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Diffstat (limited to 'libtoolame-dab/ieeefloat.c')
-rw-r--r-- | libtoolame-dab/ieeefloat.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/libtoolame-dab/ieeefloat.c b/libtoolame-dab/ieeefloat.c new file mode 100644 index 0000000..296d805 --- /dev/null +++ b/libtoolame-dab/ieeefloat.c @@ -0,0 +1,93 @@ +/* Copyright (C) 1988-1991 Apple Computer, Inc. + * All Rights Reserved. + * + * Warranty Information + * Even though Apple has reviewed this software, Apple makes no warranty + * or representation, either express or implied, with respect to this + * software, its quality, accuracy, merchantability, or fitness for a + * particular purpose. As a result, this software is provided "as is," + * and you, its user, are assuming the entire risk as to its quality + * and accuracy. + * + * This code may be used and freely distributed as long as it includes + * this copyright notice and the warranty information. + * + * Machine-independent I/O routines for IEEE FLOATing-point numbers. + * + * NaN's and infinities are converted to HUGE_VAL or HUGE, which + * happens to be infinity on IEEE machines. Unfortunately, it is + * impossible to preserve NaN's in a machine-independent way. + * Infinities are, however, preserved on IEEE machines. + * + * These routines have been tested on the following machines: + * Apple Macintosh, MPW 3.1 C compiler + * Apple Macintosh, THINK C compiler + * Silicon Graphics IRIS, MIPS compiler + * Cray X/MP and Y/MP + * Digital Equipment VAX + * Sequent Balance (Multiprocesor 386) + * NeXT + * + * + * Implemented by Malcolm Slaney and Ken Turkowski. + * + * Malcolm Slaney contributions during 1988-1990 include big- and little- + * endian file I/O, conversion to and from Motorola's extended 80-bit + * FLOATing-point format, and conversions to and from IEEE single- + * precision FLOATing-point format. + * + * In 1991, Ken Turkowski implemented the conversions to and from + * IEEE double-precision format, added more precision to the extended + * conversions, and accommodated conversions involving +/- infinity, + * NaN's, and denormalized numbers. + * + * $Id: ieeeFLOAT.c,v 1.1 1993/06/11 17:45:46 malcolm Exp $ + * + * $Log: ieeeFLOAT.c,v $ + * Revision 1.1 1993/06/11 17:45:46 malcolm + * Initial revision + * + */ + +#include <stdio.h> +#include <math.h> +#include "ieeefloat.h" +#include "common.h" + +# define FloatToUnsigned(f) ((unsigned long)(((long)((f) - 2147483648.0)) + 2147483647L + 1)) +# define UnsignedToFloat(u) (((double)((long)((u) - 2147483647L - 1))) + 2147483648.0) + +double ConvertFromIeeeExtended (bytes) + char *bytes; +{ + double f; + long expon; + unsigned long hiMant, loMant; + + expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF); + hiMant = ((unsigned long) (bytes[2] & 0xFF) << 24) + | ((unsigned long) (bytes[3] & 0xFF) << 16) | + ((unsigned long) (bytes[4] & 0xFF) << 8) | + ((unsigned long) (bytes[5] & 0xFF)); + loMant = ((unsigned long) (bytes[6] & 0xFF) << 24) + | ((unsigned long) (bytes[7] & 0xFF) << 16) | + ((unsigned long) (bytes[8] & 0xFF) << 8) | + ((unsigned long) (bytes[9] & 0xFF)); + + if (expon == 0 && hiMant == 0 && loMant == 0) { + f = 0; + } else { + if (expon == 0x7FFF) { /* Infinity or NaN */ + f = HUGE_VAL; + } else { + expon -= 16383; + f = ldexp (UnsignedToFloat (hiMant), expon -= 31); + f += ldexp (UnsignedToFloat (loMant), expon -= 32); + } + } + + if (bytes[0] & 0x80) + return -f; + else + return f; +} |