mirror of https://github.com/m-labs/artiq
223 lines
8.3 KiB
Python
223 lines
8.3 KiB
Python
from numpy import int32, int64
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from artiq.language.core import kernel, now_mu, portable, delay
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from artiq.coredevice.rtio import rtio_output, rtio_output_wide
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from artiq.language.types import TInt32, TInt64, TFloat
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class Spline:
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r"""Spline interpolating RTIO channel.
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One knot of a polynomial basis spline (B-spline) :math:`u(t)`
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is defined by the coefficients :math:`u_n` up to order :math:`n = k`.
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If the knot is evaluated starting at time :math:`t_0`, the output
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:math:`u(t)` for :math:`t > t_0, t_0` is:
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.. math::
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u(t) &= \sum_{n=0}^k \frac{u_n}{n!} (t - t_0)^n \\
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&= u_0 + u_1 (t - t_0) + \frac{u_2}{2} (t - t_0)^2 + \dots
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:param width: Width in bits of the quantity that this spline controls
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:param time_width: Width in bits of the time counter of this spline
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:param channel: RTIO channel number
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:param core_device: Core device that this spline is attached to
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:param scale: Scale for conversion between machine units and physical
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units; to be given as the "full scale physical value".
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"""
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kernel_invariants = {"channel", "core", "scale", "width",
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"time_width", "time_scale"}
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def __init__(self, width, time_width, channel, core_device, scale=1.):
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self.core = core_device
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self.channel = channel
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self.width = width
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self.scale = float((int64(1) << width) / scale)
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self.time_width = time_width
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self.time_scale = float((1 << time_width) *
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core_device.coarse_ref_period)
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@portable(flags={"fast-math"})
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def to_mu(self, value: TFloat) -> TInt32:
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"""Convert floating point `value` from physical units to 32 bit
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integer machine units."""
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return int32(round(value*self.scale))
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@portable(flags={"fast-math"})
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def from_mu(self, value: TInt32) -> TFloat:
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"""Convert 32 bit integer `value` from machine units to floating point
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physical units."""
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return value/self.scale
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@portable(flags={"fast-math"})
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def to_mu64(self, value: TFloat) -> TInt64:
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"""Convert floating point `value` from physical units to 64 bit
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integer machine units."""
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return int64(round(value*self.scale))
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@kernel
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def set_mu(self, value: TInt32):
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"""Set spline value (machine units).
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:param value: Spline value in integer machine units.
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"""
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rtio_output(now_mu(), self.channel, 0, value)
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@kernel(flags={"fast-math"})
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def set(self, value: TFloat):
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"""Set spline value.
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:param value: Spline value relative to full-scale.
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"""
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if self.width > 32:
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l = [int32(0)] * 2
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self.pack_coeff_mu([self.to_mu64(value)], l)
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rtio_output_wide(now_mu(), self.channel, 0, l)
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else:
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rtio_output(now_mu(), self.channel, 0, self.to_mu(value))
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@kernel
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def set_coeff_mu(self, value): # TList(TInt32)
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"""Set spline raw values.
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:param value: Spline packed raw values.
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"""
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rtio_output_wide(now_mu(), self.channel, 0, value)
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@portable(flags={"fast-math"})
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def pack_coeff_mu(self, coeff, packed): # TList(TInt64), TList(TInt32)
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"""Pack coefficients into RTIO data
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:param coeff: TList(TInt64) list of machine units spline coefficients.
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Lowest (zeroth) order first. The coefficient list is zero-extended
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by the RTIO gateware.
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:param packed: TList(TInt32) list for packed RTIO data. Must be
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pre-allocated. Length in bits is
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`n*width + (n - 1)*n//2*time_width`
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"""
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pos = 0
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for i in range(len(coeff)):
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wi = self.width + i*self.time_width
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ci = coeff[i]
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while wi != 0:
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j = pos//32
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used = pos - 32*j
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avail = 32 - used
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if avail > wi:
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avail = wi
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cij = int32(ci)
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if avail != 32:
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cij &= (1 << avail) - 1
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packed[j] |= cij << used
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ci >>= avail
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wi -= avail
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pos += avail
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@portable(flags={"fast-math"})
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def coeff_to_mu(self, coeff, coeff64): # TList(TFloat), TList(TInt64)
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"""Convert a floating point list of coefficients into a 64 bit
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integer (preallocated).
