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FIX: decode_huff off-by-one bug

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This commit is contained in:
Christos Choutouridis 2026-02-15 21:19:59 +02:00
parent cd2b89bd73
commit 781cb3047f
2 changed files with 8 additions and 2 deletions
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3
source/level_3/material/huff_utils.py
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@ -381,11 +381,14 @@ def decode_huff(huff_sec, huff_LUT):
while b: while b:
N += 1 N += 1
b = huff_sec[streamIndex + N] b = huff_sec[streamIndex + N]
# Skip the N leading '1' bits AND the terminating '0' delimiter.
# The encoder writes: '1'*N + '0' + <N4 bits>
streamIndex += N +1 streamIndex += N +1
N4 = N + 4 N4 = N + 4
escape_word = huff_sec[streamIndex:streamIndex + N4] escape_word = huff_sec[streamIndex:streamIndex + N4]
escape_value = 2 ** N4 + int("".join(map(str, escape_word)), 2) escape_value = 2 ** N4 + int("".join(map(str, escape_word)), 2)
nTupleDec[idx] = escape_value nTupleDec[idx] = escape_value
# We already consumed the delimiter above; now consume only N4 bits.
streamIndex += N4 streamIndex += N4
# Apply signs again # Apply signs again
nTupleDec[escIndex] *= nTupleSign[escIndex] nTupleDec[escIndex] *= nTupleSign[escIndex]

7
source/material/huff_utils.py
View File

@ -381,12 +381,15 @@ def decode_huff(huff_sec, huff_LUT):
while b: while b:
N += 1 N += 1
b = huff_sec[streamIndex + N] b = huff_sec[streamIndex + N]
streamIndex += N # Skip the N leading '1' bits AND the terminating '0' delimiter.
# The encoder writes: '1'*N + '0' + <N4 bits>
streamIndex += N +1
N4 = N + 4 N4 = N + 4
escape_word = huff_sec[streamIndex:streamIndex + N4] escape_word = huff_sec[streamIndex:streamIndex + N4]
escape_value = 2 ** N4 + int("".join(map(str, escape_word)), 2) escape_value = 2 ** N4 + int("".join(map(str, escape_word)), 2)
nTupleDec[idx] = escape_value nTupleDec[idx] = escape_value
streamIndex += N4 + 1 # We already consumed the delimiter above; now consume only N4 bits.
streamIndex += N4
# Apply signs again # Apply signs again
nTupleDec[escIndex] *= nTupleSign[escIndex] nTupleDec[escIndex] *= nTupleSign[escIndex]