diff options
Diffstat (limited to 'newlib/libm/common/s_round.c')
-rw-r--r-- | newlib/libm/common/s_round.c | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/newlib/libm/common/s_round.c b/newlib/libm/common/s_round.c new file mode 100644 index 0000000..09f19de --- /dev/null +++ b/newlib/libm/common/s_round.c @@ -0,0 +1,83 @@ +/* + * ==================================================== + * 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 round(double x) +#else + double round(x) + double x; +#endif +{ + /* Most significant word, least significant word. */ + __int32_t msw, exponent_less_1023; + __uint32_t lsw; + + EXTRACT_WORDS(msw, lsw, x); + + /* Extract exponent field. */ + exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023; + + if (exponent_less_1023 < 20) + { + if (exponent_less_1023 < 0) + { + msw &= 0x80000000; + if (exponent_less_1023 == -1) + /* Result is +1.0 or -1.0. */ + msw |= (1023 << 20); + lsw = 0; + } + else + { + __uint32_t exponent_mask = 0x000fffff >> exponent_less_1023; + if ((msw & exponent_mask) == 0 && lsw == 0) + /* x in an integral value. */ + return x; + + msw += 0x00080000 >> exponent_less_1023; + msw &= ~exponent_mask; + lsw = 0; + } + } + else if (exponent_less_1023 > 51) + { + if (exponent_less_1023 == 1024) + /* x is NaN or infinite. */ + return x + x; + else + return x; + } + else + { + __uint32_t exponent_mask = 0xffffffff >> (exponent_less_1023 - 20); + __uint32_t tmp; + + if ((lsw & exponent_mask) == 0) + /* x is an integral value. */ + return x; + + tmp = lsw + (1 << (51 - exponent_less_1023)); + if (tmp < lsw) + msw += 1; + lsw = tmp; + + lsw &= ~exponent_mask; + } + INSERT_WORDS(x, msw, lsw); + + return x; +} + +#endif /* _DOUBLE_IS_32BITS */ |