def make_wavgen_ios():
clk = Signal(False)
reset = Signal(False)
select = unsigned_bus(2)
threshold = unsigned_bus(N)
delta_phase = unsigned_bus(PHASEWIDTH)
_output = signed_bus(N)
return (clk, reset, select, threshold, delta_phase, _output)
def make_wavgen_ios():
clk = Signal(False)
reset = Signal(False)
select = unsigned_bus(2)
threshold = unsigned_bus(N)
delta_phase = unsigned_bus(PHASEWIDTH)
_output = signed_bus(N)
return (clk, reset, select, threshold, delta_phase, _output)
def vca(clk, input_signed, input_unsigned, output_signed):
a = signed_bus(18)
b = unsigned_bus(18)
ab = signed_bus(36)
@always(clk.posedge)
def get_inputs():
a.next = input_signed
b.next = input_unsigned
@always_comb
def multiply():
ab.next = a * b
@always_comb
def drive_output():
output_signed.next = (ab >> N)
return (get_inputs, multiply, drive_output)
def vca(clk, input_signed, input_unsigned, output_signed):
a = signed_bus(18)
b = unsigned_bus(18)
ab = signed_bus(36)
@always(clk.posedge)
def get_inputs():
a.next = input_signed
b.next = input_unsigned
@always_comb
def multiply():
ab.next = a * b
@always_comb
def drive_output():
output_signed.next = (ab >> N)
return (get_inputs, multiply, drive_output)
def interpolator(fastclk, clk, reset, input_data, interp_out):
# There are 800 fastclk periods during each clk period, so on each fastclk we want to
# advance 1/800th from the previous sound sample to the current sample. 800 is pretty
# close to (1<<22) divided by 5243, so we can compute a delta by multiplying the
# difference between samples by 5243, which is easy because it's constant and not too
# many non-zero bits. By accumulating this difference and right-shifting 22 bits, we
# arrive almost exactly where we want to end up after 800 accumulations.
FRACTION_BITS = 16
delay_1 = signed_bus(N)
x = signed_bus(N)
interp_step = signed_bus(N + FRACTION_BITS)
interp_data = signed_bus(N + FRACTION_BITS)
@always(fastclk.posedge, reset.posedge)
def do_stuff():
if reset:
delay_1.next = 0
interp_data.next = 0
interp_step.next = 0
else:
if clk:
interp_data.next = delay_1 << FRACTION_BITS
delay_1.next = input_data
# multiply by 5243 in binary
interp_step.next = (x << 12) + (x << 10) + (x << 6) + (x << 5) + \
(x << 4) + (x << 3) + (x << 1) + x
elif (interp_data + interp_step) < interp_data.min:
interp_data.next = interp_data.min
elif (interp_data + interp_step) >= interp_data.max:
interp_data.next = interp_data.max - 1
else:
interp_data.next = interp_data + interp_step
@always_comb
def rightshift_for_output():
x.next = input_data - delay_1
interp_out.next = interp_data >> FRACTION_BITS
return (do_stuff, rightshift_for_output)
def interpolator(fastclk, clk, reset, input_data, interp_out):
