diff --git a/src/corelib/global/qfloat16.h b/src/corelib/global/qfloat16.h index acf9220490..136571bbaf 100644 --- a/src/corelib/global/qfloat16.h +++ b/src/corelib/global/qfloat16.h @@ -107,8 +107,9 @@ private: Q_CORE_EXPORT static const quint32 mantissatable[]; Q_CORE_EXPORT static const quint32 exponenttable[]; Q_CORE_EXPORT static const quint32 offsettable[]; - Q_CORE_EXPORT static const quint32 basetable[]; - Q_CORE_EXPORT static const quint32 shifttable[]; + Q_CORE_EXPORT static const quint16 basetable[]; + Q_CORE_EXPORT static const quint16 shifttable[]; + Q_CORE_EXPORT static const quint32 roundtable[]; friend bool qIsNull(qfloat16 f) noexcept; #if !defined(QT_NO_FLOAT16_OPERATORS) @@ -173,14 +174,18 @@ inline qfloat16::qfloat16(float f) noexcept quint32 u; memcpy(&u, &f, sizeof(quint32)); const quint32 signAndExp = u >> 23; - const quint32 base = basetable[signAndExp]; - const quint32 shift = shifttable[signAndExp]; + const quint16 base = basetable[signAndExp]; + const quint16 shift = shifttable[signAndExp]; + const quint32 round = roundtable[signAndExp]; quint32 mantissa = (u & 0x007fffff); if ((signAndExp & 0xff) == 0xff) { if (mantissa) // keep nan from truncating to inf mantissa = qMax(1U << shift, mantissa); } else { - mantissa += (1U << (shift - 1)) - 1; // rounding + // round half to even + mantissa += round; + if (mantissa & (1 << shift)) + --mantissa; } // We use add as the mantissa may overflow causing diff --git a/src/corelib/global/qfloat16tables.cpp b/src/corelib/global/qfloat16tables.cpp index b87986d6b8..55173366c6 100644 --- a/src/corelib/global/qfloat16tables.cpp +++ b/src/corelib/global/qfloat16tables.cpp @@ -2,6 +2,7 @@ ** ** Copyright (C) 2016 by Southwest Research Institute (R) ** Copyright (C) 2019 Intel Corporation. +** Copyright (C) 2020 The Qt Company Ltd. ** Contact: http://www.qt-project.org/legal ** ** This file is part of the QtCore module of the Qt Toolkit. @@ -38,7 +39,7 @@ ** ****************************************************************************/ -/* This file was generated by gen_qfloat16_tables.cpp */ +/* This file was generated by util/qfloat16-tables/gen_qfloat16_tables.cpp */ #include @@ -2231,7 +2232,7 @@ const quint32 qfloat16::offsettable[64] = { 1024U, }; -const quint32 qfloat16::basetable[512] = { +const quint16 qfloat16::basetable[512] = { 0x0U, 0x0U, 0x0U, @@ -2746,7 +2747,7 @@ const quint32 qfloat16::basetable[512] = { 0xFC00U, }; -const quint32 qfloat16::shifttable[512] = { +const quint16 qfloat16::shifttable[512] = { 0x18U, 0x18U, 0x18U, @@ -3261,6 +3262,521 @@ const quint32 qfloat16::shifttable[512] = { 0xDU, }; -#endif // !__F16C__ && !__ARM_FP16_FORMAT_IEEE +const quint32 qfloat16::roundtable[512] = { +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x1000000U, +0x400001U, +0x200000U, +0x100000U, +0x80000U, +0x40000U, +0x20000U, +0x10000U, +0x8000U, +0x4000U, +0x2000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x1000000U, +0x400001U, +0x200000U, +0x100000U, +0x80000U, +0x40000U, +0x20000U, +0x10000U, +0x8000U, +0x4000U, +0x2000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x1000U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +0x0U, +}; + +#endif // !