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Optimize number parsing for 64-bit architecture

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This commit is contained in:
miloyip 2014-08-20 15:17:21 +08:00
parent 1adeecb12e
commit fdc2b569db
2 changed files with 52 additions and 25 deletions
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12
include/rapidjson/rapidjson.h
View File

@ -147,6 +147,18 @@
# endif
#endif // RAPIDJSON_ENDIAN
///////////////////////////////////////////////////////////////////////////////
// RAPIDJSON_64BIT
//! Whether using 64-bit architecture
#ifndef RAPIDJSON_64BIT
#if defined(__LP64__) || defined(_WIN64)
#define RAPIDJSON_64BIT 1
#else
#define RAPIDJSON_64BIT 0
#endif
#endif // RAPIDJSON_64BIT
///////////////////////////////////////////////////////////////////////////////
// RAPIDJSON_ALIGN

65
include/rapidjson/reader.h
View File

@ -760,7 +760,8 @@ private:
// Parse int: zero / ( digit1-9 *DIGIT )
unsigned i = 0;
bool try64bit = false;
uint64_t i64 = 0;
bool use64bit = false;
if (s.Peek() == '0') {
i = 0;
s.Take();
@ -772,7 +773,8 @@ private:
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (i >= 214748364) { // 2^31 = 2147483648
if (i != 214748364 || s.Peek() > '8') {
try64bit = true;
i64 = i;
use64bit = true;
break;
}
}
@ -782,7 +784,8 @@ private:
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (i >= 429496729) { // 2^32 - 1 = 4294967295
if (i != 429496729 || s.Peek() > '5') {
try64bit = true;
i64 = i;
use64bit = true;
break;
}
}
@ -793,14 +796,14 @@ private:
RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
// Parse 64bit int
uint64_t i64 = 0;
double d = 0.0;
bool useDouble = false;
if (try64bit) {
i64 = i;
if (use64bit) {
if (minus)
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (i64 >= RAPIDJSON_UINT64_C2(0x0CCCCCCC, 0xCCCCCCCC)) // 2^63 = 9223372036854775808
if (i64 >= RAPIDJSON_UINT64_C2(0x0CCCCCCC, 0xCCCCCCCC)) // 2^63 = 9223372036854775808
if (i64 != RAPIDJSON_UINT64_C2(0x0CCCCCCC, 0xCCCCCCCC) || s.Peek() > '8') {
d = (double)i64;
useDouble = true;
break;
}
@ -810,6 +813,7 @@ private:
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (i64 >= RAPIDJSON_UINT64_C2(0x19999999, 0x99999999)) // 2^64 - 1 = 18446744073709551615
if (i64 != RAPIDJSON_UINT64_C2(0x19999999, 0x99999999) || s.Peek() > '5') {
d = (double)i64;
useDouble = true;
break;
}
@ -818,9 +822,7 @@ private:
}
// Force double for big integer
double d = 0.0;
if (useDouble) {
d = (double)i64;
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (d >= 1.7976931348623157e307) // DBL_MAX / 10.0
RAPIDJSON_PARSE_ERROR(kParseErrorNumberTooBig, s.Tell());
@ -831,33 +833,46 @@ private:
// Parse frac = decimal-point 1*DIGIT
int expFrac = 0;
if (s.Peek() == '.') {
if (!useDouble) {
d = try64bit ? (double)i64 : (double)i;
useDouble = true;
}
s.Take();
if (s.Peek() >= '0' && s.Peek() <= '9') {
#if RAPIDJSON_64BIT
// Use i64 to store significand in 64-bit architecture
if (!useDouble) {
if (!use64bit)
i64 = i;
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (i64 >= RAPIDJSON_UINT64_C2(0x19999999, 0x99999999))
break;
else {
i64 = i64 * 10 + static_cast<unsigned>(s.Take() - '0');
--expFrac;
}
}
d = (double)i64;
}
#else
// Use double to store significand in 32-bit architecture
if (!useDouble)
d = use64bit ? (double)i64 : (double)i;
#endif
useDouble = true;
while (s.Peek() >= '0' && s.Peek() <= '9') {
d = d * 10 + (s.Take() - '0');
--expFrac;
}
else
RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
while (s.Peek() >= '0' && s.Peek() <= '9') {
if (expFrac > -16) {
d = d * 10 + (s.Peek() - '0');
--expFrac;
}
s.Take();
}
if (expFrac == 0)
RAPIDJSON_PARSE_ERROR(kParseErrorNumberMissFraction, s.Tell());
}
// Parse exp = e [ minus / plus ] 1*DIGIT
int exp = 0;
if (s.Peek() == 'e' || s.Peek() == 'E') {
if (!useDouble) {
d = try64bit ? (double)i64 : (double)i;
d = use64bit ? (double)i64 : (double)i;
useDouble = true;
}
s.Take();
@ -900,7 +915,7 @@ private:
cont = handler.Double(minus ? -d : d);
}
else {
if (try64bit) {
if (use64bit) {
if (minus)
cont = handler.Int64(-(int64_t)i64);
else