From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Tue, 19 Feb 2019 15:52:13 +0000 (+0000)
Subject: store testing of nan/inf/zero in comb Signals
X-Git-Tag: ls180-24jan2020~1863
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=468cb689dc4e797c17065e7f882b936791420afa;p=ieee754fpu.git

store testing of nan/inf/zero in comb Signals
---

diff --git a/src/add/nmigen_add_experiment.py b/src/add/nmigen_add_experiment.py
index fa4166c2..97e2fdf9 100644
--- a/src/add/nmigen_add_experiment.py
+++ b/src/add/nmigen_add_experiment.py
@@ -55,8 +55,33 @@ class FPADD(FPBase):
 
             with m.State("special_cases"):
 
+                a_nan = Signal()
+                a_zero = Signal()
+                a_inf = Signal()
+
+                b_nan = Signal()
+                b_zero = Signal()
+                b_inf = Signal()
+
+                m.d.comb += a_nan.eq(a.is_nan())
+                m.d.comb += a_zero.eq(a.is_zero())
+                m.d.comb += a_inf.eq(a.is_inf())
+
+                m.d.comb += b_nan.eq(b.is_nan())
+                m.d.comb += b_zero.eq(b.is_zero())
+                m.d.comb += b_inf.eq(b.is_inf())
+
+                b_eq_p128 = Signal()
+                m.d.comb += b_eq_p128.eq(b.e == b.P128)
+
+                s_nomatch = Signal()
+                m.d.comb += s_nomatch.eq(a.s != b.s)
+
+                m_match = Signal()
+                m.d.comb += m_match.eq(a.m == b.m)
+
                 # if a is NaN or b is NaN return NaN
-                with m.If(a.is_nan() | b.is_nan()):
+                with m.If(a_nan | b_nan):
                     m.next = "put_z"
                     m.d.sync += z.nan(1)
 
@@ -64,55 +89,55 @@ class FPADD(FPBase):
                 # under review
 
                 ## if a is zero and b is NaN return -b
-                #with m.If(a.is_zero() & (a.s==0) & b.is_nan()):
+                #with m.If(a_zero & (a.s==0) & b_nan):
                 #    m.next = "put_z"
                 #    m.d.sync += z.create(b.s, b.e, Cat(b.m[3:-2], ~b.m[0]))
 
                 ## if b is zero and a is NaN return -a
-                #with m.Elif(b.is_zero() & (b.s==0) & a.is_nan()):
+                #with m.Elif(b_zero & (b.s==0) & a_nan):
                 #    m.next = "put_z"
                 #    m.d.sync += z.create(a.s, a.e, Cat(a.m[3:-2], ~a.m[0]))
 
                 ## if a is -zero and b is NaN return -b
-                #with m.Elif(a.is_zero() & (a.s==1) & b.is_nan()):
+                #with m.Elif(a_zero & (a.s==1) & b_nan):
                 #    m.next = "put_z"
                 #    m.d.sync += z.create(a.s & b.s, b.e, Cat(b.m[3:-2], 1))
 
                 ## if b is -zero and a is NaN return -a
-                #with m.Elif(b.is_zero() & (b.s==1) & a.is_nan()):
+                #with m.Elif(b_zero & (b.s==1) & a_nan):
                 #    m.next = "put_z"
                 #    m.d.sync += z.create(a.s & b.s, a.e, Cat(a.m[3:-2], 1))
 
                 # if a is inf return inf (or NaN)
-                with m.Elif(a.is_inf()):
+                with m.Elif(a_inf):
                     m.next = "put_z"
                     m.d.sync += z.inf(a.s)
                     # if a is inf and signs don't match return NaN
-                    with m.If((b.e == b.P128) & (a.s != b.s)):
+                    with m.If(b_eq_p128 & s_nomatch):
                         m.d.sync += z.nan(1)
 
                 # if b is inf return inf
-                with m.Elif(b.is_inf()):
+                with m.Elif(b_inf):
                     m.next = "put_z"
                     m.d.sync += z.inf(b.s)
 
                 # if a is zero and b zero return signed-a/b
-                with m.Elif(a.is_zero() & b.is_zero()):
+                with m.Elif(a_zero & b_zero):
                     m.next = "put_z"
                     m.d.sync += z.create(a.s & b.s, b.e, b.m[3:-1])
 
                 # if a is zero return b
-                with m.Elif(a.is_zero()):
+                with m.Elif(a_zero):
                     m.next = "put_z"
                     m.d.sync += z.create(b.s, b.e, b.m[3:-1])
 
                 # if b is zero return a
-                with m.Elif(b.is_zero()):
+                with m.Elif(b_zero):
                     m.next = "put_z"
                     m.d.sync += z.create(a.s, a.e, a.m[3:-1])
 
                 # if a equal to -b return zero (+ve zero)
-                with m.Elif((a.s != b.s) & (a.m == b.m) & (a.e == b.e)):
+                with m.Elif(s_nomatch & m_match & (a.e == b.e)):
                     m.next = "put_z"
                     m.d.sync += z.zero(0)