libusb10_io.c revision 236944
1/* $FreeBSD: head/lib/libusb/libusb10_io.c 236944 2012-06-12 07:28:25Z hselasky $ */ 2/*- 3 * Copyright (c) 2009 Sylvestre Gallon. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/queue.h> 28 29#include <errno.h> 30#include <poll.h> 31#include <pthread.h> 32#include <stdio.h> 33#include <stdlib.h> 34#include <time.h> 35#include <unistd.h> 36 37#define libusb_device_handle libusb20_device 38 39#include "libusb20.h" 40#include "libusb20_desc.h" 41#include "libusb20_int.h" 42#include "libusb.h" 43#include "libusb10.h" 44 45UNEXPORTED void 46libusb10_add_pollfd(libusb_context *ctx, struct libusb_super_pollfd *pollfd, 47 struct libusb20_device *pdev, int fd, short events) 48{ 49 if (ctx == NULL) 50 return; /* invalid */ 51 52 if (pollfd->entry.tqe_prev != NULL) 53 return; /* already queued */ 54 55 if (fd < 0) 56 return; /* invalid */ 57 58 pollfd->pdev = pdev; 59 pollfd->pollfd.fd = fd; 60 pollfd->pollfd.events = events; 61 62 CTX_LOCK(ctx); 63 TAILQ_INSERT_TAIL(&ctx->pollfds, pollfd, entry); 64 CTX_UNLOCK(ctx); 65 66 if (ctx->fd_added_cb) 67 ctx->fd_added_cb(fd, events, ctx->fd_cb_user_data); 68} 69 70UNEXPORTED void 71libusb10_remove_pollfd(libusb_context *ctx, struct libusb_super_pollfd *pollfd) 72{ 73 if (ctx == NULL) 74 return; /* invalid */ 75 76 if (pollfd->entry.tqe_prev == NULL) 77 return; /* already dequeued */ 78 79 CTX_LOCK(ctx); 80 TAILQ_REMOVE(&ctx->pollfds, pollfd, entry); 81 pollfd->entry.tqe_prev = NULL; 82 CTX_UNLOCK(ctx); 83 84 if (ctx->fd_removed_cb) 85 ctx->fd_removed_cb(pollfd->pollfd.fd, ctx->fd_cb_user_data); 86} 87 88/* This function must be called locked */ 89 90static int 91libusb10_handle_events_sub(struct libusb_context *ctx, struct timeval *tv) 92{ 93 struct libusb_device *dev; 94 struct libusb20_device **ppdev; 95 struct libusb_super_pollfd *pfd; 96 struct pollfd *fds; 97 struct libusb_super_transfer *sxfer; 98 struct libusb_transfer *uxfer; 99 nfds_t nfds; 100 int timeout; 101 int i; 102 int err; 103 104 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb10_handle_events_sub enter"); 105 106 nfds = 0; 107 i = 0; 108 TAILQ_FOREACH(pfd, &ctx->pollfds, entry) 109 nfds++; 110 111 fds = alloca(sizeof(*fds) * nfds); 112 if (fds == NULL) 113 return (LIBUSB_ERROR_NO_MEM); 114 115 ppdev = alloca(sizeof(*ppdev) * nfds); 116 if (ppdev == NULL) 117 return (LIBUSB_ERROR_NO_MEM); 118 119 TAILQ_FOREACH(pfd, &ctx->pollfds, entry) { 120 fds[i].fd = pfd->pollfd.fd; 121 fds[i].events = pfd->pollfd.events; 122 fds[i].revents = 0; 123 ppdev[i] = pfd->pdev; 124 if (pfd->pdev != NULL) 125 libusb_get_device(pfd->pdev)->refcnt++; 126 i++; 127 } 128 129 if (tv == NULL) 130 timeout = -1; 131 else 132 timeout = (tv->tv_sec * 1000) + ((tv->tv_usec + 999) / 1000); 133 134 CTX_UNLOCK(ctx); 135 err = poll(fds, nfds, timeout); 136 CTX_LOCK(ctx); 137 138 if ((err == -1) && (errno == EINTR)) 139 err = LIBUSB_ERROR_INTERRUPTED; 140 else if (err < 0) 141 err = LIBUSB_ERROR_IO; 142 143 if (err < 1) { 144 for (i = 0; i != (int)nfds; i++) { 145 if (ppdev[i] != NULL) { 146 CTX_UNLOCK(ctx); 147 libusb_unref_device(libusb_get_device(ppdev[i])); 148 CTX_LOCK(ctx); 149 } 150 } 151 goto do_done; 152 } 153 for (i = 0; i != (int)nfds; i++) { 154 if (ppdev[i] != NULL) { 155 dev = libusb_get_device(ppdev[i]); 156 157 if (fds[i].revents == 0) 158 err = 0; /* nothing to do */ 159 else 160 err = libusb20_dev_process(ppdev[i]); 161 162 if (err) { 163 /* cancel all transfers - device is gone */ 164 libusb10_cancel_all_transfer(dev); 165 166 /* remove USB device from polling loop */ 167 libusb10_remove_pollfd(dev->ctx, &dev->dev_poll); 168 } 169 CTX_UNLOCK(ctx); 170 libusb_unref_device(dev); 171 CTX_LOCK(ctx); 172 173 } else { 174 uint8_t dummy; 175 176 while (1) { 177 if (read(fds[i].fd, &dummy, 1) != 1) 178 break; 179 } 180 } 181 } 182 183 err = 0; 184 185do_done: 186 187 /* Do all done callbacks */ 188 189 while ((sxfer = TAILQ_FIRST(&ctx->tr_done))) { 190 uint8_t flags; 191 192 TAILQ_REMOVE(&ctx->tr_done, sxfer, entry); 193 sxfer->entry.tqe_prev = NULL; 194 195 ctx->tr_done_ref++; 196 197 CTX_UNLOCK(ctx); 198 199 uxfer = (struct libusb_transfer *)( 200 ((uint8_t *)sxfer) + sizeof(*sxfer)); 201 202 /* Allow the callback to free the transfer itself. */ 203 flags = uxfer->flags; 204 205 if (uxfer->callback != NULL) 206 (uxfer->callback) (uxfer); 207 208 /* Check if the USB transfer should be automatically freed. */ 209 if (flags & LIBUSB_TRANSFER_FREE_TRANSFER) 210 libusb_free_transfer(uxfer); 211 212 CTX_LOCK(ctx); 213 214 ctx->tr_done_ref--; 215 ctx->tr_done_gen++; 216 } 217 218 /* Wakeup other waiters */ 219 pthread_cond_broadcast(&ctx->ctx_cond); 220 221 return (err); 222} 223 224/* Polling and timing */ 225 226int 227libusb_try_lock_events(libusb_context *ctx) 228{ 229 int err; 230 231 ctx = GET_CONTEXT(ctx); 232 if (ctx == NULL) 233 return (1); 234 235 err = CTX_TRYLOCK(ctx); 236 if (err) 237 return (1); 238 239 err = (ctx->ctx_handler != NO_THREAD); 240 if (err) 241 CTX_UNLOCK(ctx); 242 else 243 ctx->ctx_handler = pthread_self(); 244 245 return (err); 246} 247 248void 249libusb_lock_events(libusb_context *ctx) 250{ 251 ctx = GET_CONTEXT(ctx); 252 CTX_LOCK(ctx); 253 if (ctx->ctx_handler == NO_THREAD) 254 ctx->ctx_handler = pthread_self(); 255} 256 257void 258libusb_unlock_events(libusb_context *ctx) 259{ 260 ctx = GET_CONTEXT(ctx); 261 if (ctx->ctx_handler == pthread_self()) { 262 ctx->ctx_handler = NO_THREAD; 263 pthread_cond_broadcast(&ctx->ctx_cond); 264 } 265 CTX_UNLOCK(ctx); 266} 267 268int 269libusb_event_handling_ok(libusb_context *ctx) 270{ 271 ctx = GET_CONTEXT(ctx); 272 return (ctx->ctx_handler == pthread_self()); 273} 274 275int 276libusb_event_handler_active(libusb_context *ctx) 277{ 278 ctx = GET_CONTEXT(ctx); 279 return (ctx->ctx_handler != NO_THREAD); 280} 281 282void 283libusb_lock_event_waiters(libusb_context *ctx) 284{ 285 ctx = GET_CONTEXT(ctx); 286 CTX_LOCK(ctx); 287} 288 289void 290libusb_unlock_event_waiters(libusb_context *ctx) 291{ 292 ctx = GET_CONTEXT(ctx); 293 CTX_UNLOCK(ctx); 294} 295 296int 297libusb_wait_for_event(libusb_context *ctx, struct timeval *tv) 298{ 299 struct timespec ts; 300 int err; 301 302 ctx = GET_CONTEXT(ctx); 303 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_wait_for_event enter"); 304 305 if (tv == NULL) { 306 pthread_cond_wait(&ctx->ctx_cond, 307 &ctx->ctx_lock); 308 return (0); 309 } 310 err = clock_gettime(CLOCK_MONOTONIC, &ts); 311 if (err < 0) 312 return (LIBUSB_ERROR_OTHER); 313 314 /* 315 * The "tv" arguments points to a relative time structure and 316 * not an absolute time structure. 317 */ 318 ts.tv_sec += tv->tv_sec; 319 ts.tv_nsec += tv->tv_usec * 1000; 320 if (ts.tv_nsec >= 1000000000) { 321 ts.tv_nsec -= 1000000000; 322 ts.tv_sec++; 323 } 324 err = pthread_cond_timedwait(&ctx->ctx_cond, 325 &ctx->ctx_lock, &ts); 326 327 if (err == ETIMEDOUT) 328 return (1); 329 330 return (0); 331} 332 333int 334libusb_handle_events_timeout(libusb_context *ctx, struct timeval *tv) 335{ 336 int err; 337 338 ctx = GET_CONTEXT(ctx); 339 340 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_handle_events_timeout enter"); 341 342 libusb_lock_events(ctx); 343 344 err = libusb_handle_events_locked(ctx, tv); 345 346 libusb_unlock_events(ctx); 347 348 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_handle_events_timeout leave"); 349 350 return (err); 351} 352 353int 354libusb_handle_events(libusb_context *ctx) 355{ 356 return (libusb_handle_events_timeout(ctx, NULL)); 357} 358 359int 360libusb_handle_events_locked(libusb_context *ctx, struct timeval *tv) 361{ 362 int err; 363 364 ctx = GET_CONTEXT(ctx); 365 366 if (libusb_event_handling_ok(ctx)) { 367 err = libusb10_handle_events_sub(ctx, tv); 368 } else { 369 libusb_wait_for_event(ctx, tv); 370 err = 0; 371 } 372 return (err); 373} 374 375int 376libusb_get_next_timeout(libusb_context *ctx, struct timeval *tv) 377{ 378 /* all timeouts are currently being done by the kernel */ 379 timerclear(tv); 380 return (0); 381} 382 383void 384libusb_set_pollfd_notifiers(libusb_context *ctx, 385 libusb_pollfd_added_cb added_cb, libusb_pollfd_removed_cb removed_cb, 386 void *user_data) 387{ 388 ctx = GET_CONTEXT(ctx); 389 390 ctx->fd_added_cb = added_cb; 391 ctx->fd_removed_cb = removed_cb; 392 ctx->fd_cb_user_data = user_data; 393} 394 395struct libusb_pollfd ** 396libusb_get_pollfds(libusb_context *ctx) 397{ 398 struct libusb_super_pollfd *pollfd; 399 libusb_pollfd **ret; 400 int i; 401 402 ctx = GET_CONTEXT(ctx); 403 404 CTX_LOCK(ctx); 405 406 i = 0; 407 TAILQ_FOREACH(pollfd, &ctx->pollfds, entry) 408 i++; 409 410 ret = calloc(i + 1, sizeof(struct libusb_pollfd *)); 411 if (ret == NULL) 