#include #include #include /* * This implements the binary GCD algorithm. (Often attributed to Stein, * but as Knuth has noted, appears in a first-century Chinese math text.) * * This is faster than the division-based algorithm even on x86, which * has decent hardware division. */ #if !defined(CONFIG_CPU_NO_EFFICIENT_FFS) && !defined(CPU_NO_EFFICIENT_FFS) /* If __ffs is available, the even/odd algorithm benchmarks slower. */ unsigned long gcd(unsigned long a, unsigned long b) { unsigned long r = a | b; if (!a || !b) return r; b >>= __ffs(b); if (b == 1) return r & -r; for (;;) { a >>= __ffs(a); if (a == 1) return r & -r; if (a == b) return a << __ffs(r); if (a < b) swap(a, b); a -= b; } } #else /* If normalization is done by loops, the even/odd algorithm is a win. */ unsigned long gcd(unsigned long a, unsigned long b) { unsigned long r = a | b; if (!a || !b) return r; /* Isolate lsbit of r */ r &= -r; while (!(b & r)) b >>= 1; if (b == r) return r; for (;;) { while (!(a & r)) a >>= 1; if (a == r) return r; if (a == b) return a; if (a < b) swap(a, b); a -= b; a >>= 1; if (a & r) a += b; a >>= 1; } } #endif EXPORT_SYMBOL_GPL(gcd); p-back'>packet-rx-pump-back net-next plumbingsTobias Klauser
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authorLinus Torvalds <torvalds@linux-foundation.org>2016-12-11 11:17:54 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-11 11:17:54 -0800
commit69973b830859bc6529a7a0468ba0d80ee5117826 (patch)
tree5f11fe15ed9d9a3ab9c92242030e54b73ecdce45 /net/9p/Makefile
parent2e4333c14de06a333783d6812cf3c4998f78b0c8 (diff)
Linux 4.9
Diffstat (limited to 'net/9p/Makefile')