Subversion Repositories ssbcc

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#

# Copyright 2013, Sinclair R.F., Inc.

#

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import re;

from ssbccPeripheral import SSBCCperipheral

from ssbccUtil import SSBCCException;

class timer(SSBCCperipheral):

  """

  Simple timer to facilitate polled-loops.\n

  The timer sets a flag when the timer expires and clears the flag when it is

  read.\n

  Usage:

    PERIPHERAL timer inport=I_name \\

                     ratemethod={clk/rate|count}\n

  Where:

    inport=I_name

      specifies the symbol used by the inport instruction to get the

      unexpired/expired status of the timer

      Note:  The name must start with "I_"

    ratemethod

      specifies the method to generate the desired timer event rate:

      1st method:  clk/rate

        clk is the frequency of "i_clk" in Hz

          a number will be interpreted as the clock frequency in Hz

          a symbol will be interpreted as a parameter

            Note:  this parameter must have been declared with a "PARAMETER"

            command

        rate is the desired baud rate

          this is specified as per "clk"

      2nd method:

        specify the number of "i_clk" clock cycles between timer events

      Note:  clk, rate, and count can be parameters or constants.  For example,

             the following uses the parameter G_CLK_FREQ_HZ for the clock

             frequency and a hard-wired event rate of 1 kHz

             "baudmethod=G_CLK_FREQ_HZ/1000".

      Note:  The numeric values can have Verilog-style '_' separators between

               the digits.  For example, 100_000_000 represents 100 million.\n

  Example:  Configure the timer for 1000 kHz events and monitor for these events

            in the micro controller code.\n

            PARAMETER G_CLK_FREQ_HZ 100_000_000

            PERIPHERAL timer inport=I_TIMER ratemethod=G_CLK_FREQ_HZ/1000\n

            ; See if the timer has expired since the last time it was polled and

            ; conditionally call "timer_event" if it has.

            .inport(I_TIMER)

              .callc(timer_event)

  """

  def __init__(self,peripheralFile,config,param_list,loc):

    # Use the externally provided file name for the peripheral

    self.peripheralFile = peripheralFile;

    # Get the parameters.

    for param_tuple in param_list:

      param = param_tuple[0];

      param_arg = param_tuple[1];

      if param == 'inport':

        self.AddAttr(config,param,param_arg,'I_\w+$',loc);

      elif param == 'ratemethod':

        self.AddRateMethod(config,param,param_arg,loc);

      else:

        raise SSBCCException('Unrecognized parameter at %s: %s' % (loc,param,));

    # Ensure the required parameters are provided.

    for paramname in ('inport','ratemethod',):

      if not hasattr(self,paramname):

        raise SSBCCException('Required parameter "%s" is missing at %s' % (paramname,loc,));

    # Add the I/O port, internal signals, and the INPORT and OUTPORT symbols for this peripheral.

    name = 's__%s__expired' % self.inport;

    config.AddSignal(name, 1, loc);

    config.AddSignal('s_SETRESET_%s' % name,1,loc);

    config.AddInport((self.inport,

                     ('s__%s__expired' % self.inport, 1, 'set-reset'),

                    ),loc);

    # Add the 'clog2' function to the processor (if required).

    config.functions['clog2'] = True;

  def GenVerilog(self,fp,config):

    body = self.LoadCore(self.peripheralFile,'.v');

    for subs in (

                  (r'\bL__',            'L__@NAME@__',),

                  (r'\bs__',            's__@NAME@__',),

                  (r'@RATEMETHOD@',     str(self.ratemethod),),

                  (r'@NAME@',           self.inport,),

                ):

      body = re.sub(subs[0],subs[1],body);

    body = self.GenVerilogFinal(config,body);

    fp.write(body);