137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan/* ===-- udivsi3.c - Implement __udivsi3 -----------------------------------=== 237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * The LLVM Compiler Infrastructure 437a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 59ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant * This file is dual licensed under the MIT and the University of Illinois Open 69ad441ffec97db647fee3725b3424284fb913e14Howard Hinnant * Source Licenses. See LICENSE.TXT for details. 737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * ===----------------------------------------------------------------------=== 937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 1037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * This file implements __udivsi3 for the compiler_rt library. 1137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * 1237a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * ===----------------------------------------------------------------------=== 1337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan */ 14b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 15b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar#include "int_lib.h" 16b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 1737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan/* Returns: a / b */ 18b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 1937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan/* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */ 20b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar 210193b74976719b8aea4cb8874ba36b75836a8d6eChandler CarruthARM_EABI_FNALIAS(uidiv, udivsi3) 2237b97d1cf4501b94347e0b4e880f4b25825a289fAnton Korobeynikov 23cd25a5ffd64c5be8d4d838d21fd252ce246b898cStephen Canon/* This function should not call __divsi3! */ 241c5f89b1dd741135a4007ab577723d422f421eecAnton KorobeynikovCOMPILER_RT_ABI su_int 25b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar__udivsi3(su_int n, su_int d) 26b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar{ 27b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; 28b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar su_int q; 29b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar su_int r; 30b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar unsigned sr; 3137a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* special cases */ 32b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar if (d == 0) 3337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan return 0; /* ?! */ 34b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar if (n == 0) 35b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return 0; 36b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar sr = __builtin_clz(d) - __builtin_clz(n); 3737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* 0 <= sr <= n_uword_bits - 1 or sr large */ 3837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan if (sr > n_uword_bits - 1) /* d > r */ 39b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return 0; 4037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan if (sr == n_uword_bits - 1) /* d == 1 */ 41b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return n; 42b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar ++sr; 4337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* 1 <= sr <= n_uword_bits - 1 */ 4437a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* Not a special case */ 45b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar q = n << (n_uword_bits - sr); 46b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar r = n >> sr; 47b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar su_int carry = 0; 48b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar for (; sr > 0; --sr) 49b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar { 5037a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* r:q = ((r:q) << 1) | carry */ 51b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar r = (r << 1) | (q >> (n_uword_bits - 1)); 52b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar q = (q << 1) | carry; 5337a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan /* carry = 0; 5437a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * if (r.all >= d.all) 5537a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * { 5637a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * r.all -= d.all; 5737a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * carry = 1; 5837a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan * } 5937a6a455466e5b197311771a777ab241e471ed8aEdward O'Callaghan */ 60b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); 61b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar carry = s & 1; 62b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar r -= d & s; 63b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar } 64b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar q = (q << 1) | carry; 65b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar return q; 66b3a6901e66f55b35aa9e01bcb24134e6a65ea004Daniel Dunbar} 67