diff options
author | Milo Yip <miloyip@gmail.com> | 2014-09-16 15:38:18 +0400 |
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committer | Milo Yip <miloyip@gmail.com> | 2014-09-16 15:38:18 +0400 |
commit | 475b242087a562897eecf4b1b00cce256bdea6de (patch) | |
tree | aa519065a272a352049669aeb50489e934cb6e1e /include/rapidjson | |
parent | 5171775d4cb2d069ec6797f0024ae811e85d3f1d (diff) |
Minor refactoring before optimization trial
Diffstat (limited to 'include/rapidjson')
-rw-r--r-- | include/rapidjson/internal/strtod.h | 50 | ||||
-rw-r--r-- | include/rapidjson/reader.h | 4 |
2 files changed, 32 insertions, 22 deletions
diff --git a/include/rapidjson/internal/strtod.h b/include/rapidjson/internal/strtod.h index c45bca6e..e1c09e17 100644 --- a/include/rapidjson/internal/strtod.h +++ b/include/rapidjson/internal/strtod.h @@ -29,7 +29,7 @@ namespace rapidjson { namespace internal { -inline double StrtodFastPath(double significand, int exp) { +inline double FastPath(double significand, int exp) { if (exp < -308) return 0.0; else if (exp >= 0) @@ -38,14 +38,14 @@ inline double StrtodFastPath(double significand, int exp) { return significand / internal::Pow10(-exp); } -inline double NormalPrecision(double d, int p) { +inline double StrtodNormalPrecision(double d, int p) { if (p < -308) { // Prevent expSum < -308, making Pow10(p) = 0 - d = StrtodFastPath(d, -308); - d = StrtodFastPath(d, p + 308); + d = FastPath(d, -308); + d = FastPath(d, p + 308); } else - d = StrtodFastPath(d, p); + d = FastPath(d, p); return d; } @@ -124,25 +124,24 @@ inline int CheckWithinHalfULP(double b, const BigInteger& d, int dExp, bool* adj return cmp; } -inline double FullPrecision(double d, int p, const char* decimals, size_t length, size_t decimalPosition, int exp) { - RAPIDJSON_ASSERT(d >= 0.0); - RAPIDJSON_ASSERT(length >= 1); - +inline bool StrtodFast(double d, int p, double* result) { // Use fast path for string-to-double conversion if possible // see http://www.exploringbinary.com/fast-path-decimal-to-floating-point-conversion/ - if (p > 22) { - if (p < 22 + 16) { - // Fast Path Cases In Disguise - d *= internal::Pow10(p - 22); - p = 22; - } + if (p > 22 && p < 22 + 16) { + // Fast Path Cases In Disguise + d *= internal::Pow10(p - 22); + p = 22; } - if (p >= -22 && p <= 22 && d <= 9007199254740991.0) // 2^53 - 1 - return StrtodFastPath(d, p); - - // Use slow-path with BigInteger comparison + if (p >= -22 && p <= 22 && d <= 9007199254740991.0) { // 2^53 - 1 + *result = FastPath(d, p); + return true; + } + else + return false; +} +inline double StrtodBigInteger(double d, int p, const char* decimals, size_t length, size_t decimalPosition, int exp) { // Trim leading zeros while (*decimals == '0' && length > 1) { length--; @@ -170,7 +169,7 @@ inline double FullPrecision(double d, int p, const char* decimals, size_t length const BigInteger dInt(decimals, length); const int dExp = (int)decimalPosition - (int)length + exp; - Double approx = NormalPrecision(d, p); + Double approx = StrtodNormalPrecision(d, p); for (int i = 0; i < 10; i++) { bool adjustToNegative; int cmp = CheckWithinHalfULP(approx.Value(), dInt, dExp, &adjustToNegative); @@ -191,6 +190,17 @@ inline double FullPrecision(double d, int p, const char* decimals, size_t length return approx.Value(); } +inline double StrtodFullPrecision(double d, int p, const char* decimals, size_t length, size_t decimalPosition, int exp) { + RAPIDJSON_ASSERT(d >= 0.0); + RAPIDJSON_ASSERT(length >= 1); + + double result; + if (StrtodFast(d, p, &result)) + return result; + + return StrtodBigInteger(d, p, decimals, length, decimalPosition, exp); +} + } // namespace internal } // namespace rapidjson diff --git a/include/rapidjson/reader.h b/include/rapidjson/reader.h index c03a4ce5..77c9528b 100644 --- a/include/rapidjson/reader.h +++ b/include/rapidjson/reader.h @@ -941,9 +941,9 @@ private: if (useDouble) {
int p = exp + expFrac;
if (parseFlags & kParseFullPrecisionFlag)
- d = internal::FullPrecision(d, p, decimal, length, decimalPosition, exp);
+ d = internal::StrtodFullPrecision(d, p, decimal, length, decimalPosition, exp);
else
- d = internal::NormalPrecision(d, p);
+ d = internal::StrtodNormalPrecision(d, p);
cont = handler.Double(minus ? -d : d);
}
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