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| 1 | #+TITLE: Core | ||
| 2 | * Overview | ||
| 3 | This document describes and outlines a small API for | ||
| 4 | sndkit. It is primarily designed to be a small layer on top | ||
| 5 | of Patchwerk, a library used to build up directed audio | ||
| 6 | graphs. A large portion of the functionality is based on | ||
| 7 | what is found in runt-patchwerk. Just simpler. | ||
| 8 | |||
| 9 | In addition to maintaining an instance of patchwerk, the | ||
| 10 | sndkit API provides a stack and a register system. The | ||
| 11 | stack is the primary means of sharing data between nodes. | ||
| 12 | Registers are for more persitently used values. | ||
| 13 | * Tangled files | ||
| 14 | =core.h= and =core.c=. | ||
| 15 | |||
| 16 | #+NAME: core.h | ||
| 17 | #+BEGIN_SRC c :tangle core.h | ||
| 18 | #ifndef SKPW_H | ||
| 19 | #define SKPW_H | ||
| 20 | |||
| 21 | #ifndef SKFLT | ||
| 22 | #define SKFLT float | ||
| 23 | #endif | ||
| 24 | |||
| 25 | <<typedefs>> | ||
| 26 | #ifdef SK_CORE_PRIV | ||
| 27 | <<structs>> | ||
| 28 | <<core>> | ||
| 29 | #endif | ||
| 30 | <<macros>> | ||
| 31 | <<funcdefs>> | ||
| 32 | #endif | ||
| 33 | #+END_SRC | ||
| 34 | |||
| 35 | #+NAME: core.c | ||
| 36 | #+BEGIN_SRC c :tangle core.c | ||
| 37 | #include <stdlib.h> | ||
| 38 | #include <math.h> | ||
| 39 | #include "patchwerk.h" | ||
| 40 | #define SK_CORE_PRIV | ||
| 41 | #include "core.h" | ||
| 42 | <<enums>> | ||
| 43 | <<funcs>> | ||
| 44 | #+END_SRC | ||
| 45 | * Engine Management | ||
| 46 | All this behavior is defined in a struct called =sk_core=. | ||
| 47 | |||
| 48 | Creating/freeing is done with =sk_core_new= and | ||
| 49 | =sk_core_del=. | ||
| 50 | |||
| 51 | #+NAME: funcdefs | ||
| 52 | #+BEGIN_SRC c | ||
| 53 | sk_core * sk_core_new(int sr); | ||
| 54 | void sk_core_del(sk_core *core); | ||
| 55 | #+END_SRC | ||
| 56 | |||
| 57 | #+NAME: funcs | ||
| 58 | #+BEGIN_SRC c | ||
| 59 | sk_core * sk_core_new(int sr) | ||
| 60 | { | ||
| 61 | sk_core *core; | ||
| 62 | pw_patch *patch; | ||
| 63 | |||
| 64 | core = malloc(sizeof(sk_core)); | ||
| 65 | core->patch = malloc(pw_patch_size()); | ||
| 66 | |||
| 67 | patch = core->patch; | ||
| 68 | pw_patch_init(patch, 64); | ||
| 69 | pw_patch_alloc(patch, 8, 10); | ||
| 70 | pw_patch_srate_set(patch, sr); | ||
| 71 | |||
| 72 | sk_stack_init(&core->stack); | ||
| 73 | return core; | ||
| 74 | } | ||
| 75 | #+END_SRC | ||
| 76 | |||
| 77 | #+NAME: funcs | ||
| 78 | #+BEGIN_SRC c | ||
| 79 | void sk_core_del(sk_core *core) | ||
| 80 | { | ||
| 81 | if (core == NULL) return; | ||
| 82 | |||
| 83 | pw_patch_destroy(core->patch); | ||
| 84 | pw_patch_free_nodes(core->patch); | ||
| 85 | free(core->patch); | ||
| 86 | |||
| 87 | free(core); | ||
| 88 | core = NULL; | ||
| 89 | } | ||
| 90 | #+END_SRC | ||
| 91 | |||
| 92 | #+NAME: typedefs | ||
| 93 | #+BEGIN_SRC c | ||
| 94 | typedef struct sk_core sk_core; | ||
| 95 | #+END_SRC | ||
| 96 | |||
| 97 | #+NAME: core | ||
| 98 | #+BEGIN_SRC c | ||
| 99 | struct sk_core { | ||
| 100 | pw_patch *patch; | ||
| 101 | sk_stack stack; | ||
| 102 | }; | ||
| 103 | #+END_SRC | ||
| 104 | |||
| 105 | A internal block of audio can be computed with | ||
