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base repository: m-labs/migen
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head repository: m-labs/migen
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compare: 408a85f0226e
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  • 2 commits
  • 1 file changed
  • 1 contributor

Commits on Mar 29, 2016

  1. bitcontainer: handle unary ops (closes #44)

    @jordens
    jordens committed Mar 29, 2016
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    a2a1c30 View commit details

  2. bitcontainer: handle Mux (closes #46)

    @jordens
    jordens committed Mar 29, 2016
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    408a85f View commit details
Showing with 28 additions and 27 deletions.
  1. +28 −27 migen/fhdl/bitcontainer.py
55 changes: 28 additions & 27 deletions migen/fhdl/bitcontainer.py
View file
Original file line number Diff line number Diff line change
@@ -26,6 +26,21 @@ def bits_for(n, require_sign_bit=False):
return r


def _bitwise_binary_bits_sign(a, b):
if not a[1] and not b[1]:
# both operands unsigned
return max(a[0], b[0]), False
elif a[1] and b[1]:
# both operands signed
return max(a[0], b[0]), True
elif not a[1] and b[1]:
# first operand unsigned (add sign bit), second operand signed
return max(a[0] + 1, b[0]), True
else:
# first signed, second operand unsigned (add sign bit)
return max(a[0], b[0] + 1), True


def value_bits_sign(v):
"""Bit length and signedness of a value.
@@ -53,18 +68,13 @@ def value_bits_sign(v):
elif isinstance(v, f._Operator):
obs = list(map(value_bits_sign, v.operands))
if v.op == "+" or v.op == "-":
if not obs[0][1] and not obs[1][1]:
# both operands unsigned
return max(obs[0][0], obs[1][0]) + 1, False
elif obs[0][1] and obs[1][1]:
# both operands signed
return max(obs[0][0], obs[1][0]) + 1, True
elif not obs[0][1] and obs[1][1]:
# first operand unsigned (add sign bit), second operand signed
return max(obs[0][0] + 1, obs[1][0]) + 1, True
else:
# first signed, second operand unsigned (add sign bit)
return max(obs[0][0], obs[1][0] + 1) + 1, True
if len(obs) == 1:
if v.op == "-" and not obs[0][1]:
return obs[0][0] + 1, True
else:
return obs[0]
n, s = _bitwise_binary_bits_sign(*obs)
return n + 1, s
elif v.op == "*":
if not obs[0][1] and not obs[1][1]:
# both operands unsigned
@@ -88,23 +98,14 @@ def value_bits_sign(v):
extra = 0
return obs[0][0] + extra, obs[0][1]
elif v.op == "&" or v.op == "^" or v.op == "|":
if not obs[0][1] and not obs[1][1]:
# both operands unsigned
return max(obs[0][0], obs[1][0]), False
elif obs[0][1] and obs[1][1]:
# both operands signed
return max(obs[0][0], obs[1][0]), True
elif not obs[0][1] and obs[1][1]:
# first operand unsigned (add sign bit), second operand signed
return max(obs[0][0] + 1, obs[1][0]), True
else:
# first signed, second operand unsigned (add sign bit)
return max(obs[0][0], obs[1][0] + 1), True
elif v.op == "<" or v.op == "<=" or v.op == "==" or v.op == "!=" \
or v.op == ">" or v.op == ">=":
return 1, False
return _bitwise_binary_bits_sign(*obs)
elif (v.op == "<" or v.op == "<=" or v.op == "==" or v.op == "!=" or
v.op == ">" or v.op == ">="):
return 1, False
elif v.op == "~":
return obs[0]
elif v.op == "m":
return _bitwise_binary_bits_sign(obs[1], obs[2])
else:
raise TypeError
elif isinstance(v, f._Slice):