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Assert that there are no collisions in invtab. 

Signed-off-by: Daira Hopwood <daira@jacaranda.org>
This commit is contained in:
Daira Hopwood 2020-11-30 12:00:50 +00:00
parent 79738d2cb7
commit 7bf9015957
1 changed files with 5 additions and 2 deletions
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squareroottab.sage
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@ -53,9 +53,12 @@ class SqrtField:
(self.hash_xor, self.hash_mod) = (hash_xor, hash_mod)
# Now invert gtab[3].
invtab = [0]*hash_mod
invtab = [1]*hash_mod
for j in range(256):
invtab[self.hash(gtab[3][j])] = (256-j) % 256
h = self.hash(gtab[3][j])
# 1 is the last value to be assigned, so this ensures there are no collisions.
assert invtab[h] == 1
invtab[h] = (256-j) % 256
gtab[3] = gtab[3][:128]