summaryrefslogtreecommitdiffstats
path: root/src/gbm/main/gbm.c
blob: 250151871d9dc92c27de0e8b5e1958b3b55961fa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
/*
 * Copyright © 2011 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Benjamin Franzke <benjaminfranzke@googlemail.com>
 */

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

#ifdef MAJOR_IN_MKDEV
#include <sys/mkdev.h>
#endif
#ifdef MAJOR_IN_SYSMACROS
#include <sys/sysmacros.h>
#endif
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>

#include "gbm.h"
#include "gbmint.h"
#include "backend.h"

/** Returns the file description for the gbm device
 *
 * \return The fd that the struct gbm_device was created with
 */
GBM_EXPORT int
gbm_device_get_fd(struct gbm_device *gbm)
{
   return gbm->fd;
}

/** Get the backend name for the given gbm device
 *
 * \return The backend name string - this belongs to the device and must not
 * be freed
 */
GBM_EXPORT const char *
gbm_device_get_backend_name(struct gbm_device *gbm)
{
   return gbm->name;
}

/** Test if a format is supported for a given set of usage flags.
 *
 * \param gbm The created buffer manager
 * \param format The format to test
 * \param usage A bitmask of the usages to test the format against
 * \return 1 if the format is supported otherwise 0
 *
 * \sa enum gbm_bo_flags for the list of flags that the format can be
 * tested against
 *
 * \sa enum gbm_bo_format for the list of formats
 */
GBM_EXPORT int
gbm_device_is_format_supported(struct gbm_device *gbm,
                               uint32_t format, uint32_t usage)
{
   return gbm->is_format_supported(gbm, format, usage);
}

/** Get the number of planes that are required for a given format+modifier
 *
 * \param gbm The gbm device returned from gbm_create_device()
 * \param format The format to query
 * \param modifier The modifier to query
 */
GBM_EXPORT int
gbm_device_get_format_modifier_plane_count(struct gbm_device *gbm,
                                           uint32_t format,
                                           uint64_t modifier)
{
   return gbm->get_format_modifier_plane_count(gbm, format, modifier);
}

/** Destroy the gbm device and free all resources associated with it.
 *
 * \param gbm The device created using gbm_create_device()
 */
GBM_EXPORT void
gbm_device_destroy(struct gbm_device *gbm)
{
   gbm->refcount--;
   if (gbm->refcount == 0)
      gbm->destroy(gbm);
}

/** Create a gbm device for allocating buffers
 *
 * The file descriptor passed in is used by the backend to communicate with
 * platform for allocating the memory. For allocations using DRI this would be
 * the file descriptor returned when opening a device such as \c
 * /dev/dri/card0
 *
 * \param fd The file descriptor for a backend specific device
 * \return The newly created struct gbm_device. The resources associated with
 * the device should be freed with gbm_device_destroy() when it is no longer
 * needed. If the creation of the device failed NULL will be returned.
 */
GBM_EXPORT struct gbm_device *
gbm_create_device(int fd)
{
   struct gbm_device *gbm = NULL;
   struct stat buf;

   if (fd < 0 || fstat(fd, &buf) < 0 || !S_ISCHR(buf.st_mode)) {
      errno = EINVAL;
      return NULL;
   }

   gbm = _gbm_create_device(fd);
   if (gbm == NULL)
      return NULL;

   gbm->dummy = gbm_create_device;
   gbm->stat = buf;
   gbm->refcount = 1;

   return gbm;
}

/** Get the width of the buffer object
 *
 * \param bo The buffer object
 * \return The width of the allocated buffer object
 *
 */
GBM_EXPORT uint32_t
gbm_bo_get_width(struct gbm_bo *bo)
{
   return bo->width;
}

/** Get the height of the buffer object
 *
 * \param bo The buffer object
 * \return The height of the allocated buffer object
 */
GBM_EXPORT uint32_t
gbm_bo_get_height(struct gbm_bo *bo)
{
   return bo->height;
}

/** Get the stride of the buffer object
 *
 * This is calculated by the backend when it does the allocation in
 * gbm_bo_create()
 *
 * \param bo The buffer object
 * \return The stride of the allocated buffer object in bytes
 */
GBM_EXPORT uint32_t
gbm_bo_get_stride(struct gbm_bo *bo)
{
   return gbm_bo_get_stride_for_plane(bo, 0);
}

