| 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 | byte buffer_use_count[BUFSIZE]; |
| 16 | |
| 17 | proctype switcher() |
| 18 | { |
| 19 | int prev_off, new_off, tmp_commit; |
| 20 | int size; |
| 21 | |
| 22 | cmpxchg_loop: |
| 23 | atomic { |
| 24 | prev_off = write_off; |
| 25 | size = SUBBUF_SIZE - (prev_off % SUBBUF_SIZE); |
| 26 | new_off = prev_off + size; |
| 27 | if |
| 28 | :: new_off - read_off > BUFSIZE -> |
| 29 | goto not_needed; |
| 30 | :: else -> skip |
| 31 | fi; |
| 32 | } |
| 33 | atomic { |
| 34 | if |
| 35 | :: prev_off != write_off -> goto cmpxchg_loop |
| 36 | :: else -> write_off = new_off; |
| 37 | fi; |
| 38 | } |
| 39 | |
| 40 | atomic { |
| 41 | tmp_commit = commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] + size; |
| 42 | commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] = tmp_commit; |
| 43 | if |
| 44 | :: tmp_commit % SUBBUF_SIZE == 0 -> deliver++ |
| 45 | :: else -> skip |
| 46 | fi; |
| 47 | } |
| 48 | not_needed: |
| 49 | skip; |
| 50 | } |
| 51 | |
| 52 | proctype tracer(byte size) |
| 53 | { |
| 54 | int prev_off, new_off, tmp_commit; |
| 55 | int i; |
| 56 | int j; |
| 57 | |
| 58 | cmpxchg_loop: |
| 59 | atomic { |
| 60 | prev_off = write_off; |
| 61 | new_off = prev_off + size; |
| 62 | } |
| 63 | atomic { |
| 64 | if |
| 65 | :: new_off - read_off > BUFSIZE -> goto lost |
| 66 | :: else -> skip |
| 67 | fi; |
| 68 | } |
| 69 | atomic { |
| 70 | if |
| 71 | :: prev_off != write_off -> goto cmpxchg_loop |
| 72 | :: else -> write_off = new_off; |
| 73 | fi; |
| 74 | i = 0; |
| 75 | do |
| 76 | :: i < size -> |
| 77 | buffer_use_count[(prev_off + i) % BUFSIZE] |
| 78 | = buffer_use_count[(prev_off + i) % BUFSIZE] + 1; |
| 79 | i++ |
| 80 | :: i >= size -> break |
| 81 | od; |
| 82 | } |
| 83 | do |
| 84 | :: j < BUFSIZE -> |
| 85 | assert(buffer_use_count[j] < 2); |
| 86 | j++ |
| 87 | :: j >= BUFSIZE -> break |
| 88 | od; |
| 89 | |
| 90 | |
| 91 | |
| 92 | // writing to buffer... |
| 93 | |
| 94 | atomic { |
| 95 | i = 0; |
| 96 | do |
| 97 | :: i < size -> |
| 98 | buffer_use_count[(prev_off + i) % BUFSIZE] |
| 99 | = buffer_use_count[(prev_off + i) % BUFSIZE] - 1; |
| 100 | i++ |
| 101 | :: i >= size -> break |
| 102 | od; |
| 103 | tmp_commit = commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] + size; |
| 104 | commit_count[(prev_off % BUFSIZE) / SUBBUF_SIZE] = tmp_commit; |
| 105 | if |
| 106 | :: tmp_commit % SUBBUF_SIZE == 0 -> deliver++ |
| 107 | :: else -> skip |
| 108 | fi; |
| 109 | } |
| 110 | goto end; |
| 111 | lost: |
| 112 | events_lost++; |
| 113 | end: |
| 114 | refcount = refcount - 1; |
| 115 | } |
| 116 | |
| 117 | proctype reader() |
| 118 | { |
| 119 | int i; |
