[FFmpeg-cvslog] random_seed: Reorder if clauses for gathering entropy

[Martin Storsjö]

ffmpeg | branch: master | Martin Storsjö <martin at martin.st> | Wed Feb  5 23:59:34 2025 +0200| [b053f1173d979ce6267ba440ae9a6f6f44285f0c] | committer: Martin Storsjö

random_seed: Reorder if clauses for gathering entropy

Make it easier to add more cases.

This should be a pure refactoring, with no functional changes.

Signed-off-by: Martin Storsjö <martin at martin.st>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b053f1173d979ce6267ba440ae9a6f6f44285f0c
---

 libavutil/random_seed.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c
index 8a4e4f1fc0..ca084b40da 100644
--- a/libavutil/random_seed.c
+++ b/libavutil/random_seed.c
@@ -98,17 +98,20 @@ static uint32_t get_generic_seed(void)
 
     for (;;) {
         clock_t t = clock();
-        if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t) {
-            last_td = t - last_t;
-            buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U);
+        int incremented_i = 0;
+        int cur_td = t - last_t;
+        if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) < t) {
+            buffer[++i & 511] += cur_td % 3294638521U;
+            incremented_i = 1;
         } else {
-            last_td = t - last_t;
-            buffer[++i & 511] += last_td % 3294638521U;
-            if ((t - init_t) >= CLOCKS_PER_SEC>>5)
-                if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
-                    break;
+            buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (cur_td % 3294638521U);
+        }
+        if (incremented_i && (t - init_t) >= CLOCKS_PER_SEC>>5) {
+            if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8)
+                break;
         }
         last_t = t;
+        last_td = cur_td;
         if (!init_t)
             init_t = t;
     }