Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 1 | /* ===-- ashrti3.c - Implement __ashrti3 -----------------------------------=== |
| 2 | * |
| 3 | * The LLVM Compiler Infrastructure |
| 4 | * |
| 5 | * This file is distributed under the University of Illinois Open Source |
| 6 | * License. See LICENSE.TXT for details. |
| 7 | * |
| 8 | * ===----------------------------------------------------------------------=== |
| 9 | * |
| 10 | * This file implements __ashrti3 for the compiler_rt library. |
| 11 | * |
| 12 | * ===----------------------------------------------------------------------=== |
| 13 | */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 14 | |
| 15 | #if __x86_64 |
| 16 | |
| 17 | #include "int_lib.h" |
| 18 | |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 19 | /* Returns: arithmetic a >> b */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 20 | |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 21 | /* Precondition: 0 <= b < bits_in_tword */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 22 | |
| 23 | ti_int |
| 24 | __ashrti3(ti_int a, si_int b) |
| 25 | { |
| 26 | const int bits_in_dword = (int)(sizeof(di_int) * CHAR_BIT); |
| 27 | twords input; |
| 28 | twords result; |
| 29 | input.all = a; |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 30 | if (b & bits_in_dword) /* bits_in_dword <= b < bits_in_tword */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 31 | { |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 32 | /* result.high = input.high < 0 ? -1 : 0 */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 33 | result.high = input.high >> (bits_in_dword - 1); |
| 34 | result.low = input.high >> (b - bits_in_dword); |
| 35 | } |
Edward O'Callaghan | 2bf6272 | 2009-08-05 04:02:56 +0000 | [diff] [blame^] | 36 | else /* 0 <= b < bits_in_dword */ |
Daniel Dunbar | b3a6901 | 2009-06-26 16:47:03 +0000 | [diff] [blame] | 37 | { |
| 38 | if (b == 0) |
| 39 | return a; |
| 40 | result.high = input.high >> b; |
| 41 | result.low = (input.high << (bits_in_dword - b)) | (input.low >> b); |
| 42 | } |
| 43 | return result.all; |
| 44 | } |
| 45 | |
| 46 | #endif |