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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 6934 | serge | 1 | /* |
| 2 | * Copyright (C) 2003 Bernardo Innocenti |
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| 3 | * |
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| 4 | * Based on former do_div() implementation from asm-parisc/div64.h: |
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| 5 | * Copyright (C) 1999 Hewlett-Packard Co |
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| 6 | * Copyright (C) 1999 David Mosberger-Tang |
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| 7 | * |
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| 8 | * |
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| 9 | * Generic C version of 64bit/32bit division and modulo, with |
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| 10 | * 64bit result and 32bit remainder. |
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| 11 | * |
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| 12 | * The fast case for (n>>32 == 0) is handled inline by do_div(). |
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| 13 | * |
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| 14 | * Code generated for this function might be very inefficient |
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| 15 | * for some CPUs. __div64_32() can be overridden by linking arch-specific |
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| 6936 | serge | 16 | * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S |
| 17 | * or by defining a preprocessor macro in arch/include/asm/div64.h. |
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| 6934 | serge | 18 | */ |
| 19 | |||
| 6587 | serge | 20 | #include |
| 21 | #include |
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| 22 | #include |
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| 23 | |||
| 6934 | serge | 24 | /* Not needed on 64bit architectures */ |
| 25 | #if BITS_PER_LONG == 32 |
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| 26 | |||
| 6936 | serge | 27 | #ifndef __div64_32 |
| 6934 | serge | 28 | uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base) |
| 29 | { |
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| 30 | uint64_t rem = *n; |
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| 31 | uint64_t b = base; |
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| 32 | uint64_t res, d = 1; |
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| 33 | uint32_t high = rem >> 32; |
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| 34 | |||
| 35 | /* Reduce the thing a bit first */ |
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| 36 | res = 0; |
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| 37 | if (high >= base) { |
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| 38 | high /= base; |
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| 39 | res = (uint64_t) high << 32; |
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| 40 | rem -= (uint64_t) (high*base) << 32; |
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| 41 | } |
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| 42 | |||
| 43 | while ((int64_t)b > 0 && b < rem) { |
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| 44 | b = b+b; |
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| 45 | d = d+d; |
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| 46 | } |
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| 47 | |||
| 48 | do { |
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| 49 | if (rem >= b) { |
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| 50 | rem -= b; |
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| 51 | res += d; |
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| 52 | } |
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| 53 | b >>= 1; |
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| 54 | d >>= 1; |
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| 55 | } while (d); |
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| 56 | |||
| 57 | *n = res; |
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| 58 | return rem; |
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| 59 | } |
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| 60 | EXPORT_SYMBOL(__div64_32); |
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| 6936 | serge | 61 | #endif |
| 6934 | serge | 62 | |
| 63 | #ifndef div_s64_rem |
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| 6587 | serge | 64 | s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) |
| 65 | { |
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| 7143 | serge | 66 | u64 quotient; |
| 6587 | serge | 67 | |
| 7143 | serge | 68 | if (dividend < 0) { |
| 69 | quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder); |
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| 70 | *remainder = -*remainder; |
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| 71 | if (divisor > 0) |
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| 72 | quotient = -quotient; |
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| 73 | } else { |
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| 74 | quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder); |
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| 75 | if (divisor < 0) |
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| 76 | quotient = -quotient; |
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| 77 | } |
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| 78 | return quotient; |
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| 6587 | serge | 79 | } |
| 6934 | serge | 80 | EXPORT_SYMBOL(div_s64_rem); |
| 81 | #endif |
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| 6587 | serge | 82 | |
| 6934 | serge | 83 | /** |
| 84 | * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder |
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| 85 | * @dividend: 64bit dividend |
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| 86 | * @divisor: 64bit divisor |
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| 87 | * @remainder: 64bit remainder |
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| 88 | * |
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| 89 | * This implementation is a comparable to algorithm used by div64_u64. |
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| 90 | * But this operation, which includes math for calculating the remainder, |
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| 91 | * is kept distinct to avoid slowing down the div64_u64 operation on 32bit |
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| 92 | * systems. |
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| 93 | */ |
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| 94 | #ifndef div64_u64_rem |