| 106 | =sk_core_compute=. Usually this size is 64 samples. | ||
| 107 | |||
| 108 | #+NAME: funcdefs | ||
| 109 | #+BEGIN_SRC c | ||
| 110 | void sk_core_compute(sk_core *core); | ||
| 111 | #+END_SRC | ||
| 112 | |||
| 113 | #+NAME: funcs | ||
| 114 | #+BEGIN_SRC c | ||
| 115 | void sk_core_compute(sk_core *core) | ||
| 116 | { | ||
| 117 | pw_patch_compute(core->patch); | ||
| 118 | } | ||
| 119 | #+END_SRC | ||
| 120 | |||
| 121 | Building up nodes involves interacting with the patchwerk | ||
| 122 | API. To get the top level struct of that opaquely, use | ||
| 123 | =sk_core_patch=. | ||
| 124 | |||
| 125 | #+NAME: funcdefs | ||
| 126 | #+BEGIN_SRC c | ||
| 127 | pw_patch * sk_core_patch(sk_core *core); | ||
| 128 | #+END_SRC | ||
| 129 | |||
| 130 | #+NAME: funcs | ||
| 131 | #+BEGIN_SRC c | ||
| 132 | pw_patch * sk_core_patch(sk_core *core) | ||
| 133 | { | ||
| 134 | return core->patch; | ||
| 135 | } | ||
| 136 | #+END_SRC | ||
| 137 | |||
| 138 | The function =sk_core_seconds_to_blocks= converts | ||
| 139 | seconds to a number of render blocks. | ||
| 140 | |||
| 141 | #+NAME: funcdefs | ||
| 142 | #+BEGIN_SRC c | ||
| 143 | size_t sk_core_seconds_to_blocks(sk_core *core, SKFLT secs); | ||
| 144 | #+END_SRC | ||
| 145 | |||
| 146 | #+NAME: funcs | ||
| 147 | #+BEGIN_SRC c | ||
| 148 | size_t sk_core_seconds_to_blocks(sk_core *core, SKFLT secs) | ||
| 149 | { | ||
| 150 | size_t nblocks; | ||
| 151 | int sr; | ||
| 152 | |||
| 153 | sr = pw_patch_srate_get(core->patch); | ||
| 154 | nblocks = floor((sr * secs) / 64) + 1; | ||
| 155 | |||
| 156 | return nblocks; | ||
| 157 | } | ||
| 158 | #+END_SRC | ||
| 159 | * Stack | ||
| 160 | ** Core Data Types | ||
| 161 | An item on a stack is contained in a thing known as a | ||
| 162 | =stacklet=. A stacklet has integer for a type flag, a | ||
| 163 | floating point number for numerical values, and a generic | ||
| 164 | pointer for C structures. | ||
| 165 | |||
| 166 | #+NAME: typedefs | ||
| 167 | #+BEGIN_SRC c | ||
| 168 | typedef struct sk_stacklet sk_stacklet; | ||
| 169 | #+END_SRC | ||
| 170 | |||
| 171 | #+NAME: structs | ||
| 172 | #+BEGIN_SRC c | ||
| 173 | struct sk_stacklet { | ||
| 174 | int type; | ||
| 175 | SKFLT f; | ||
| 176 | void *ptr; | ||
| 177 | }; | ||
| 178 | <<stack_struct>> | ||
| 179 | #+END_SRC | ||
| 180 | |||
| 181 | A stacklet is initialized with the function | ||
| 182 | =sk_stacklet_init=. | ||
| 183 | |||
| 184 | #+NAME: funcdefs | ||
| 185 | #+BEGIN_SRC c | ||
| 186 | void sk_stacklet_init(sk_stacklet *s); | ||
| 187 | #+END_SRC | ||
| 188 | |||
| 189 | #+NAME: funcs | ||
| 190 | #+BEGIN_SRC c | ||
| 191 | void sk_stacklet_init(sk_stacklet *s) | ||
| 192 | { | ||
| 193 | s->type = SK_TYPE_NONE; | ||
| 194 | s->f = 0; | ||
| 195 | s->ptr = NULL; | ||
| 196 | } | ||
| 197 | #+END_SRC | ||
| 198 | |||
| 199 | An array of stacklets forms the foundation of a =sk_stack=. | ||
| 200 | |||
| 201 | #+NAME: typedefs | ||
| 202 | #+BEGIN_SRC c | ||
| 203 | typedef struct sk_stack sk_stack; | ||
| 204 | #+END_SRC | ||
| 205 | |||
| 206 | The stack will be hard coded to be 16. | ||
| 207 | |||
| 208 | An integer =pos= is used to keep track of position. | ||
| 209 | |||
| 210 | #+NAME: stack_struct | ||
