037global_variables.cc - mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

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generated by cgit-pink 1.4.1-2-gfad0 (git 2.36.2.497.gbbea4dcf42) at 2024-10-21 20:09:16 +0000

*circular-buffer <- put-index *circular-buffer, full, *empty 137 # mark its slot as empty 138 full <- add full, 1 139 { 140 # wrap full around to 0 if necessary 141 len:num <- length *circular-buffer 142 at-end?:bool <- greater-or-equal full, len 143 break-unless at-end? 144 full <- copy 0 145 } 146 # write back 147 *chan <- put *chan, first-full:offset, full 148 #? $print [relinquishing lock after reading], 10/newline 149 reset lock 150 ] 151 152 # todo: create a notion of iterator and iterable so we can read/write whole 153 # aggregates (arrays, lists, ..) of _elems at once. 154 155 scenario channel-initialization [ 156 run [ 157 local-scope 158 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 159 chan:&:channel:num <- get *source, chan:offset 160 10:num/raw <- get *chan, first-full:offset 161 11:num/raw <- get *chan, first-free:offset 162 ] 163 memory-should-contain [ 164 10 <- 0 # first-full 165 11 <- 0 # first-free 166 ] 167 ] 168 169 scenario channel-write-increments-free [ 170 local-scope 171 _, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 172 run [ 173 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 174 chan:&:channel:num <- get *sink, chan:offset 175 10:num/raw <- get *chan, first-full:offset 176 11:num/raw <- get *chan, first-free:offset 177 ] 178 memory-should-contain [ 179 10 <- 0 # first-full 180 11 <- 1 # first-free 181 ] 182 ] 183 184 scenario channel-read-increments-full [ 185 local-scope 186 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 187 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 188 run [ 189 _, _, <a href='075channel.mu.html#L36'>source</a> <- read <a href='075channel.mu.html#L36'>source</a> 190 chan:&:channel:num <- get *source, chan:offset 191 10:num/raw <- get *chan, first-full:offset 192 11:num/raw <- get *chan, first-free:offset 193 ] 194 memory-should-contain [ 195 10 <- 1 # first-full 196 11 <- 1 # first-free 197 ] 198 ] 199 200 scenario channel-wrap [ 201 local-scope 202 # channel with just 1 slot 203 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 1/capacity 204 chan:&:channel:num <- get *source, chan:offset 205 # write and read a value 206 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 207 _, _, <a href='075channel.mu.html#L36'>source</a> <- read <a href='075channel.mu.html#L36'>source</a> 208 run [ 209 # first-free will now be 1 210 10:num/raw <- get *chan, first-free:offset 211 11:num/raw <- get *chan, first-free:offset 212 # write second value, verify that first-free wraps 213 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 214 20:num/raw <- get *chan, first-free:offset 215 # read second value, verify that first-full wraps 216 _, _, <a href='075channel.mu.html#L36'>source</a> <- read <a href='075channel.mu.html#L36'>source</a> 217 30:num/raw <- get *chan, first-full:offset 218 ] 219 memory-should-contain [ 220 10 <- 1 # first-free after first write 221 11 <- 1 # first-full after first read 222 20 <- 0 # first-free after second write, wrapped 223 30 <- 0 # first-full after second read, wrapped 224 ] 225 ] 226 227 scenario channel-new-empty-not-full [ 228 run [ 229 local-scope 230 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 231 chan:&:channel:num <- get *source, chan:offset 232 10:bool/raw <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 233 11:bool/raw <- <a href='075channel.mu.html#L373'>channel-full?</a> chan 234 ] 235 memory-should-contain [ 236 10 <- 1 # empty? 237 11 <- 0 # full? 238 ] 239 ] 240 241 scenario channel-write-not-empty [ 242 local-scope 243 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 244 chan:&:channel:num <- get *source, chan:offset 245 run [ 246 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 247 10:bool/raw <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 248 11:bool/raw <- <a href='075channel.mu.html#L373'>channel-full?</a> chan 249 ] 250 memory-should-contain [ 251 10 <- 0 # empty? 252 11 <- 0 # full? 253 ] 254 ] 255 256 scenario channel-write-full [ 257 local-scope 258 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 1/capacity 259 chan:&:channel:num <- get *source, chan:offset 260 run [ 261 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 262 10:bool/raw <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 263 11:bool/raw <- <a href='075channel.mu.html#L373'>channel-full?</a> chan 264 ] 265 memory-should-contain [ 266 10 <- 0 # empty? 