/** Get the stride for the given plane
 *
 * \param bo The buffer object
 * \param plane for which you want the stride
 *
 * \sa gbm_bo_get_stride()
 */
GBM_EXPORT uint32_t
gbm_bo_get_stride_for_plane(struct gbm_bo *bo, int plane)
{
   return bo->gbm->bo_get_stride(bo, plane);
}

/** Get the format of the buffer object
 *
 * The format of the pixels in the buffer.
 *
 * \param bo The buffer object
 * \return The format of buffer object, one of the GBM_FORMAT_* codes
 */
GBM_EXPORT uint32_t
gbm_bo_get_format(struct gbm_bo *bo)
{
   return bo->format;
}

/** Get the bit-per-pixel of the buffer object's format
 *
 * The bits-per-pixel of the buffer object's format.
 *
 * Note; The 'in-memory pixel' concept makes no sense for YUV formats
 * (pixels are the result of the combination of multiple memory sources:
 * Y, Cb & Cr; usually these are even in separate buffers), so YUV
 * formats are not supported by this function.
 *
 * \param bo The buffer object
 * \return The number of bits0per-pixel of the buffer object's format.
 */
GBM_EXPORT uint32_t
gbm_bo_get_bpp(struct gbm_bo *bo)
{
   switch (bo->format) {
      default:
         return 0;
      case GBM_FORMAT_C8:
      case GBM_FORMAT_R8:
      case GBM_FORMAT_RGB332:
      case GBM_FORMAT_BGR233:
         return 8;
      case GBM_FORMAT_GR88:
      case GBM_FORMAT_XRGB4444:
      case GBM_FORMAT_XBGR4444:
      case GBM_FORMAT_RGBX4444:
      case GBM_FORMAT_BGRX4444:
      case GBM_FORMAT_ARGB4444:
      case GBM_FORMAT_ABGR4444:
      case GBM_FORMAT_RGBA4444:
      case GBM_FORMAT_BGRA4444:
      case GBM_FORMAT_XRGB1555:
      case GBM_FORMAT_XBGR1555:
      case GBM_FORMAT_RGBX5551:
      case GBM_FORMAT_BGRX5551:
      case GBM_FORMAT_ARGB1555:
      case GBM_FORMAT_ABGR1555:
      case GBM_FORMAT_RGBA5551:
      case GBM_FORMAT_BGRA5551:
      case GBM_FORMAT_RGB565:
      case GBM_FORMAT_BGR565:
         return 16;
      case GBM_FORMAT_RGB888:
      case GBM_FORMAT_BGR888:
         return 24;
      case GBM_FORMAT_XRGB8888:
      case GBM_FORMAT_XBGR8888:
      case GBM_FORMAT_RGBX8888:
      case GBM_FORMAT_BGRX8888:
      case GBM_FORMAT_ARGB8888:
      case GBM_FORMAT_ABGR8888:
      case GBM_FORMAT_RGBA8888:
      case GBM_FORMAT_BGRA8888:
      case GBM_FORMAT_XRGB2101010:
      case GBM_FORMAT_XBGR2101010:
      case GBM_FORMAT_RGBX1010102:
      case GBM_FORMAT_BGRX1010102:
      case GBM_FORMAT_ARGB2101010:
      case GBM_FORMAT_ABGR2101010:
      case GBM_FORMAT_RGBA1010102:
      case GBM_FORMAT_BGRA1010102:
         return 32;
   }
}

/** Get the offset for the data of the specified plane
 *
 * Extra planes, and even the first plane, may have an offset from the start of
 * the buffer object. This function will provide the offset for the given plane
 * to be used in various KMS APIs.
 *
 * \param bo The buffer object
 * \return The offset
 */
GBM_EXPORT uint32_t
gbm_bo_get_offset(struct gbm_bo *bo, int plane)
{
   return bo->gbm->bo_get_offset(bo, plane);
}

/** Get the gbm device used to create the buffer object
 *
 * \param bo The buffer object
 * \return Returns the gbm device with which the buffer object was created
 */
GBM_EXPORT struct gbm_device *
gbm_bo_get_device(struct gbm_bo *bo)
{
	return bo->gbm;
}

/** Get the handle of the buffer object
 *
 * This is stored in the platform generic union gbm_bo_handle type. However
 * the format of this handle is platform specific.
 *
 * \param bo The buffer object
 * \return Returns the handle of the allocated buffer object
 */
GBM_EXPORT union gbm_bo_handle
gbm_bo_get_handle(struct gbm_bo *bo)
{
   return bo->handle;
}

/** Get a DMA-BUF file descriptor for the buffer object
 *
 * This function creates a DMA-BUF (also known as PRIME) file descriptor
 * handle for the buffer object.  Each call to gbm_bo_get_fd() returns a new
 * file descriptor and the caller is responsible for closing the file
 * descriptor.

