1 """IEEE754 Floating Point Divider
3 Relevant bugreport: http://bugs.libre-riscv.org/show_bug.cgi?id=99
6 from nmigen
import Module
, Signal
, Cat
, Elaboratable
7 from nmigen
.cli
import main
, verilog
9 from ieee754
.fpcommon
.fpbase
import FPNumBaseRecord
10 from ieee754
.fpcommon
.fpbase
import FPState
11 from ieee754
.fpcommon
.denorm
import FPSCData
12 from .div0
import FPDivStage0Data
15 class FPDivStage1Mod(Elaboratable
):
17 def __init__(self
, width
, id_wid
):
24 return FPDivStage0Data(self
.width
, self
.id_wid
) # Q/Rem (etc) in...
27 return FPDivStage0Data(self
.width
, self
.id_wid
) # ... Q/Rem (etc) out
32 def setup(self
, m
, i
):
33 """ links module to inputs and outputs
35 m
.submodules
.div0
= self
36 m
.d
.comb
+= self
.i
.eq(i
)
38 def elaborate(self
, platform
):
41 # XXX TODO, actual DIV code here. this class would be
42 # here is where Q and R are used, TODO: Q/REM (etc) need to be in
45 # NOTE: this does ONE step of Q/REM processing. it does NOT do
46 # MULTIPLE stages of Q/REM processing. it *MUST* be PURE
47 # combinatorial and one step ONLY.
49 # store intermediate tests (and zero-extended mantissas)
50 am0
= Signal(len(self
.i
.a
.m
)+1, reset_less
=True)
51 bm0
= Signal(len(self
.i
.b
.m
)+1, reset_less
=True)
53 am0
.eq(Cat(self
.i
.a
.m
, 0)),
54 bm0
.eq(Cat(self
.i
.b
.m
, 0))
56 # same-sign (both negative or both positive) div mantissas
57 with m
.If(~self
.i
.out_do_z
):
58 m
.d
.comb
+= [self
.o
.z
.e
.eq(self
.i
.a
.e
+ self
.i
.b
.e
+ 1),
59 # TODO: no, not product, first stage Q and R etc. etc.
61 self
.o
.product
.eq(am0
* bm0
* 4),
62 self
.o
.z
.s
.eq(self
.i
.a
.s ^ self
.i
.b
.s
)
65 m
.d
.comb
+= self
.o
.oz
.eq(self
.i
.oz
)
66 m
.d
.comb
+= self
.o
.out_do_z
.eq(self
.i
.out_do_z
)
67 m
.d
.comb
+= self
.o
.mid
.eq(self
.i
.mid
)