test accounting for sig_total_bits separately

Author: tgross35

src/math/generic/scalbn.rs

@@ -1,8 +1,14 @@
+#![allow(unused)]
+
 use super::super::support::Hexf;
 use super::super::{CastFrom, CastInto, Float, IntTy, MinInt};
 
-extern crate std;
-use std::dbg;
+// extern crate std;
+// use std::dbg;
+
+macro_rules! dbg {
+    ($($tt:tt)*) => {};
+}
 
 /// Scale the exponent.
 ///
@@ -68,9 +74,18 @@ where
             }
         }
     } else if n < exp_min {
-        let mul = f_exp_min * f_exp_subnorm;
-        let add = (exp_max - 1) - sig_total_bits as i32;
+        // WIP: for `f16` can this scale by `exp_max` rather than `(max - 1) - sig_bits`?
+        // That scale is only 3.
+        //
+
+        n += sig_total_bits as i32;
+
+        // let mul = f_exp_min * f_exp_subnorm;
+        // let add = -exp_min - sig_total_bits as i32;
+        let mul = f_exp_min;
+        let add = -exp_min;
         dbg!(Hexf(mul), add);
+        let mut b = false;
 
         x *= mul;
         n += add;
@@ -79,7 +94,7 @@ where
             x *= mul;
             n += add;
             dbg!(Hexf(x), n);
-            if F::BITS < 32 {
+            if F::BITS < 32 && false {
                 if n < exp_min {
                     x *= mul;
                     n += add;
@@ -128,19 +143,21 @@ where
                 }
             } else if n < exp_min {
                 n = exp_min;
+                b = true;
                 dbg!(Hexf(x), n);
             }
         }
+
+        if !b {
+            n -= sig_total_bits as i32;
+        }
     }
 
     dbg!(Hexf(x), n);
     let scale = F::from_parts(false, (F::EXP_BIAS as i32 + n) as u32, zero);
     let ret = x * scale;
     dbg!(Hexf(scale), Hexf(ret));
     ret
-
-    // let ret = dbg!(x) * dbg!(F::from_parts(false, (F::EXP_BIAS as i32 + n) as u32, zero));
-    // dbg!(ret)
 }
 
 #[cfg(test)]