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https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk
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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libm/] [common/] [s_trunc.c] - Rev 193
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/* * ==================================================== * 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 */
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