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1 | /** @file |
2 | Compiler intrinsic for 32-bit unsigned div, ported from LLVM code. | |
3 | ||
4 | Copyright (c) 2008-2009, Apple Inc. All rights reserved. | |
5 | ||
6 | All rights reserved. This program and the accompanying materials | |
7 | are licensed and made available under the terms and conditions of the BSD License | |
8 | which accompanies this distribution. The full text of the license may be found at | |
9 | http://opensource.org/licenses/bsd-license.php | |
10 | ||
11 | THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, | |
12 | WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. | |
13 | ||
14 | **/ | |
15 | /** | |
16 | University of Illinois/NCSA | |
17 | Open Source License | |
18 | ||
19 | Copyright (c) 2003-2008 University of Illinois at Urbana-Champaign. | |
20 | All rights reserved. | |
21 | ||
22 | Developed by: | |
23 | ||
24 | LLVM Team | |
25 | ||
26 | University of Illinois at Urbana-Champaign | |
27 | ||
28 | http://llvm.org | |
29 | ||
30 | Permission is hereby granted, free of charge, to any person obtaining a copy of | |
31 | this software and associated documentation files (the "Software"), to deal with | |
32 | the Software without restriction, including without limitation the rights to | |
33 | use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies | |
34 | of the Software, and to permit persons to whom the Software is furnished to do | |
35 | so, subject to the following conditions: | |
36 | ||
37 | * Redistributions of source code must retain the above copyright notice, | |
38 | this list of conditions and the following disclaimers. | |
39 | ||
40 | * Redistributions in binary form must reproduce the above copyright notice, | |
41 | this list of conditions and the following disclaimers in the | |
42 | documentation and/or other materials provided with the distribution. | |
43 | ||
44 | * Neither the names of the LLVM Team, University of Illinois at | |
45 | Urbana-Champaign, nor the names of its contributors may be used to | |
46 | endorse or promote products derived from this Software without specific | |
47 | prior written permission. | |
48 | ||
49 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
50 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS | |
51 | FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE | |
52 | CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
53 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, | |
54 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE | |
55 | SOFTWARE. | |
56 | **/ | |
57 | ||
58 | ||
59 | #include "Llvm_int_lib.h" | |
60 | ||
61 | ||
62 | // Returns: n / d | |
63 | ||
64 | // Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide | |
65 | ||
66 | UINT32 | |
67 | __udivsi3(UINT32 n, UINT32 d) | |
68 | { | |
69 | const unsigned n_uword_bits = sizeof(UINT32) * CHAR_BIT; | |
70 | UINT32 q; | |
71 | UINT32 r; | |
72 | unsigned sr; | |
73 | ||
74 | // special cases | |
75 | if (d == 0) { | |
76 | // ASSERT (FALSE); | |
77 | return 0; // ?! | |
78 | } | |
79 | if (n == 0) | |
80 | return 0; | |
81 | ||
82 | sr = COUNT_LEADING_ZEROS(d) - COUNT_LEADING_ZEROS(n); | |
83 | // 0 <= sr <= n_uword_bits - 1 or sr large | |
84 | if (sr > n_uword_bits - 1) // d > r | |
85 | return 0; | |
86 | if (sr == n_uword_bits - 1) // d == 1 | |
87 | return n; | |
88 | ++sr; | |
89 | // 1 <= sr <= n_uword_bits - 1 | |
90 | // Not a special case | |
91 | q = n << (n_uword_bits - sr); | |
92 | r = n >> sr; | |
93 | UINT32 carry = 0; | |
94 | for (; sr > 0; --sr) | |
95 | { | |
96 | // r:q = ((r:q) << 1) | carry | |
97 | r = (r << 1) | (q >> (n_uword_bits - 1)); | |
98 | q = (q << 1) | carry; | |
99 | // carry = 0; | |
100 | // if (r.all >= d.all) | |
101 | // { | |
102 | // r.all -= d.all; | |
103 | // carry = 1; | |
104 | // } | |
105 | const INT32 s = (INT32)(d - r - 1) >> (n_uword_bits - 1); | |
106 | carry = s & 1; | |
107 | r -= d & s; | |
108 | } | |
109 | q = (q << 1) | carry; | |
110 | return q; | |
111 | } |