412 goto done; 413 414 i = 0; 415 TAILQ_FOREACH(pollfd, &ctx->pollfds, entry) 416 ret[i++] = &pollfd->pollfd; 417 ret[i] = NULL; 418 419done: 420 CTX_UNLOCK(ctx); 421 return (ret); 422} 423 424 425/* Synchronous device I/O */ 426 427int 428libusb_control_transfer(libusb_device_handle *devh, 429 uint8_t bmRequestType, uint8_t bRequest, uint16_t wValue, uint16_t wIndex, 430 uint8_t *data, uint16_t wLength, unsigned int timeout) 431{ 432 struct LIBUSB20_CONTROL_SETUP_DECODED req; 433 int err; 434 uint16_t actlen; 435 436 if (devh == NULL) 437 return (LIBUSB_ERROR_INVALID_PARAM); 438 439 if ((wLength != 0) && (data == NULL)) 440 return (LIBUSB_ERROR_INVALID_PARAM); 441 442 LIBUSB20_INIT(LIBUSB20_CONTROL_SETUP, &req); 443 444 req.bmRequestType = bmRequestType; 445 req.bRequest = bRequest; 446 req.wValue = wValue; 447 req.wIndex = wIndex; 448 req.wLength = wLength; 449 450 err = libusb20_dev_request_sync(devh, &req, data, 451 &actlen, timeout, 0); 452 453 if (err == LIBUSB20_ERROR_PIPE) 454 return (LIBUSB_ERROR_PIPE); 455 else if (err == LIBUSB20_ERROR_TIMEOUT) 456 return (LIBUSB_ERROR_TIMEOUT); 457 else if (err) 458 return (LIBUSB_ERROR_NO_DEVICE); 459 460 return (actlen); 461} 462 463static void 464libusb10_do_transfer_cb(struct libusb_transfer *transfer) 465{ 466 libusb_context *ctx; 467 int *pdone; 468 469 ctx = GET_CONTEXT(NULL); 470 471 DPRINTF(ctx, LIBUSB_DEBUG_TRANSFER, "sync I/O done"); 472 473 pdone = transfer->user_data; 474 *pdone = 1; 475} 476 477/* 478 * TODO: Replace the following function. Allocating and freeing on a 479 * per-transfer basis is slow. --HPS 480 */ 481static int 482libusb10_do_transfer(libusb_device_handle *devh, 483 uint8_t endpoint, uint8_t *data, int length, 484 int *transferred, unsigned int timeout, int type) 485{ 486 libusb_context *ctx; 487 struct libusb_transfer *xfer; 488 int done; 489 int ret; 490 491 if (devh == NULL) 492 return (LIBUSB_ERROR_INVALID_PARAM); 493 494 if ((length != 0) && (data == NULL)) 495 return (LIBUSB_ERROR_INVALID_PARAM); 496 497 xfer = libusb_alloc_transfer(0); 498 if (xfer == NULL) 499 return (LIBUSB_ERROR_NO_MEM); 500 501 ctx = libusb_get_device(devh)->ctx; 502 503 xfer->dev_handle = devh; 504 xfer->endpoint = endpoint; 505 xfer->type = type; 506 xfer->timeout = timeout; 507 xfer->buffer = data; 508 xfer->length = length; 509 xfer->user_data = (void *)&done; 510 xfer->callback = libusb10_do_transfer_cb; 511 done = 0; 512 513 if ((ret = libusb_submit_transfer(xfer)) < 0) { 514 libusb_free_transfer(xfer); 515 return (ret); 516 } 517 while (done == 0) { 518 if ((ret = libusb_handle_events(ctx)) < 0) { 519 libusb_cancel_transfer(xfer); 520 usleep(1000); /* nice it */ 521 } 522 } 523 524 *transferred = xfer->actual_length; 525 526 switch (xfer->status) { 527 case LIBUSB_TRANSFER_COMPLETED: 528 ret = 0; 529 break; 530 case LIBUSB_TRANSFER_TIMED_OUT: 531 ret = LIBUSB_ERROR_TIMEOUT; 532 