fhdl/arrays: use correct BV for intermediate signals

diff --git a/examples/basic/arrays.py b/examples/basic/arrays.py
index 4081f85130e2b5423a91a0eb0fda9a15120fb341..0dc33243178bed0e1019e8b712ae01bb117eb24c 100644 (file)
--- a/examples/basic/arrays.py
+++ b/examples/basic/arrays.py
@@ -4,8 +4,8 @@ from migen.fhdl import verilog
 dx = 5
 dy = 5
 
-x = Signal(BV(bits_for(dx)))
-y = Signal(BV(bits_for(dy)))
+x = Signal(BV(bits_for(dx-1)))
+y = Signal(BV(bits_for(dy-1)))
 out = Signal()
 
 my_2d_array = Array(Array(Signal() for a in range(dx)) for b in range(dy))

diff --git a/migen/fhdl/tools.py b/migen/fhdl/tools.py
index f790029669ec05bae8405633a884e4d8ab6b0316..a2f3f78a4b4c50057b29f5be072c16854cba3271 100644 (file)
--- a/migen/fhdl/tools.py
+++ b/migen/fhdl/tools.py
@@ -126,6 +126,44 @@ def insert_reset(rst, sl):
        resetcode = [t.eq(t.reset) for t in targets]
        return If(rst, *resetcode).Else(*sl.l)
 
+def value_bv(v):
+       if isinstance(v, Constant):
+               return v.bv
+       elif isinstance(v, Signal):
+               return v.bv
+       elif isinstance(v, _Operator):
+               obv = map(value_bv, v.operands)
+               if v.op == "+" or v.op == "-":
+                       return BV(max(obv[0].width, obv[1].width) + 1,
+                               obv[0].signed and obv[1].signed)
+               elif v.op == "*":
+                       signed = obv[0].signed and obv[1].signed
+                       if signed:
+                               return BV(obv[0].width + obv[1].width - 1, signed)
+                       else:
+                               return BV(obv[0].width + obv[1].width, signed)
+               elif v.op == "<<" or v.op == ">>":
+                       return obv[0].bv
+               elif v.op == "&" or v.op == "^" or v.op == "|":
+                       return BV(max(obv[0].width, obv[1].width),
+                               obv[0].signed and obv[1].signed)
+               elif v.op == "<" or v.op == "<=" or v.op == "==" or v.op == "!=" \
+                 or v.op == ">" or v.op == ">=":
+                         return BV(1)
+               else:
+                       raise TypeError
+       elif isinstance(v, _Slice):
+               return BV(v.stop - v.start, value_bv(v.value).signed)
+       elif isinstance(v, Cat):
+               return BV(sum(value_bv(sv).width for sv in v.l))
+       elif isinstance(v, Replicate):
+               return BV(value_bv(v.v).width*v.n)
+       elif isinstance(v, _ArrayProxy):
+               bvc = map(value_bv, v.choices)
+               return BV(max(bv.width for bv in bvc), any(bv.signed for bv in bvc))
+       else:
+               raise TypeError
+
 def _lower_arrays_values(vl):
        r = []
        extra_comb = []
@@ -134,9 +172,13 @@ def _lower_arrays_values(vl):
                extra_comb += e
                r.append(v2)
        return r, extra_comb
-       
+
 def _lower_arrays_value(v):
-       if isinstance(v, _Operator):
+       if isinstance(v, Constant):
+               return v, []
+       elif isinstance(v, Signal):
+               return v, []
+       elif isinstance(v, _Operator):
                op2, e = _lower_arrays_values(v.operands)
                return _Operator(v.op, op2), e
        elif isinstance(v, _Slice):
@@ -148,13 +190,9 @@ def _lower_arrays_value(v):
        elif isinstance(v, Replicate):
                v2, e = _lower_arrays_value(v.v)
                return Replicate(v2, v.n), e
-       elif isinstance(v, Constant):
-               return v, []
-       elif isinstance(v, Signal):
-               return v, []
        elif isinstance(v, _ArrayProxy):
                choices2, e = _lower_arrays_values(v.choices)
-               array_muxed = Signal(BV(32)) # TODO: use the correct BV
+               array_muxed = Signal(value_bv(v))
                cases = [[Constant(n), _Assign(array_muxed, choice)]
                        for n, choice in enumerate(choices2)]
                cases[-1][0] = Default()