| /* nearbyint long double. |
| IBM extended format long double version. |
| Copyright (C) 2004, 2006 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include <sysdep.h> |
| #include <math_ldbl_opt.h> |
| |
| .section ".toc","aw" |
| .LC0: /* 2**52 */ |
| .tc FD_43300000_0[TC],0x4330000000000000 |
| .section ".text" |
| |
| /* long double [fp1,fp2] nearbyintl (long double x [fp1,fp2]) |
| IEEE 1003.1 nearbyintl function. nearbyintl is simular to the rintl |
| but does raise the "inexact" exception. This implementation is |
| based on rintl but explicitly maskes the inexact exception on entry |
| and clears any pending inexact before restoring the exception mask |
| on exit. |
| |
| PowerPC64 long double uses the IBM extended format which is |
| represented two 64-floating point double values. The values are |
| non-overlapping giving an effective precision of 106 bits. The first |
| double contains the high order bits of mantisa and is always rounded |
| to represent a normal rounding of long double to double. Since the |
| long double value is sum of the high and low values, the low double |
| normally has the opposite sign to compensate for the this rounding. |
| |
| For long double there are two cases: |
| 1) |x| < 2**52, all the integer bits are in the high double. |
| floor the high double and set the low double to -0.0. |
| 2) |x| >= 2**52, Rounding involves both doubles. |
| See the comment before lable .L2 for details. |
| */ |
| ENTRY (__nearbyintl) |
| mffs fp11 /* Save current FPSCR. */ |
| lfd fp13,.LC0@toc(2) |
| fabs fp0,fp1 |
| mtfsb0 28 /* Disable "inexact" exceptions. */ |
| fsub fp12,fp13,fp13 /* generate 0.0 */ |
| fabs fp9,fp2 |
| fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */ |
| fcmpu cr6,fp1,fp12 /* if (x > 0.0) */ |
| bnl- cr7,.L2 |
| fmr fp2,fp12 |
| bng- cr6,.L4 |
| fadd fp1,fp1,fp13 /* x+= TWO52; */ |
| fsub fp1,fp1,fp13 /* x-= TWO52; */ |
| b .L9 |
| .L4: |
| bnl- cr6,.L9 /* if (x < 0.0) */ |
| fsub fp1,fp13,fp1 /* x = TWO52 - x; */ |
| fsub fp0,fp1,fp13 /* x = - (x - TWO52); */ |
| fneg fp1,fp0 |
| .L9: |
| mtfsb0 6 /* Clear any pending "inexact" exceptions. */ |
| mtfsf 0x01,fp11 /* restore exception mask. */ |
| blr |
| |
| /* The high double is > TWO52 so we need to round the low double and |
| perhaps the high double. This gets a bit tricky so we use the |
| following algorithm: |
| |
| tau = floor(x_high/TWO52); |
| x0 = x_high - tau; |
| x1 = x_low + tau; |
| r1 = nearbyint(x1); |
| y_high = x0 + r1; |
| y_low = r1 - tau; |
| return y; */ |
| .L2: |
| fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */ |
| fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */ |
| bge- cr7,.L9 /* return x; */ |
| beq- cr0,.L9 |
| fdiv fp8,fp1,fp13 /* x_high/TWO52 */ |
| fctidz fp0,fp8 |
| fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */ |
| fsub fp3,fp1,fp8 /* x0 = x_high - tau; */ |
| fadd fp4,fp2,fp8 /* x1 = x_low + tau; */ |
| |
| fcmpu cr6,fp4,fp12 /* if (x1 > 0.0) */ |
| bng- cr6,.L8 |
| fadd fp5,fp4,fp13 /* r1 = x1 + TWO52; */ |
| fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */ |
| b .L6 |
| .L8: |
| fmr fp5,fp4 |
| bge- cr6,.L6 /* if (x1 < 0.0) */ |
| fsub fp5,fp13,fp4 /* r1 = TWO52 - x1; */ |
| fsub fp0,fp5,fp13 /* r1 = - (r1 - TWO52); */ |
| fneg fp5,fp0 |
| .L6: |
| fadd fp1,fp3,fp5 /* y_high = x0 + r1; */ |
| fsub fp2,fp5,fp8 /* y_low = r1 - tau; */ |
| b .L9 |
| END (__nearbyintl) |
| |
| long_double_symbol (libm, __nearbyintl, nearbyintl) |