| 211 | #+BEGIN_SRC c | ||
| 212 | #define SK_STACKSIZE 16 | ||
| 213 | struct sk_stack { | ||
| 214 | sk_stacklet stack[SK_STACKSIZE]; | ||
| 215 | int pos; | ||
| 216 | }; | ||
| 217 | #+END_SRC | ||
| 218 | |||
| 219 | A stack is initialized with =sk_stack_init=. | ||
| 220 | |||
| 221 | #+NAME: funcdefs | ||
| 222 | #+BEGIN_SRC c | ||
| 223 | void sk_stack_init(sk_stack *s); | ||
| 224 | #+END_SRC | ||
| 225 | |||
| 226 | The position is set to be negative, indicating an empty | ||
| 227 | stack. | ||
| 228 | |||
| 229 | #+NAME: funcs | ||
| 230 | #+BEGIN_SRC c | ||
| 231 | void sk_stack_init(sk_stack *s) | ||
| 232 | { | ||
| 233 | int i; | ||
| 234 | |||
| 235 | for (i = 0; i < SK_STACKSIZE; i++) { | ||
| 236 | sk_stacklet_init(&s->stack[i]); | ||
| 237 | } | ||
| 238 | |||
| 239 | s->pos = -1; | ||
| 240 | } | ||
| 241 | #+END_SRC | ||
| 242 | ** Types | ||
| 243 | The typeflag currently supports the following types: | ||
| 244 | |||
| 245 | #+NAME: enums | ||
| 246 | #+BEGIN_SRC c | ||
| 247 | enum { | ||
| 248 | SK_TYPE_NONE, | ||
| 249 | SK_TYPE_CONSTANT, | ||
| 250 | SK_TYPE_CABLE, | ||
| 251 | SK_TYPE_TABLE, | ||
| 252 | SK_TYPE_GENERIC | ||
| 253 | }; | ||
| 254 | #+END_SRC | ||
| 255 | ** Push/Pop | ||
| 256 | Push and pop are the core operations for the stack. Both | ||
| 257 | return non-zero values on error. | ||
| 258 | |||
| 259 | =sk_stack_pop= will pop a value off the stack and save it | ||
| 260 | to the stacklet variable =s=. | ||
| 261 | |||
| 262 | =sk_stack_push= will push an initialized stacklet to the | ||
| 263 | stack, and save that value to stacklet variable =s= to | ||
| 264 | be filled with some item. | ||
| 265 | |||
| 266 | #+NAME: funcdefs | ||
| 267 | #+BEGIN_SRC c | ||
| 268 | int sk_stack_pop(sk_stack *stack, sk_stacklet **out); | ||
| 269 | int sk_stack_push(sk_stack *stack, sk_stacklet **out); | ||
| 270 | #+END_SRC | ||
| 271 | |||
| 272 | #+NAME: funcs | ||
| 273 | #+BEGIN_SRC c | ||
| 274 | int sk_stack_pop(sk_stack *stack, sk_stacklet **out) | ||
| 275 | { | ||
| 276 | sk_stacklet *s; | ||
| 277 | /* no items on stack */ | ||
| 278 | if (stack->pos < 0) return 1; | ||
| 279 | |||
| 280 | /* stack overflow */ | ||
| 281 | if (stack->pos >= SK_STACKSIZE) return 2; | ||
| 282 | |||
| 283 | s = &stack->stack[stack->pos]; | ||
| 284 | stack->pos--; | ||
| 285 | |||
| 286 | *out = s; | ||
| 287 | return 0; | ||
| 288 | } | ||
| 289 | #+END_SRC | ||
| 290 | |||
| 291 | #+NAME: funcs | ||
| 292 | #+BEGIN_SRC c | ||
| 293 | int sk_stack_push(sk_stack *stack, sk_stacklet **out) | ||
| 294 | { | ||
| 295 | sk_stacklet *s; | ||
| 296 | |||
| 297 | if (stack->pos >= (SK_STACKSIZE - 1)) return 1; | ||
| 298 | stack->pos++; | ||
| 299 | s = &stack->stack[stack->pos]; | ||
| 300 | |||
| 301 | sk_stacklet_init(s); | ||
| 302 | *out = s; | ||
| 303 | return 0; | ||
| 304 | } | ||
| 305 | #+END_SRC | ||
| 306 | * Parameters and Cables | ||
| 307 | =sndkit_param= is an abstraction used to deal with | ||
| 308 | patchwerk cables, and is designed to link up with the | ||
| 309 | sndkit stack and patchwerk nodes. | ||
| 310 | |||
| 311 | A sndkit parameter can either be a patchwerk cable from a | ||
| 312 | node or a constant value. If it is cable, it will properly | ||