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| 95 | u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) |
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| 96 | { |
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| 97 | u32 high = divisor >> 32; |
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| 98 | u64 quot; |
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| 99 | |||
| 100 | if (high == 0) { |
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| 101 | u32 rem32; |
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| 102 | quot = div_u64_rem(dividend, divisor, &rem32); |
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| 103 | *remainder = rem32; |
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| 104 | } else { |
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| 105 | int n = 1 + fls(high); |
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| 106 | quot = div_u64(dividend >> n, divisor >> n); |
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| 107 | |||
| 108 | if (quot != 0) |
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| 109 | quot--; |
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| 110 | |||
| 111 | *remainder = dividend - quot * divisor; |
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| 112 | if (*remainder >= divisor) { |
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| 113 | quot++; |
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| 114 | *remainder -= divisor; |
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| 115 | } |
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| 116 | } |
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| 117 | |||
| 118 | return quot; |
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| 119 | } |
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| 120 | EXPORT_SYMBOL(div64_u64_rem); |
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| 121 | #endif |
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| 122 | |||
| 123 | /** |
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| 124 | * div64_u64 - unsigned 64bit divide with 64bit divisor |
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| 125 | * @dividend: 64bit dividend |
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| 126 | * @divisor: 64bit divisor |
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| 127 | * |
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| 128 | * This implementation is a modified version of the algorithm proposed |
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| 129 | * by the book 'Hacker's Delight'. The original source and full proof |
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| 130 | * can be found here and is available for use without restriction. |
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| 131 | * |
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| 132 | * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt' |
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| 133 | */ |
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| 134 | #ifndef div64_u64 |
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| 135 | u64 div64_u64(u64 dividend, u64 divisor) |
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| 136 | { |
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| 137 | u32 high = divisor >> 32; |
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| 138 | u64 quot; |
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| 139 | |||
| 140 | if (high == 0) { |
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| 141 | quot = div_u64(dividend, divisor); |
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| 142 | } else { |
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| 143 | int n = 1 + fls(high); |
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| 144 | quot = div_u64(dividend >> n, divisor >> n); |
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| 145 | |||
| 146 | if (quot != 0) |
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| 147 | quot--; |
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| 148 | if ((dividend - quot * divisor) >= divisor) |
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| 149 | quot++; |
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| 150 | } |
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| 151 | |||
| 152 | return quot; |
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| 153 | } |
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| 154 | EXPORT_SYMBOL(div64_u64); |
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| 155 | #endif |
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| 156 | |||
| 157 | /** |
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| 158 | * div64_s64 - signed 64bit divide with 64bit divisor |
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| 159 | * @dividend: 64bit dividend |
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| 160 | * @divisor: 64bit divisor |
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| 161 | */ |
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| 162 | #ifndef div64_s64 |
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| 163 | s64 div64_s64(s64 dividend, s64 divisor) |
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| 164 | { |
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| 165 | s64 quot, t; |
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| 166 | |||
| 167 | quot = div64_u64(abs(dividend), abs(divisor)); |
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| 168 | t = (dividend ^ divisor) >> 63; |
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| 169 | |||
| 170 | return (quot ^ t) - t; |
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| 171 | } |
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| 172 | EXPORT_SYMBOL(div64_s64); |
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| 173 | #endif |
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| 174 | |||
| 175 | #endif /* BITS_PER_LONG == 32 */ |
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| 176 | |||
| 177 | /* |
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| 178 | * Iterative div/mod for use when dividend is not expected to be much |
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| 179 | * bigger than divisor. |
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| 180 | */ |
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| 181 | u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) |
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| 182 | { |
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| 183 | return __iter_div_u64_rem(dividend, divisor, remainder); |
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| 184 | } |
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| 185 | EXPORT_SYMBOL(iter_div_u64_rem); |