| 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 | |