shithub: dav1d

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Simplify msac subexp decoding

--- a/src/msac.c

+++ b/src/msac.c

@@ -101,17 +101,17 @@

 }

 int dav1d_msac_decode_subexp(MsacContext *const s, const int ref,

-                             const int n, const unsigned k)

+                             const int n, unsigned k)

 {

-    int i = 0;

-    int a = 0;

-    int b = k;

-    while ((2 << b) < n) {

-        if (!dav1d_msac_decode_bool_equi(s)) break;

-        b = k + i++;

-        a = (1 << b);

+    assert(n >> k == 8);

+

+    unsigned a = 0;

+    if (dav1d_msac_decode_bool_equi(s)) {

+        if (dav1d_msac_decode_bool_equi(s))

+            k += dav1d_msac_decode_bool_equi(s) + 1;

+        a = 1 << k;

     }

-    const unsigned v = dav1d_msac_decode_bools(s, b) + a;

+    const unsigned v = dav1d_msac_decode_bools(s, k) + a;

     return ref * 2 <= n ? inv_recenter(ref, v) :

                           n - 1 - inv_recenter(n - 1 - ref, v);

 }