OpenRAM/compiler/characterizer/stimuli.py

"""
This file generates the test structure and stimulus for an sram
simulation.  There are various functions that can be be used to
generate stimulus for other simulations as well.
"""

import tech
import debug
import subprocess
import os
import sys
import numpy as np
from globals import OPTS

vdd_voltage = tech.spice["supply_voltage"]
gnd_voltage = tech.spice["gnd_voltage"]
vdd_name = tech.spice["vdd_name"]
gnd_name = tech.spice["gnd_name"]
pmos_name = tech.spice["pmos_name"]
nmos_name = tech.spice["nmos_name"]
tx_width = tech.spice["minwidth_tx"]
tx_length = tech.spice["channel"]

def inst_sram(stim_file, abits, dbits, sram_name):
    """function to instatiate the sram subckt"""
    stim_file.write("Xsram ")
    for i in range(dbits):
        stim_file.write("D[{0}] ".format(i))
    for i in range(abits):
        stim_file.write("A[{0}] ".format(i))
    for i in tech.spice["control_signals"]:
        stim_file.write("{0} ".format(i))
    stim_file.write("{0} ".format(tech.spice["clk"]))
    stim_file.write("{0} {1} ".format(vdd_name, gnd_name))
    stim_file.write("{0}\n\n".format(sram_name))


def inst_model(stim_file, pins, model_name):
    """function to instantiate a model"""
    stim_file.write("X{0} ".format(model_name))
    for pin in pins:
        stim_file.write("{0} ".format(pin))
    stim_file.write("{0}\n".format(model_name))


def create_inverter(stim_file, size=1, beta=2.5):
    """Generates inverter for the top level signals (only for sim purposes)"""
    stim_file.write(".SUBCKT test_inv in out {0} {1}\n".format(vdd_name, gnd_name))
    stim_file.write("mpinv out in {0} {0} {1} w={2}u l={3}u\n".format(vdd_name,
                                                                      pmos_name,
                                                                      beta * size * tx_width,
                                                                      tx_length))
    stim_file.write("mninv out in {0} {0} {1} w={2}u l={3}u\n".format(gnd_name,
                                                                      nmos_name,
                                                                      size * tx_width,
                                                                      tx_length))
    stim_file.write(".ENDS test_inv\n")


def create_buffer(stim_file, buffer_name, size=[1,3], beta=2.5):
    """Generates buffer for top level signals (only for sim
    purposes). Size is pair for PMOS, NMOS width multiple. It includes
    a beta of 3."""

    stim_file.write(".SUBCKT test_{2} in out {0} {1}\n".format(vdd_name, 
                                                                   gnd_name,
                                                                   buffer_name))
    stim_file.write("mpinv1 out_inv in {0} {0} {1} w={2}u l={3}u\n".format(vdd_name,
                                                                           pmos_name,
                                                                           beta * size[0] * tx_width,
                                                                           tx_length))
    stim_file.write("mninv1 out_inv in {0} {0} {1} w={2}u l={3}u\n".format(gnd_name,
                                                                           nmos_name,
                                                                           size[0] * tx_width,
                                                                           tx_length))
    stim_file.write("mpinv2 out out_inv {0} {0} {1} w={2}u l={3}u\n".format(vdd_name,
                                                                                pmos_name,
                                                                                beta * size[1] * tx_width,
                                                                                tx_length))
    stim_file.write("mninv2 out out_inv {0} {0} {1} w={2}u l={3}u\n".format(gnd_name,
                                                                                nmos_name,
                                                                                size[1] * tx_width,
                                                                                tx_length))
    stim_file.write(".ENDS test_{0}\n\n".format(buffer_name))


def inst_buffer(stim_file, buffer_name, signal_list):
    """Adds buffers to each top level signal that is in signal_list (only for sim purposes)"""
    for signal in signal_list:
        stim_file.write("X{0}_buffer {0} {0}_buf {1} {2} test_{3}\n".format(signal,
                                                                            "test"+vdd_name,
                                                                            "test"+gnd_name,
                                                                            buffer_name))


def inst_inverter(stim_file, signal_list):
    """Adds inv for each signal that needs its inverted version (only for sim purposes)"""
    for signal in signal_list:
        stim_file.write("X{0}_inv {0} {0}_inv {1} {2} test_inv\n".format(signal,
                                                                         "test"+vdd_name,
                                                                         "test"+gnd_name))


def inst_accesstx(stim_file, dbits):
    """Adds transmission gate for inputs to data-bus (only for sim purposes)"""
    stim_file.write("* Tx Pin-list: Drain Gate Source Body\n")
    for i in range(dbits):
        pmos_access_string="mp{0} DATA[{0}] acc_en D[{0}] {1} {2} w={3}u l={4}u\n"
        stim_file.write(pmos_access_string.format(i,
                                                  "test"+vdd_name,
                                                  pmos_name,
                                                  2 * tx_width,
                                                  tx_length))
        nmos_access_string="mn{0} DATA[{0}] acc_en_inv D[{0}] {1} {2} w={3}u l={4}u\n"
        stim_file.write(nmos_access_string.format(i,
                                                  "test"+gnd_name,
                                                  nmos_name,
                                                  2 * tx_width,
                                                  tx_length))