| 313 | manage the buffer stack in patchwerk. If it is a constant, | ||
| 314 | it will only manipulate the sndkit stack. | ||
| 315 | ** Struct | ||
| 316 | A parameter is stored in a struct called =sk_param=. | ||
| 317 | |||
| 318 | #+NAME: typedefs | ||
| 319 | #+BEGIN_SRC c | ||
| 320 | typedef struct { | ||
| 321 | char type; | ||
| 322 | union { | ||
| 323 | pw_cable *c; | ||
| 324 | SKFLT f; | ||
| 325 | } data; | ||
| 326 | } sk_param; | ||
| 327 | #+END_SRC | ||
| 328 | ** Getting a Parameter | ||
| 329 | Get a parameter from the core stack via =sk_param_get=. | ||
| 330 | |||
| 331 | #+NAME: funcdefs | ||
| 332 | #+BEGIN_SRC c | ||
| 333 | int sk_param_get(sk_core *core, sk_param *p); | ||
| 334 | #+END_SRC | ||
| 335 | |||
| 336 | Getting a parameter is a matter of popping from the stack | ||
| 337 | and checking the type. A constant will set the constant | ||
| 338 | value and flag in the param struct. A cable will set the | ||
| 339 | cable value and flag in the param struct, and will also pop | ||
| 340 | from the buffer stack. | ||
| 341 | |||
| 342 | #+NAME: funcs | ||
| 343 | #+BEGIN_SRC c | ||
| 344 | int sk_param_get(sk_core *core, sk_param *p) | ||
| 345 | { | ||
| 346 | sk_stack *stk; | ||
| 347 | sk_stacklet *s; | ||
| 348 | int rc; | ||
| 349 | |||
| 350 | stk = &core->stack; | ||
| 351 | |||
| 352 | rc = sk_stack_pop(stk, &s); | ||
| 353 | SK_ERROR_CHECK(rc); | ||
| 354 | |||
| 355 | if (s->type == SK_TYPE_CONSTANT) { | ||
| 356 | p->type = 0; | ||
| 357 | p->data.f = s->f; | ||
| 358 | } else if (s->type == SK_TYPE_CABLE) { | ||
| 359 | p->type = 1; | ||
| 360 | p->data.c = (pw_cable *)s->ptr; | ||
| 361 | pw_cable_pop(p->data.c); | ||
| 362 | } else { | ||
| 363 | /* Wrong type! */ | ||
| 364 | return 1; | ||
| 365 | } | ||
| 366 | |||
| 367 | return 0; | ||
| 368 | } | ||
| 369 | #+END_SRC | ||
| 370 | ** Setting a Parameter | ||
| 371 | Set a parameter with =sk_param_set=. | ||
| 372 | |||
| 373 | #+NAME: funcdefs | ||
| 374 | #+BEGIN_SRC c | ||
| 375 | int sk_param_set(sk_core *core, | ||
| 376 | pw_node *node, | ||
| 377 | sk_param *p, | ||
| 378 | int cid); | ||
| 379 | #+END_SRC | ||
| 380 | |||
| 381 | #+NAME: funcs | ||
| 382 | #+BEGIN_SRC c | ||
| 383 | int sk_param_set(sk_core *core, | ||
| 384 | pw_node *node, | ||
| 385 | sk_param *p, | ||
| 386 | int cid) | ||
| 387 | { | ||
| 388 | pw_cable *c; | ||
| 389 | |||
| 390 | pw_node_get_cable(node, cid, &c); | ||
| 391 | if (p->type == 0) { | ||
| 392 | pw_cable_set_value(c, p->data.f); | ||
| 393 | } else { | ||
| 394 | int rc; | ||
| 395 | rc = pw_cable_connect(p->data.c, c); | ||
| 396 | SK_PW_ERROR_CHECK(rc); | ||
| 397 | } | ||
| 398 | return 0; | ||
| 399 | } | ||
| 400 | #+END_SRC | ||
| 401 | |||
| 402 | Setting a parameter will properly assign the internal value | ||
| 403 | to a cable of a node. This node's cable is referenced by | ||
| 404 | its index position. A constant parameter will set the node | ||
| 405 | cable as a consant. A cable parameter will be connected to | ||
| 406 | the node cable. | ||
| 407 | ** Pushing Constants | ||
| 408 | Constant values can be pushed to the stack with the | ||
| 409 | function =sk_core_constant=. | ||
| 410 | |||
| 411 | #+NAME: funcdefs | ||
