1 /* llround function. PowerPC32 on 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., 1 Franklin Street, Fifth Floor, Boston MA
21 #include <math_ldbl_opt.h>
23 .section .rodata.cst12,"aM",@progbits,12
25 .LC0: /* 0x1.0000000000000p+52 == 2^52 */
28 .long 0x3f000000 /* Use this for 0.5 */
32 /* long [r3] lround (float x [fp1])
33 IEEE 1003.1 lround function. IEEE specifies "round to the nearest
34 integer value, rounding halfway cases away from zero, regardless of
35 the current rounding mode." However PowerPC Architecture defines
36 "round to Nearest" as "Choose the best approximation. In case of a
37 tie, choose the one that is even (least significant bit o).".
38 So we can't use the PowerPC "round to Nearest" mode. Instead we set
39 "round toward Zero" mode and round by adding +-0.5 before rounding
42 It is necessary to detect when x is (+-)0x1.fffffffffffffp-2
43 because adding +-0.5 in this case will cause an erroneous shift,
44 carry and round. We simply return 0 if 0.5 > x > -0.5. Likewise
45 if x is and odd number between +-(2^52 and 2^53-1) a shift and
46 carry will erroneously round if biased with +-0.5. Therefore if x
47 is greater/less than +-2^52 we don't need to bias the number with
52 cfi_adjust_cfa_offset (16)
56 # ifdef HAVE_ASM_PPC_REL16
59 addis r9,r9,.LC0-1b@ha
62 bl _GLOBAL_OFFSET_TABLE_@local-4
72 lfd fp9,.LC0@l(r9) /* Load 2^52 into fpr9. */
73 lfs fp10,.LC0@l+8(r9) /* Load 0.5 into fpr10. */
75 fabs fp2,fp1 /* Get the absolute value of x. */
76 fsub fp12,fp10,fp10 /* Compute 0.0 into fpr12. */
77 fcmpu cr6,fp2,fp10 /* if |x| < 0.5 */
78 fcmpu cr7,fp2,fp9 /* if |x| >= 2^52 */
79 fcmpu cr1,fp1,fp12 /* x is negative? x < 0.0 */
80 blt- cr6,.Lretzero /* 0.5 > x < -0.5 so just return 0. */
81 bge- cr7,.Lnobias /* 2^52 > x < -2^52 just convert with no bias. */
82 fadd fp3,fp2,fp10 /* |x|+=0.5 bias to prepare to round. */
83 bge cr1,.Lconvert /* x is positive so don't negate x. */
84 fnabs fp3,fp3 /* -(|x|+=0.5) */
86 fctidz fp4,fp3 /* Convert to Integer double word round toward 0. */
91 lwz r4,12(r1) /* Load return as integer. */
96 .Lretzero: /* 0.5 > x > -0.5 */
97 li r3,0 /* return 0. */
105 weak_alias (__llround, llround)
107 strong_alias (__llround, __llroundf)
108 weak_alias (__llround, llroundf)
110 #ifdef NO_LONG_DOUBLE
111 weak_alias (__llround, llroundl)
112 strong_alias (__llround, __llroundl)
114 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
115 compat_symbol (libm, __llround, llroundl, GLIBC_2_1)