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| author | Damien George <damien.p.george@gmail.com> | 2017-05-17 16:33:07 +1000 |
|---|---|---|
| committer | Damien George <damien.p.george@gmail.com> | 2017-05-18 17:32:42 +1000 |
| commit | eb4c37f7a47f4afa630ffd754c579a8c4a81ad93 (patch) | |
| tree | 1949c6c0add635390553b0afa827cb78abf4810e | |
| parent | d007351b3377f97316c4af2adcec164fb5e56dca (diff) | |
| download | micropython-eb4c37f7a47f4afa630ffd754c579a8c4a81ad93.tar.gz micropython-eb4c37f7a47f4afa630ffd754c579a8c4a81ad93.zip | |
py/sequence: Fix boundary errors when slicing with a negative step.
| -rw-r--r-- | py/sequence.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/py/sequence.c b/py/sequence.c index cd1a966179..32db640dc1 100644 --- a/py/sequence.c +++ b/py/sequence.c @@ -88,15 +88,22 @@ bool mp_seq_get_fast_slice_indexes(mp_uint_t len, mp_obj_t slice, mp_bound_slice if (start < 0) { start = len + start; if (start < 0) { - start = 0; + if (indexes->step < 0) { + start = -1; + } else { + start = 0; + } } } else if (indexes->step > 0 && (mp_uint_t)start > len) { start = len; - } else if (indexes->step < 0 && (mp_uint_t)start > len - 1) { + } else if (indexes->step < 0 && (mp_uint_t)start >= len) { start = len - 1; } if (stop < 0) { stop = len + stop; + if (stop < 0) { + stop = -1; + } if (indexes->step < 0) { stop += 1; } |