def gen_pulse(stim_file, sig_name, v1=gnd_voltage, v2=vdd_voltage, offset=0, period=1, t_rise=0, t_fall=0):
    """Generates a periodic signal with 50% duty cycle and slew rates. Period is measured
    from 50% to 50%."""
    pulse_string="V{0} {0} 0 PULSE ({1} {2} {3}n {4}n {5}n {6}n {7}n)\n"
    stim_file.write(pulse_string.format(sig_name, 
                                        v1,
                                        v2,
                                        offset,
                                        t_rise,
                                        t_fall, 
                                        0.5*period-0.5*t_rise-0.5*t_fall,
                                        period))


def gen_pwl(stim_file, sig_name, clk_times, data_values, period, slew, setup):
    # the initial value is not a clock time
    debug.check(len(clk_times)+1==len(data_values),"Clock and data value lengths don't match.")
    # shift signal times earlier for setup time
    times = np.array(clk_times) - setup*period
    values = np.array(data_values) * vdd_voltage
    half_slew = 0.5 * slew
    stim_file.write("V{0} {0} 0 PWL (0n {1}v ".format(sig_name, values[0]))
    for i in range(len(times)):
        stim_file.write("{0}n {1}v {2}n {3}v ".format(times[i]-half_slew,
                                                      values[i],
                                                      times[i]+half_slew,
                                                      values[i+1]))
    stim_file.write(")\n")

def gen_data(stim_file, clk_times, sig_name, period, slew):
    """Generates the PWL data inputs for a simulation timing test."""
    # values for NOP, W1, W0, W1, R0, W1, W0, R1, NOP
    # we are asserting the opposite value on the other side of the tx gate during
    # the read to be "worst case". Otherwise, it can actually assist the read.
    values = [0, 1, 0, 1, 1, 1, 0, 0, 0 ]
    gen_pwl(stim_file, sig_name, clk_times, values, period, slew, 0.05)


def gen_addr(stim_file, clk_times, addr, period, slew):
    """Generates the address inputs for a simulation timing test. 
    One cycle is different to clear the bus
    """
    
    zero_values = [0, 0, 0, 1, 0, 0, 1, 0, 0 ]
    ones_values = [1, 1, 1, 0, 1, 1, 0, 1, 1 ]
    
    for i in range(len(addr)):
        sig_name = "A[{0}]".format(i)
        if addr[i]=="1":
            gen_pwl(stim_file, sig_name, clk_times, ones_values, period, slew, 0.05)
        else:
            gen_pwl(stim_file, sig_name, clk_times, zero_values, period, slew, 0.05)

def gen_constant(stim_file, sig_name, v_val):
    """Generates a constant signal with reference voltage and the voltage value"""
    stim_file.write("V{0} {0} 0 DC {1}\n".format(sig_name, v_val))

def gen_csb(stim_file, clk_times, period, slew):
    """ Generates the PWL CSb signal"""
    # values for NOP, W1, W0, W1, R0, W1, W0, R1, NOP
    values = [1, 0, 0, 0, 0, 0, 0, 0, 1]
    gen_pwl(stim_file, "csb", clk_times, values, period, slew, 0.05)

def gen_web(stim_file, clk_times, period, slew):
    """ Generates the PWL WEb signal"""
    # values for NOP, W1, W0, W1, R0, W1, W0, R1, NOP
    values = [1, 0, 0, 0, 1, 0, 0, 1, 1]
    gen_pwl(stim_file, "web", clk_times, values, period, slew, 0.05)
    
    values = [1, 0, 0, 0, 1, 0, 0, 1, 1]
    gen_pwl(stim_file, "acc_en", clk_times, values, period, slew, 0)
    values = [0, 1, 1, 1, 0, 1, 1, 0, 0]
    gen_pwl(stim_file, "acc_en_inv", clk_times, values, period, slew, 0)
    
def gen_oeb(stim_file, clk_times, period, slew):
    """ Generates the PWL WEb signal"""
    # values for NOP, W1, W0, W1, R0, W1, W0, R1, NOP
    values = [1, 1, 1, 1, 0, 1, 1, 0, 1]
    gen_pwl(stim_file, "oeb", clk_times, values, period, slew, 0.05)




def get_inverse_voltage(value):
    if value > 0.5*vdd_voltage:
        return gnd_voltage
    elif value <= 0.5*vdd_voltage:
        return vdd_voltage
    else:
        debug.error("Invalid value to get an inverse of: {0}".format(value))

def get_inverse_value(value):
    if value > 0.5:
        return 0
    elif value <= 0.5:
        return 1
    else:
        debug.error("Invalid value to get an inverse of: {0}".format(value))
        

