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import subprocess
import re
class SpiceBackend:
"""This is what actually does all of the spice stuff"""
def __init__(self, device_file: str):
self.conductance = 0
self.voltage = 0
self.current = 0
self.time = 0
def simulate(self, voltage_signal: float, return_current: bool = False) -> float:
"""runs the simulation for one time step"""
len_voltage_signal = 1
try:
len_voltage_signal = len(voltage_signal)
except:
voltage_signal = [voltage_signal]
if return_current:
current = np.zeros(len_voltage_signal)
for t in enumerate(len_voltage_signal):
result = self.run_spice(voltage_signal)
single_current = result.current
self.conductance = result.conductance
if return_current:
current[t] = single_current
if return_current:
return current
def set_conductance(self, conductance: float):
"""Handled by spice now"""
"""Could probably still add some safety checks just to be sure later"""
self.conductance = conductance
def run_spice(self, voltage: float) -> float:
"""returns the current after given a voltage signal"""
#need to find a way to pass voltage signal to ngspice here
#also maybe a time series resolution??
result = subprocess.run(
["ngspice" "-b" "spicefile.cir"],
capture_output=True,
text=True
)
if result.returncode != 0:
raise RuntimeError(result.stderr)
# parse current into float variable
output = result.stdout
#is there a better (less rigid) way of grabbing the output
current_match = re.search("final_current = ([-\deE.+]+)", output)
if current_match is None:
raise RuntimeError("Could not find current in ngspice output")
current = float(current_match.group(1))
if abs(voltage) > 1e-12:
conductance = current / voltage
else:
conductance = self.conductance
return {
"current": current,
"conductance": conductance,
}
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