[x265] [PATCH 3/4] Test: Update values used in check_nquant_primitive

[Hari Limaye]

Change the calculation of the `qBits` parameter in
check_nquant_primitive to be more similar to the calling code in
quant.cpp, rather than using `rand() % 32` to generate a value. The
changes are based on the generation of qBits in check_quant_primitive.

This ensures that the `qBits` parameter in the test is always non-zero,
in order to allow use of non-saturating narrowing instructions in
optimised nquant implementations.
---
 source/test/mbdstharness.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/source/test/mbdstharness.cpp b/source/test/mbdstharness.cpp
index ba85ad420..cceadd833 100644
--- a/source/test/mbdstharness.cpp
+++ b/source/test/mbdstharness.cpp
@@ -260,8 +260,14 @@ bool MBDstHarness::check_nquant_primitive(nquant_t ref, nquant_t opt)
         uint32_t optReturnValue = 0;
         uint32_t refReturnValue = 0;
 
-        int bits = rand() % 32;
-        int valueToAdd = rand() % (1 << bits);
+        int log2TrSize = rand() % 4 + 2;
+        const int qp = rand() % (QP_MAX_SPEC + QP_BD_OFFSET + 1);
+        const int per = qp / 6;
+        const int transformShift = MAX_TR_DYNAMIC_RANGE - X265_DEPTH - log2TrSize;
+
+        /* Right shift of non-RDOQ quantizer level = (coeff*Q + offset)>>q_bits */
+        int bits = QUANT_SHIFT + per + transformShift;
+        int valueToAdd = (1 << (bits - 1));
         int cmp_size = sizeof(short) * height * width;
         int numCoeff = height * width;
 
-- 
2.42.1

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