1 /* ===-- udivsi3.c - Implement __udivsi3 -----------------------------------=== 2 * 3 * The LLVM Compiler Infrastructure 4 * 5 * This file is dual licensed under the MIT and the University of Illinois Open 6 * Source Licenses. See LICENSE.TXT for details. 7 * 8 * ===----------------------------------------------------------------------=== 9 * 10 * This file implements __udivsi3 for the compiler_rt library. 11 * 12 * ===----------------------------------------------------------------------=== 13 */ 14 15 #include "int_lib.h" 16 17 /* Returns: a / b */ 18 19 /* Translated from Figure 3-40 of The PowerPC Compiler Writer's Guide */ 20 21 ARM_EABI_FNALIAS(uidiv, udivsi3); 22 23 COMPILER_RT_ABI su_int 24 __udivsi3(su_int n, su_int d) 25 { 26 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; 27 su_int q; 28 su_int r; 29 unsigned sr; 30 /* special cases */ 31 if (d == 0) 32 return 0; /* ?! */ 33 if (n == 0) 34 return 0; 35 sr = __builtin_clz(d) - __builtin_clz(n); 36 /* 0 <= sr <= n_uword_bits - 1 or sr large */ 37 if (sr > n_uword_bits - 1) /* d > r */ 38 return 0; 39 if (sr == n_uword_bits - 1) /* d == 1 */ 40 return n; 41 ++sr; 42 /* 1 <= sr <= n_uword_bits - 1 */ 43 /* Not a special case */ 44 q = n << (n_uword_bits - sr); 45 r = n >> sr; 46 su_int carry = 0; 47 for (; sr > 0; --sr) 48 { 49 /* r:q = ((r:q) << 1) | carry */ 50 r = (r << 1) | (q >> (n_uword_bits - 1)); 51 q = (q << 1) | carry; 52 /* carry = 0; 53 * if (r.all >= d.all) 54 * { 55 * r.all -= d.all; 56 * carry = 1; 57 * } 58 */ 59 const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); 60 carry = s & 1; 61 r -= d & s; 62 } 63 q = (q << 1) | carry; 64 return q; 65 } 66