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:param coeff: TList(TFloat) list of coefficients in physical units.
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:param coeff64: TList(TInt64) preallocated list of coefficients in
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machine units.
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"""
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for i in range(len(coeff)):
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vi = coeff[i] * self.scale
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for j in range(i):
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vi *= self.time_scale
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ci = int64(round(vi))
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coeff64[i] = ci
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# artiq.wavesynth.coefficients.discrete_compensate:
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if i == 2:
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coeff64[1] += ci >> self.time_width + 1
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elif i == 3:
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coeff64[2] += ci >> self.time_width
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coeff64[1] += ci // 6 >> 2*self.time_width
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def coeff_as_packed_mu(self, coeff64):
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"""Pack 64 bit integer machine units coefficients into 32 bit integer
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RTIO data list.
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This is a host-only method that can be used to generate packed
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spline knot data to be frozen into kernels at compile time.
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"""
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n = len(coeff64)
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width = n*self.width + (n - 1)*n//2*self.time_width
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packed = [int32(0)] * ((width + 31)//32)
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self.pack_coeff_mu(coeff64, packed)
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return packed
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def coeff_as_packed(self, coeff):
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"""Convert floating point spline coefficients into 32 bit integer
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packed data.
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This is a host-only method that can be used to generate packed
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spline knot data to be frozen into kernels at compile time.
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"""
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coeff64 = [int64(0)] * len(coeff)
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self.coeff_to_mu(coeff, coeff64)
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return self.coeff_as_packed_mu(coeff64)
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@kernel(flags={"fast-math"})
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def set_coeff(self, coeff): # TList(TFloat)
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"""Set spline coefficients.
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Missing coefficients (high order) are zero-extended byt the RTIO
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gateware.
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If more coefficients are supplied than the gateware supports the extra
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coefficients are ignored.
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:param value: List of floating point spline knot coefficients,
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lowest order (constant) coefficient first. Units are the
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unit of this spline's value times increasing powers of 1/s.
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"""
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n = len(coeff)
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coeff64 = [int64(0)] * n
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self.coeff_to_mu(coeff, coeff64)
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width = n*self.width + (n - 1)*n//2*self.time_width
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packed = [int32(0)] * ((width + 31)//32)
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self.pack_coeff_mu(coeff64, packed)
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self.set_coeff_mu(packed)
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@kernel(flags={"fast-math"})
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def smooth(self, start: TFloat, stop: TFloat, duration: TFloat,
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order: TInt32):
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"""Initiate an interpolated value change.
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For zeroth order (step) interpolation, the step is at
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`start + duration/2`.
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First order interpolation corresponds to a linear value ramp from
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`start` to `stop` over `duration`.
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The third order interpolation is constrained to have zero first
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order derivative at both `start` and `stop`.
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For first order and third order interpolation (linear and cubic)
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the interpolator needs to be stopped (or fed a new spline knot)
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explicitly at the stop time.
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This method advances the timeline by `duration`.
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:param start: Initial value of the change. In physical units.
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:param stop: Final value of the change. In physical units.
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:param duration: Duration of the interpolation. In physical units.
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:param order: Order of the interpolation. Only 0, 1,
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and 3 are valid: step, linear, cubic.
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"""
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if order == 0:
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delay(duration/2.)
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self.set_coeff([stop])
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delay(duration/2.)
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elif order == 1:
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self.set_coeff([start, (stop - start)/duration])
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delay(duration)
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elif order == 3:
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v2 = 6.*(stop - start)/(duration*duration)
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self.set_coeff([start, 0., v2, -2.*v2/duration])
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delay(duration)
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else:
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raise ValueError("Invalid interpolation order. "
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"Supported orders are: 0, 1, 3.")
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