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Merge pull request #1922 from jack-perisich/grisu2_precision

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Fix small errors in dtoa output for certain doubles
This commit is contained in:
Milo Yip 2021-08-10 22:16:46 +08:00 committed by GitHub
commit 28c59ab4c6
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 8 additions and 3 deletions
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10
include/rapidjson/internal/dtoa.h
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@ -58,7 +58,11 @@ inline int CountDecimalDigit32(uint32_t n) {
}
inline void DigitGen(const DiyFp& W, const DiyFp& Mp, uint64_t delta, char* buffer, int* len, int* K) {
static const uint32_t kPow10[] = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000 };
static const uint64_t kPow10[] = { 1U, 10U, 100U, 1000U, 10000U, 100000U, 1000000U, 10000000U, 100000000U,
1000000000U, 10000000000U, 100000000000U, 1000000000000U,
10000000000000U, 100000000000000U, 1000000000000000U,
10000000000000000U, 100000000000000000U, 1000000000000000000U,
10000000000000000000U };
const DiyFp one(uint64_t(1) << -Mp.e, Mp.e);
const DiyFp wp_w = Mp - W;
uint32_t p1 = static_cast<uint32_t>(Mp.f >> -one.e);
@ -86,7 +90,7 @@ inline void DigitGen(const DiyFp& W, const DiyFp& Mp, uint64_t delta, char* buff
uint64_t tmp = (static_cast<uint64_t>(p1) << -one.e) + p2;
if (tmp <= delta) {
*K += kappa;
GrisuRound(buffer, *len, delta, tmp, static_cast<uint64_t>(kPow10[kappa]) << -one.e, wp_w.f);
GrisuRound(buffer, *len, delta, tmp, kPow10[kappa] << -one.e, wp_w.f);
return;
}
}
@ -103,7 +107,7 @@ inline void DigitGen(const DiyFp& W, const DiyFp& Mp, uint64_t delta, char* buff
if (p2 < delta) {
*K += kappa;
int index = -kappa;
GrisuRound(buffer, *len, delta, p2, one.f, wp_w.f * (index < 9 ? kPow10[index] : 0));
GrisuRound(buffer, *len, delta, p2, one.f, wp_w.f * (index < 20 ? kPow10[index] : 0));
return;
}
}

1
test/unittest/dtoatest.cpp
View File

@ -38,6 +38,7 @@ TEST(dtoa, normal) {
TEST_DTOA(0.123456789012, "0.123456789012");
TEST_DTOA(1234567.8, "1234567.8");
TEST_DTOA(-79.39773355813419, "-79.39773355813419");
TEST_DTOA(-36.973846435546875, "-36.973846435546875");
TEST_DTOA(0.000001, "0.000001");
TEST_DTOA(0.0000001, "1e-7");
TEST_DTOA(1e30, "1e30");