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mdbx: avoud int64-to-double conversion key_from_jsonInteger().

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More for https://github.com/leo-yuriev/libmdbx/issues/76

This is expected to be a workaround for the MSVC2019 bug
"MSVCRT.lib(ftol3.obj) : error LNK2001: unresolved external symbol __except1".
https://ci.appveyor.com/project/leo-yuriev/libmdbx/builds/30273569/job/lurrftum1nkbu5a3#L109

Change-Id: Ie6da02b14d0b973c7172af063caf4fdc44bf89ac
This commit is contained in:
Leonid Yuriev 2020-01-22 19:41:01 +03:00
parent b77f4faadd
commit ebcbcbfe31
1 changed files with 32 additions and 26 deletions
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58
src/elements/core.c
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@ -17377,8 +17377,7 @@ uint32_t mdbx_key_from_ptrfloat(const float *const ieee754_32bit) {
#define IEEE754_DOUBLE_MAX 0x7FF
#define IEEE754_DOUBLE_IMPLICIT_LEAD UINT64_C(0x0010000000000000)
#define IEEE754_DOUBLE_MANTISSA_MASK UINT64_C(0x000FFFFFFFFFFFFF)
#define JSON_MAX_SAFE_INTEGER ((INT64_C(1) << 53) - 1)
#define JSON_MIN_SAFE_INTEGER (-JSON_MAX_SAFE_INTEGER)
#define IEEE754_DOUBLE_MANTISSA_AMAX UINT64_C(0x001FFFFFFFFFFFFF)
static __inline int clz64(uint64_t value) {
#if __GNUC_PREREQ(4, 1) || __has_builtin(__builtin_clzl)
@ -17421,21 +17420,31 @@ static __inline int clz64(uint64_t value) {
return debruijn_clz64[value * UINT64_C(0x03F79D71B4CB0A89) >> 58];
}
static uint64_t round_mantissa(const uint64_t u64, int shift) {
assert(shift < 0 && u64 > 0);
shift = -shift;
const unsigned half = 1 << (shift - 1);
const unsigned lsb = 1 & (unsigned)(u64 >> shift);
const unsigned tie2even = 1 ^ lsb;
return (u64 + half - tie2even) >> shift;
}
uint64_t mdbx_key_from_jsonInteger(const int64_t json_integer) {
const uint64_t biased_zero = UINT64_C(0x8000000000000000);
if (json_integer > 0) {
if (unlikely(json_integer > JSON_MAX_SAFE_INTEGER))
goto fallback;
const uint64_t u64 = json_integer;
const int extra_zeros =
clz64(u64) - (64 - IEEE754_DOUBLE_MANTISSA_SIZE - 1);
assert(extra_zeros >= 0);
const uint64_t mantissa = u64 << extra_zeros;
assert(mantissa >= IEEE754_DOUBLE_IMPLICIT_LEAD);
assert(mantissa <=
IEEE754_DOUBLE_MANTISSA_MASK + IEEE754_DOUBLE_IMPLICIT_LEAD);
int shift = clz64(u64) - (64 - IEEE754_DOUBLE_MANTISSA_SIZE - 1);
uint64_t mantissa = u64 << shift;
if (unlikely(shift < 0)) {
mantissa = round_mantissa(u64, shift);
if (mantissa > IEEE754_DOUBLE_MANTISSA_AMAX)
mantissa = round_mantissa(u64, --shift);
}
assert(mantissa >= IEEE754_DOUBLE_IMPLICIT_LEAD &&
mantissa <= IEEE754_DOUBLE_MANTISSA_AMAX);
const uint64_t exponent =
IEEE754_DOUBLE_BIAS + IEEE754_DOUBLE_MANTISSA_SIZE - extra_zeros;
IEEE754_DOUBLE_BIAS + IEEE754_DOUBLE_MANTISSA_SIZE - shift;
assert(exponent > 0 && exponent <= IEEE754_DOUBLE_MAX);
const uint64_t key = biased_zero +
(exponent << IEEE754_DOUBLE_MANTISSA_SIZE) +
@ -17445,18 +17454,19 @@ uint64_t mdbx_key_from_jsonInteger(const int64_t json_integer) {
}
if (json_integer < 0) {
if (unlikely(json_integer < JSON_MIN_SAFE_INTEGER))
goto fallback;
const uint64_t u64 = -json_integer;
const int extra_zeros =
clz64(u64) - (64 - IEEE754_DOUBLE_MANTISSA_SIZE - 1);
assert(extra_zeros >= 0);
const uint64_t mantissa = u64 << extra_zeros;
assert(mantissa >= IEEE754_DOUBLE_IMPLICIT_LEAD);
assert(mantissa <=
IEEE754_DOUBLE_MANTISSA_MASK + IEEE754_DOUBLE_IMPLICIT_LEAD);
int shift = clz64(u64) - (64 - IEEE754_DOUBLE_MANTISSA_SIZE - 1);
uint64_t mantissa = u64 << shift;
if (unlikely(shift < 0)) {
mantissa = round_mantissa(u64, shift);
if (mantissa > IEEE754_DOUBLE_MANTISSA_AMAX)
mantissa = round_mantissa(u64, --shift);
}
assert(mantissa >= IEEE754_DOUBLE_IMPLICIT_LEAD &&
mantissa <= IEEE754_DOUBLE_MANTISSA_AMAX);
const uint64_t exponent =
IEEE754_DOUBLE_BIAS + IEEE754_DOUBLE_MANTISSA_SIZE - extra_zeros;
IEEE754_DOUBLE_BIAS + IEEE754_DOUBLE_MANTISSA_SIZE - shift;
assert(exponent > 0 && exponent <= IEEE754_DOUBLE_MAX);
const uint64_t key = biased_zero -
(exponent << IEEE754_DOUBLE_MANTISSA_SIZE) -
@ -17466,10 +17476,6 @@ uint64_t mdbx_key_from_jsonInteger(const int64_t json_integer) {
}
return biased_zero;
fallback:;
const double ieee754_64bit = (double)json_integer;
return double2key(&ieee754_64bit);
}
/*** Attribute support functions for Nexenta **********************************/