projects / urcu.git / blame
| Commit | Line | Data |
|---|---|---|
| 656c7dc1 MD |
1 | /* |
| 2 | * This program is free software; you can redistribute it and/or modify | |
| 3 | * it under the terms of the GNU General Public License as published by | |
| 4 | * the Free Software Foundation; either version 2 of the License, or | |
| 5 | * (at your option) any later version. | |
| 6 | * | |
| 7 | * This program is distributed in the hope that it will be useful, | |
| 8 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 10 | * GNU General Public License for more details. | |
| 11 | * | |
| 12 | * You should have received a copy of the GNU General Public License | |
| 13 | * along with this program; if not, write to the Free Software | |
| 14 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
| 15 | * | |
| 16 | * Copyright (c) 2009 Mathieu Desnoyers | |
| 17 | */ | |
| 18 | ||
| 19 | /* 16 CPUs max (byte has 8 bits, divided in two) */ | |
| 20 | ||
| 21 | #ifndef CONFIG_BITS_PER_BYTE | |
| 22 | #define BITS_PER_BYTE 8 | |
| 23 | #else | |
| 24 | #define BITS_PER_BYTE CONFIG_BITS_PER_BYTE | |
| 25 | #endif | |
| 26 | ||
| 27 | #define HBPB (BITS_PER_BYTE / 2) /* 4 */ | |
| 28 | #define HMASK ((1 << HBPB) - 1) /* 0x0F */ | |
| 29 | ||
| 30 | /* for byte type */ | |
| 31 | #define LOW_HALF(val) ((val) & HMASK) | |
| 32 | #define LOW_HALF_INC 1 | |
| 33 | ||
| 34 | #define HIGH_HALF(val) ((val) & (HMASK << HBPB)) | |
| 35 | #define HIGH_HALF_INC (1 << HBPB) | |
| 36 | ||
| 37 | byte lock = 0; | |
| 38 | byte refcount = 0; | |
| 39 | ||
| 40 | inline spin_lock(lock, ticket) | |
| 41 | { | |
| 42 | atomic { | |
| 43 | ticket = HIGH_HALF(lock) >> HBPB; | |
| 44 | lock = lock + HIGH_HALF_INC; /* overflow expected */ | |
| 45 | } | |
| 46 | ||
| d149fa02 MD |
47 | /* busy-wait */ |
| 48 | LOW_HALF(lock) == ticket -> 1; | |
| 656c7dc1 MD |
49 | } |
| 50 | ||
| 51 | inline spin_unlock(lock) | |
| 52 | { | |
| 53 | lock = HIGH_HALF(lock) | LOW_HALF(lock + LOW_HALF_INC); | |
| 54 | } | |
| 55 | ||
| 56 | proctype proc_X() | |
| 57 | { | |
| 58 | byte ticket; | |
| 59 | ||
| 60 | do | |
| d149fa02 | 61 | :: spin_lock(lock, ticket); |
| 656c7dc1 MD |
62 | refcount = refcount + 1; |
| 63 | refcount = refcount - 1; | |
| 64 | spin_unlock(lock); | |
| 65 | od; | |
| 66 | } | |
| 67 | ||
| 68 | init | |
| 69 | { | |
| 70 | run proc_X(); | |
| 71 | run proc_X(); | |
| 72 | run proc_X(); | |
| 73 | run proc_X(); | |
| 74 | run proc_X(); | |
| 75 | } |