+ mantissa = lp_mantissa(dst_type);
+
+ if (src_width <= (mantissa + 1)) {
+ /*
+ * The source width matches fits what can be represented in floating
+ * point (i.e., mantissa + 1 bits). So do a straight multiplication
+ * followed by casting. No further rounding is necessary.
+ */
+
+ scale = 1.0/(double)((1ULL << src_width) - 1);