small optimisation, move subtraction of -126 from exponent into FPNumBase module...

[ieee754fpu.git] / src / add / fpbase.py

diff --git a/src/add/fpbase.py b/src/add/fpbase.py
index d8073d5355ae1f787c9b07e73eae0cb02f49d276..58b4994a4de4ea8904156dca641e41bb6e0f3d27 100644 (file)
--- a/src/add/fpbase.py
+++ b/src/add/fpbase.py
@@ -96,6 +96,7 @@ class FPNumBase:
         self.is_overflowed = Signal(reset_less=True)
         self.is_denormalised = Signal(reset_less=True)
         self.exp_128 = Signal(reset_less=True)
+        self.exp_sub_n126 = Signal((e_width, True), reset_less=True)
         self.exp_lt_n126 = Signal(reset_less=True)
         self.exp_gt_n126 = Signal(reset_less=True)
         self.exp_gt127 = Signal(reset_less=True)
@@ -112,8 +113,9 @@ class FPNumBase:
         m.d.comb += self.is_overflowed.eq(self._is_overflowed())
         m.d.comb += self.is_denormalised.eq(self._is_denormalised())
         m.d.comb += self.exp_128.eq(self.e == self.P128)
-        m.d.comb += self.exp_gt_n126.eq(self.e > self.N126)
-        m.d.comb += self.exp_lt_n126.eq(self.e < self.N126)
+        m.d.comb += self.exp_sub_n126.eq(self.e - self.N126)
+        m.d.comb += self.exp_gt_n126.eq(self.exp_sub_n126 > 0)
+        m.d.comb += self.exp_lt_n126.eq(self.exp_sub_n126 < 0)
         m.d.comb += self.exp_gt127.eq(self.e > self.P127)
         m.d.comb += self.exp_n127.eq(self.e == self.N127)
         m.d.comb += self.exp_n126.eq(self.e == self.N126)