Skip to content

Fix NTT issue on odd-numbered butterfly stages #51

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Sep 26, 2024
Merged

Fix NTT issue on odd-numbered butterfly stages #51

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
38 changes: 20 additions & 18 deletions kerngen/pisa_generators/ntt.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,25 +36,21 @@ def butterflies_ops(
"""Helper to return butterflies pisa operations for NTT/INTT"""
ntt_stages_div_by_two = context.ntt_stages % 2

# generate the stages, which depends on the total ntt stages.
stage_dst_srcs = [
(
(stage, outtmp, output)
if ntt_stages_div_by_two == stage % 2
else (stage, output, outtmp)
)
for stage in range(context.ntt_stages)
]

# For INTTs, start with input0 on the first stage destinations
if init_input is True:
# intt
stage_dst_srcs = [
(
(stage, outtmp, output)
if ntt_stages_div_by_two == stage % 2
else (stage, output, outtmp)
)
for stage in range(context.ntt_stages)
]
stage_dst_srcs[0] = (
(0, outtmp, input0) if ntt_stages_div_by_two == 0 else (0, output, input0)
)
else:
# ntt
stage_dst_srcs = [
((stage, outtmp, output) if stage % 2 == 0 else (stage, output, outtmp))
for stage in range(context.ntt_stages)
]

return [
op(
Expand Down Expand Up @@ -94,15 +90,21 @@ def to_pisa(self) -> list[PIsaOp]:
# TODO We need to decide whether output symbols need to be defined
outtmp = Polys("outtmp", self.output.parts, self.output.rns)

# Essentially a scalar mul since psi 1 part
mul = Mul(self.context, self.output, self.input0, psi)
# control the input for the butterfly method.
if self.context.ntt_stages % 2 == 0:
# Essentially a scalar mul since psi 1 part
mul = Mul(self.context, self.output, self.input0, psi)
butterfly_input = outtmp
else:
mul = Mul(self.context, outtmp, self.input0, psi)
butterfly_input = self.input0

butterflies = butterflies_ops(
pisa_op.NTT,
context=self.context,
output=self.output,
outtmp=outtmp,
input0=self.input0,
input0=butterfly_input,
)

return mixed_to_pisa_ops(mul, butterflies)
Expand Down