break; 533 case LIBUSB_TRANSFER_OVERFLOW: 534 ret = LIBUSB_ERROR_OVERFLOW; 535 break; 536 case LIBUSB_TRANSFER_STALL: 537 ret = LIBUSB_ERROR_PIPE; 538 break; 539 case LIBUSB_TRANSFER_NO_DEVICE: 540 ret = LIBUSB_ERROR_NO_DEVICE; 541 break; 542 default: 543 ret = LIBUSB_ERROR_OTHER; 544 break; 545 } 546 547 libusb_free_transfer(xfer); 548 return (ret); 549} 550 551int 552libusb_bulk_transfer(libusb_device_handle *devh, 553 uint8_t endpoint, uint8_t *data, int length, 554 int *transferred, unsigned int timeout) 555{ 556 libusb_context *ctx; 557 int ret; 558 559 ctx = GET_CONTEXT(NULL); 560 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_bulk_transfer enter"); 561 562 ret = libusb10_do_transfer(devh, endpoint, data, length, transferred, 563 timeout, LIBUSB_TRANSFER_TYPE_BULK); 564 565 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_bulk_transfer leave"); 566 return (ret); 567} 568 569int 570libusb_interrupt_transfer(libusb_device_handle *devh, 571 uint8_t endpoint, uint8_t *data, int length, 572 int *transferred, unsigned int timeout) 573{ 574 libusb_context *ctx; 575 int ret; 576 577 ctx = GET_CONTEXT(NULL); 578 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_interrupt_transfer enter"); 579 580 ret = libusb10_do_transfer(devh, endpoint, data, length, transferred, 581 timeout, LIBUSB_TRANSFER_TYPE_INTERRUPT); 582 583 DPRINTF(ctx, LIBUSB_DEBUG_FUNCTION, "libusb_interrupt_transfer leave"); 584 return (ret); 585} 586 587uint8_t * 588libusb_get_iso_packet_buffer(struct libusb_transfer *transfer, uint32_t off) 589{ 590 uint8_t *ptr; 591 uint32_t n; 592 593 if (transfer->num_iso_packets < 0) 594 return (NULL); 595 596 if (off >= (uint32_t)transfer->num_iso_packets) 597 return (NULL); 598 599 ptr = transfer->buffer; 600 if (ptr == NULL) 601 return (NULL); 602 603 for (n = 0; n != off; n++) { 604 ptr += transfer->iso_packet_desc[n].length; 605 } 606 return (ptr); 607} 608 609uint8_t * 610libusb_get_iso_packet_buffer_simple(struct libusb_transfer *transfer, uint32_t off) 611{ 612 uint8_t *ptr; 613 614 if (transfer->num_iso_packets < 0) 615 return (NULL); 616 617 if (off >= (uint32_t)transfer->num_iso_packets) 618 return (NULL); 619 620 ptr = transfer->buffer; 621 if (ptr == NULL) 622 return (NULL); 623 624 ptr += transfer->iso_packet_desc[0].length * off; 625 626 return (ptr); 627} 628 629void 630libusb_set_iso_packet_lengths(struct libusb_transfer *transfer, uint32_t length) 631{ 632 int n; 633 634 if (transfer->num_iso_packets < 0) 635 return; 636 637 for (n = 0; n != transfer->num_iso_packets; n++) 638 transfer->iso_packet_desc[n].length = length; 639} 640 641uint8_t * 642libusb_control_transfer_get_data(struct libusb_transfer *transfer) 643{ 644 if (transfer->buffer == NULL) 645 return (NULL); 646 647 return (transfer->buffer + LIBUSB_CONTROL_SETUP_SIZE); 648} 649 650struct libusb_control_setup * 651libusb_control_transfer_get_setup(struct