diff options
Diffstat (limited to 'drivers/gpu/drm/i915/selftests/i915_random.c')
| -rw-r--r-- | drivers/gpu/drm/i915/selftests/i915_random.c | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/drivers/gpu/drm/i915/selftests/i915_random.c b/drivers/gpu/drm/i915/selftests/i915_random.c index 1f415ce47018..716a3f19f030 100644 --- a/drivers/gpu/drm/i915/selftests/i915_random.c +++ b/drivers/gpu/drm/i915/selftests/i915_random.c @@ -41,18 +41,37 @@ u64 i915_prandom_u64_state(struct rnd_state *rnd) return x; } -void i915_random_reorder(unsigned int *order, unsigned int count, - struct rnd_state *state) +void i915_prandom_shuffle(void *arr, size_t elsz, size_t count, + struct rnd_state *state) { - unsigned int i, j; + char stack[128]; + + if (WARN_ON(elsz > sizeof(stack) || count > U32_MAX)) + return; + + if (!elsz || !count) + return; + + /* Fisher-Yates shuffle courtesy of Knuth */ + while (--count) { + size_t swp; + + swp = i915_prandom_u32_max_state(count + 1, state); + if (swp == count) + continue; - for (i = 0; i < count; i++) { - BUILD_BUG_ON(sizeof(unsigned int) > sizeof(u32)); - j = i915_prandom_u32_max_state(count, state); - swap(order[i], order[j]); + memcpy(stack, arr + count * elsz, elsz); + memcpy(arr + count * elsz, arr + swp * elsz, elsz); + memcpy(arr + swp * elsz, stack, elsz); } } +void i915_random_reorder(unsigned int *order, unsigned int count, + struct rnd_state *state) +{ + i915_prandom_shuffle(order, sizeof(*order), count, state); +} + unsigned int *i915_random_order(unsigned int count, struct rnd_state *state) { unsigned int *order, i; |