service plugin and qdecimal library has been added
This commit is contained in:
Zdenek Jonak
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Dear Qt users,
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I would like to announce initial public release of QDecimal library.
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Most computers today support binary floating-point in hardware. While suitable
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for many purposes, binary floating-point arithmetic should not be used
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for financial, commercial, and user-centric applications because the
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decimal data used in these applications cannot be represented exactly
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using binary floating-point.
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The General Decimal Arithmetic (GDA) specification aims to address
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deficiencies in the binary floating-point arithmetic, and defines a
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decimal arithmetic which meets the requirements of commercial,
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financial, and human-oriented applications. It also matches the
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decimal arithmetic in the IEEE 754-2008 Standard for Floating Point
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Arithmetic.
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The decNumber library is full implementation of the GDA specification
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and also matches the decimal arithmetic in the IEEE 754-2008 Standard
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for Floating Point Arithmetic.
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The QDecimal is a thin layer around IBM's decNumber library which
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implements the General Decimal Arithmetic Specification in ANSI C. [1]
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The QDecimal/decNumberlibrary [2,3] fully implements the specification,
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and hence supports integer, fixed-point, and floating-point decimal
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numbers directly, including infinite, NaN (Not a Number), and
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subnormal values. Both arbitrary-precision and fixed-size
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representations are supported.
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The aim of the QDecimal library [4] is to extend decNumber functionality
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to C++ language and Qt framework by using idioms, tecniques and best
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practices in both tecnologies. For instance, inline functions are used
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heavily to aid optimization, operator overloading and conversion
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operators are defined to aid type casting in between the types defined
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by QDecimal. Further these types are integrated with Qt object model
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by introducing them to Qt meta type system.
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CONTENTS
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Following classes are defined by QDecimal library:
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QDecNumber (based on decNumber):
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----------
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decNumber module uses an arbitrary-precision decimal number
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representation designed for efficient computation in software and
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implements the arithmetic and logical operations, together with a
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number of conversions and utilities. Once a number is held as a
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decNumber, no further conversions are necessary to carry out
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arithmetic.
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The decNumber representation is variable-length and machine-dependent
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(for example, it contains integers which may be big-endian or
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little-endian).
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QDecNumber encapsulates decNumber and reimplements global functions
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that operates upon decNumber as member functions with the same name.
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QDecContext (based on decContext):
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-----------
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Most functions in the decNumber module take as an argument a
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decContext structure, which provides the context for operations
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(precision, rounding mode, etc.) and also controls the handling of
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exceptional conditions (corresponding to the flags and trap enablers
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in a hardware floating-point implementation).
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QDecContext encapsulates decContext and provides decNumber library
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functions that operates upon decContext as member functions.
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QDecSingle (based on decSingle/decimal32):
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----------
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decimal32 is a 32-bit decimal floating-point representation which
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provides 7 decimal digits of precision in a compressed format.
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decSingle module provides the functions for the decimal32 format; this
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format is intended for storage and interchange only and so the module
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provides utilities and conversions but no arithmetic functions.
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QDecSingle encapsulates decSingle and provides decNumber library
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functions that operates upon decSingle as member functions with the
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same name.
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QDecDouble (based on decDouble/decimal64):
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----------
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decimal64 is a 64-bit decimal floating-point representation which
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provides 16 decimal digits of precision in a compressed format.
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decDouble module provides the functions for the decimal64 format; this
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format is an IEEE 754 basic format and so a full set of arithmetic and
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other functions is included.
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QDecDouble encapsulates decDouble and provides decNumber library
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functions that operates upon decSingle as member functions with the
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same name.
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QDecQuad (based on decQuad/decimal128):
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--------
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decimal128 is a 128-bit decimal floating-point representation which
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provides 34 decimal digits of precision in a compressed format.
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decQuad module provides the functions for the decimal128 format; this
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format is an IEEE 754 basic format; it contains the same set of
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functions as decDouble.
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QDecQuad encapsulates decQuad and provides decNumber library functions
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that operates upon decSingle as member functions with the same name.
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QDecPacked (based on decPacked):
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---------
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The decPacked format is the classic packed decimal format implemented
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by IBM S/360 and later machines, where each digit is encoded as a
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4-bit binary sequence (BCD) and a number is ended by a 4-bit sign
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indicator. The decPacked module accepts variable lengths, allowing for
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very large numbers (up to a billion digits), and also allows the
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specification of a scale.
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QDecPacked augments decPacked by encapsulating reference counted byte
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array and scale of the decimal point as member variables, thus, freeing up
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user of this class from memory management and keeping track of scale value.
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LICENSE
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QDecimal is under the terms of the LGPL v2.1.
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decNumber is under the terms of ICU v1.8.1
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See COPYRIGHT file within the package for terms of the these licenses.
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Both licences allow commercial and non-commercial use of the software.
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PLATFORMS
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QDecimal should be usable in all platforms on which Qt 4.7.x or
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greater is supported:
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We regularly test on following platforms:
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Solaris 11 x86 (sstudio 12.2 CC 5.11)
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Linux x64 2.6.38 (Ubuntu 11.04 - gcc 4.5.2)
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Linux x86 2.6.38 (Ubuntu 11.04- gcc 4.5.2)
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Windows XP (msvc 2008)
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CREDITS
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We are grateful to Mike Cowlishaw et al. from IBM for making decNumber package
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available. Further, Mr. Cowlishaw has kindly helped us while making
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QDecimal production ready.
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REFERENCES
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[1] General Decimal Arithmetic Specification
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http://speleotrove.com/decimal/decarith.html
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[2] The decNumber Library
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http://speleotrove.com/decimal/decnumber.html
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[3] General Decimal Arithmetic
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http://speleotrove.com/decimal
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[4] QDecimal Project Home
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http://code.google.com/p/qdecimal
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Regards,
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Semih Cemiloglu
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semih (at) cemiloglu.org
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PGP/GPG KeyId: FCEE9B7A on keyserver.pgp.com
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Fingerprint: ED8F48028DE03BE0A2C95E0FACC5043BFCEE9B7A
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