libusb_transfer *transfer) 652{ 653 return ((struct libusb_control_setup *)transfer->buffer); 654} 655 656void 657libusb_fill_control_setup(uint8_t *buf, uint8_t bmRequestType, 658 uint8_t bRequest, uint16_t wValue, 659 uint16_t wIndex, uint16_t wLength) 660{ 661 struct libusb_control_setup *req = (struct libusb_control_setup *)buf; 662 663 /* The alignment is OK for all fields below. */ 664 req->bmRequestType = bmRequestType; 665 req->bRequest = bRequest; 666 req->wValue = htole16(wValue); 667 req->wIndex = htole16(wIndex); 668 req->wLength = htole16(wLength); 669} 670 671void 672libusb_fill_control_transfer(struct libusb_transfer *transfer, 673 libusb_device_handle *devh, uint8_t *buf, 674 libusb_transfer_cb_fn callback, void *user_data, 675 uint32_t timeout) 676{ 677 struct libusb_control_setup *setup = (struct libusb_control_setup *)buf; 678 679 transfer->dev_handle = devh; 680 transfer->endpoint = 0; 681 transfer->type = LIBUSB_TRANSFER_TYPE_CONTROL; 682 transfer->timeout = timeout; 683 transfer->buffer = buf; 684 if (setup != NULL) 685 transfer->length = LIBUSB_CONTROL_SETUP_SIZE 686 + le16toh(setup->wLength); 687 else 688 transfer->length = 0; 689 transfer->user_data = user_data; 690 transfer->callback = callback; 691 692} 693 694void 695libusb_fill_bulk_transfer(struct libusb_transfer *transfer, 696 libusb_device_handle *devh, uint8_t endpoint, uint8_t *buf, 697 int length, libusb_transfer_cb_fn callback, void *user_data, 698 uint32_t timeout) 699{ 700 transfer->dev_handle = devh; 701 transfer->endpoint = endpoint; 702 transfer->type = LIBUSB_TRANSFER_TYPE_BULK; 703 transfer->timeout = timeout; 704 transfer->buffer = buf; 705 transfer->length = length; 706 transfer->user_data = user_data; 707 transfer->callback = callback; 708} 709 710void 711libusb_fill_interrupt_transfer(struct libusb_transfer *transfer, 712 libusb_device_handle *devh, uint8_t endpoint, uint8_t *buf, 713 int length, libusb_transfer_cb_fn callback, void *user_data, 714 uint32_t timeout) 715{ 716 transfer->dev_handle = devh; 717 transfer->endpoint = endpoint; 718 transfer->type = LIBUSB_TRANSFER_TYPE_INTERRUPT; 719 transfer->timeout = timeout; 720 transfer->buffer = buf; 721 transfer->length = length; 722 transfer->user_data = user_data; 723 transfer->callback = callback; 724} 725 726void 727libusb_fill_iso_transfer(struct libusb_transfer *transfer, 728 libusb_device_handle *devh, uint8_t endpoint, uint8_t *buf, 729 int length, int npacket, libusb_transfer_cb_fn callback, 730 void *user_data, uint32_t timeout) 731{ 732 transfer->dev_handle = devh; 733 transfer->endpoint = endpoint; 734 transfer->type = LIBUSB_TRANSFER_TYPE_ISOCHRONOUS; 735 transfer->timeout = timeout; 736 transfer->buffer = buf; 737 transfer->length = length; 738 transfer->num_iso_packets = npacket; 739 transfer->user_data = user_data; 740 transfer->callback = callback; 741} 742 743