1 files changed, 70 insertions, 0 deletions
diff --git a/19_bits_arr/numToBits.c b/19_bits_arr/numToBits.c
new file mode 100644
index 0000000..c7538da
--- /dev/null
+++ b/19_bits_arr/numToBits.c
@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+/*
+ * Helper function that retrieves numbers 'bit' value
+ * ie: 1's 31st bit is 1
+ */
+int getNthBit(uint32_t number, int bit) {
+  if (bit <0 || bit >= 32) {
+    printf("Bit %d is invalid\n", bit);
+    exit (EXIT_FAILURE);
+  }
+  return (number & (1<<bit)) != 0;
+}
+
+/*
+ *
+ * This function takes in two arrays: nums (of length nNums), and
+ * bits (of length nBits). This function should:
+ *
+ * - Check that there is enough space in bits to hold all the bits
+ *   of "nums".  Note that each number in "nums" will results in 32
+ *   bits in "bits".  If this is not true, your function should
+ *   print a message with the format:
+ *	"Invalid call to numToBits! nBits is %d, nNums is %d\n",
+ *   (where the first %d is nBits, and the second %d is nNums)
+ *   then return without doing anything else.
+ *
+ * - Put the individual bits of each number into the "bits" array.
+ *   The bits put into this array should be ordered so that the first
+ *   32 bits represent nums[0], the next 32 bits are nums[1], and so
+ *   on.  Within each number, the most significant bit (bit 31) should
+ *   come first, and the least significant bit (bit 0) should come last.
+ *   That is, bits[0] should be bit 31 of nums[0], bits[1] should
+ *   be bit 30 of nums[0], and so on.
+ */
+void numToBits(uint32_t * nums, int nNums, int * bits, int nBits) {
+  if (nBits != nNums * 32) {
+    printf("Invalid call to numToBits! nBits is %d, nNums is %d\n", nBits, nNums);
+    return;
+  }
+  for (int i = 0; i < nNums; i++) {
+    for (int j = 0; j < 32; j++) {
+      bits[i*32 + j] = getNthBit(nums[i], 31 - j);
+    }
+  }
+}
+
+void doTest(uint32_t * nums, int n) {
+  int bits[n *32];
+  numToBits(nums, n, bits, n*32);
+  for (int i =0; i < n; i++) {
+    printf(" %9d (%8X) => ", nums[i], nums[i]);
+    for (int j = 0; j < 32; j++) {
+      printf("%d", bits[i*32 + j]);
+    }
+    printf("\n");
+  }
+}
+
+int main(void) {
+  uint32_t array1[] = { 1, 2, 3, 4, 5, 15, 109};
+  uint32_t array2[] = { 123456789, 987654321 };
+  int bits[7*32-1];
+  doTest (array1, 7);
+  doTest (array2, 2);
+  numToBits(array1,7, bits , 7*32-1);
+  return EXIT_SUCCESS;
+}