1 files changed, 86 insertions, 0 deletions
diff --git a/verilog-integer.py b/verilog-integer.py
new file mode 100644
index 0000000..e9a1ba5
--- /dev/null
+++ b/verilog-integer.py
@@ -0,0 +1,86 @@
+# Code to parse Verilog's integer constant syntax so that we can
+# generate C headers from Verilog constants.
+#
+# Doesn't attempt to handle the analogue states ("x", "z", "?").
+#
+# Reference: http://verilog.renerta.com/source/vrg00020.htm
+
+class VerilogInteger(object):
+
+  radix = dict(b = 2, o = 8, d = 10, h = 16)
+
+  def __init__(self, input):
+    head, sep, tail = input.lower().translate(None, " \t_").partition("'")
+    self.input = input
+    self.code  = tail[0] if tail else None
+
+    if not sep:
+      self.width  = 32
+      self.value  = int(head)
+
+    elif self.code in self.radix:
+      self.width  = int(head) if head else 32
+      self.value  = int(tail[1:], self.radix[self.code])
+      if self.width <= 0 or self.value < 0:
+        raise ValueError
+
+    else:
+      raise ValueError
+
+    if self.width is not None:
+      mask = (1L << self.width) - 1
+      if self.value > mask:
+        self.value &= mask
+      elif self.value < -mask:
+        self.value = -( -self.value & mask)
+
+  @property
+  def C(self):
+    if self.code is None:
+      return str(self.value)
+    elif self.code == "d":
+      return "{0:d}".format(self.value)
+    elif self.code == "o":
+      return "0{0:0{1}o}".format(self.value, (self.width + 2) / 3)
+    else:
+      return "0x{0:0{1}x}".format(self.value, (self.width + 3) / 4)
+
+  @property
+  def Verilog(self):
+    if self.code is None:
+      return str(self.value)
+    else:
+      fmt = "x" if self.code == "h" else self.code
+      return "{0.width}'{0.code}{0.value:{1}}".format(self, fmt)
+
+
+if __name__ == "__main__":
+
+  def show(*args):
+    print "{:20} | {:20} | {:20}".format(*args)
+
+  show("C", "Verilog", "Input")
+  show("-" * 20, "-" * 20, "-" * 20)
+
+  def test(x):
+    v = VerilogInteger(x)
+    show(v.C, v.Verilog, v.input)
+
+  test("15")
+  test("'h f")
+  test("'o 17")
+  test("'d 15")
+  test("'b 1111")
+  test("'b 1_1_1_1")
+  test("10 'd 20")
+  test("6'o 71")
+  test("8'b0")
+  test("8'b00000000")
+  test("8'b1")
+  test("8'b00000001")
+
+  try:
+    for line in open("/tmp/sample-verilog-numbers"):
+      test(line.strip())
+  except IOError:
+    pass