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Limit significand to 17 digits for fast path

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Should fix gcc debug error in tranvis. May need further refactoring.
This commit is contained in:
miloyip 2014-09-15 15:54:15 +08:00
parent bea4fa7f6a
commit b29acfb90d
2 changed files with 25 additions and 8 deletions
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4
include/rapidjson/internal/strtod.h
View File

@ -447,12 +447,11 @@ inline int CheckWithinHalfULP(double b, const BigInteger& d, int dExp, bool* adj
return cmp; return cmp;
} }
inline double FullPrecision(double d, int dExp, const char* decimals, size_t length) { 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(d >= 0.0);
// Use fast path for string-to-double conversion if possible // Use fast path for string-to-double conversion if possible
// see http://www.exploringbinary.com/fast-path-decimal-to-floating-point-conversion/ // see http://www.exploringbinary.com/fast-path-decimal-to-floating-point-conversion/
int p = dExp;
if (p > 22) { if (p > 22) {
if (p < 22 + 16) { if (p < 22 + 16) {
// Fast Path Cases In Disguise // Fast Path Cases In Disguise
@ -468,6 +467,7 @@ inline double FullPrecision(double d, int dExp, const char* decimals, size_t len
return 0.0; return 0.0;
const BigInteger dInt(decimals, length); const BigInteger dInt(decimals, length);
const int dExp = (int)decimalPosition - (int)length + exp;
Double approx = NormalPrecision(d, p); Double approx = NormalPrecision(d, p);
for (int i = 0; i < 10; i++) { for (int i = 0; i < 10; i++) {
bool adjustToNegative; bool adjustToNegative;

29
include/rapidjson/reader.h
View File

@ -779,6 +779,7 @@ private:
unsigned i = 0; unsigned i = 0;
uint64_t i64 = 0; uint64_t i64 = 0;
bool use64bit = false; bool use64bit = false;
int significandDigit = 0;
if (s.Peek() == '0') { if (s.Peek() == '0') {
i = 0; i = 0;
s.TakePush(); s.TakePush();
@ -796,6 +797,7 @@ private:
} }
} }
i = i * 10 + static_cast<unsigned>(s.TakePush() - '0'); i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
significandDigit++;
} }
else else
while (s.Peek() >= '0' && s.Peek() <= '9') { while (s.Peek() >= '0' && s.Peek() <= '9') {
@ -807,6 +809,7 @@ private:
} }
} }
i = i * 10 + static_cast<unsigned>(s.TakePush() - '0'); i = i * 10 + static_cast<unsigned>(s.TakePush() - '0');
significandDigit++;
} }
} }
else else
@ -825,6 +828,7 @@ private:
break; break;
} }
i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0'); i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
significandDigit++;
} }
else else
while (s.Peek() >= '0' && s.Peek() <= '9') { while (s.Peek() >= '0' && s.Peek() <= '9') {
@ -835,6 +839,7 @@ private:
break; break;
} }
i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0'); i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
significandDigit++;
} }
} }
@ -849,8 +854,13 @@ private:
// Parse frac = decimal-point 1*DIGIT // Parse frac = decimal-point 1*DIGIT
int expFrac = 0; int expFrac = 0;
size_t decimalPosition;
if (s.Peek() == '.') { if (s.Peek() == '.') {
s.Take(); s.Take();
decimalPosition = s.Length();
if (!(s.Peek() >= '0' && s.Peek() <= '9'))
RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
if (!useDouble) { if (!useDouble) {
#if RAPIDJSON_64BIT #if RAPIDJSON_64BIT
@ -864,6 +874,8 @@ private:
else { else {
i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0'); i64 = i64 * 10 + static_cast<unsigned>(s.TakePush() - '0');
--expFrac; --expFrac;
if (i64 != 0)
significandDigit++;
} }
} }
@ -876,13 +888,18 @@ private:
} }
while (s.Peek() >= '0' && s.Peek() <= '9') { while (s.Peek() >= '0' && s.Peek() <= '9') {
d = d * 10.0 + (s.TakePush() - '0'); if (significandDigit < 17) {
--expFrac; d = d * 10.0 + (s.TakePush() - '0');
--expFrac;
if (d != 0.0)
significandDigit++;
}
else
s.TakePush();
} }
if (expFrac == 0)
RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
} }
else
decimalPosition = s.Length(); // decimal position at the end of integer.
// Parse exp = e [ minus / plus ] 1*DIGIT // Parse exp = e [ minus / plus ] 1*DIGIT
int exp = 0; int exp = 0;
@ -924,7 +941,7 @@ private:
if (useDouble) { if (useDouble) {
int p = exp + expFrac; int p = exp + expFrac;
if (parseFlags & kParseFullPrecisionFlag) if (parseFlags & kParseFullPrecisionFlag)
d = internal::FullPrecision(d, p, decimal, length); d = internal::FullPrecision(d, p, decimal, length, decimalPosition, exp);
else else
d = internal::NormalPrecision(d, p); d = internal::NormalPrecision(d, p);