Implement faster mju_isZeroByte.

PiperOrigin-RevId: 814148714 Change-Id: Iaf5ed9d3502eaaaee8d46a986f2db00811ae0707
2025-10-02 02:53:02 -07:00
parent 401bf431b8
commit 91257896c0
4 changed files with 42 additions and 21 deletions
@@ -1332,26 +1332,8 @@ int mju_isZero(const mjtNum* vec, int n) {

 // return 1 if all elements are 0
 int mju_isZeroByte(const unsigned char* vec, int n) {
-  size_t i = 0;
-
-  // unroll using 8-byte chunks
-  const uint64_t* vec64 = (const uint64_t*)vec;
-  size_t n64 = n / sizeof(uint64_t);
-  for (; i < n64; ++i) {
-    if (vec64[i]) {
-      return 0;
-    }
-  }
-
-  // remaining bytes
-  i *= sizeof(uint64_t);
-  for (; i < n; ++i) {
-    if (vec[i]) {
-      return 0;
-    }
-  }
-
-  return 1;
+  if (!n || *vec) return !n;
+  return memcmp(vec, vec + 1, n - 1) == 0;
 }