diff options
Diffstat (limited to 'REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S')
| -rw-r--r-- | REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S b/REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S new file mode 100644 index 0000000000..3e910ac322 --- /dev/null +++ b/REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S @@ -0,0 +1,88 @@ +/* llroundf function. PowerPC64 version. + Copyright (C) 2004-2017 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> + + .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) +weak_alias (__llroundf, llroundf) +weak_alias (__lroundf, lroundf) + |