bigint* b);
+void bigint_sub(struct bigint* c, struct bigint* a, struct bigint* b);
+void bigint_mult(
+  struct bigint* prod,
+  struct bigint* mcand,
+  struct bigint* mplier);
+
+void bigint_div(
+  struct bigint* quotient,
+  struct bigint* remainder,
+  struct bigint* dividend,
+  struct bigint* divisor);
+
+void bigint_fact(
+  struct bigint* result,
+  struct bigint* in);
+
+#endif

Labs/Lab09/ec.c

+/* ec.c FACTORIAL test */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "bigint.h"
+
+int main(int argc, char* argv[]){
+  struct bigint *a = bigint_init("110010", 512); // 50
+  struct bigint *b = bigint_init("", 512);
+
+  char a_str[512];
+  char b_str[512];
+
+  bigint_hexstr(a_str, a);
+  bigint_fact(b, a);      // a!, factorial
+  bigint_hexstr(b_str, b);
+
+  printf("   %s! = %s\n", a_str, b_str);
+  free(a);
+  free(b);
+
+  return 0;
+}

Labs/Lab09/ex1.c

+/* ex1.c */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "bigint.h"
+
+int main(int argc, char* argv[]){
+  struct bigint *a = bigint_init("1011", 4);
+  char a_str[8];
+
+  bigint_str(a_str, a);
+
+  printf("%d, %s\n", a->N, a_str);
+
+  free(a);
+
+  return 0;
+}

Labs/Lab09/ex2.c

+/* ex2.c ADD test */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "bigint.h"
+
+int main(int argc, char* argv[]){
+  struct bigint *a = bigint_init("1001", 8);  // 9
+  struct bigint *b = bigint_init("1100", 8);  // 12
+  struct bigint *c = bigint_init("", 8);      // 0
+  char a_str[16];
+  char b_str[16];
+  char c_str[16];
+
+  bigint_str(a_str, a);
+  bigint_str(b_str, b);
+
+  bigint_add(c, a, b);     // 21 = 10101
+  bigint_str(c_str, c);
+
+  printf("ADD test\n");
+  printf("   %s\n", a_str);
+  printf("+  %s\n", b_str);
+  printf("------------\n");
+  printf("   %s\n", c_str);
+
+  free(a);
+  free(b);
+  free(c);
+
+  return 0;
+}

Labs/Lab09/ex3.c

+/* ex3.c MULT test */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "bigint.h"
+
+int main(int argc, char* argv[]){
+  struct bigint *a = bigint_init("1001", 8);  // 9
+  struct bigint *b = bigint_init("1100", 8);  // 12
+  struct bigint *c = bigint_init("", 8);     // 0
+  char a_str[16];
+  char b_str[16];
+  char c_str[16];
+
+  bigint_str(a_str, a);
+  bigint_str(b_str, b);
+
+  bigint_mult(c, a, b);    // 9 * 12 = 108 = 0b1101100
+  bigint_str(c_str, c);
+
+  printf("MULT test\n");
+  printf("   %s\n", a_str);
+  printf("x  %s\n", b_str);
+  printf("------------\n");
+  printf("   %s\n", c_str);
+
+  free(a);
+  free(b);
+  free(c);
+
+  return 0;
+}

Labs/Lab09/ex4.c

+/* ex4.c DIV test */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "bigint.h"
+
+int main(int argc, char* argv[]){
+  struct bigint *a = bigint_init("1001010", 16);  // 74 = dividend
+  struct bigint *b = bigint_init("10101", 16);    // 21 = divisor
+  struct bigint *quo = bigint_init("", 16);       // 0
+  struct bigint *rem = bigint_init("", 16);       // 0
+
+  char a_str[32];
+  char b_str[32];
+  char q_str[32];
+  char r_str[32];
+
+  bigint_str(a_str, a);
+  bigint_str(b_str, b);
+
+  bigint_div(quo, rem, a, b);    //74/21 = 3 R 11
+
+  bigint_str(q_str, quo);
+  bigint_str(r_str, rem);
+
+  printf("   %s\n", a_str);
+  printf("   --------- --------- = %s R %s \n", q_str, r_str);
+  printf("   %s\n", b_str);
+
+  free(a);
+  free(b);
+  free(quo);
+  free(rem);
+
+  return 0;
+}