267 11 <- 1 # full? 268 ] 269 ] 270 271 scenario channel-read-not-full [ 272 local-scope 273 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 1/capacity 274 chan:&:channel:num <- get *source, chan:offset 275 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 34 276 run [ 277 _, _, <a href='075channel.mu.html#L36'>source</a> <- read <a href='075channel.mu.html#L36'>source</a> 278 10:bool/raw <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 279 11:bool/raw <- <a href='075channel.mu.html#L373'>channel-full?</a> chan 280 ] 281 memory-should-contain [ 282 10 <- 1 # empty? 283 11 <- 0 # full? 284 ] 285 ] 286 287 scenario channel-clear [ 288 local-scope 289 # create a channel with a few items 290 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:num, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:num <- <a href='075channel.mu.html#L44'>new-channel</a> 3/capacity 291 chan:&:channel:num <- get *sink, chan:offset 292 <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 30 293 <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 31 294 <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 32 295 run [ 296 <a href='075channel.mu.html#L304'>clear</a> <a href='075channel.mu.html#L36'>source</a> 297 10:bool/raw <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 298 ] 299 memory-should-contain [ 300 10 <- 1 # after the call to 'clear', the channel should be empty 301 ] 302 ] 303 304 def <a href='075channel.mu.html#L304'>clear</a> in:&:<a href='075channel.mu.html#L36'>source</a>:_elem -> in:&:<a href='075channel.mu.html#L36'>source</a>:_elem [ 305 local-scope 306 load-inputs 307 chan:&:channel:_elem <- get *in, chan:offset 308 { 309 empty?:bool <- <a href='075channel.mu.html#L362'>channel-empty?</a> chan 310 break-if empty? 311 _, _, in <- read in 312 loop 313 } 314 ] 315 316 ## cancelling channels 317 318 # every channel comes with a boolean signifying if it's been closed 319 # initially this boolean is false 320 container channel:_elem [ 321 closed?:bool 322 ] 323 324 # a channel can be closed from either the source or the sink 325 # both routines can modify the 'closed?' bit, but they can only ever set it, so this is a benign race 326 def close x:&:<a href='075channel.mu.html#L36'>source</a>:_elem -> x:&:<a href='075channel.mu.html#L36'>source</a>:_elem [ 327 local-scope 328 load-inputs 329 chan:&:channel:_elem <- get *x, chan:offset 330 *chan <- put *chan, closed?:offset, 1/true 331 ] 332 def close x:&:<a href='075channel.mu.html#L40'>sink</a>:_elem -> x:&:<a href='075channel.mu.html#L40'>sink</a>:_elem [ 333 local-scope 334 load-inputs 335 chan:&:channel:_elem <- get *x, chan:offset 336 *chan <- put *chan, closed?:offset, 1/true 337 ] 338 339 # once a channel is closed from one side, no further operations are expected from that side 340 # if a channel is closed for reading, 341 # no further writes will be let through 342 # if a channel is closed for writing, 343 # future reads continue until the channel empties, 344 # then the channel is also closed for reading 345 after <a href='075channel.mu.html#L65'><channel-write-initial></a> [ 346 closed?:bool <- get *chan, closed?:offset 347 return-if closed? 348 ] 349 after <a href='075channel.mu.html#L125'><channel-read-empty></a> [ 350 closed?:bool <- get *chan, closed?:offset 351 { 352 break-unless closed? 353 empty-result:&:_elem <- new _elem:type 354 current-routine-is-unblocked 355 return *empty-result, 1/true 356 } 357 ] 358 359 ## helpers 360 361 # An empty channel has first-free and first-full both at the same value. 362 def <a href='075channel.mu.html#L362'>channel-empty?</a> chan:&:channel:_elem -> result:bool [ 363 local-scope 364 load-inputs 365 # return chan.first-full == chan.first-free 366 full:num <- get *chan, first-full:offset 367 free:num <- get *chan, first-free:offset 368 result <- equal full, free 369 ] 370 371 # A full channel has first-free just before first-full, wasting one slot. 372 # (Other alternatives: <a href="https://www.snellman.net/blog/archive/2016-12-13-ring-buffers">https://www.snellman.net/blog/archive/2016-12-13-ring-buffers</a>) 373 def <a href='075channel.mu.html#L373'>channel-full?</a> chan:&:channel:_elem -> result:bool [ 374 local-scope 375 load-inputs 376 # tmp = chan.first-free + 1 377 tmp:num <- get *chan, first-free:offset 378 tmp <- add tmp, 1 379 { 380 # if tmp == chan.capacity, tmp = 0 381 len:num <- <a href='075channel.mu.html#L391'>capacity</a> chan 382 at-end?:bool <- greater-or-equal tmp, len 383 break-unless at-end? 384 tmp <- copy 0 385 } 386 # return chan.first-full == tmp 387 full:num <- get *chan, first-full:offset 388 result <- equal full, tmp 389 ] 390 391 def <a href='075channel.mu.html#L391'>capacity</a> chan:&:channel:_elem -> result:num [ 392 local-scope 393 load-inputs 394 q:&:@:_elem <- get *chan, data:offset 395 result <- length *q 396 ] 397 398 ## helpers for channels of characters in particular 399 400 def <a