Tom Rini | 10e4779 | 2018-05-06 17:58:06 -0400 | [diff] [blame] | 1 | // SPDX-License-Identifier: BSD-3-Clause |
Stefan Roese | dfafe7a | 2017-11-29 16:23:31 +0100 | [diff] [blame] | 2 | /* |
| 3 | * This file is copied from the coreboot repository as part of |
| 4 | * the libpayload project: |
| 5 | * |
| 6 | * Copyright 2014 Google Inc. |
Stefan Roese | dfafe7a | 2017-11-29 16:23:31 +0100 | [diff] [blame] | 7 | */ |
| 8 | |
Tom Rini | 412a021 | 2024-04-27 08:10:56 -0600 | [diff] [blame] | 9 | #include <linux/types.h> |
Stefan Roese | dfafe7a | 2017-11-29 16:23:31 +0100 | [diff] [blame] | 10 | |
| 11 | union overlay64 { |
| 12 | u64 longw; |
| 13 | struct { |
| 14 | u32 lower; |
| 15 | u32 higher; |
| 16 | } words; |
| 17 | }; |
| 18 | |
| 19 | u64 __ashldi3(u64 num, unsigned int shift) |
| 20 | { |
| 21 | union overlay64 output; |
| 22 | |
| 23 | output.longw = num; |
| 24 | if (shift >= 32) { |
| 25 | output.words.higher = output.words.lower << (shift - 32); |
| 26 | output.words.lower = 0; |
| 27 | } else { |
| 28 | if (!shift) |
| 29 | return num; |
| 30 | output.words.higher = (output.words.higher << shift) | |
| 31 | (output.words.lower >> (32 - shift)); |
| 32 | output.words.lower = output.words.lower << shift; |
| 33 | } |
| 34 | return output.longw; |
| 35 | } |
| 36 | |
| 37 | u64 __lshrdi3(u64 num, unsigned int shift) |
| 38 | { |
| 39 | union overlay64 output; |
| 40 | |
| 41 | output.longw = num; |
| 42 | if (shift >= 32) { |
| 43 | output.words.lower = output.words.higher >> (shift - 32); |
| 44 | output.words.higher = 0; |
| 45 | } else { |
| 46 | if (!shift) |
| 47 | return num; |
| 48 | output.words.lower = output.words.lower >> shift | |
| 49 | (output.words.higher << (32 - shift)); |
| 50 | output.words.higher = output.words.higher >> shift; |
| 51 | } |
| 52 | return output.longw; |
| 53 | } |
| 54 | |
| 55 | #define MAX_32BIT_UINT ((((u64)1) << 32) - 1) |
| 56 | |
| 57 | static u64 _64bit_divide(u64 dividend, u64 divider, u64 *rem_p) |
| 58 | { |
| 59 | u64 result = 0; |
| 60 | |
| 61 | /* |
| 62 | * If divider is zero - let the rest of the system care about the |
| 63 | * exception. |
| 64 | */ |
| 65 | if (!divider) |
| 66 | return 1 / (u32)divider; |
| 67 | |
| 68 | /* As an optimization, let's not use 64 bit division unless we must. */ |
| 69 | if (dividend <= MAX_32BIT_UINT) { |
| 70 | if (divider > MAX_32BIT_UINT) { |
| 71 | result = 0; |
| 72 | if (rem_p) |
| 73 | *rem_p = divider; |
| 74 | } else { |
| 75 | result = (u32)dividend / (u32)divider; |
| 76 | if (rem_p) |
| 77 | *rem_p = (u32)dividend % (u32)divider; |
| 78 | } |
| 79 | return result; |
| 80 | } |
| 81 | |
| 82 | while (divider <= dividend) { |
| 83 | u64 locald = divider; |
| 84 | u64 limit = __lshrdi3(dividend, 1); |
| 85 | int shifts = 0; |
| 86 | |
| 87 | while (locald <= limit) { |
| 88 | shifts++; |
| 89 | locald = locald + locald; |
| 90 | } |
| 91 | result |= __ashldi3(1, shifts); |
| 92 | dividend -= locald; |
| 93 | } |
| 94 | |
| 95 | if (rem_p) |
| 96 | *rem_p = dividend; |
| 97 | |
| 98 | return result; |
| 99 | } |
| 100 | |
| 101 | u64 __udivdi3(u64 num, u64 den) |
| 102 | { |
| 103 | return _64bit_divide(num, den, NULL); |
| 104 | } |
| 105 | |
| 106 | u64 __umoddi3(u64 num, u64 den) |
| 107 | { |
| 108 | u64 v = 0; |
| 109 | |
| 110 | _64bit_divide(num, den, &v); |
| 111 | return v; |
| 112 | } |