working on "duff" example led me to futzing with gdb, found out the gdb tutorial is kinda (a lot) outdated

gowrikumar/src/11-duff.c

@@ -0,0 +1,37 @@
+/**
+ * :author: Dan Buch (daniel.buch@gmail.com)
+ */
+
+#include <stdio.h>
+
+void duff(register char *to, register char *from, register int count)
+{
+    register int n = (count + 7) / 8;
+    switch (count % 8) {
+        case 0: do { *to++ = *from++;
+        case 7: *to++ = *from++;
+        case 6: *to++ = *from++;
+        case 5: *to++ = *from++;
+        case 4: *to++ = *from++;
+        case 3: *to++ = *from++;
+        case 2: *to++ = *from++;
+        case 1: *to++ = *from++;
+        } while (--n > 0);
+    }
+}
+
+int main()
+{
+    char * to = "dogs cats babies";
+    char * from = "monkey hat pants";
+    int i = 16;
+    printf("to = %s\n", to);
+    printf("from = %s\n", from);
+    /* And here comes the segfault... */
+    duff(to, from, i);
+    printf("to = %s\n", to);
+    printf("from = %s\n", from);
+}
+
+/* vim:filetype=c:fileencoding=utf-8
+ */

gowrikumar/src/11b-duff.c

@@ -0,0 +1,40 @@
+/**
+ * :author: Dan Buch (daniel.buch@gmail.com)
+ */
+
+#include <stdio.h>
+
+void duff(register char *to, register char *from, register int count)
+{
+    register int n;
+
+    int remainder = count % 8;
+    if (remainder == 0) {
+        n = (count + 7) / 8;
+        do {
+            *to++ = *from++;
+        } while (--n > 0);
+    } else if (remainder <= 7 && remainder > 0) {
+        int i;
+        int c;
+        for (i = 0; (c = from[i] && c != EOF); i++) {
+            to[i] = c;
+        }
+    }
+}
+
+int main()
+{
+    char * to = "dogs cats babies";
+    char * from = "monkey hat pants";
+    int i = 11;
+    printf("to = %s\n", to);
+    printf("from = %s\n", from);
+    /* And here comes the segfault... */
+    duff(to, from, i);
+    printf("to = %s\n", to);
+    printf("from = %s\n", from);
+}
+
+/* vim:filetype=c:fileencoding=utf-8
+ */