1 /* llround function. PowerPC64 version.
2 Copyright (C) 2004, 2006, 2007, 2008 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 #include <math_ldbl_opt.h>
25 .tc FD_43300000_0[TC],0x4330000000000000
27 .tc FD_3fe00000_0[TC],0x3fe0000000000000
30 /* long long [r3] llround (double x [fp1])
31 IEEE 1003.1 llround function. IEEE specifies "round to the nearest
32 integer value, rounding halfway cases away from zero, regardless of
33 the current rounding mode." However PowerPC Architecture defines
34 "round to Nearest" as "Choose the best approximation. In case of a
35 tie, choose the one that is even (least significant bit o).".
36 So we can't use the PowerPC "round to Nearest" mode. Instead we set
37 "round toward Zero" mode and round by adding +-0.5 before rounding
40 It is necessary to detect when x is (+-)0x1.fffffffffffffp-2
41 because adding +-0.5 in this case will cause an erroneous shift,
42 carry and round. We simply return 0 if 0.5 > x > -0.5. Likewise
43 if x is and odd number between +-(2^52 and 2^53-1) a shift and
44 carry will erroneously round if biased with +-0.5. Therefore if x
45 is greater/less than +-2^52 we don't need to bias the number with
50 lfd fp9,.LC0@toc(2) /* Load 2^52 into fpr9. */
51 lfd fp10,.LC1@toc(2)/* Load 0.5 into fpr10. */
52 fabs fp2,fp1 /* Get the absolute value of x. */
53 fsub fp12,fp10,fp10 /* Compute 0.0 into fp12. */
54 fcmpu cr6,fp2,fp10 /* if |x| < 0.5 */
55 fcmpu cr7,fp2,fp9 /* if |x| >= 2^52 */
56 fcmpu cr1,fp1,fp12 /* x is negative? x < 0.0 */
57 blt- cr6,.Lretzero /* 0.5 > x < -0.5 so just return 0. */
58 bge- cr7,.Lnobias /* 2^52 > x < -2^52 just convert with no bias. */
59 fadd fp3,fp2,fp10 /* |x|+=0.5 bias to prepare to round. */
60 bge cr1,.Lconvert /* x is positive so don't negate x. */
61 fnabs fp3,fp3 /* -(|x|+=0.5) */
63 fctidz fp4,fp3 /* Convert to Integer double word round toward 0. */
68 ld r3,-16(r1) /* Load return as integer. */
71 .Lretzero: /* 0.5 > x > -0.5 */
72 li r3,0 /* return 0. */
79 strong_alias (__llround, __lround)
80 weak_alias (__llround, llround)
81 weak_alias (__lround, lround)
84 weak_alias (__llround, llroundl)
85 strong_alias (__llround, __llroundl)
86 weak_alias (__lround, lroundl)
87 strong_alias (__lround, __lroundl)
89 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
90 compat_symbol (libm, __llround, llroundl, GLIBC_2_1)
91 compat_symbol (libm, __lround, lroundl, GLIBC_2_1)