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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
a33d42dd CW |
2 | #include <linux/bitops.h> |
3 | #include <linux/kernel.h> | |
4 | #include <linux/random.h> | |
5 | #include <linux/slab.h> | |
6 | #include <linux/types.h> | |
7 | ||
8 | #include "drm_random.h" | |
9 | ||
10 | static inline u32 drm_prandom_u32_max_state(u32 ep_ro, struct rnd_state *state) | |
11 | { | |
12 | return upper_32_bits((u64)prandom_u32_state(state) * ep_ro); | |
13 | } | |
14 | ||
15 | void drm_random_reorder(unsigned int *order, unsigned int count, | |
16 | struct rnd_state *state) | |
17 | { | |
18 | unsigned int i, j; | |
19 | ||
20 | for (i = 0; i < count; ++i) { | |
21 | BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); | |
22 | j = drm_prandom_u32_max_state(count, state); | |
23 | swap(order[i], order[j]); | |
24 | } | |
25 | } | |
26 | EXPORT_SYMBOL(drm_random_reorder); | |
27 | ||
28 | unsigned int *drm_random_order(unsigned int count, struct rnd_state *state) | |
29 | { | |
30 | unsigned int *order, i; | |
31 | ||
0ee931c4 | 32 | order = kmalloc_array(count, sizeof(*order), GFP_KERNEL); |
a33d42dd CW |
33 | if (!order) |
34 | return order; | |
35 | ||
36 | for (i = 0; i < count; i++) | |
37 | order[i] = i; | |
38 | ||
39 | drm_random_reorder(order, count, state); | |
40 | return order; | |
41 | } | |
42 | EXPORT_SYMBOL(drm_random_order); |