2.7

1 files changed, 23 insertions, 0 deletions

diff --git a/2/7.c b/2/7.c
new file mode 100644
index 0000000..e35ec2e
--- /dev/null
+++ b/2/7.c
@@ -0,0 +1,23 @@
+#include <stdio.h>
+
+/* inverts n bits of x starting at p */
+unsigned invert(unsigned x, int p, int n);
+
+int main(int argc, char * argv[]) {
+    return 0;
+}
+
+unsigned invert(unsigned x, int p, int n) {
+  unsigned xUnset, xSet, xInv;
+
+  // mask to unset n bits starting at p:
+  xUnset = (~0 << p) | ~(~0 << (p - n));
+
+  // mask to extract bits to invert:
+  xSet = ~xUnset;
+
+  // mask out x and copy inverted bits into unset bits:
+  xInv = (x & xUnset) | ~(x & xSet);
+
+  return xInv;
+}
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