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5ce98c3f | 1 | /* llroundf function. PowerPC64 version. |
b168057a | 2 | Copyright (C) 2004-2015 Free Software Foundation, Inc. |
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3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Lesser General Public | |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Lesser General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Lesser General Public | |
59ba27a6 PE |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ | |
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18 | |
19 | #include <sysdep.h> | |
20 | ||
21 | .section ".toc","aw" | |
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22 | .LC0: /* 2^23 */ |
23 | .tc FD_41600000_0[TC],0x4160000000000000 | |
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24 | .LC1: /* 0.5 */ |
25 | .tc FD_3fe00000_0[TC],0x3fe0000000000000 | |
26 | .section ".text" | |
9c84384c | 27 | |
5ce98c3f | 28 | /* long long [r3] llroundf (float x [fp1]) |
9c84384c | 29 | IEEE 1003.1 llroundf function. IEEE specifies "roundf to the nearest |
f964490f RM |
30 | integer value, rounding halfway cases away from zero, regardless of |
31 | the current rounding mode." However PowerPC Architecture defines | |
9c84384c JM |
32 | "roundf to Nearest" as "Choose the best approximation. In case of a |
33 | tie, choose the one that is even (least significant bit o).". | |
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34 | So we can't use the PowerPC "round to Nearest" mode. Instead we set |
35 | "round toward Zero" mode and round by adding +-0.5 before rounding | |
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36 | to the integer value. |
37 | ||
38 | It is necessary to detect when x is (+-)0x1.fffffffffffffp-2 | |
39 | because adding +-0.5 in this case will cause an erroneous shift, | |
40 | carry and round. We simply return 0 if 0.5 > x > -0.5. Likewise | |
41 | if x is and odd number between +-(2^23 and 2^24-1) a shift and | |
42 | carry will erroneously round if biased with +-0.5. Therefore if x | |
43 | is greater/less than +-2^23 we don't need to bias the number with | |
44 | +-0.5. */ | |
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45 | |
46 | ENTRY (__llroundf) | |
d7d06f79 | 47 | CALL_MCOUNT 0 |
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48 | lfd fp9,.LC0@toc(2) /* Load 2^23 into fpr9. */ |
49 | lfd fp10,.LC1@toc(2)/* Load 0.5 into fpr10. */ | |
50 | fabs fp2,fp1 /* Get the absolute value of x. */ | |
51 | fsub fp12,fp10,fp10 /* Compute 0.0 into fp12. */ | |
52 | fcmpu cr6,fp2,fp10 /* if |x| < 0.5 */ | |
9ea8bfec UD |
53 | fcmpu cr7,fp2,fp9 /* if |x| >= 2^23 */ |
54 | fcmpu cr1,fp1,fp12 /* x is negative? x < 0.0 */ | |
c1e6b459 | 55 | blt- cr6,.Lretzero /* 0.5 > x < -0.5 so just return 0. */ |
9ea8bfec | 56 | bge- cr7,.Lnobias /* 2^23 > x < -2^23 just convert with no bias. */ |
c1e6b459 | 57 | fadd fp3,fp2,fp10 /* |x|+=0.5 bias to prepare to round. */ |
9ea8bfec | 58 | bge cr1,.Lconvert /* x is positive so don't negate x. */ |
c1e6b459 UD |
59 | fnabs fp3,fp3 /* -(|x|+=0.5) */ |
60 | .Lconvert: | |
61 | fctidz fp4,fp3 /* Convert to Integer double word round toward 0. */ | |
62 | stfd fp4,-16(r1) | |
63 | nop | |
64 | nop | |
5ce98c3f | 65 | nop |
c1e6b459 UD |
66 | ld r3,-16(r1) /* Load return as integer. */ |
67 | .Lout: | |
5ce98c3f | 68 | blr |
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69 | .Lretzero: /* 0.5 > x > -0.5 */ |
70 | li r3,0 /* return 0. */ | |
71 | b .Lout | |
72 | .Lnobias: | |
73 | fmr fp3,fp1 | |
74 | b .Lconvert | |
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75 | END (__llroundf) |
76 | ||
77 | strong_alias (__llroundf, __lroundf) | |
78 | weak_alias (__llroundf, llroundf) | |
79 | weak_alias (__lroundf, lroundf) | |
80 |