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 /* This function should not call __divsi3! */ 22 COMPILER_RT_ABI su_int 23 __udivsi3(su_int n, su_int d) 24 { 25 const unsigned n_uword_bits = sizeof(su_int) * CHAR_BIT; 26 su_int q; 27 su_int r; 28 unsigned sr; 29 /* special cases */ 30 if (d == 0) 31 return 0; /* ?! */ 32 if (n == 0) 33 return 0; 34 sr = __builtin_clz(d) - __builtin_clz(n); 35 /* 0 <= sr <= n_uword_bits - 1 or sr large */ 36 if (sr > n_uword_bits - 1) /* d > r */ 37 return 0; 38 if (sr == n_uword_bits - 1) /* d == 1 */ 39 return n; 40 ++sr; 41 /* 1 <= sr <= n_uword_bits - 1 */ 42 /* Not a special case */ 43 q = n << (n_uword_bits - sr); 44 r = n >> sr; 45 su_int carry = 0; 46 for (; sr > 0; --sr) 47 { 48 /* r:q = ((r:q) << 1) | carry */ 49 r = (r << 1) | (q >> (n_uword_bits - 1)); 50 q = (q << 1) | carry; 51 /* carry = 0; 52 * if (r.all >= d.all) 53 * { 54 * r.all -= d.all; 55 * carry = 1; 56 * } 57 */ 58 const si_int s = (si_int)(d - r - 1) >> (n_uword_bits - 1); 59 carry = s & 1; 60 r -= d & s; 61 } 62 q = (q << 1) | carry; 63 return q; 64 } 65 66 #if defined(__ARM_EABI__) 67 AEABI_RTABI su_int __aeabi_uidiv(su_int n, su_int d) COMPILER_RT_ALIAS(__udivsi3); 68 #endif 69