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 /* This function should not call __divsi3! */ 24 COMPILER_RT_ABI su_int 25 __udivsi3(su_int n, su_int d) 26 { 27 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; 28 su_int q; 29 su_int r; 30 unsigned sr; 31 /* special cases */ 32 if (d == 0) 33 return 0; /* ?! */ 34 if (n == 0) 35 return 0; 36 sr = __builtin_clz(d) - __builtin_clz(n); 37 /* 0 <= sr <= n_uword_bits - 1 or sr large */ 38 if (sr > n_uword_bits - 1) /* d > r */ 39 return 0; 40 if (sr == n_uword_bits - 1) /* d == 1 */ 41 return n; 42 ++sr; 43 /* 1 <= sr <= n_uword_bits - 1 */ 44 /* Not a special case */ 45 q = n << (n_uword_bits - sr); 46 r = n >> sr; 47 su_int carry = 0; 48 for (; sr > 0; --sr) 49 { 50 /* r:q = ((r:q) << 1) | carry */ 51 r = (r << 1) | (q >> (n_uword_bits - 1)); 52 q = (q << 1) | carry; 53 /* carry = 0; 54 * if (r.all >= d.all) 55 * { 56 * r.all -= d.all; 57 * carry = 1; 58 * } 59 */ 60 const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); 61 carry = s & 1; 62 r -= d & s; 63 } 64 q = (q << 1) | carry; 65 return q; 66 } 67
