2.6

1 files changed, 35 insertions, 0 deletions

diff --git a/2/6.c b/2/6.c
new file mode 100644
index 0000000..67d7c09
--- /dev/null
+++ b/2/6.c
@@ -0,0 +1,35 @@
+#include <stdio.h>
+
+unsigned setbits(unsigned x, int p, int n, unsigned y);
+
+int main(int argc, char *argv[]) {
+  int p, n;
+  unsigned x, y;
+
+  p = 5;
+  n = 3;
+  x = 0;
+  y = 7;
+
+  printf("New bit field: %x\n", setbits(x, p, n, y));
+
+  return 0;
+}
+
+unsigned setbits(unsigned x, int p, int n, unsigned y) {
+  unsigned yLO, yLOA, xUnset, xPrime;
+
+  // extract LO n bits from y
+  yLO = y & ~(~0 << n);
+
+  // align extracted LO bits of y to position p:
+  yLOA = yLO << (p + 1 - n);
+
+  // create mask with n bits from position p unset:
+  xUnset = (~0 << p) | ~(~0 << (p - n));
+
+  // mask out n bits from x starting at position p:
+  xPrime = x & xUnset;
+
+  return xPrime | yLOA;
+}
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