1/* Generic signed 32 bit division implementation. 2 Copyright (C) 2009-2020 Free Software Foundation, Inc. 3 Contributed by Embecosm on behalf of Adapteva, Inc. 4 5This file is part of GCC. 6 7This file is free software; you can redistribute it and/or modify it 8under the terms of the GNU General Public License as published by the 9Free Software Foundation; either version 3, or (at your option) any 10later version. 11 12This file is distributed in the hope that it will be useful, but 13WITHOUT ANY WARRANTY; without even the implied warranty of 14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15General Public License for more details. 16 17Under Section 7 of GPL version 3, you are granted additional 18permissions described in the GCC Runtime Library Exception, version 193.1, as published by the Free Software Foundation. 20 21You should have received a copy of the GNU General Public License and 22a copy of the GCC Runtime Library Exception along with this program; 23see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24<http://www.gnu.org/licenses/>. */ 25 26typedef union { unsigned int i; float f; } fu; 27 28/* Although the semantics of the function ask for signed / unsigned inputs, 29 for the actual implementation we use unsigned numbers. */ 30unsigned int __divsi3 (unsigned int a, unsigned int b); 31 32unsigned int 33__divsi3 (unsigned int a, unsigned int b) 34{ 35 unsigned int sign = (int) (a ^ b) >> 31; 36 unsigned int d, t, s0, s1, s2, r0, r1; 37 fu u0, u1, u2, u1b, u2b; 38 39 a = abs (a); 40 b = abs (b); 41 42 if (b > a) 43 return 0; 44 45 /* Compute difference in number of bits in S0. */ 46 u0.i = 0x40000000; 47 u1b.i = u2b.i = u0.i; 48 u1.i = a; 49 u2.i = b; 50 u1.i = a | u0.i; 51 t = 0x4b800000 | ((a >> 23) & 0xffff); 52 if (a >> 23) 53 { 54 u1.i = t; 55 u1b.i = 0x4b800000; 56 } 57 u2.i = b | u0.i; 58 t = 0x4b800000 | ((b >> 23) & 0xffff); 59 if (b >> 23) 60 { 61 u2.i = t; 62 u2b.i = 0x4b800000; 63 } 64 u1.f = u1.f - u1b.f; 65 u2.f = u2.f - u2b.f; 66 s1 = u1.i >> 23; 67 s2 = u2.i >> 23; 68 s0 = s1 - s2; 69 70 b <<= s0; 71 d = b - 1; 72 73 r0 = 1 << s0; 74 r1 = 0; 75 t = a - b; 76 if (t <= a) 77 { 78 a = t; 79 r1 = r0; 80 } 81 82#define STEP(n) case n: a += a; t = a - d; if (t <= a) a = t; 83 switch (s0) 84 { 85 STEP (31) 86 STEP (30) 87 STEP (29) 88 STEP (28) 89 STEP (27) 90 STEP (26) 91 STEP (25) 92 STEP (24) 93 STEP (23) 94 STEP (22) 95 STEP (21) 96 STEP (20) 97 STEP (19) 98 STEP (18) 99 STEP (17) 100 STEP (16) 101 STEP (15) 102 STEP (14) 103 STEP (13) 104 STEP (12) 105 STEP (11) 106 STEP (10) 107 STEP (9) 108 STEP (8) 109 STEP (7) 110 STEP (6) 111 STEP (5) 112 STEP (4) 113 STEP (3) 114 STEP (2) 115 STEP (1) 116 case 0: ; 117 } 118 r0 = r1 | (r0-1 & a); 119 return (r0 ^ sign) - sign; 120} 121