Small edits to spec.
Chris Pressey
7 years ago
| 131 | 131 | ... |
| 132 | 132 | } |
| 133 | 133 | |
| 134 | The `inputs` are sometimes called the routine's READS set, while the | |
| 135 | `outputs` and `trashes` are collectively called the WRITES set. | |
| 134 | The union of the `outputs` and `trashes` is sometimes collectively called | |
| 135 | "the WRITES" of the routine, for historical reasons and as shorthand. | |
| 136 | 136 | |
| 137 | 137 | Routines may call only routines previously defined in the program source. |
| 138 | 138 | Thus, directly recursive routines are not allowed. (However, routines may |
| 149 | 149 | that routine is called. At the end of a routine, all memory locations listed |
| 150 | 150 | as outputs must be initialized. |
| 151 | 151 | |
| 152 | A routine can also be declared as "external", in which case its body need | |
| 153 | not be defined but an absolute address must be given for where the routine | |
| 154 | is located in memory. | |
| 152 | A literal word can given instead of the body of the routine. This word is the | |
| 153 | absolute address of an "external" routine located in memory but not defined by | |
| 154 | the SixtyPical program. | |
| 155 | 155 | |
| 156 | 156 | routine chrout |
| 157 | 157 | inputs a |
| 204 | 204 | |
| 205 | 205 | If and only if dest is a byte table, the index-memory-location must be given. |
| 206 | 206 | |
| 207 | ### copy ### | |
| 208 | ||
| 209 | copy <src-memory-location>, <dest-memory-location> | |
| 210 | ||
| 211 | Reads from src and writes to dest. Differs from `st` in that is able to | |
| 212 | copy more general types of data (for example, vectors,) and it trashes the | |
| 213 | `z` and `n` flags and the `a` register. | |
| 214 | ||
| 215 | * It is illegal if dest is read-only. | |
| 216 | * It is illegal if dest does not occur in the WRITES of the current routine. | |
| 217 | * It is illegal if src is not of same type as dest. | |
| 218 | * It is illegal if src is uninitialized. | |
| 219 | ||
| 220 | After execution, dest is considered initialized, and `z` and `n`, and | |
| 221 | `a` are considered uninitialized. | |
| 222 | ||
| 207 | 223 | ### add dest, src ### |
| 208 | 224 | |
| 209 | 225 | add <dest-memory-location>, <src-memory-location> |
| 342 | 358 | |
| 343 | 359 | Just before the goto, |
| 344 | 360 | |
| 345 | * It is illegal if any of the memory locations in the target executable's | |
| 346 | READS list is uninitialized. | |
| 361 | * It is illegal if any of the memory locations in the target routine's | |
| 362 | `inputs` list is uninitialized. | |
| 347 | 363 | |
| 348 | 364 | In addition, |
| 349 | 365 | |
| 389 | 405 | } |
| 390 | 406 | } until z |
| 391 | 407 | |
| 392 | "until" is optional, but if omitted, must be replaced with "forever". | |
| 393 | ||
| 394 | ### copy ### | |
| 395 | ||
| 396 | copy <src-memory-location>, <dest-memory-location> | |
| 397 | ||
| 398 | Reads from src and writes to dest. Differs from `st` in that is able to | |
| 399 | copy more general types of data (for example, vectors,) and it trashes the | |
| 400 | `z` and `n` flags and the `a` register. | |
| 401 | ||
| 402 | * It is illegal if dest is read-only. | |
| 403 | * It is illegal if dest does not occur in the WRITES of the current routine. | |
| 404 | * It is illegal if src is not of same type as dest. | |
| 405 | * It is illegal if src is uninitialized. | |
| 406 | ||
| 407 | After execution, dest is considered initialized, and `z` and `n`, and | |
| 408 | `a` are considered uninitialized. | |
| 408 | "until" is optional, but if omitted, must be replaced with "forever": | |
| 409 | ||
| 410 | repeat { | |
| 411 | cmp y, 25 | |
| 412 | if z { | |
| 413 | } | |
| 414 | } forever | |
| 415 | ||
| 416 | The sense of the test can be inverted with `not`. | |
| 417 | ||
| 418 | repeat { | |
| 419 | cmp y, 25 | |
| 420 | if z { | |
| 421 | } | |
| 422 | } until not z | |
| 409 | 423 | |
| 410 | 424 | Grammar |
| 411 | 425 | ------- |