1 /* $NetBSD: floatdisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt Exp $ */ 2 3 /*- 4 * Copyright (c) 2013 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Matt Thomas of 3am Software Foundry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: floatdisf_ieee754.c,v 1.2 2013/08/24 00:51:48 matt Exp $"); 35 #endif /* LIBC_SCCS and not lint */ 36 37 #if defined(SOFTFLOAT) || defined(__ARM_EABI__) 38 #include "softfloat/softfloat-for-gcc.h" 39 #endif 40 41 #include <limits.h> 42 #include <machine/ieee.h> 43 #include "quad.h" 44 45 float __floatdisf(quad_t); 46 47 /* 48 * Convert signed quad to float. 49 */ 50 float 51 __floatdisf(quad_t x) 52 { 53 union ieee_single_u ux = { .sngu_f = 0.0 }; 54 55 if (x == 0) 56 return 0.0; 57 if (x == 1) 58 return 1.0; 59 60 if (x < 0) { 61 if (x == QUAD_MIN) 62 return -0x1.0p63; 63 ux.sngu_sign = 1; 64 x = -x; 65 } 66 #if defined(_LP64) || defined(__mips_n32) 67 u_int l = __builtin_clzll(x); 68 x <<= (l + 1); /* clear implicit bit */ 69 70 ux.sngu_frac = (u_quad_t)x >> (64 - SNG_FRACBITS); 71 #else 72 union uu u = { .uq = x }; 73 uint32_t frac; 74 u_int l; 75 if (u.ul[H] == 0) { 76 l = __builtin_clz(u.ul[L]); 77 frac = u.ul[L] << (l + 1); /* clear implicit bit */ 78 l += 32; 79 } else { 80 l = __builtin_clz(u.ul[H]); 81 frac = u.ul[H] << (l + 1); /* clear implicit bit */ 82 frac |= u.ul[L] >> (32 - (l + 1)); 83 } 84 85 ux.sngu_frac = frac >> (32 - SNG_FRACBITS); 86 #endif 87 ux.sngu_exp = SNG_EXP_BIAS + 63 - l; 88 89 return ux.sngu_f; 90 } 91