def write_parameters(self, spec, machine_time_step, weight_scales):
# Write alpha to spec
fixed_point_alpha = plasticity_helpers.float_to_fixed(self.__alpha)
spec.write_value(data=fixed_point_alpha, data_type=DataType.INT32)
# Write lookup table
spec.write_array(self.__tau_data)
def write_parameters(self, spec, machine_time_step, weight_scales):
# Check timestep is valid
if machine_time_step != 1000:
raise NotImplementedError("STDP LUT generation currently only "
"supports 1ms timesteps")
# Write alpha to spec
fixed_point_alpha = plasticity_helpers.float_to_fixed(
self._alpha, plasticity_helpers.STDP_FIXED_POINT_ONE)
spec.write_value(data=fixed_point_alpha, data_type=DataType.INT32)
# Write lookup table
plasticity_helpers.write_exp_lut(spec, self.tau, LOOKUP_TAU_SIZE,
LOOKUP_TAU_SHIFT)
def write_parameters(self, spec, machine_time_step, weight_scales):
# Check timestep is valid
if machine_time_step != 1000:
raise NotImplementedError("STDP LUT generation currently only "
"supports 1ms timesteps")
# Write alpha to spec
fixed_point_alpha = plasticity_helpers.float_to_fixed(
self._alpha, plasticity_helpers.STDP_FIXED_POINT_ONE)
spec.write_value(data=fixed_point_alpha, data_type=DataType.INT32)
# Write lookup table
plasticity_helpers.write_exp_lut(
spec, self.tau, LOOKUP_TAU_SIZE, LOOKUP_TAU_SHIFT)
def write_parameters(self, spec, machine_time_step, weight_scales):
# Write peak time in timesteps
peak_time_data = int(self.peak_time * (1000.0 / machine_time_step) -
LOOKUP_SIN_SIZE / 2 + 0.5)
print "peak time data:", peak_time_data, "peak_time:", self.peak_time
spec.write_value(data=peak_time_data, data_type=DataType.INT32)
# Calculate time constant reciprocal
time_constant_reciprocal = (1.0 / float(self.tau)) * (
machine_time_step / 1000.0)
# This offset is the quasi-symmetry point
sinadd_pwr = 20
zero_offset = math.atan(-1. / sinadd_pwr)
max_value = math.exp(-zero_offset) * math.cos(zero_offset)**sinadd_pwr
# Generate LUT
last_value = None
for i in range(-LOOKUP_SIN_SIZE / 2,
-LOOKUP_SIN_SIZE / 2 + LOOKUP_SIN_SIZE):
# Apply shift to get time from index
time = (i << LOOKUP_SIN_SHIFT)
# Multiply by time constant and calculate negative exponential
value = float(time) * time_constant_reciprocal + zero_offset
# we want a single bump only, so we clip the arg at pi/2
if abs(value) > math.pi / 2.:
exp_float = 0.0
else:
exp_float = math.exp(-value) * math.cos(
value)**sinadd_pwr / max_value
print i, exp_float
# Convert to fixed-point and write to spec
last_value = plasticity_helpers.float_to_fixed(
exp_float, plasticity_helpers.STDP_FIXED_POINT_ONE)
spec.write_value(data=last_value, data_type=DataType.INT16)
self._tau_last_entry = float(last_value) / float(
plasticity_helpers.STDP_FIXED_POINT_ONE)