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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 | |