def gen_meas_delay(stim_file, meas_name, trig_name, targ_name, trig_val, targ_val, trig_dir, targ_dir, trig_td, targ_td):
    """Creates the .meas statement for the measurement of delay"""
    measure_string=".meas tran {0} TRIG v({1}) VAL={2} {3}=1 TD={4}n TARG v({5}) VAL={6} {7}=1 TD={8}n\n\n"
    stim_file.write(measure_string.format(meas_name,
                                          trig_name,
                                          trig_val,
                                          trig_dir,
                                          trig_td,
                                          targ_name,
                                          targ_val,
                                          targ_dir,
                                          targ_td))
    
def gen_meas_power(stim_file, meas_name, t_initial, t_final):
    """Creates the .meas statement for the measurement of avg power"""
    # power mea cmd is different in different spice:
    if OPTS.spice_name == "hspice":
        power_exp = "power"
    else:
        power_exp = "par('(-1*v(" + str(vdd_name) + ")*I(v" + str(vdd_name) + "))')"
    stim_file.write(".meas tran {0} avg {1} from={2}n to={3}n\n\n".format(meas_name,
                                                                        power_exp,
                                                                        t_initial,
                                                                        t_final))
    stim_file.write("\n")
    
def write_control(stim_file, end_time):
    # UIC is needed for ngspice to converge
    stim_file.write(".TRAN 5p {0}n UIC\n".format(end_time))
    if OPTS.spice_name == "ngspice":
        # ngspice sometimes has convergence problems if not using gear method
        # which is more accurate, but slower than the default trapezoid method
        stim_file.write(".OPTIONS POST=1 RUNLVL=4 PROBE method=gear\n")
    else:
        stim_file.write(".OPTIONS POST=1 RUNLVL=4 PROBE\n")

    # create plots for all signals
    stim_file.write("* probe is used for hspice/xa, while plot is used in ngspice\n")
    if OPTS.debug_level>0:
        if OPTS.spice_name in ["hspice","xa"]:
            stim_file.write(".probe V(*)\n")
        else:
            stim_file.write(".plot V(*)\n")
    else:
        stim_file.write("*.probe V(*)\n")
        stim_file.write("*.plot V(*)\n")

    # end the stimulus file
    stim_file.write(".end\n\n")


def write_include(stim_file, models):
    """Writes include statements, inputs are lists of model files"""
    for item in list(models):
        if os.path.isfile(item):
            stim_file.write(".include \"{0}\"\n\n".format(item))
        else:
            debug.error("Could not find spice model: {0}\nSet SPICE_MODEL_DIR to over-ride path.\n".format(item))


def write_supply(stim_file):
    """Writes supply voltage statements"""
    stim_file.write("V{0} {0} 0.0 {1}\n".format(vdd_name, vdd_voltage))
    stim_file.write("V{0} {0} 0.0 {1}\n".format(gnd_name, gnd_voltage))
    # This is for the test power supply
    stim_file.write("V{0} {0} 0.0 {1}\n".format("test"+vdd_name, vdd_voltage))
    stim_file.write("V{0} {0} 0.0 {1}\n\n".format("test"+gnd_name, gnd_voltage))


def run_sim():
    """Run hspice in batch mode and output rawfile to parse."""
    temp_stim = "{0}stim.sp".format(OPTS.openram_temp)
    import datetime
    start_time = datetime.datetime.now()
    debug.check(OPTS.spice_exe!="","No spice simulator has been found.")
    
    if OPTS.spice_name == "xa":
        # Output the xa configurations here. FIXME: Move this to write it once.
        xa_cfg = open("{}xa.cfg".format(OPTS.openram_temp), "w")
        xa_cfg.write("set_sim_level -level 7\n")
        xa_cfg.write("set_powernet_level 7 -node vdd\n")
        xa_cfg.close()
        cmd = "{0} {1} -c {2}xa.cfg -o {2}xa -mt 2".format(OPTS.spice_exe,
                                               temp_stim,
                                               OPTS.openram_temp)
        valid_retcode=0
    elif OPTS.spice_name == "hspice":
        # TODO: Should make multithreading parameter a configuration option
        cmd = "{0} -mt 2 -i {1} -o {2}timing".format(OPTS.spice_exe,
                                                     temp_stim,
                                                     OPTS.openram_temp)
        valid_retcode=0
    else:
        cmd = "{0} -b -o {2}timing.lis {1}".format(OPTS.spice_exe,
                                                   temp_stim,
                                                   OPTS.openram_temp)
        # for some reason, ngspice-25 returns 1 when it only has acceptable warnings
        valid_retcode=1

        
    spice_stdout = open("{0}spice_stdout.log".format(OPTS.openram_temp), 'w')
    spice_stderr = open("{0}spice_stderr.log".format(OPTS.openram_temp), 'w')

    debug.info(3, cmd)
    retcode = subprocess.call(cmd, stdout=spice_stdout, stderr=spice_stderr, shell=True)

    spice_stdout.close()
    spice_stderr.close()
    
    if (retcode > valid_retcode):
        debug.error("Spice simulation error: " + cmd, -1)
    else:
        end_time = datetime.datetime.now()
        delta_time = round((end_time-start_time).total_seconds(),1)
        debug.info(2,"*** Spice: {} seconds".format(delta_time))