| 1 | //#define NUMPROCS 5 |
| 2 | #define NUMPROCS 4 |
| 3 | #define BUFSIZE 4 |
| 4 | #define NR_SUBBUFS 2 |
| 5 | #define SUBBUF_SIZE (BUFSIZE / NR_SUBBUFS) |
| 6 | |
| 7 | byte write_off = 0; |
| 8 | byte read_off = 0; |
| 9 | byte events_lost = 0; |
| 10 | byte deliver = 0; // Number of subbuffers delivered |
| 11 | byte refcount = 0; |
| 12 | |
| 13 | byte commit_count[NR_SUBBUFS]; |
| 14 | |
| 15 | proctype switcher() |
| 16 | { |
| 17 | int prev_off, new_off, tmp_commit; |
| 18 | int size; |
| 19 | |
| 20 | cmpxchg_loop: |
| 21 | atomic { |
| 22 | prev_off = write_off; |
| 23 | size = SUBBUF_SIZE - (prev_off % SUBBUF_SIZE); |
| 24 | new_off = prev_off + size; |
| 25 | if |
| 26 | :: new_off - read_off > BUFSIZE -> |
| 27 | goto not_needed; |
| 28 | :: else -> skip |
| 29 | fi; |
| 30 | } |
| 31 | atomic { |
| 32 | if |
| 33 | :: prev_off != write_off -> goto cmpxchg_loop |
| 34 | :: else -> write_off = new_off; |
| 35 | fi; |
| 36 | } |
| 37 | |
| 38 | atomic { |
| 39 | tmp_commit = commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] + size; |
| 40 | commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] = tmp_commit; |
| 41 | if |
| 42 | :: tmp_commit % SUBBUF_SIZE == 0 -> deliver++ |
| 43 | :: else -> skip |
| 44 | fi; |
| 45 | } |
| 46 | not_needed: |
| 47 | skip; |
| 48 | } |
| 49 | |
| 50 | proctype tracer(byte size) |
| 51 | { |
| 52 | int prev_off, new_off, tmp_commit; |
| 53 | |
| 54 | cmpxchg_loop: |
| 55 | atomic { |
| 56 | prev_off = write_off; |
| 57 | new_off = prev_off + size; |
| 58 | } |
| 59 | atomic { |
| 60 | if |
| 61 | :: new_off - read_off > BUFSIZE -> goto lost |
| 62 | :: else -> skip |
| 63 | fi; |
| 64 | } |
| 65 | atomic { |
| 66 | if |
| 67 | :: prev_off != write_off -> goto cmpxchg_loop |
| 68 | :: else -> write_off = new_off; |
| 69 | fi; |
| 70 | } |
| 71 | |
| 72 | atomic { |
| 73 | tmp_commit = commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] + size; |
| 74 | commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] = tmp_commit; |
| 75 | if |
| 76 | :: tmp_commit % SUBBUF_SIZE == 0 -> deliver++ |
| 77 | :: else -> skip |
| 78 | fi; |
| 79 | } |
| 80 | goto end; |
| 81 | lost: |
| 82 | events_lost++; |
| 83 | end: |
| 84 | refcount = refcount - 1; |
| 85 | } |
| 86 | |
| 87 | proctype reader() |
| 88 | { |
| 89 | //atomic { |
| 90 | // do |
| 91 | // :: (deliver == (NUMPROCS - events_lost) / SUBBUF_SIZE) -> break; |
| 92 | // od; |
| 93 | //} |
| 94 | // made atomic to use less memory. Not really true. |
| 95 | atomic { |
| 96 | do |
| 97 | :: write_off - read_off >= SUBBUF_SIZE && commit_count[(read_off % BUFSIZE) / SUBBUF_SIZE] % SUBBUF_SIZE == 0 -> |
| 98 | read_off = read_off + SUBBUF_SIZE; |
| 99 | :: read_off >= (NUMPROCS - events_lost) -> break; |
| 100 | od; |
| 101 | } |
| 102 | } |
| 103 | |
| 104 | proctype cleaner() |
| 105 | { |
| 106 | atomic { |
| 107 | do |
| 108 | :: refcount == 0 -> |
| 109 | run switcher(); |
| 110 | break; |
| 111 | od; |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | init { |
| 116 | int i = 0; |
| 117 | int j = 0; |
| 118 | int sum = 0; |
| 119 | int commit_sum = 0; |
| 120 | |
| 121 | atomic { |
| 122 | i = 0; |
| 123 | do |
| 124 | :: i < NR_SUBBUFS -> |
| 125 | commit_count[i] = 0; |
| 126 | i++ |
| 127 | :: i >= NR_SUBBUFS -> break |
| 128 | od; |
| 129 | run reader(); |
| 130 | run cleaner(); |
| 131 | i = 0; |
| 132 | do |
| 133 | :: i < NUMPROCS -> |
| 134 | refcount = refcount + 1; |
| 135 | run tracer(1); |
| 136 | i++ |
| 137 | :: i >= NUMPROCS -> break |
| 138 | od; |
| 139 | run switcher(); |
| 140 | } |
| 141 | atomic { |
| 142 | assert(write_off - read_off >= 0); |
| 143 | j = 0; |
| 144 | commit_sum = 0; |
| 145 | do |
| 146 | :: j < NR_SUBBUFS -> |
| 147 | commit_sum = commit_sum + commit_count[j]; |
| 148 | j++ |
| 149 | :: j >= NR_SUBBUFS -> break |
| 150 | od; |
| 151 | assert(commit_sum <= write_off); |
| 152 | //assert(events_lost == 0); |
| 153 | } |
| 154 | } |