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lib/div64.c
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/* * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com> * * Based on former do_div() implementation from asm-parisc/div64.h: * Copyright (C) 1999 Hewlett-Packard Co * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com> * * * Generic C version of 64bit/32bit division and modulo, with * 64bit result and 32bit remainder. * * The fast case for (n>>32 == 0) is handled inline by do_div(). * * Code generated for this function might be very inefficient * for some CPUs. __div64_32() can be overridden by linking arch-specific |
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* assembly versions such as arch/powerpc/lib/div64.S and arch/sh/lib/div64.S. |
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*/ |
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#include <div64.h> |
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#include <linux/types.h> |
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#include <linux/compiler.h> |
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uint32_t notrace __div64_32(uint64_t *n, uint32_t base) |
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{ uint64_t rem = *n; uint64_t b = base; uint64_t res, d = 1; uint32_t high = rem >> 32; /* Reduce the thing a bit first */ res = 0; if (high >= base) { high /= base; res = (uint64_t) high << 32; rem -= (uint64_t) (high*base) << 32; } while ((int64_t)b > 0 && b < rem) { b = b+b; d = d+d; } do { if (rem >= b) { rem -= b; res += d; } b >>= 1; d >>= 1; } while (d); *n = res; return rem; } |