1 files changed, 37 insertions, 0 deletions

diff --git a/q3/checksum.c b/q3/checksum.c
new file mode 100644
index 0000000..513ae17
--- /dev/null
+++ b/q3/checksum.c
@@ -0,0 +1,37 @@
+#include <stdio.h>
+#include <stdio.h>
+
+int checksum() {
+    unsigned int parts[9];
+    unsigned int sum;
+    printf("Enter the parts, one per line:\n");
+    for (int i = 0; i < 9; i++) {
+        scanf("%X", &parts[i]);
+        sum += parts[i];
+        while (sum >> 16)
+            sum = (sum & 0xffff) + (sum >> 16);
+    }
+    return ~sum;
+}
+
+int main() {
+    printf("--- SENDER ---\n");
+    int sender_checksum = checksum();
+    printf("\n--- RECV ---\n");
+    int recv_checksum = checksum();
+    printf("Sent checksum: %x\n", sender_checksum);
+    printf("Recieved checksum: %x\n", recv_checksum);
+    if (sender_checksum == recv_checksum) {
+        printf("Matching checksums!\n");
+        return 0;
+    } else {
+        printf("Mismatched checksums!\n");
+        return 0;
+    }
+}
+
+// 00004500 00000073 00000000 00004000 00004011 0000c0a8 00000001 0000c0a8 000000c7
+// checksum - ffffb861
+
+// 00004500 0000003c 00001c46 00004000 00004006 0000ac10 00000a63 0000ac10 00000a0c
+// checksum - 0000b1e6