1/* 2 * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com> 3 * 4 * Based on former do_div() implementation from asm-parisc/div64.h: 5 * Copyright (C) 1999 Hewlett-Packard Co 6 * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com> 7 * 8 * 9 * Generic C version of 64bit/32bit division and modulo, with 10 * 64bit result and 32bit remainder. 11 * 12 * The fast case for (n>>32 == 0) is handled inline by do_div(). 13 * 14 * Code generated for this function might be very inefficient 15 * for some CPUs. __div64_32() can be overridden by linking arch-specific 16 * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S. 17 */ 18 19#include <linux/types.h> 20#include <linux/module.h> 21#include <asm/div64.h> 22 23/* Not needed on 64bit architectures */ 24#if BITS_PER_LONG == 32 25 26uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) 27{ 28 uint64_t rem = *n; 29 uint64_t b = base; 30 uint64_t res, d = 1; 31 uint32_t high = rem >> 32; 32 33 /* Reduce the thing a bit first */ 34 res = 0; 35 if (high >= base) { 36 high /= base; 37 res = (uint64_t) high << 32; 38 rem -= (uint64_t) (high*base) << 32; 39 } 40 41 while ((int64_t)b > 0 && b < rem) { 42 b = b+b; 43 d = d+d; 44 } 45 46 do { 47 if (rem >= b) { 48 rem -= b; 49 res += d; 50 } 51 b >>= 1; 52 d >>= 1; 53 } while (d); 54 55 *n = res; 56 return rem; 57} 58 59EXPORT_SYMBOL(__div64_32); 60 61/* 64bit divisor, dividend and result. dynamic precision */ 62uint64_t div64_64(uint64_t dividend, uint64_t divisor) 63{ 64 uint32_t high, d; 65 66 high = divisor >> 32; 67 if (high) { 68 unsigned int shift = fls(high); 69 70 d = divisor >> shift; 71 dividend >>= shift; 72 } else 73 d = divisor; 74 75 do_div(dividend, d); 76 77 return dividend; 78} 79EXPORT_SYMBOL(div64_64); 80 81#endif /* BITS_PER_LONG == 32 */ 82