href='075channel.mu.html#L400'>buffer-lines</a> in:&:<a href='075channel.mu.html#L36'>source</a>:char, buffered-out:&:<a href='075channel.mu.html#L40'>sink</a>:char -> buffered-out:&:<a href='075channel.mu.html#L40'>sink</a>:char, in:&:<a href='075channel.mu.html#L36'>source</a>:char [ 401 local-scope 402 load-inputs 403 # repeat forever 404 eof?:bool <- copy 0/false 405 { 406 line:&:<a href='061text.mu.html#L120'>buffer</a>:char <- <a href='061text.mu.html#L125'>new-buffer</a> 30 407 # read characters from 'in' until newline, copy into line 408 { 409 +next-character 410 c:char, eof?:bool, in <- read in 411 break-if eof? 412 # drop a character on backspace 413 { 414 # special-case: if it's a backspace 415 backspace?:bool <- equal c, 8 416 break-unless backspace? 417 # drop previous character 418 { 419 buffer-length:num <- get *line, length:offset 420 buffer-empty?:bool <- equal buffer-length, 0 421 break-if buffer-empty? 422 buffer-length <- subtract buffer-length, 1 423 *line <- put *line, length:offset, buffer-length 424 } 425 # and don't append this one 426 loop +next-character 427 } 428 # append anything else 429 line <- append line, c 430 line-done?:bool <- equal c, 10/newline 431 break-if line-done? 432 loop 433 } 434 # copy line into 'buffered-out' 435 i:num <- copy 0 436 line-contents:text <- get *line, data:offset 437 max:num <- get *line, length:offset 438 { 439 done?:bool <- greater-or-equal i, max 440 break-if done? 441 c:char <- index *line-contents, i 442 buffered-out <- <a href='075channel.mu.html#L60'>write</a> buffered-out, c 443 i <- add i, 1 444 loop 445 } 446 { 447 break-unless eof? 448 buffered-out <- close buffered-out 449 return 450 } 451 loop 452 } 453 ] 454 455 scenario buffer-lines-blocks-until-newline [ 456 run [ 457 local-scope 458 <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:char, <a href='075channel.mu.html#L40'>sink</a>:&:<a href='075channel.mu.html#L40'>sink</a>:char <- <a href='075channel.mu.html#L44'>new-channel</a> 10/capacity 459 _, buffered-stdin:&:<a href='075channel.mu.html#L40'>sink</a>:char/buffered-stdin <- <a href='075channel.mu.html#L44'>new-channel</a> 10/capacity 460 buffered-chan:&:channel:char <- get *buffered-stdin, chan:offset 461 empty?:bool <- <a href='075channel.mu.html#L362'>channel-empty?</a> buffered-chan 462 assert empty?, [ 463 F buffer-lines-blocks-until-newline: channel should be empty after init] 464 # buffer stdin into buffered-stdin, try to read from buffered-stdin 465 buffer-routine:num <- start-running <a href='075channel.mu.html#L400'>buffer-lines</a>, <a href='075channel.mu.html#L36'>source</a>, buffered-stdin 466 wait-for-routine-to-block buffer-routine 467 empty? <- <a href='075channel.mu.html#L362'>channel-empty?</a> buffered-chan 468 assert empty?:bool, [ 469 F buffer-lines-blocks-until-newline: channel should be empty after <a href='075channel.mu.html#L400'>buffer-lines</a> bring-up] 470 # write 'a' 471 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 97/a 472 restart buffer-routine 473 wait-for-routine-to-block buffer-routine 474 empty? <- <a href='075channel.mu.html#L362'>channel-empty?</a> buffered-chan 475 assert empty?:bool, [ 476 F buffer-lines-blocks-until-newline: channel should be empty after writing 'a'] 477 # write 'b' 478 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 98/b 479 restart buffer-routine 480 wait-for-routine-to-block buffer-routine 481 empty? <- <a href='075channel.mu.html#L362'>channel-empty?</a> buffered-chan 482 assert empty?:bool, [ 483 F buffer-lines-blocks-until-newline: channel should be empty after writing 'b'] 484 # write newline 485 <a href='075channel.mu.html#L40'>sink</a> <- <a href='075channel.mu.html#L60'>write</a> <a href='075channel.mu.html#L40'>sink</a>, 10/newline 486 restart buffer-routine 487 wait-for-routine-to-block buffer-routine 488 empty? <- <a href='075channel.mu.html#L362'>channel-empty?</a> buffered-chan 489 data-emitted?:bool <- not empty? 490 assert data-emitted?, [ 491 F buffer-lines-blocks-until-newline: channel should contain data after writing newline] 492 trace 1, [test], [reached end] 493 ] 494 trace-should-contain [ 495 test: reached end 496 ] 497 ] 498 499 def <a href='075channel.mu.html#L499'>drain</a> <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:char -> result:text, <a href='075channel.mu.html#L36'>source</a>:&:<a href='075channel.mu.html#L36'>source</a>:char [ 500 local-scope 501 load-inputs 502 buf:&:<a href='061text.mu.html#L120'>buffer</a>:char <- <a href='061text.mu.html#L125'>new-buffer</a> 30 503 { 504 c:char, done?:bool <- read <a href='075channel.mu.html#L36'>source</a> 505 break-if done? 506 buf <- append buf, c 507 loop 508 } 509 result <- <a href='061text.mu.html#L338'>buffer-to-array</a> buf 510 ] </pre> </body> </html>