| 412 | #+BEGIN_SRC c | ||
| 413 | int sk_core_constant(sk_core *core, SKFLT x); | ||
| 414 | #+END_SRC | ||
| 415 | |||
| 416 | #+NAME: funcs | ||
| 417 | #+BEGIN_SRC c | ||
| 418 | int sk_core_constant(sk_core *core, SKFLT x) | ||
| 419 | { | ||
| 420 | int rc; | ||
| 421 | sk_stacklet *s; | ||
| 422 | sk_stack *stk; | ||
| 423 | |||
| 424 | stk = &core->stack; | ||
| 425 | |||
| 426 | rc = sk_stack_push(stk, &s); | ||
| 427 | SK_ERROR_CHECK(rc); | ||
| 428 | |||
| 429 | s->type = SK_TYPE_CONSTANT; | ||
| 430 | s->f = x; | ||
| 431 | |||
| 432 | return 0; | ||
| 433 | } | ||
| 434 | #+END_SRC | ||
| 435 | ** Pushing Output | ||
| 436 | An signal cable from a node is pushed to the stack via | ||
| 437 | =sk_param_out=. | ||
| 438 | |||
| 439 | #+NAME: funcdefs | ||
| 440 | #+BEGIN_SRC c | ||
| 441 | int sk_param_out(sk_core *core, | ||
| 442 | pw_node *node, | ||
| 443 | int cid); | ||
| 444 | #+END_SRC | ||
| 445 | |||
| 446 | Cables need to be pushed in the order they are created in | ||
| 447 | the patch. The onus is on the developers of the node to | ||
| 448 | make sure this is done properly. Don't worry, | ||
| 449 | this is less tricky than it sounds. If done correctly, this | ||
| 450 | process can be mostly automated or abstracted away. | ||
| 451 | |||
| 452 | #+NAME: funcs | ||
| 453 | #+BEGIN_SRC c | ||
| 454 | int sk_param_out(sk_core *core, | ||
| 455 | pw_node *node, | ||
| 456 | int cid) | ||
| 457 | { | ||
| 458 | pw_cable *c; | ||
| 459 | sk_stacklet *s; | ||
| 460 | sk_stack *stk; | ||
| 461 | int rc; | ||
| 462 | |||
| 463 | stk = &core->stack; | ||
| 464 | |||
| 465 | rc = sk_stack_push(stk, &s); | ||
| 466 | SK_ERROR_CHECK(rc); | ||
| 467 | rc = pw_node_get_cable(node, cid, &c); | ||
| 468 | SK_PW_ERROR_CHECK(rc); | ||
| 469 | |||
| 470 | s->type = SK_TYPE_CABLE; | ||
| 471 | s->ptr = c; | ||
| 472 | |||
| 473 | return 0; | ||
| 474 | } | ||
| 475 | #+END_SRC | ||
| 476 | |||
| 477 | =sk_param_out= will take an output cable of a node | ||
| 478 | (referenced by index), and push it onto the sndkit stack. | ||
| 479 | It will also push the cable's buffer onto the stack. | ||
| 480 | * Error Checking | ||
| 481 | =SK_ERROR_CHECK= is a convenient macro used that will | ||
| 482 | check an error code and exit if it is non-zero. | ||
| 483 | |||
| 484 | #+NAME: macros | ||
| 485 | #+BEGIN_SRC c | ||
| 486 | #define SK_ERROR_CHECK(rc) if (rc) return rc; | ||
| 487 | #+END_SRC | ||
| 488 | |||
| 489 | #+NAME: macros | ||
| 490 | #+BEGIN_SRC c | ||
| 491 | #define SK_PW_ERROR_CHECK(rc) if(rc != PW_OK) {\ | ||
| 492 | fprintf(stderr, "Error: %s\n", pw_error(rc));\ | ||
| 493 | return 1;\ | ||
| 494 | } | ||
| 495 | #+END_SRC | ||
| 496 | * Tables | ||
| 497 | A small abstraction for dealing with tables that are managed | ||
| 498 | by patchwerk. | ||
| 499 | * Registers | ||
| 500 | ** TODO regset/regget | ||
| 501 | ** TODO regmrk | ||
| 502 | marks a register as being used | ||
| 503 | ** TODO regclr | ||
| 504 | clears the register, making it free to be claimed. | ||
| 505 | ** TODO regnxt | ||
| 506 | returns the next free register | ||
| 507 | * Buffer Operations | ||
| 508 | ** TODO bdup | ||
| 509 | ** TODO bhold/bunhold | ||
| 510 | ** TODO bdrop | ||