1 /* $NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $ */ 2 3 /*- 4 * Copyright (c) 2014 Joerg Sonnenberger <joerg@NetBSD.org>. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 21 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 22 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 23 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 24 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 25 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 26 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 27 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 28 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __RCSID("$NetBSD: floatunditf_ieee754.c,v 1.1 2014/01/30 15:06:18 joerg Exp $"); 34 35 #include <math.h> 36 #include <machine/ieee.h> 37 #include <limits.h> 38 39 #ifdef __HAVE_LONG_DOUBLE 40 41 long double __floatunditf(uint64_t x); 42 43 /* 44 * Convert uint64_t to long double. 45 */ 46 long double 47 __floatunditf(uint64_t x) 48 { 49 int exponent, zeros; 50 union ieee_ext_u ux; 51 52 /* Use the easier conversion routine for uint32_t if possible. */ 53 if (x <= UINT32_MAX) 54 return (long double)(uint32_t)x; 55 56 zeros = __builtin_clzll(x); 57 #ifdef LDBL_IMPLICIT_NBIT 58 exponent = 64 - zeros; 59 x <<= zeros + 1; 60 #else 61 exponent = 63 - zeros; 62 x <<= zeros; 63 #endif 64 65 ux.extu_exp = EXT_EXP_BIAS + exponent; 66 ux.extu_frach = (x >> (64 - EXT_FRACHBITS)); 67 x <<= EXT_FRACHBITS; 68 #ifdef EXT_FRACHMBITS 69 ux.extu_frachm = (x >> (64 - EXT_FRACHMBITS)); 70 x <<= EXT_FRACHMBITS; 71 #endif 72 #ifdef EXT_FRACLMBITS 73 ux.extu_fraclm = (x >> (64 - EXT_FRACLMBITS)); 74 x <<= EXT_FRACLMBITS; 75 #endif 76 ux.extu_fracl = (x >> (64 - EXT_FRACLBITS)); 77 ux.extu_sign = 0; 78 79 return ux.extu_ld; 80 } 81 #endif /* __HAVE_LONG_DOUBLE */ 82