From 3ab7016632c825949f32b72d06ac324b6672b9f6 Mon Sep 17 00:00:00 2001 From: Glen Mabey Date: Sat, 22 Jun 2013 19:43:46 -0500 Subject: New qfloat16 class This constitutes a fairly complete submission of an entirely new floating point type which conforms to IEEE 754 as a 16-bit storage class. Conversion between qfloat16 and float is currently performed through a sequence of lookup tables. Global-level functions qRound(), qRound64(), qFuzzyCompare(), qFuzzyIsNull(), and qIsNull() each with a qfloat16 parameter have been included for completeness. [ChangeLog][QtCore] Added new qfloat16 class. Change-Id: Ia52eb27846965c14f8140c00faf5ba33c9443976 Reviewed-by: Thiago Macieira --- src/tools/qfloat16-tables/gen_qfloat16_tables.cpp | 161 ++++++++++++++++++++++ src/tools/qfloat16-tables/qfloat16-tables.pro | 9 ++ 2 files changed, 170 insertions(+) create mode 100644 src/tools/qfloat16-tables/gen_qfloat16_tables.cpp create mode 100644 src/tools/qfloat16-tables/qfloat16-tables.pro (limited to 'src/tools/qfloat16-tables') diff --git a/src/tools/qfloat16-tables/gen_qfloat16_tables.cpp b/src/tools/qfloat16-tables/gen_qfloat16_tables.cpp new file mode 100644 index 0000000000..f5051e25fc --- /dev/null +++ b/src/tools/qfloat16-tables/gen_qfloat16_tables.cpp @@ -0,0 +1,161 @@ +/**************************************************************************** +** +** Copyright (C) 2016 by Southwest Research Institute (R) +** Contact: http://www.qt-project.org/legal +** +** This file is part of the QtCore module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include +#include + +quint32 convertmantissa(qint32 i) +{ + quint32 m = i << 13; // Zero pad mantissa bits + quint32 e = 0; // Zero exponent + + while (!(m & 0x00800000)) { // While not normalized + e -= 0x00800000; // Decrement exponent (1<<23) + m <<= 1; // Shift mantissa + } + m &= ~0x00800000; // Clear leading 1 bit + e += 0x38800000; // Adjust bias ((127-14)<<23) + return m | e; // Return combined number +} + +// we first build these tables up and then print them out as a separate step in order +// to more closely map the implementation given in the paper. +quint32 basetable[512]; +quint32 shifttable[512]; + +#define PRINTHEX(a) "0x" + QByteArray::number(a,16).toUpper() + "U,\n" + +qint32 main(qint32 argc, char **argv) +{ + if (argc < 2) { + qWarning() << "Must provide output filename as argument."; + return -1; + } + + QFile fid(argv[1]); + if (!fid.open(QIODevice::WriteOnly | QIODevice::Text)) { + qWarning() << "Abort: Failed to open/create file" << fid.fileName(); + return -1; + } + quint32 i; + + fid.write("/* This file was generated by gen_qfloat16_tables.cpp */\n\n"); + fid.write("#include \n\n"); + + fid.write("QT_BEGIN_NAMESPACE\n\n"); + + fid.write("const quint32 qfloat16::mantissatable[2048] = {\n"); + fid.write("0,\n"); + for (i = 1; i < 1024; i++) + fid.write(PRINTHEX(convertmantissa(i))); + for (i = 1024; i < 2048; i++) + fid.write(PRINTHEX(0x38000000U + ((i - 1024) << 13))); + fid.write("};\n\n"); + + fid.write("const quint32 qfloat16::exponenttable[64] = {\n"); + fid.write("0,\n"); + for (i = 1; i < 31; i++) + fid.write(PRINTHEX(i << 23)); + fid.write("0x47800000U,\n"); // 31 + fid.write("0x80000000U,\n"); // 32 + for (i = 33; i < 63; i++) + fid.write(PRINTHEX(0x80000000U + ((i - 32) << 23))); + fid.write("0xC7800000U,\n"); // 63 + fid.write("};\n\n"); + + fid.write("const quint32 qfloat16::offsettable[64] = {\n"); + fid.write("0,\n"); + for (i = 1; i < 32; i++) + fid.write("1024U,\n"); + fid.write("0,\n"); + for (i = 33; i < 64; i++) + fid.write("1024U,\n"); + fid.write("};\n\n"); + + qint32 e; + for (i = 0; i < 256; ++i) { + e = i - 127; + if (e < -24) { // Very small numbers map to zero + basetable[i | 0x000] = 0x0000; + basetable[i | 0x100] = 0x8000; + shifttable[i | 0x000] = 24; + shifttable[i | 0x100] = 24; + + } 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; + + } 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; + + } 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; + + } 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; + } + } + + fid.write("const quint32 qfloat16::basetable[512] = {\n"); + for (i = 0; i < 512; i++) + fid.write(PRINTHEX(basetable[i])); + + fid.write("};\n\n"); + + fid.write("const quint32 qfloat16::shifttable[512] = {\n"); + for (i = 0; i < 512; i++) + fid.write(PRINTHEX(shifttable[i])); + + fid.write("};\n\n"); + + fid.write("QT_END_NAMESPACE\n"); + fid.close(); + return 0; +} diff --git a/src/tools/qfloat16-tables/qfloat16-tables.pro b/src/tools/qfloat16-tables/qfloat16-tables.pro new file mode 100644 index 0000000000..a7d10ac197 --- /dev/null +++ b/src/tools/qfloat16-tables/qfloat16-tables.pro @@ -0,0 +1,9 @@ +option(host_build) + +CONFIG += force_bootstrap +SOURCES += gen_qfloat16_tables.cpp + +load(qt_tool) + +lib.CONFIG = dummy_install +INSTALLS = lib -- cgit v1.2.3