__ARM_FP16_FORMAT_IEEE QT_END_NAMESPACE diff --git a/tests/auto/corelib/global/qfloat16/tst_qfloat16.cpp b/tests/auto/corelib/global/qfloat16/tst_qfloat16.cpp index 20d8a1d895..82ad6b1c38 100644 --- a/tests/auto/corelib/global/qfloat16/tst_qfloat16.cpp +++ b/tests/auto/corelib/global/qfloat16/tst_qfloat16.cpp @@ -32,6 +32,10 @@ #include +//#define DO_FULL_TEST + +static_assert(sizeof(float) == sizeof(quint32), "Float not 32-bit"); + class tst_qfloat16: public QObject { Q_OBJECT @@ -48,6 +52,11 @@ private slots: void promotionTests(); void arithOps_data(); void arithOps(); +#if defined DO_FULL_TEST + void floatToFloat16Full_data(); + void floatToFloat16Full(); + void floatFromFloat16Full(); +#endif void floatToFloat16(); void floatFromFloat16(); void finite_data(); @@ -344,6 +353,63 @@ void tst_qfloat16::arithOps() QVERIFY(qFuzzyCompare(r4,1.f/val2)); } +#if defined DO_FULL_TEST +void tst_qfloat16::floatToFloat16Full_data() +{ + QTest::addColumn("group"); + for (quint32 j = 0x00; j < 0x100; ++j) + QTest::addRow("%02x", j) << j; + +} + +void tst_qfloat16::floatToFloat16Full() +{ + QFETCH(quint32, group); + for (quint32 j = 0x00; j < 0x100; ++j) { + quint32 data[1<<16]; + qfloat16 out[1<<16]; + qfloat16 expected[1<<16]; + float in[1<<16]; + + for (int i = 0; i < (1<<16); ++i) + data[i] = (group << 24) | (j << 16) | i; + + memcpy(in, data, (1<<16)*sizeof(float)); + + for (int i = 0; i < (1<<16); ++i) + expected[i] = qfloat16(in[i]); + + qFloatToFloat16(out, in, 1<<16); + + for (int i = 0; i < (1<<16); ++i) { + if (out[i] != expected[i]) + QVERIFY(qIsNaN(out[i]) && qIsNaN(expected[i])); + } + } +} + +void tst_qfloat16::floatFromFloat16Full() +{ + quint16 data[1<<16]; + float out[1<<16]; + float expected[1<<16]; + + for (int i = 0; i < (1<<16); ++i) + data[i] = i; + + const qfloat16 *in = reinterpret_cast(data); + + for (int i = 0; i < (1<<16); ++i) + expected[i] = float(in[i]); + + qFloatFromFloat16(out, in, 1<<16); + + for (int i = 0; i < (1<<16); ++i) + if (out[i] != expected[i]) + QVERIFY(qIsNaN(out[i]) && qIsNaN(expected[i])); +} +#endif + void tst_qfloat16::floatToFloat16() { constexpr int count = 10000; @@ -505,8 +571,8 @@ void tst_qfloat16::limits() // See also: qNaN() and infinity() QCOMPARE(qFpClassify(high10), FP_NORMAL); // How many digits are significant ? (Casts avoid linker errors ...) - QCOMPARE(int(Bounds::digits10), 3); // ~9.78e-4 has enough sigificant digits: - qfloat16 below(9.781e-4f), above(9.789e-4f); // both round to ~9.785e-4 + QCOMPARE(int(Bounds::digits10), 3); // ~9.88e-4 has enough sigificant digits: + qfloat16 below(9.876e-4f), above(9.884e-4f); // both round to ~9.88e-4 QVERIFY(below == above); QCOMPARE(int(Bounds::max_digits10), 5); // we need 5 to distinguish these two: QVERIFY(qfloat16(1000.5f) != qfloat16(1001.4f)); diff --git