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@@ -0,0 +1,62 @@
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+#include <linux/bitops.h>
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+#include <asm/types.h>
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+
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+/**
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+ * hweightN - returns the hamming weight of a N-bit word
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+ * @x: the word to weigh
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+ *
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+ * The Hamming Weight of a number is the total number of bits set in it.
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+ */
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+
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+unsigned int __sw_hweight32(unsigned int w)
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+{
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+#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
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+ w -= (w >> 1) & 0x55555555;
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+ w = (w & 0x33333333) + ((w >> 2) & 0x33333333);
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+ w = (w + (w >> 4)) & 0x0f0f0f0f;
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+ return (w * 0x01010101) >> 24;
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+#else
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+ unsigned int res = w - ((w >> 1) & 0x55555555);
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+ res = (res & 0x33333333) + ((res >> 2) & 0x33333333);
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+ res = (res + (res >> 4)) & 0x0F0F0F0F;
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+ res = res + (res >> 8);
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+ return (res + (res >> 16)) & 0x000000FF;
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+#endif
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+}
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+
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+unsigned int __sw_hweight16(unsigned int w)
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+{
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+ unsigned int res = w - ((w >> 1) & 0x5555);
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+ res = (res & 0x3333) + ((res >> 2) & 0x3333);
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+ res = (res + (res >> 4)) & 0x0F0F;
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+ return (res + (res >> 8)) & 0x00FF;
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+}
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+
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+unsigned int __sw_hweight8(unsigned int w)
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+{
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+ unsigned int res = w - ((w >> 1) & 0x55);
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+ res = (res & 0x33) + ((res >> 2) & 0x33);
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+ return (res + (res >> 4)) & 0x0F;
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+}
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+
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+unsigned long __sw_hweight64(__u64 w)
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+{
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+#if BITS_PER_LONG == 32
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+ return __sw_hweight32((unsigned int)(w >> 32)) +
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+ __sw_hweight32((unsigned int)w);
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+#elif BITS_PER_LONG == 64
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+#ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
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+ w -= (w >> 1) & 0x5555555555555555ul;
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+ w = (w & 0x3333333333333333ul) + ((w >> 2) & 0x3333333333333333ul);
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+ w = (w + (w >> 4)) & 0x0f0f0f0f0f0f0f0ful;
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+ return (w * 0x0101010101010101ul) >> 56;
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+#else
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+ __u64 res = w - ((w >> 1) & 0x5555555555555555ul);
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+ res = (res & 0x3333333333333333ul) + ((res >> 2) & 0x3333333333333333ul);
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+ res = (res + (res >> 4)) & 0x0F0F0F0F0F0F0F0Ful;
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+ res = res + (res >> 8);
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+ res = res + (res >> 16);
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+ return (res + (res >> 32)) & 0x00000000000000FFul;
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+#endif
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+#endif
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+}
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