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Diffstat (limited to 'snd/ieeecvt.c')
| -rw-r--r-- | snd/ieeecvt.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/snd/ieeecvt.c b/snd/ieeecvt.c new file mode 100644 index 0000000..731871a --- /dev/null +++ b/snd/ieeecvt.c @@ -0,0 +1,183 @@ +/* + * C O N V E R T T O I E E E E X T E N D E D + */ + +/* Copyright (C) 1988-1991 Apple Computer, Inc. + * All rights reserved. + * + * 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 + * + * + * 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. + */ + +#include "math.h" + +#ifndef HUGE_VAL +#ifdef HUGE +#define HUGE_VAL HUGE +#else +/* WARNING: this is machine-dependent and should come from math.h */ +#define HUGE_VAL 1.797693134862315e308 +#endif /* HUGE */ +#endif /*HUGE_VAL*/ + +# define FloatToUnsigned(f) ((unsigned long)(((long)(f - 2147483648.0)) + 2147483647L) + 1) + +void ConvertToIeeeExtended(double num, char *bytes) +{ + int sign; + int expon; + double fMant, fsMant; + unsigned long hiMant, loMant; + + if (num < 0) { + sign = 0x8000; + num *= -1; + } else { + sign = 0; + } + + if (num == 0) { + expon = 0; hiMant = 0; loMant = 0; + } + else { + fMant = frexp(num, &expon); + if ((expon > 16384) || !(fMant < 1)) { /* Infinity or NaN */ + expon = sign|0x7FFF; hiMant = 0; loMant = 0; /* infinity */ + } + else { /* Finite */ + expon += 16382; + if (expon < 0) { /* denormalized */ + fMant = ldexp(fMant, expon); + expon = 0; + } + expon |= sign; + fMant = ldexp(fMant, 32); + fsMant = floor(fMant); + hiMant = FloatToUnsigned(fsMant); + fMant = ldexp(fMant - fsMant, 32); + fsMant = floor(fMant); + loMant = FloatToUnsigned(fsMant); + } + } + + bytes[0] = (char) (expon >> 8); + bytes[1] = (char) expon; + bytes[2] = (char) (hiMant >> 24); + bytes[3] = (char) (hiMant >> 16); + bytes[4] = (char) (hiMant >> 8); + bytes[5] = (char) hiMant; + bytes[6] = (char) (loMant >> 24); + bytes[7] = (char) (loMant >> 16); + bytes[8] = (char) (loMant >> 8); + bytes[9] = (char) loMant; +} + + +/* + * C O N V E R T F R O M I E E E E X T E N D E D + */ + +/* + * Copyright (C) 1988-1991 Apple Computer, Inc. + * All rights reserved. + * + * 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 + * + * + * 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. + */ + +#ifndef HUGE_VAL +# define HUGE_VAL HUGE +#endif /*HUGE_VAL*/ + +# define UnsignedToFloat(u) (((double)((long)(u - 2147483647L - 1))) + 2147483648.0) + +/**************************************************************** + * Extended precision IEEE floating-point conversion routine. + ****************************************************************/ + +double ConvertFromIeeeExtended(unsigned char *bytes /* LCN */) +{ + double f; + int 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; +} + + + |