| /* long double floor function. |
| 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] floorl (long double x [fp1,fp2]) |
| IEEE 1003.1 floor function. |
| |
| 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 (__floorl) |
| mffs fp11 /* Save current FPU rounding mode. */ |
| lfd fp13,.LC0@toc(2) |
| fabs fp0,fp1 |
| fabs fp9,fp2 |
| fsub fp12,fp13,fp13 /* generate 0.0 */ |
| fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */ |
| fcmpu cr6,fp1,fp12 /* if (x > 0.0) */ |
| bnl- cr7,.L2 |
| mtfsfi 7,3 /* Set rounding mode toward -inf. */ |
| fneg fp2,fp12 /* set low double to -0.0. */ |
| ble- cr6,.L0 |
| fadd fp1,fp1,fp13 /* x+= TWO52; */ |
| fsub fp1,fp1,fp13 /* x-= TWO52; */ |
| fcmpu cr5,fp1,fp12 /* if (x > 0.0) */ |
| mtfsf 0x01,fp11 /* restore previous rounding mode. */ |
| bnelr+ cr5 |
| fmr fp1,fp12 /* x must be +0.0 for the 0.0 case. */ |
| blr |
| .L0: |
| bge- cr6,.L1 /* if (x < 0.0) */ |
| fsub fp1,fp1,fp13 /* x-= TWO52; */ |
| fadd fp1,fp1,fp13 /* x+= TWO52; */ |
| .L1: |
| mtfsf 0x01,fp11 /* restore previous rounding mode. */ |
| blr |
| |
| |
| /* The high double is > TWO52 so we need to round the low double and |
| perhaps the high double. In this case we have to round the low |
| double and handle any adjustment to the high double that may be |
| caused by rounding (up). This is complicated by the fact that the |
| high double may already be rounded and the low double may have the |
| opposite sign to compensate.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 = rint(x1); |
| y_high = x0 + r1; |
| y_low = x0 - y_high + r1; |
| return y; */ |
| .L2: |
| fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */ |
| fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */ |
| fcmpu cr5,fp2,fp12 /* if (x_low > 0.0) */ |
| bgelr- cr7 /* return x; */ |
| beqlr- cr0 |
| mtfsfi 7,3 /* Set rounding mode toward -inf. */ |
| fdiv fp8,fp1,fp13 /* x_high/TWO52 */ |
| |
| bng- cr6,.L6 /* if (x > 0.0) */ |
| fctidz fp0,fp8 |
| fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */ |
| bng cr5,.L4 /* if (x_low > 0.0) */ |
| fmr fp3,fp1 |
| fmr fp4,fp2 |
| b .L5 |
| .L4: /* if (x_low < 0.0) */ |
| fsub fp3,fp1,fp8 /* x0 = x_high - tau; */ |
| fadd fp4,fp2,fp8 /* x1 = x_low + tau; */ |
| .L5: |
| fadd fp5,fp4,fp13 /* r1 = r1 + TWO52; */ |
| fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */ |
| b .L9 |
| .L6: /* if (x < 0.0) */ |
| fctidz fp0,fp8 |
| fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */ |
| bnl cr5,.L7 /* if (x_low < 0.0) */ |
| fmr fp3,fp1 |
| fmr fp4,fp2 |
| b .L8 |
| .L7: /* if (x_low > 0.0) */ |
| fsub fp3,fp1,fp8 /* x0 = x_high - tau; */ |
| fadd fp4,fp2,fp8 /* x1 = x_low + tau; */ |
| .L8: |
| fsub fp5,fp4,fp13 /* r1-= TWO52; */ |
| fadd fp5,fp5,fp13 /* r1+= TWO52; */ |
| .L9: |
| mtfsf 0x01,fp11 /* restore previous rounding mode. */ |
| fadd fp1,fp3,fp5 /* y_high = x0 + r1; */ |
| fsub fp2,fp3,fp1 /* y_low = x0 - y_high + r1; */ |
| fadd fp2,fp2,fp5 |
| blr |
| END (__floorl) |
| |
| long_double_symbol (libm, __floorl, floorl) |