Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 1 | /*===-- ashrdi3.c - Implement __ashrdi3 -----------------------------------=== |
| 2 | * |
| 3 | * The LLVM Compiler Infrastructure |
| 4 | * |
Howard Hinnant | 9ad441f | 2010-11-16 22:13:33 +0000 | [diff] [blame^] | 5 | * This file is dual licensed under the MIT and the University of Illinois Open |
| 6 | * Source Licenses. See LICENSE.TXT for details. |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | * |
| 10 | * This file implements __ashrdi3 for the compiler_rt library. |
| 11 | * |
| 12 | * ===----------------------------------------------------------------------=== |
| 13 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 14 | |
| 15 | #include "int_lib.h" |
| 16 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 17 | /* Returns: arithmetic a >> b */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 18 | |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 19 | /* Precondition: 0 <= b < bits_in_dword */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 20 | |
| 21 | di_int |
| 22 | __ashrdi3(di_int a, si_int b) |
| 23 | { |
| 24 | const int bits_in_word = (int)(sizeof(si_int) * CHAR_BIT); |
| 25 | dwords input; |
| 26 | dwords result; |
| 27 | input.all = a; |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 28 | if (b & bits_in_word) /* bits_in_word <= b < bits_in_dword */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 29 | { |
Edward O'Callaghan | 8bf1e09 | 2009-08-09 18:41:02 +0000 | [diff] [blame] | 30 | /* result.s.high = input.s.high < 0 ? -1 : 0 */ |
| 31 | result.s.high = input.s.high >> (bits_in_word - 1); |
| 32 | result.s.low = input.s.high >> (b - bits_in_word); |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 33 | } |
Edward O'Callaghan | 37a6a45 | 2009-08-07 20:30:09 +0000 | [diff] [blame] | 34 | else /* 0 <= b < bits_in_word */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 35 | { |
| 36 | if (b == 0) |
| 37 | return a; |
Edward O'Callaghan | 8bf1e09 | 2009-08-09 18:41:02 +0000 | [diff] [blame] | 38 | result.s.high = input.s.high >> b; |
| 39 | result.s.low = (input.s.high << (bits_in_word - b)) | (input.s.low >> b); |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 40 | } |
| 41 | return result.all; |
| 42 | } |