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-rw-r--r--ch2/2-06.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/ch2/2-06.c b/ch2/2-06.c
new file mode 100644
index 0000000..918f583
--- /dev/null
+++ b/ch2/2-06.c
@@ -0,0 +1,22 @@
+#include<stdio.h>
+
+/*
+ * Set n bits in x starting at position p to rightmost n bits of y.
+ */
+
+unsigned setbits(unsigned x, unsigned p, unsigned n, unsigned y) {
+ // Create a basa from x that zeroes out all of the bits to be set.
+ unsigned a = x & ~(~(~0 << n) << (p + 1 - n));
+
+ // Create a mask from y that zeroes out all of the bits except those to set.
+ unsigned b = (y & ~(~0 << n)) << (p + 1 - n);
+
+ // Apply the mask to the base.
+ return a | b;
+}
+
+int main() {
+ printf("%x\n", setbits(0xaa, 3, 3, 0x33));
+ printf("%x\n", setbits(0x00, 3, 3, 0xff));
+ return 0;
+}