Mercurial > repos > dawe > srf2fastq
view srf2fastq/io_lib-1.12.2/io_lib/fpoint.c @ 0:d901c9f41a6a default tip
Migrated tool version 1.0.1 from old tool shed archive to new tool shed repository
author | dawe |
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date | Tue, 07 Jun 2011 17:48:05 -0400 |
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/* * Copyright (c) Medical Research Council 1994. All rights reserved. * * Permission to use, copy, modify and distribute this software and its * documentation for any purpose is hereby granted without fee, provided that * this copyright and notice appears in all copies. * * This file was written by James Bonfield, Simon Dear, Rodger Staden, * as part of the Staden Package at the MRC Laboratory of Molecular * Biology, Hills Road, Cambridge, CB2 2QH, United Kingdom. * * MRC disclaims all warranties with regard to this software. */ #include <math.h> #include "io_lib/fpoint.h" /* extern double log ( double x ) ; extern double exp ( double x ) ; */ #define IEEE float int_to_float(int in) /* ** interpret the integer in as a ** floating point number in IEEE format */ { /* Assume `in' is stored as a float according to the ANSI IEEE 754-1985 standard. See the tables below: s = sign ( 1 bit) e = biased exponent (8 bits) f = fraction (23 bits) floating point number = (-1)^s 2^(e-127) 1.f Bits Name Content 31 Sign 1 iff number is negative 23-30 Exponent Eight-Bit exponent, biased by 127 0-22 Fraction 23-bit fraction component of normalised significant. The "one" bit is "hidden" If IEEE floating point format is supported on your machine... ensure there is a #define IEEE somewhere. */ #ifdef IEEE union { int i; float f; } cvt; cvt.i = in; return cvt.f; #else int fraction; int exponent; int sign; fraction = in & ( (1<<23)-1 ); exponent = (in >> 23) & ( (1<<8)-1 ); sign = (in >> 31); return (float) ( (sign?-1.0:1.0) * exp ( log ( (double) 2.0) * (double) (exponent - 127 - 23) ) * (double) ((1<<23)+fraction)) ; #endif }