 * \param bo The buffer object
 * \return Returns a file descriptor referring to the underlying buffer or -1
 * if an error occurs.
 */
GBM_EXPORT int
gbm_bo_get_fd(struct gbm_bo *bo)
{
   return bo->gbm->bo_get_fd(bo);
}

/** Get the number of planes for the given bo.
 *
 * \param bo The buffer object
 * \return The number of planes
 */
GBM_EXPORT int
gbm_bo_get_plane_count(struct gbm_bo *bo)
{
   return bo->gbm->bo_get_planes(bo);
}

/** Get the handle for the specified plane of the buffer object
 *
 * This function gets the handle for any plane associated with the BO. When
 * dealing with multi-planar formats, or formats which might have implicit
 * planes based on different underlying hardware it is necessary for the client
 * to be able to get this information to pass to the DRM.
 *
 * \param bo The buffer object
 * \param plane the plane to get a handle for
 *
 * \sa gbm_bo_get_handle()
 */
GBM_EXPORT union gbm_bo_handle
gbm_bo_get_handle_for_plane(struct gbm_bo *bo, int plane)
{
   return bo->gbm->bo_get_handle(bo, plane);
}

/**
 * Get the chosen modifier for the buffer object
 *
 * This function returns the modifier that was chosen for the object. These
 * properties may be generic, or platform/implementation dependent.
 *
 * \param bo The buffer object
 * \return Returns the selected modifier (chosen by the implementation) for the
 * BO.
 * \sa gbm_bo_create_with_modifiers() where possible modifiers are set
 * \sa gbm_surface_create_with_modifiers() where possible modifiers are set
 * \sa define DRM_FORMAT_MOD_* in drm_fourcc.h for possible modifiers
 */
GBM_EXPORT uint64_t
gbm_bo_get_modifier(struct gbm_bo *bo)
{
   return bo->gbm->bo_get_modifier(bo);
}

/** Write data into the buffer object
 *
 * If the buffer object was created with the GBM_BO_USE_WRITE flag,
 * this function can be used to write data into the buffer object.  The
 * data is copied directly into the object and it's the responsibility
 * of the caller to make sure the data represents valid pixel data,
 * according to the width, height, stride and format of the buffer object.
 *
 * \param bo The buffer object
 * \param buf The data to write
 * \param count The number of bytes to write
 * \return Returns 0 on success, otherwise -1 is returned an errno set
 */
GBM_EXPORT int
gbm_bo_write(struct gbm_bo *bo, const void *buf, size_t count)
{
   return bo->gbm->bo_write(bo, buf, count);
}

/** Set the user data associated with a buffer object
 *
 * \param bo The buffer object
 * \param data The data to associate to the buffer object
 * \param destroy_user_data A callback (which may be %NULL) that will be
 * called prior to the buffer destruction
 */
GBM_EXPORT void
gbm_bo_set_user_data(struct gbm_bo *bo, void *data,
		     void (*destroy_user_data)(struct gbm_bo *, void *))
{
   bo->user_data = data;
   bo->destroy_user_data = destroy_user_data;
}

/** Get the user data associated with a buffer object
 *
 * \param bo The buffer object
 * \return Returns the user data associated with the buffer object or %NULL
 * if no data was associated with it
 *
 * \sa gbm_bo_set_user_data()
 */
GBM_EXPORT void *
gbm_bo_get_user_data(struct gbm_bo *bo)
{
   return bo->user_data;
}

/**
 * Destroys the given buffer object and frees all resources associated with
 * it.
 *
 * \param bo The buffer object
 */
GBM_EXPORT void
gbm_bo_destroy(struct gbm_bo *bo)
{
   if (bo->destroy_user_data)
      bo->destroy_user_data(bo, bo->user_data);

   bo->gbm->bo_destroy(bo);
}

/**
 * Allocate a buffer object for the given dimensions
 *
 * \param gbm The gbm device returned from gbm_create_device()
 * \param width The width for the buffer
 * \param height The height for the buffer
 * \param format The format to use for the buffer, from GBM_FORMAT_* or
 * GBM_BO_FORMAT_* tokens
 * \param usage The union of the usage flags for this buffer
 *
 * \return A newly allocated buffer that should be freed with gbm_bo_destroy()
 * when no longer needed. If an error occurs during allocation %NULL will be
 * returned and errno set.
 *
 * \sa enum gbm_bo_flags for the list of usage flags
 */
GBM_EXPORT struct gbm_bo *
gbm_bo_create(struct gbm_device *gbm,
              uint32_t width, uint32_t height,
              uint32_t format, uint32_t usage)
{
   if (width == 0 || height == 0) {
      errno = EINVAL;
      return NULL;
   }

