Update gemmini_params.h

Author: hngenc

include/gemmini_params.h

@@ -59,6 +59,12 @@ typedef uint32_t acc_scale_t_bits;
                      i % 2 == 0 ? i : next)); \
          result; })
 
+// Rounding right shift equation: https://riscv.github.io/documents/riscv-v-spec/#_vector_fixed_point_rounding_mode_register_vxrm
+#define ROUNDING_RIGHT_SHIFT_BITS(x, shift) \
+((shift) > 0 ? (((x) >> (shift)) + \
+    (((shift) == 0 ? 0 : (((x) >> ((shift)-1)) & 1)) & \
+         ((((shift) <= 1 ? 0 : ((x) & ((1 << ((shift)-1)) - 1))) != 0) | (((x) >> (shift)) & 1)))) : ((x) << (-(shift))))
+
 #define ACC_SCALE(x, scale) \
     ({float y = ROUND_NEAR_EVEN((x) * (scale)); y > INT8_MAX ? INT8_MAX : (y < INT8_MIN ? INT8_MIN : (acc_t)y);})