[flac-dev] [PATCH 2] more changes in bitmath.h

[lvqcl]

1) FLAC supports only MSVS 2005 and newer, so (_MSC_VER >= 1400)
is always true and can be removed.


2) The argument for FLAC__clz_uint32() is of FLAC__uint32 type, so
FLAC__clz_soft_uint32() should have the same argument type.


3) The patch removes unnecessary parentheses around 'word' variable.


4) It also replaces "sizeof(FLAC__uint32) * CHAR_BIT  - 1 - FLAC__clz_uint32(v)"
with "FLAC__clz_uint32(v) ^ 31U" (and the same for 64-bit version).

"sizeof(FLAC__uint32) * CHAR_BIT" must be 32, or the code won't work.
So it's simpler to use "31 - FLAC__clz_uint32(v)" or even better,
"FLAC__clz_uint32(v) ^ 31".

Why XORing is better: gcc implements __builtin_clz as bsr^31, so
FLAC__bitmath_ilog2() now calculates 31 - (bsr^31). GCC is unable
to simplify it to just bsr. But it can do it for (bsr^31)^31.


5) The patch adds FLAC__U64L() for a big constant.
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