README.txt
1
2
3libmpdec
4========
5
6libmpdec is a fast C/C++ library for correctly-rounded arbitrary precision
7decimal floating point arithmetic. It is a complete implementation of
8Mike Cowlishaw/IBM's General Decimal Arithmetic Specification.
9
10
11Files required for the Python _decimal module
12=============================================
13
14 Core files for small and medium precision arithmetic
15 ----------------------------------------------------
16
17 basearith.{c,h} -> Core arithmetic in base 10**9 or 10**19.
18 bits.h -> Portable detection of least/most significant one-bit.
19 constants.{c,h} -> Constants that are used in multiple files.
20 context.c -> Context functions.
21 io.{c,h} -> Conversions between mpd_t and ASCII strings,
22 mpd_t formatting (allows UTF-8 fill character).
23 memory.{c,h} -> Allocation handlers with overflow detection
24 and functions for switching between static
25 and dynamic mpd_t.
26 mpdecimal.{c,h} -> All (quiet) functions of the specification.
27 typearith.h -> Fast primitives for double word multiplication,
28 division etc.
29
30 Visual Studio only:
31 ~~~~~~~~~~~~~~~~~~~
32 vccompat.h -> snprintf <==> sprintf_s and similar things.
33 vcstdint.h -> stdint.h (included in VS 2010 but not in VS 2008).
34 vcdiv64.asm -> Double word division used in typearith.h. VS 2008 does
35 not allow inline asm for x64. Also, it does not provide
36 an intrinsic for double word division.
37
38 Files for bignum arithmetic:
39 ----------------------------
40
41 The following files implement the Fast Number Theoretic Transform
42 used for multiplying coefficients with more than 1024 words (see
43 mpdecimal.c: _mpd_fntmul()).
44
45 umodarith.h -> Fast low level routines for unsigned modular arithmetic.
46 numbertheory.{c,h} -> Routines for setting up the Number Theoretic Transform.
47 difradix2.{c,h} -> Decimation in frequency transform, used as the
48 "base case" by the following three files:
49
50 fnt.{c,h} -> Transform arrays up to 4096 words.
51 sixstep.{c,h} -> Transform larger arrays of length 2**n.
52 fourstep.{c,h} -> Transform larger arrays of length 3 * 2**n.
53
54 convolute.{c,h} -> Fast convolution using one of the three transform
55 functions.
56 transpose.{c,h} -> Transpositions needed for the sixstep algorithm.
57 crt.{c,h} -> Chinese Remainder Theorem: use information from three
58 transforms modulo three different primes to get the
59 final result.
60
61
62Pointers to literature, proofs and more
63=======================================
64
65 literature/
66 -----------
67
68 REFERENCES.txt -> List of relevant papers.
69 bignum.txt -> Explanation of the Fast Number Theoretic Transform (FNT).
70 fnt.py -> Verify constants used in the FNT; Python demo for the
71 O(N**2) discrete transform.
72
73 matrix-transform.txt -> Proof for the Matrix Fourier Transform used in
74 fourstep.c.
75 six-step.txt -> Show that the algorithm used in sixstep.c is
76 a variant of the Matrix Fourier Transform.
77 mulmod-64.txt -> Proof for the mulmod64 algorithm from
78 umodarith.h.
79 mulmod-ppro.txt -> Proof for the x87 FPU modular multiplication
80 from umodarith.h.
81 umodarith.lisp -> ACL2 proofs for many functions from umodarith.h.
82
83
84Library Author
85==============
86
87 Stefan Krah <skrah@bytereef.org>
88
89
90
91