| /* llroundf function. PowerPC64 version. |
| Copyright (C) 2004-2018 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, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <sysdep.h> |
| #include <libm-alias-float.h> |
| |
| .section ".toc","aw" |
| .LC0: /* 2^23 */ |
| .tc FD_41600000_0[TC],0x4160000000000000 |
| .LC1: /* 0.5 */ |
| .tc FD_3fe00000_0[TC],0x3fe0000000000000 |
| .LC2: /* 2^52 */ |
| .tc FD_43300000_0[TC],0x4330000000000000 |
| .section ".text" |
| |
| /* long long [r3] llroundf (float x [fp1]) |
| IEEE 1003.1 llroundf function. IEEE specifies "roundf to the nearest |
| integer value, rounding halfway cases away from zero, regardless of |
| the current rounding mode." However PowerPC Architecture defines |
| "roundf to Nearest" as "Choose the best approximation. In case of a |
| tie, choose the one that is even (least significant bit o).". |
| So we can't use the PowerPC "round to Nearest" mode. Instead we set |
| "round toward Zero" mode and round by adding +-0.5 before rounding |
| to the integer value. |
| |
| It is necessary to detect when x is (+-)0x1.fffffffffffffp-2 |
| because adding +-0.5 in this case will cause an erroneous shift, |
| carry and round. We simply return 0 if 0.5 > x > -0.5. Likewise |
| if x is and odd number between +-(2^23 and 2^24-1) a shift and |
| carry will erroneously round if biased with +-0.5. Therefore if x |
| is greater/less than +-2^23 we don't need to bias the number with |
| +-0.5. */ |
| |
| ENTRY (__llroundf) |
| CALL_MCOUNT 0 |
| lfd fp9,.LC0@toc(2) /* Load 2^23 into fpr9. */ |
| lfd fp10,.LC1@toc(2)/* Load 0.5 into fpr10. */ |
| lfd fp11,.LC2@toc(2) /* Load 2^52 into fpr11. */ |
| fabs fp2,fp1 /* Get the absolute value of x. */ |
| fsub fp12,fp10,fp10 /* Compute 0.0 into fp12. */ |
| fcmpu cr6,fp2,fp10 /* if |x| < 0.5 */ |
| fcmpu cr7,fp2,fp9 /* if |x| >= 2^23 */ |
| fcmpu cr1,fp1,fp12 /* x is negative? x < 0.0 */ |
| blt- cr6,.Lretzero /* 0.5 > x < -0.5 so just return 0. */ |
| bge- cr7,.Lnobias /* 2^23 > x < -2^23 just convert with no bias. */ |
| /* Test whether an integer to avoid spurious "inexact". */ |
| fadd fp3,fp2,fp11 |
| fsub fp3,fp3,fp11 |
| fcmpu cr5,fp2,fp3 |
| beq cr5,.Lnobias |
| fadd fp3,fp2,fp10 /* |x|+=0.5 bias to prepare to round. */ |
| bge cr1,.Lconvert /* x is positive so don't negate x. */ |
| fnabs fp3,fp3 /* -(|x|+=0.5) */ |
| .Lconvert: |
| fctidz fp4,fp3 /* Convert to Integer double word round toward 0. */ |
| stfd fp4,-16(r1) |
| nop |
| nop |
| nop |
| ld r3,-16(r1) /* Load return as integer. */ |
| .Lout: |
| blr |
| .Lretzero: /* 0.5 > x > -0.5 */ |
| li r3,0 /* return 0. */ |
| b .Lout |
| .Lnobias: |
| fmr fp3,fp1 |
| b .Lconvert |
| END (__llroundf) |
| |
| strong_alias (__llroundf, __lroundf) |
| libm_alias_float (__llround, llround) |
| libm_alias_float (__lround, lround) |
| |