1 /* Generic unsigned 32 bit division implementation.
2 Copyright (C) 2009-2020 Free Software Foundation, Inc.
3 Contributed by Embecosm on behalf of Adapteva, Inc.
4
5 This file is part of GCC.
6
7 This file is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by the
9 Free Software Foundation; either version 3, or (at your option) any
10 later version.
11
12 This file is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 General Public License for more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 typedef union { unsigned int i; float f; } fu;
27
28 unsigned int __udivsi3 (unsigned int a, unsigned int b);
29
30 unsigned int
__udivsi3(unsigned int a,unsigned int b)31 __udivsi3 (unsigned int a, unsigned int b)
32 {
33 unsigned int d, t, s0, s1, s2, r0, r1;
34 fu u0, u1, u2, u1b, u2b;
35
36 if (b > a)
37 return 0;
38
39 /* Compute difference in number of bits in S0. */
40 u0.i = 0x40000000;
41 u1b.i = u2b.i = u0.i;
42 u1.i = a;
43 u2.i = b;
44 u1.i = a | u0.i;
45 t = 0x4b800000 | ((a >> 23) & 0xffff);
46 if (a >> 23)
47 {
48 u1.i = t;
49 u1b.i = 0x4b800000;
50 }
51 u2.i = b | u0.i;
52 t = 0x4b800000 | ((b >> 23) & 0xffff);
53 if (b >> 23)
54 {
55 u2.i = t;
56 u2b.i = 0x4b800000;
57 }
58 u1.f = u1.f - u1b.f;
59 u2.f = u2.f - u2b.f;
60 s1 = u1.i >> 23;
61 s2 = u2.i >> 23;
62 s0 = s1 - s2;
63
64 b <<= s0;
65 d = b - 1;
66
67 r0 = 1 << s0;
68 r1 = 0;
69 t = a - b;
70 if (t <= a)
71 {
72 a = t;
73 r1 = r0;
74 }
75
76 #define STEP(n) case n: a += a; t = a - d; if (t <= a) a = t;
77 switch (s0)
78 {
79 STEP (31)
80 STEP (30)
81 STEP (29)
82 STEP (28)
83 STEP (27)
84 STEP (26)
85 STEP (25)
86 STEP (24)
87 STEP (23)
88 STEP (22)
89 STEP (21)
90 STEP (20)
91 STEP (19)
92 STEP (18)
93 STEP (17)
94 STEP (16)
95 STEP (15)
96 STEP (14)
97 STEP (13)
98 STEP (12)
99 STEP (11)
100 STEP (10)
101 STEP (9)
102 STEP (8)
103 STEP (7)
104 STEP (6)
105 STEP (5)
106 STEP (4)
107 STEP (3)
108 STEP (2)
109 STEP (1)
110 case 0: ;
111 }
112 r0 = r1 | (r0-1 & a);
113 return r0;
114 }
115