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Diffstat (limited to 'newlib/libm/common/s_trunc.c')
-rw-r--r-- | newlib/libm/common/s_trunc.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/newlib/libm/common/s_trunc.c b/newlib/libm/common/s_trunc.c new file mode 100644 index 0000000..c3ca154 --- /dev/null +++ b/newlib/libm/common/s_trunc.c @@ -0,0 +1,69 @@ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunPro, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +#include "fdlibm.h" + +#ifndef _DOUBLE_IS_32BITS + +#ifdef __STDC__ + double trunc(double x) +#else + double trunc(x) + double x; +#endif +{ + int signbit; + /* Most significant word, least significant word. */ + int msw; + unsigned int lsw; + int exponent_less_1023; + + EXTRACT_WORDS(msw, lsw, x); + + /* Extract sign bit. */ + signbit = msw & 0x80000000; + + /* Extract exponent field. */ + exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023; + + if (exponent_less_1023 < 20) + { + /* All significant digits are in msw. */ + if (exponent_less_1023 < 0) + { + /* -1 < x < 1, so result is +0 or -0. */ + INSERT_WORDS(x, signbit, 0); + } + else + { + /* All relevant fraction bits are in msw, so lsw of the result is 0. */ + INSERT_WORDS(x, signbit | (msw & ~(0x000fffff >> exponent_less_1023)), 0); + } + } + else if (exponent_less_1023 > 51) + { + if (exponent_less_1023 == 1024) + { + /* x is infinite, or not a number, so trigger an exception. */ + return x + x; + } + /* All bits in the fraction fields of the msw and lsw are needed in the result. */ + } + else + { + /* All fraction bits in msw are relevant. Truncate irrelevant + bits from lsw. */ + INSERT_WORDS(x, msw, lsw & ~(0xffffffffu >> (exponent_less_1023 - 20))); + } + return x; +} + +#endif /* _DOUBLE_IS_32BITS */ |