1 /* long double floor function.
2 IBM extended format long double version.
3 Copyright (C) 2004, 2006 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
22 #include <math_ldbl_opt.h>
26 .tc FD_43300000_0[TC],0x4330000000000000
29 /* long double [fp1,fp2] floorl (long double x [fp1,fp2])
30 IEEE 1003.1 floor function.
32 PowerPC64 long double uses the IBM extended format which is
33 represented two 64-floating point double values. The values are
34 non-overlapping giving an effective precision of 106 bits. The first
35 double contains the high order bits of mantisa and is always rounded
36 to represent a normal rounding of long double to double. Since the
37 long double value is sum of the high and low values, the low double
38 normally has the opposite sign to compensate for the this rounding.
40 For long double there are two cases:
41 1) |x| < 2**52, all the integer bits are in the high double.
42 floor the high double and set the low double to -0.0.
43 2) |x| >= 2**52, Rounding involves both doubles.
44 See the comment before lable .L2 for details.
48 mffs fp11 /* Save current FPU rounding mode. */
52 fsub fp12,fp13,fp13 /* generate 0.0 */
53 fcmpu cr7,fp0,fp13 /* if (fabs(x) > TWO52) */
54 fcmpu cr6,fp1,fp12 /* if (x > 0.0) */
56 mtfsfi 7,3 /* Set rounding mode toward -inf. */
57 fneg fp2,fp12 /* set low double to -0.0. */
59 fadd fp1,fp1,fp13 /* x+= TWO52; */
60 fsub fp1,fp1,fp13 /* x-= TWO52; */
61 fcmpu cr5,fp1,fp12 /* if (x > 0.0) */
62 mtfsf 0x01,fp11 /* restore previous rounding mode. */
64 fmr fp1,fp12 /* x must be +0.0 for the 0.0 case. */
67 bge- cr6,.L1 /* if (x < 0.0) */
68 fsub fp1,fp1,fp13 /* x-= TWO52; */
69 fadd fp1,fp1,fp13 /* x+= TWO52; */
71 mtfsf 0x01,fp11 /* restore previous rounding mode. */
75 /* The high double is > TWO52 so we need to round the low double and
76 perhaps the high double. In this case we have to round the low
77 double and handle any adjustment to the high double that may be
78 caused by rounding (up). This is complicated by the fact that the
79 high double may already be rounded and the low double may have the
80 opposite sign to compensate.This gets a bit tricky so we use the
83 tau = floor(x_high/TWO52);
88 y_low = x0 - y_high + r1;
91 fcmpu cr7,fp9,fp13 /* if (|x_low| > TWO52) */
92 fcmpu cr0,fp9,fp12 /* || (|x_low| == 0.0) */
93 fcmpu cr5,fp2,fp12 /* if (x_low > 0.0) */
94 bgelr- cr7 /* return x; */
96 mtfsfi 7,3 /* Set rounding mode toward -inf. */
97 fdiv fp8,fp1,fp13 /* x_high/TWO52 */
99 bng- cr6,.L6 /* if (x > 0.0) */
101 fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
102 bng cr5,.L4 /* if (x_low > 0.0) */
106 .L4: /* if (x_low < 0.0) */
107 fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
108 fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
110 fadd fp5,fp4,fp13 /* r1 = r1 + TWO52; */
111 fsub fp5,fp5,fp13 /* r1 = r1 - TWO52; */
113 .L6: /* if (x < 0.0) */
115 fcfid fp8,fp0 /* tau = floor(x_high/TWO52); */
116 bnl cr5,.L7 /* if (x_low < 0.0) */
120 .L7: /* if (x_low > 0.0) */
121 fsub fp3,fp1,fp8 /* x0 = x_high - tau; */
122 fadd fp4,fp2,fp8 /* x1 = x_low + tau; */
124 fsub fp5,fp4,fp13 /* r1-= TWO52; */
125 fadd fp5,fp5,fp13 /* r1+= TWO52; */
127 mtfsf 0x01,fp11 /* restore previous rounding mode. */
128 fadd fp1,fp3,fp5 /* y_high = x0 + r1; */
129 fsub fp2,fp3,fp1 /* y_low = x0 - y_high + r1; */
134 long_double_symbol (libm, __floorl, floorl)