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author | Zack Weinberg <zackw@panix.com> | 2017-06-08 15:39:03 -0400 |
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committer | Zack Weinberg <zackw@panix.com> | 2017-06-08 15:39:03 -0400 |
commit | 5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch) | |
tree | 4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/sysdeps/powerpc/powerpc64/fpu/s_llroundf.S | |
parent | 199fc19d3aaaf57944ef036e15904febe877fc93 (diff) | |
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Prepare for radical source tree reorganization.zack/build-layout-experiment
All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).
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) + |