| 120 | int j; |
| 121 | //atomic { |
| 122 | // do |
| 123 | // :: (deliver == (NUMPROCS - events_lost) / SUBBUF_SIZE) -> break; |
| 124 | // od; |
| 125 | //} |
| 126 | do |
| 127 | :: (write_off / SUBBUF_SIZE) - (read_off / SUBBUF_SIZE) > 0 && commit_count[(read_off % BUFSIZE) / SUBBUF_SIZE] % SUBBUF_SIZE == 0 -> |
| 128 | atomic { |
| 129 | i = 0; |
| 130 | do |
| 131 | :: i < SUBBUF_SIZE -> |
| 132 | buffer_use_count[(read_off + i) % BUFSIZE] |
| 133 | = buffer_use_count[(read_off + i) % BUFSIZE] + 1; |
| 134 | i++ |
| 135 | :: i >= SUBBUF_SIZE -> break |
| 136 | od; |
| 137 | } |
| 138 | j = 0; |
| 139 | do |
| 140 | :: j < BUFSIZE -> |
| 141 | assert(buffer_use_count[j] < 2); |
| 142 | j++ |
| 143 | :: j >= BUFSIZE -> break |
| 144 | od; |
| 145 | |
| 146 | // reading from buffer... |
| 147 | |
| 148 | atomic { |
| 149 | i = 0; |
| 150 | do |
| 151 | :: i < SUBBUF_SIZE -> |
| 152 | buffer_use_count[(read_off + i) % BUFSIZE] |
| 153 | = buffer_use_count[(read_off + i) % BUFSIZE] - 1; |
| 154 | i++ |
| 155 | :: i >= SUBBUF_SIZE -> break |
| 156 | od; |
| 157 | read_off = read_off + SUBBUF_SIZE; |
| 158 | } |
| 159 | :: read_off >= (NUMPROCS - events_lost) -> break; |
| 160 | od; |
| 161 | } |
| 162 | |
| 163 | proctype cleaner() |
| 164 | { |
| 165 | atomic { |
| 166 | do |
| 167 | :: refcount == 0 -> |
| 168 | run switcher(); |
| 169 | break; |
| 170 | od; |
| 171 | } |
| 172 | } |
| 173 | |
| 174 | init { |
| 175 | int i = 0; |
| 176 | int j = 0; |
| 177 | int sum = 0; |
| 178 | int commit_sum = 0; |
| 179 | |
| 180 | atomic { |
| 181 | i = 0; |
| 182 | do |
| 183 | :: i < NR_SUBBUFS -> |
| 184 | commit_count[i] = 0; |
| 185 | i++ |
| 186 | :: i >= NR_SUBBUFS -> break |
| 187 | od; |
| 188 | i = 0; |
| 189 | do |
| 190 | :: i < BUFSIZE -> |
| 191 | buffer_use_count[i] = 0; |
| 192 | i++ |
| 193 | :: i >= BUFSIZE -> break |
| 194 | od; |
| 195 | run reader(); |
| 196 | run cleaner(); |
| 197 | i = 0; |
| 198 | do |
| 199 | :: i < NUMPROCS -> |
| 200 | refcount = refcount + 1; |
| 201 | run tracer(1); |
| 202 | i++ |
| 203 | :: i >= NUMPROCS -> break |
| 204 | od; |
| 205 | run switcher(); |
| 206 | } |
| 207 | atomic { |
| 208 | assert(write_off - read_off >= 0); |
| 209 | j = 0; |
| 210 | commit_sum = 0; |
| 211 | do |
| 212 | :: j < NR_SUBBUFS -> |
| 213 | commit_sum = commit_sum + commit_count[j]; |
| 214 | j++ |
| 215 | :: j >= NR_SUBBUFS -> break |
| 216 | od; |
| 217 | assert(commit_sum <= write_off); |
| 218 | j = 0; |
| 219 | do |
| 220 | :: j < BUFSIZE -> |
| 221 | assert(buffer_use_count[j] < 2); |
| 222 | j++ |
| 223 | :: j >= BUFSIZE -> break |
| 224 | od; |
| 225 | |
| 226 | //assert(events_lost == 0); |
| 227 | } |
| 228 | } |