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ircd::uleb128: Ensure ceiling for result at the type length.

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This commit is contained in:
Jason Volk 2019-10-16 19:26:46 -07:00
parent 538c3530f3
commit 6d380dcb6c
1 changed files with 7 additions and 3 deletions
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10
include/ircd/leb128.h
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@ -110,9 +110,11 @@ inline size_t
ircd::uleb128::length(const uint64_t &val)
noexcept
{
static const int max_mask {0x0000007f};
const int mask
{
_mm_movemask_pi8(__m64(val))
_mm_movemask_pi8(__m64(val)) & max_mask
};
return __builtin_ctz(~mask) + 1;
@ -123,9 +125,11 @@ inline size_t
ircd::uleb128::length(const uint128_t &val)
noexcept
{
static const int max_mask {0x00007fff};
const int mask
{
_mm_movemask_epi8(__m128i(val))
_mm_movemask_epi8(__m128i(val)) & max_mask
};
return __builtin_ctz(~mask) + 1;
@ -144,7 +148,7 @@ noexcept
constexpr const T control_mask {0x80};
size_t i(0);
for(; i < sizeof(T); ++i)
for(; i < sizeof(T) - 1; ++i)
if(~val & (control_mask << (i * 8)))
break;