# There are 800 fastclk periods during each clk period, so on each fastclk we want to
# advance 1/800th from the previous sound sample to the current sample. 800 is pretty
# close to (1<<22) divided by 5243, so we can compute a delta by multiplying the
# difference between samples by 5243, which is easy because it's constant and not too
# many non-zero bits. By accumulating this difference and right-shifting 22 bits, we
# arrive almost exactly where we want to end up after 800 accumulations.
FRACTION_BITS = 16
delay_1 = signed_bus(N)
x = signed_bus(N)
interp_step = signed_bus(N + FRACTION_BITS)
interp_data = signed_bus(N + FRACTION_BITS)
@always(fastclk.posedge, reset.posedge)
def do_stuff():
if reset:
delay_1.next = 0
interp_data.next = 0
interp_step.next = 0
else:
if clk:
interp_data.next = delay_1 << FRACTION_BITS
delay_1.next = input_data
# multiply by 5243 in binary
interp_step.next = (x << 12) + (x << 10) + (x << 6) + (x << 5) + \
(x << 4) + (x << 3) + (x << 1) + x
elif (interp_data + interp_step) < interp_data.min:
interp_data.next = interp_data.min
elif (interp_data + interp_step) >= interp_data.max:
interp_data.next = interp_data.max - 1
else:
interp_data.next = interp_data + interp_step
@always_comb
def rightshift_for_output():
x.next = input_data - delay_1
interp_out.next = interp_data >> FRACTION_BITS
return (do_stuff, rightshift_for_output)
def delta_sigma_dac(fastclk, clk, reset, input_data, dac_bit):
interp_result = signed_bus(N)
interp_result_unsigned = unsigned_bus(N)
# the input of the Xilinx multiplier is an 18-bit factor
vc_estimate = unsigned_bus(16)
# the output of the Xilinx multiplier is a 36-bit product
sum_of_products = unsigned_bus(32)
dac_bit_internal = Signal(False)
@always_comb
def drive_dac_bit():
dac_bit.next = dac_bit_internal
@always(fastclk.posedge, reset.posedge)
def do_stuff():
# sum_of_products is the next value for vc_estimate, with lots of fraction
# bits. vc_estimate already has fraction bits beyond N. All these fraction
# bits are helpful in keeping out audible artifacts.
if reset:
dac_bit_internal.next = 0
vc_estimate.next = 1 << 15
else:
dac_bit_internal.next = interp_result_unsigned > (
sum_of_products >> (32 - N))
vc_estimate.next = sum_of_products >> 16
@always_comb
def multiply():
if dac_bit_internal:
if A + (B * vc_estimate) >= (1 << 32):
sum_of_products.next = (1 << 32) - 1
else:
sum_of_products.next = A + (B * vc_estimate)
else:
sum_of_products.next = B * vc_estimate
things = [
# Interpolation is a huge help with anti-aliasing.
interpolator(fastclk, clk, reset, input_data, interp_result),
drive_dac_bit,
do_stuff,
multiply,
signed_to_unsigned(N, interp_result, interp_result_unsigned)
]
return things
def delta_sigma_dac(fastclk, clk, reset, input_data, dac_bit):
interp_result = signed_bus(N)
interp_result_unsigned = unsigned_bus(N)
# the input of the Xilinx multiplier is an 18-bit factor
vc_estimate = unsigned_bus(16)
# the output of the Xilinx multiplier is a 36-bit product
sum_of_products = unsigned_bus(32)
dac_bit_internal = Signal(False)
@always_comb
def drive_dac_bit():
dac_bit.next = dac_bit_internal
@always(fastclk.posedge, reset.posedge)
def do_stuff():
# sum_of_products is the next value for vc_estimate, with lots of fraction
# bits. vc_estimate already has fraction bits beyond N. All these fraction
# bits are helpful in keeping out audible artifacts.
if reset:
dac_bit_internal.next = 0
vc_estimate.next = 1 << 15
else:
dac_bit_internal.next = interp_result_unsigned > (sum_of_products >> (32 - N))
vc_estimate.next = sum_of_products >> 16
@always_comb
def multiply():
if dac_bit_internal:
if A + (B * vc_estimate) >= (1 << 32):
sum_of_products.next = (1 << 32) - 1
else:
sum_of_products.next = A + (B * vc_estimate)
else:
