diff options
| -rw-r--r-- | Objects/longobject.c | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/Objects/longobject.c b/Objects/longobject.c index 54d59c3..250db7c 100644 --- a/Objects/longobject.c +++ b/Objects/longobject.c @@ -388,7 +388,6 @@ _PyLong_AsByteArray(PyLongObject* v, accumbits = 0; carry = do_twos_comp ? 1 : 0; for (i = 0; i < ndigits; ++i) { - unsigned int numnewbits = SHIFT; twodigits thisdigit = v->ob_digit[i]; if (do_twos_comp) { thisdigit = (thisdigit ^ MASK) + carry; @@ -399,22 +398,25 @@ _PyLong_AsByteArray(PyLongObject* v, significant than what's already in accum, so needs to be prepended to accum. */ accum |= thisdigit << accumbits; + accumbits += SHIFT; - /* How many new bits did we add? The most-significant digit - may be (probably is) at least partly empty. */ + /* The most-significant digit may be (probably is) at least + partly empty. */ if (i == ndigits - 1) { - twodigits bitmask = 1 << (SHIFT - 1); - twodigits signbit = do_twos_comp << (SHIFT - 1); + /* Count # of sign bits -- they needn't be stored, + * although for signed conversion we need later to + * make sure at least one sign bit gets stored. + * First shift conceptual sign bit to real sign bit. + */ + stwodigits s = (stwodigits)(thisdigit << + (8*sizeof(stwodigits) - SHIFT)); unsigned int nsignbits = 0; - while ((thisdigit & bitmask) == signbit && bitmask) { + while ((s < 0) == do_twos_comp && nsignbits < SHIFT) { ++nsignbits; - bitmask >>= 1; - signbit >>= 1; + s <<= 1; } - assert(nsignbits <= SHIFT); - numnewbits -= nsignbits; + accumbits -= nsignbits; } - accumbits += numnewbits; /* Store as many bytes as possible. */ while (accumbits >= 8) { |