From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Thu, 4 Apr 2019 21:35:03 +0000 (+0100)
Subject: add create2 functions, for use later
X-Git-Tag: ls180-24jan2020~1345
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=08cc069dd3bdece2058d27171b73469a9fd3a09f;p=ieee754fpu.git

add create2 functions, for use later
---

diff --git a/src/add/fpbase.py b/src/add/fpbase.py
index b15c21ca..b31ab21c 100644
--- a/src/add/fpbase.py
+++ b/src/add/fpbase.py
@@ -87,6 +87,8 @@ class FPNumBase:
         self.s = Signal(reset_less=True)           # Sign bit
 
         self.mzero = Const(0, (m_width, False))
+        m_msb = 1<<(self.m_width-2)
+        self.msb1 = Const(m_msb, (m_width, False))
         self.m1s = Const(-1, (m_width, False))
         self.P128 = Const(e_max, (e_width, True))
         self.P127 = Const(e_max-1, (e_width, True))
@@ -186,6 +188,25 @@ class FPNumOut(FPNumBase):
     def zero(self, s):
         return self.create(s, self.N127, 0)
 
+    def create2(self, s, e, m):
+        """ creates a value from sign / exponent / mantissa
+
+            bias is added here, to the exponent
+        """
+        e = e + self.P127 # exp (add on bias)
+        return Cat(m[0:self.e_start],
+                   e[0:self.e_end-self.e_start],
+                   s)
+
+    def nan2(self, s):
+        return self.create2(s, self.P128, self.msb1)
+
+    def inf2(self, s):
+        return self.create2(s, self.P128, self.mzero)
+
+    def zero2(self, s):
+        return self.create2(s, self.N127, self.mzero)
+
 
 class MultiShiftRMerge:
     """ shifts down (right) and merges lower bits into m[0].