sum_of_products.next = B * vc_estimate
things = [
# Interpolation is a huge help with anti-aliasing.
interpolator(fastclk, clk, reset, input_data, interp_result),
drive_dac_bit,
do_stuff,
multiply,
signed_to_unsigned(N, interp_result, interp_result_unsigned)
]
return things
def fpga(fastclk, reset, param_data, param_clk, audio_req, audio_ack, dac_bit):
aclk_counter = unsigned_bus(10)
clk = Signal(False)
# audio rate clock
@always(fastclk.posedge, reset.posedge)
def drive_audio_clock():
if reset:
aclk_counter.next = 0
clk.next = True
elif aclk_counter >= 800:
aclk_counter.next = 0
clk.next = True
else:
aclk_counter.next = aclk_counter + 1
clk.next = False
ignored, ignored2, select, threshold, delta_phase, wavgen_output = make_wavgen_ios()
keydown = Signal(False)
select = unsigned_bus(2)
attack = unsigned_bus(4)
decay = unsigned_bus(4)
sustain = unsigned_bus(4)
_release = unsigned_bus(4)
amplitude = unsigned_bus(N)
_output = signed_bus(N)
# more bits than we really need, 18 bits would give 6.5536 seconds
input_driver_count = unsigned_bus(24)
@always(clk.posedge, reset.posedge)
def drive_inputs():
attack.next = 3
decay.next = 5
sustain.next = 8
_release.next = 0
delta_phase.next = DELTA_PHASE
select.next = 1
threshold.next = HALF
keydown.next = 0
if reset:
keydown.next = 0
input_driver_count.next = 0
elif input_driver_count >= 5 * SECOND:
keydown.next = 0
input_driver_count.next = 0
elif input_driver_count < 2 * SECOND:
keydown.next = 1
input_driver_count.next = input_driver_count + 1
else:
keydown.next = 0
input_driver_count.next = input_driver_count + 1
drivers = [
drive_audio_clock,
drive_inputs,
waveform_generator(clk, reset, select, threshold, delta_phase, wavgen_output),
# adsr(clk, reset, keydown, attack, decay, sustain, _release, amplitude),
# vca(fastclk, reset, wavgen_output, amplitude, _output),
delta_sigma_dac(fastclk, clk, reset, wavgen_output, dac_bit),
]
return drivers
def make_dsig_ios():
fastclk = Signal(False)
clk = Signal(False)
input_data = signed_bus(N)
dac_bit = Signal(False)
return (fastclk, clk, input_data, dac_bit)
def make_ios():
clk = Signal(False)
input_signed = signed_bus(N)
input_unsigned = unsigned_bus(N)
output_signed = signed_bus(N)
return (clk, input_signed, input_unsigned, output_signed)
def fpga(fastclk, reset, param_data, param_clk, audio_req, audio_ack, dac_bit):
aclk_counter = unsigned_bus(10)
clk = Signal(False)
# audio rate clock
@always(fastclk.posedge, reset.posedge)
def drive_audio_clock():
if reset:
aclk_counter.next = 0
clk.next = True
elif aclk_counter >= 800:
aclk_counter.next = 0
clk.next = True
else:
aclk_counter.next = aclk_counter + 1
clk.next = False
ignored, ignored2, select, threshold, delta_phase, wavgen_output = make_wavgen_ios(
)
keydown = Signal(False)
select = unsigned_bus(2)
attack = unsigned_bus(4)
decay = unsigned_bus(4)
sustain = unsigned_bus(4)
_release = unsigned_bus(4)
amplitude = unsigned_bus(N)
_output = signed_bus(N)
# more bits than we really need, 18 bits would give 6.5536 seconds
input_driver_count = unsigned_bus(24)
@always(clk.posedge, reset.posedge)
def drive_inputs():
attack.next = 3
decay.next = 5
sustain.next = 8
_release.next = 0
delta_phase.next = DELTA_PHASE
select.next = 1
threshold.next = HALF
keydown.next = 0
if reset:
keydown.next = 0
input_driver_count.next = 0
elif input_driver_count >= 5 * SECOND:
keydown.next = 0
input_driver_count.next = 0
elif input_driver_count < 2 * SECOND:
keydown.next = 1
input_driver_count.next = input_driver_count + 1
else:
keydown.next = 0
input_driver_count.next = input_driver_count + 1
drivers = [
drive_audio_clock,
drive_inputs,
waveform_generator(clk, reset, select, threshold, delta_phase,
wavgen_output),
# adsr(clk, reset, keydown, attack, decay, sustain, _release, amplitude),
# vca(fastclk, reset, wavgen_output, amplitude, _output),
delta_sigma_dac(fastclk, clk, reset, wavgen_output, dac_bit),
]
return drivers
def make_dsig_ios():
fastclk = Signal(False)
clk = Signal(False)
input_data = signed_bus(N)
dac_bit = Signal(False)
return (fastclk, clk, input_data, dac_bit)
def make_ios():
clk = Signal(False)
input_signed = signed_bus(N)
input_unsigned = unsigned_bus(N)
output_signed = signed_bus(N)
return (clk, input_signed, input_unsigned, output_signed)
