Generates a Spectre input stimulus file for n vectors. Run with --help for details and an example.

spectre_vector_stimulus.py

#!/usr/bin/python

'''
    Outputs a Cadence ADE stimulus file for n input vectors.

    Supports Python 2.x only. I created this for use on a RHEL
    box running Cadence.

    Global variables
        SOURCE: the source type generated for each bit of the vectors.
        VDD: the value for a HIGH in your process.
'''

import sys

# Process voltage
VDD = 1.1

# Clock period and input delay, in ns
CLOCK_PERIOD = 1e3

# Voltage source definition in Spectre SPICE syntax
SOURCE = '%s (%s 0) vsource type=pulse val0=%.2f val1=%.2f delay=0 ' \
         'rise=50p fall=50p period=%.2fn width=%.2fn'

# Backport of bin() from 2.6
# http://code.activestate.com/recipes/219300-format-integer-as-binary-string/#c7
def bin(x):
    """
    bin(number) -> string

    Stringifies an int or long in base 2.
    """
    if x < 0:
        return '-' + bin(-x)
    out = []
    if x == 0:
        out.append('0')
    while x > 0:
        out.append('01'[x & 1])
        x >>= 1
        pass
    try:
        return '0b' + ''.join(reversed(out))
    except NameError, ne2:
        out.reverse()
    return '0b' + ''.join(out)

def exit_with_error(msg):
    print 'ERROR: ' + msg
    sys.exit(0)

def generate_stimulus_file(inputs, clock):
    stimulus_file = [
        'simulator lang=spectre',

        # Clock source
        '_vCLK (CLK 0) vsource type=pulse val0=0 val1=1.1 delay=0 ' \
        'rise=50p fall=50p period=%.2fn width=%.2fn' % (clock, clock/2),

        # Carry in source
        '_vCin (Cin 0) vsource dc=0',
    ]

    # Input count
    i = 1

    # Loop over each input vector
    for name, num in inputs.items():
        # For each number, generate one line (source) for each bit; LSB first
        for j, bit in enumerate(reversed(num)):
            node = r'%s\\<%d\\>' % (name, j)
            source = '_v' + node

            # First cycle behavior
            if bit == '0':
                val0, val1 = VDD, 0
            else:
                val0, val1 = 0, VDD

            period = i * clock * 2

            # Append line to file
            line = SOURCE % (source, node, val0, val1, period, period/2)
            stimulus_file.append(line)

        i += 1

    return stimulus_file

def main():
    args = sys.argv[1:]

    # Dirty command line argument parser for Python 2.4 :(
    # NEVER DO THIS
    # Too hurried to make it more reliable
    if len(args) == 0 or args[0] in ['-h', '--help']:
        print 'Cadence Spectre input stimulus file generator.'
        print 'Takes a set of vector inputs and numbers in decimal format.'
        print 'Example: ./stimulus.py -c 1000 -n 16 A,B 15,25'
        print 'This will generate sources that output 15 and 25 in binary with a 1 ns clock period'
        print 'and with 16 input sources each.'
        print '-c and -n are OPTIONAL, but when specified, MUST be in order.'
        sys.exit(0)

    n = -1
    clock = CLOCK_PERIOD

    # Take any optional args
    if len(args) == 4 and args[0] == '-c':
        clock = float(args[1])
        args = args[2:]
    elif len(args) == 6 and args[2] == '-n':
        clock = float(args[1])
        n = int(args[3])
        args = args[4:]
    else:
        exit_with_error('Wrong order of optional args. Run with --help for an example.')

    try:
        names = args[0].split(',')
        values = args[1].split(',')
    except:
        exit_with_error('Wrong input format. Run with --help for an example.')

    # Setup input dict
    # Convert decimal number to binary string
    try:
        inputs = {}

        for k, v in zip(names, values):
            num = bin(int(v)).split('b')[1]

            if n != -1:
                pre = '0' * (n-len(num)) # Prepend zeroes if needed

            inputs[k] = pre + num
    except ValueError:
        exit_with_error('Invalid input format. Values MUST be integers.')

    lines = generate_stimulus_file(inputs, clock)

    # Write stimulus file to disk
    f = open('input_stimulus.scs', 'w')
    f.write('\n'.join(lines) + '\n')
    f.close()

if __name__ == '__main__':
    main()