# Copyright (C) Jonathan P Dawson 2013
# 2013-12-12
-from nmigen import Module, Signal, Cat, Const, Elaboratable
+from nmigen import Module, Signal, Cat, Const
from nmigen.cli import main, verilog
from math import log
+from ieee754.fpcommon.modbase import FPModBase
from ieee754.fpcommon.fpbase import FPNumDecode
from nmutil.singlepipe import StageChain
from ieee754.pipeline import DynamicPipe
from ieee754.fpcommon.denorm import (FPSCData, FPAddDeNormMod)
-class FPAddSpecialCasesMod(Elaboratable):
+class FPAddSpecialCasesMod(FPModBase):
""" special cases: NaNs, infs, zeros, denormalised
NOTE: some of these are unique to add. see "Special Operations"
https://steve.hollasch.net/cgindex/coding/ieeefloat.html
"""
def __init__(self, pspec):
- self.pspec = pspec
- self.i = self.ispec()
- self.o = self.ospec()
+ super().__init__(pspec, "specialcases")
def ispec(self):
return FPADDBaseData(self.pspec)
def ospec(self):
return FPSCData(self.pspec, True)
- def setup(self, m, i):
- """ links module to inputs and outputs
- """
- m.submodules.specialcases = self
- m.d.comb += self.i.eq(i)
-
- def process(self, i):
- return self.o
-
def elaborate(self, platform):
m = Module()
-
- #m.submodules.sc_out_z = self.o.z
+ comb = m.d.comb
# decode: XXX really should move to separate stage
width = self.pspec.width
b1 = FPNumBaseRecord(width)
m.submodules.sc_decode_a = a1 = FPNumDecode(None, a1)
m.submodules.sc_decode_b = b1 = FPNumDecode(None, b1)
- m.d.comb += [a1.v.eq(self.i.a),
+ comb += [a1.v.eq(self.i.a),
b1.v.eq(self.i.b),
self.o.a.eq(a1),
self.o.b.eq(b1)
]
+ # temporaries used below
s_nomatch = Signal(reset_less=True)
- m.d.comb += s_nomatch.eq(a1.s != b1.s)
-
m_match = Signal(reset_less=True)
- m.d.comb += m_match.eq(a1.m == b1.m)
-
e_match = Signal(reset_less=True)
- m.d.comb += e_match.eq(a1.e == b1.e)
-
aeqmb = Signal(reset_less=True)
- m.d.comb += aeqmb.eq(s_nomatch & m_match & e_match)
-
abz = Signal(reset_less=True)
- m.d.comb += abz.eq(a1.is_zero & b1.is_zero)
-
abnan = Signal(reset_less=True)
- m.d.comb += abnan.eq(a1.is_nan | b1.is_nan)
-
bexp128s = Signal(reset_less=True)
- m.d.comb += bexp128s.eq(b1.exp_128 & s_nomatch)
+
+ comb += s_nomatch.eq(a1.s != b1.s)
+ comb += m_match.eq(a1.m == b1.m)
+ comb += e_match.eq(a1.e == b1.e)
+ comb += aeqmb.eq(s_nomatch & m_match & e_match)
+ comb += abz.eq(a1.is_zero & b1.is_zero)
+ comb += abnan.eq(a1.is_nan | b1.is_nan)
+ comb += bexp128s.eq(b1.exp_128 & s_nomatch)
# default bypass
- m.d.comb += self.o.out_do_z.eq(1)
+ comb += self.o.out_do_z.eq(1)
# if a is NaN or b is NaN return NaN
with m.If(abnan):
- m.d.comb += self.o.z.nan(0)
+ comb += self.o.z.nan(0)
# XXX WEIRDNESS for FP16 non-canonical NaN handling
# under review
## if a is zero and b is NaN return -b
#with m.If(a.is_zero & (a.s==0) & b.is_nan):
- # m.d.comb += self.o.out_do_z.eq(1)
- # m.d.comb += z.create(b.s, b.e, Cat(b.m[3:-2], ~b.m[0]))
+ # comb += self.o.out_do_z.eq(1)
+ # comb += 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):
- # m.d.comb += self.o.out_do_z.eq(1)
- # m.d.comb += z.create(a.s, a.e, Cat(a.m[3:-2], ~a.m[0]))
+ # comb += self.o.out_do_z.eq(1)
+ # comb += 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):
- # m.d.comb += self.o.out_do_z.eq(1)
- # m.d.comb += z.create(a.s & b.s, b.e, Cat(b.m[3:-2], 1))
+ # comb += self.o.out_do_z.eq(1)
+ # comb += 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):
- # m.d.comb += self.o.out_do_z.eq(1)
- # m.d.comb += z.create(a.s & b.s, a.e, Cat(a.m[3:-2], 1))
+ # comb += self.o.out_do_z.eq(1)
+ # comb += 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(a1.is_inf):
- m.d.comb += self.o.z.inf(a1.s)
+ comb += self.o.z.inf(a1.s)
# if a is inf and signs don't match return NaN
with m.If(bexp128s):
- m.d.comb += self.o.z.nan(0)
+ comb += self.o.z.nan(0)
# if b is inf return inf
with m.Elif(b1.is_inf):
- m.d.comb += self.o.z.inf(b1.s)
+ comb += self.o.z.inf(b1.s)
# if a is zero and b zero return signed-a/b
with m.Elif(abz):
- m.d.comb += self.o.z.create(a1.s & b1.s, b1.e, b1.m[3:-1])
+ comb += self.o.z.create(a1.s & b1.s, b1.e, b1.m[3:-1])
# if a is zero return b
with m.Elif(a1.is_zero):
- m.d.comb += self.o.z.create(b1.s, b1.e, b1.m[3:-1])
+ comb += self.o.z.create(b1.s, b1.e, b1.m[3:-1])
# if b is zero return a
with m.Elif(b1.is_zero):
- m.d.comb += self.o.z.create(a1.s, a1.e, a1.m[3:-1])
+ comb += self.o.z.create(a1.s, a1.e, a1.m[3:-1])
# if a equal to -b return zero (+ve zero)
with m.Elif(aeqmb):
- m.d.comb += self.o.z.zero(0)
+ comb += self.o.z.zero(0)
# Denormalised Number checks next, so pass a/b data through
with m.Else():
- m.d.comb += self.o.out_do_z.eq(0)
+ comb += self.o.out_do_z.eq(0)
- m.d.comb += self.o.oz.eq(self.o.z.v)
- m.d.comb += self.o.ctx.eq(self.i.ctx)
+ comb += self.o.oz.eq(self.o.z.v)
+ comb += self.o.ctx.eq(self.i.ctx)
return m
def __init__(self, pspec):
self.pspec = pspec
super().__init__(pspec)
- self.out = self.ospec()
def ispec(self):
return FPADDBaseData(self.pspec) # SC ispec