a/util/qfloat16-tables/gen_qfloat16_tables.cpp b/util/qfloat16-tables/gen_qfloat16_tables.cpp index 5d7bab01d2..af172c5513 100644 --- a/util/qfloat16-tables/gen_qfloat16_tables.cpp +++ b/util/qfloat16-tables/gen_qfloat16_tables.cpp @@ -2,6 +2,7 @@ ** ** Copyright (C) 2016 by Southwest Research Institute (R) ** Copyright (C) 2019 Intel Corporation. +** Copyright (C) 2020 The Qt Company Ltd. ** Contact: http://www.qt-project.org/legal ** ** This file is part of the QtCore module of the Qt Toolkit. @@ -71,6 +72,7 @@ uint32_t convertmantissa(int32_t i) // to more closely map the implementation given in the paper. uint32_t basetable[512]; uint32_t shifttable[512]; +uint32_t roundtable[512]; int main() { @@ -113,50 +115,76 @@ int main() int32_t e; for (i = 0; i < 256; ++i) { e = i - 127; - if (e < -24) { // Very small numbers map to zero + if (e < -25) { // Very small numbers map to zero basetable[i | 0x000] = 0x0000; basetable[i | 0x100] = 0x8000; shifttable[i | 0x000] = 24; shifttable[i | 0x100] = 24; + roundtable[i | 0x000] = 0; + roundtable[i | 0x100] = 0; } else if (e < -14) { // Small numbers map to denorms basetable[i | 0x000] = (0x0400 >> (-e - 14)); basetable[i | 0x100] = (0x0400 >> (-e - 14)) | 0x8000; shifttable[i | 0x000] = -e - 1; shifttable[i | 0x100] = -e - 1; + if (e == -25) { + // rounds up + roundtable[i | 0x000] = (1 << 24); + roundtable[i | 0x100] = (1 << 24); + } else if (e == -24) { + // rounds half up + roundtable[i | 0x000] = (1 << 22) + 1; + roundtable[i | 0x100] = (1 << 22) + 1; + } else { + roundtable[i | 0x000] = (1 << (-e - 2)); + roundtable[i | 0x100] = (1 << (-e - 2)); + } } else if (e <= 15) { // Normal numbers just lose precision basetable[i | 0x000] = ((e + 15) << 10); basetable[i | 0x100] = ((e + 15) << 10) | 0x8000; shifttable[i | 0x000] = 13; shifttable[i | 0x100] = 13; + roundtable[i | 0x000] = (1 << 12); + roundtable[i | 0x100] = (1 << 12); } else if (e < 128) { // Large numbers map to Infinity basetable[i | 0x000] = 0x7C00; basetable[i | 0x100] = 0xFC00; shifttable[i | 0x000] = 24; shifttable[i | 0x100] = 24; + roundtable[i | 0x000] = 0; + roundtable[i | 0x100] = 0; } else { // Infinity and NaN's stay Infinity and NaN's basetable[i | 0x000] = 0x7C00; basetable[i | 0x100] = 0xFC00; shifttable[i | 0x000] = 13; shifttable[i | 0x100] = 13; + roundtable[i | 0x000] = 0; + roundtable[i | 0x100] = 0; } } - printf("const quint32 qfloat16::basetable[512] = {\n"); + printf("const quint16 qfloat16::basetable[512] = {\n"); for (i = 0; i < 512; i++) printf("0x%XU,\n", basetable[i]); printf("};\n\n"); - printf("const quint32 qfloat16::shifttable[512] = {\n"); + printf("const quint16 qfloat16::shifttable[512] = {\n"); for (i = 0; i < 512; i++) printf("0x%XU,\n", shifttable[i]); printf("};\n\n"); + printf("const quint32 qfloat16::roundtable[512] = {\n"); + for (i = 0; i < 512; i++) + printf("0x%XU,\n", roundtable[i]); + + printf("};\n\n"); + printf("#endif // !__ARM_FP16_FORMAT_IEEE\n\n"); printf("QT_END_NAMESPACE\n"); return 0;