- m.d.comb += sabx.eq(a1.s ^ b1.s)
-
- abnan = Signal(reset_less=True)
- m.d.comb += abnan.eq(a1.is_nan | b1.is_nan)
-
- abinf = Signal(reset_less=True)
- m.d.comb += abinf.eq(a1.is_inf & b1.is_inf)
-
- # if a is NaN or b is NaN return NaN
- with m.If(abnan):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.nan(0)
-
- # if a is inf and b is Inf return NaN
- with m.Elif(abinf):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.nan(0)
-
- # if a is inf return inf
- with m.Elif(a1.is_inf):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.inf(sabx)
-
- # if b is inf return zero
- with m.Elif(b1.is_inf):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.zero(sabx)
-
- # if a is zero return zero (or NaN if b is zero)
- with m.Elif(a1.is_zero):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.zero(sabx)
- # b is zero return NaN
- with m.If(b1.is_zero):
- m.d.comb += self.o.z.nan(0)
-
- # if b is zero return Inf
- with m.Elif(b1.is_zero):
- m.d.comb += self.o.out_do_z.eq(1)
- m.d.comb += self.o.z.inf(sabx)
-
- # Denormalised Number checks next, so pass a/b data through
- with m.Else():
- m.d.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)
+ t_abnan = Signal(reset_less=True)
+ t_abinf = Signal(reset_less=True)
+ t_a1inf = Signal(reset_less=True)
+ t_b1inf = Signal(reset_less=True)
+ t_a1zero = Signal(reset_less=True)
+ t_b1zero = Signal(reset_less=True)
+ t_abz = Signal(reset_less=True)
+ t_special_div = Signal(reset_less=True)
+ t_special_sqrt = Signal(reset_less=True)
+ t_special_rsqrt = Signal(reset_less=True)
+
+ comb += sabx.eq(a1.s ^ b1.s)
+ comb += t_abnan.eq(a1.is_nan | b1.is_nan)
+ comb += t_abinf.eq(a1.is_inf & b1.is_inf)
+ comb += t_a1inf.eq(a1.is_inf)
+ comb += t_b1inf.eq(b1.is_inf)
+ comb += t_abz.eq(a1.is_zero & b1.is_zero)
+ comb += t_a1zero.eq(a1.is_zero)
+ comb += t_b1zero.eq(b1.is_zero)
+
+ # prepare inf/zero/nans
+ z_zero = FPNumBaseRecord(width, False, name="z_zero")
+ z_zeroab = FPNumBaseRecord(width, False, name="z_zeroab")
+ z_nan = FPNumBaseRecord(width, False, name="z_nan")
+ z_infa = FPNumBaseRecord(width, False, name="z_infa")
+ z_infb = FPNumBaseRecord(width, False, name="z_infb")
+ z_infab = FPNumBaseRecord(width, False, name="z_infab")
+ comb += z_zero.zero(0)
+ comb += z_zeroab.zero(sabx)
+ comb += z_nan.nan(0)
+ comb += z_infa.inf(a1.s)
+ comb += z_infb.inf(b1.s)
+ comb += z_infab.inf(sabx)
+
+ comb += t_special_div.eq(Cat(t_b1zero, t_a1zero, t_b1inf, t_a1inf,
+ t_abinf, t_abnan).bool())
+
+ # select one of 3 different sets of specialcases (DIV, SQRT, RSQRT)
+ with m.Switch(self.i.ctx.op):
+
+ ########## DIV ############
+ with m.Case(int(DP.UDivRem)):
+
+ # any special cases?
+ comb += self.o.out_do_z.eq(t_special_div)
+
+ # if a is NaN or b is NaN return NaN
+ # if a is inf and b is Inf return NaN
+ # if a is inf return inf
+ # if b is inf return zero
+ # if a is zero return zero (or NaN if b is zero)
+ # b is zero return NaN
+ # if b is zero return Inf
+
+ # sigh inverse order on the above, Mux-cascade
+ oz = 0
+ oz = Mux(t_b1zero, z_infab.v, oz)
+ oz = Mux(t_a1zero, Mux(t_b1zero, z_nan.v, z_zeroab.v), oz)
+ oz = Mux(t_b1inf, z_zeroab.v, oz)
+ oz = Mux(t_a1inf, z_infab.v, oz)
+ oz = Mux(t_abinf, z_nan.v, oz)
+ oz = Mux(t_abnan, z_nan.v, oz)
+
+ comb += self.o.oz.eq(oz)
+
+ ########## SQRT ############
+ with m.Case(int(DP.SqrtRem)):
+
+ # if a is zero return zero
+ with m.If(a1.is_zero):
+ comb += self.o.z.zero(a1.s)
+
+ # -ve number is NaN
+ with m.Elif(a1.s):
+ comb += self.o.z.nan(0)
+
+ # if a is inf return inf
+ with m.Elif(a1.is_inf):
+ comb += self.o.z.inf(sabx)
+
+ # if a is NaN return NaN
+ with m.Elif(a1.is_nan):
+ comb += self.o.z.nan(0)
+
+ # Denormalised Number checks next, so pass a/b data through
+ with m.Else():
+ comb += self.o.out_do_z.eq(0)
+
+ comb += self.o.oz.eq(self.o.z.v)
+
+ ########## RSQRT ############
+ with m.Case(int(DP.RSqrtRem)):
+
+ # if a is NaN return canonical NaN
+ with m.If(a1.is_nan):
+ comb += self.o.z.nan(0)
+
+ # if a is +/- zero return +/- INF
+ with m.Elif(a1.is_zero):
+ # this includes the "weird" case 1/sqrt(-0) == -Inf
+ comb += self.o.z.inf(a1.s)
+
+ # -ve number is canonical NaN
+ with m.Elif(a1.s):
+ comb += self.o.z.nan(0)
+
+ # if a is inf return zero (-ve already excluded, above)
+ with m.Elif(a1.is_inf):
+ comb += self.o.z.zero(0)
+
+ # Denormalised Number checks next, so pass a/b data through
+ with m.Else():
+ comb += self.o.out_do_z.eq(0)
+
+ comb += self.o.oz.eq(self.o.z.v)
+
+ # pass through context
+ comb += self.o.ctx.eq(self.i.ctx)