   return gbm->bo_create(gbm, width, height, format, usage, NULL, 0);
}

GBM_EXPORT struct gbm_bo *
gbm_bo_create_with_modifiers(struct gbm_device *gbm,
                             uint32_t width, uint32_t height,
                             uint32_t format,
                             const uint64_t *modifiers,
                             const unsigned int count)
{
   if (width == 0 || height == 0) {
      errno = EINVAL;
      return NULL;
   }

   if ((count && !modifiers) || (modifiers && !count)) {
      errno = EINVAL;
      return NULL;
   }

   return gbm->bo_create(gbm, width, height, format, 0, modifiers, count);
}
/**
 * Create a gbm buffer object from an foreign object
 *
 * This function imports a foreign object and creates a new gbm bo for it.
 * This enabled using the foreign object with a display API such as KMS.
 * Currently three types of foreign objects are supported, indicated by the type
 * argument:
 *
 *   GBM_BO_IMPORT_WL_BUFFER
 *   GBM_BO_IMPORT_EGL_IMAGE
 *   GBM_BO_IMPORT_FD
 *
 * The gbm bo shares the underlying pixels but its life-time is
 * independent of the foreign object.
 *
 * \param gbm The gbm device returned from gbm_create_device()
 * \param type The type of object we're importing
 * \param buffer Pointer to the external object
 * \param usage The union of the usage flags for this buffer
 *
 * \return A newly allocated buffer object that should be freed with
 * gbm_bo_destroy() when no longer needed. On error, %NULL is returned
 * and errno is set.
 *
 * \sa enum gbm_bo_flags for the list of usage flags
 */
GBM_EXPORT struct gbm_bo *
gbm_bo_import(struct gbm_device *gbm,
              uint32_t type, void *buffer, uint32_t usage)
{
   return gbm->bo_import(gbm, type, buffer, usage);
}

/**
 * Map a region of a gbm buffer object for cpu access
 *
 * This function maps a region of a gbm bo for cpu read and/or write
 * access.
 *
 * \param bo The buffer object
 * \param x The X (top left origin) starting position of the mapped region for
 * the buffer
 * \param y The Y (top left origin) starting position of the mapped region for
 * the buffer
 * \param width The width of the mapped region for the buffer
 * \param height The height of the mapped region for the buffer
 * \param flags The union of the GBM_BO_TRANSFER_* flags for this buffer
 * \param stride Ptr for returned stride in bytes of the mapped region
 * \param map_data Returned opaque ptr for the mapped region
 *
 * \return Address of the mapped buffer that should be unmapped with
 * gbm_bo_unmap() when no longer needed. On error, %NULL is returned
 * and errno is set.
 *
 * \sa enum gbm_bo_transfer_flags for the list of flags
 */
GBM_EXPORT void *
gbm_bo_map(struct gbm_bo *bo,
              uint32_t x, uint32_t y,
              uint32_t width, uint32_t height,
              uint32_t flags, uint32_t *stride, void **map_data)
{
   if (!bo || width == 0 || height == 0 || !stride || !map_data) {
      errno = EINVAL;
      return NULL;
   }

   return bo->gbm->bo_map(bo, x, y, width, height,
                          flags, stride, map_data);
}

/**
 * Unmap a previously mapped region of a gbm buffer object
 *
 * This function unmaps a region of a gbm bo for cpu read and/or write
 * access.
 *
 * \param bo The buffer object
 * \param map_data opaque ptr returned from prior gbm_bo_map
 */
GBM_EXPORT void
gbm_bo_unmap(struct gbm_bo *bo, void *map_data)
{
   bo->gbm->bo_unmap(bo, map_data);
}

/**
 * Allocate a surface object
 *
 * \param gbm The gbm device returned from gbm_create_device()
 * \param width The width for the surface
 * \param height The height for the surface
 * \param format The format to use for the surface
 *
 * \return A newly allocated surface that should be freed with
 * gbm_surface_destroy() when no longer needed. If an error occurs
 * during allocation %NULL will be returned.
 *
 * \sa enum gbm_bo_format for the list of formats
 */
GBM_EXPORT struct gbm_surface *
gbm_surface_create(struct gbm_device *gbm,
                   uint32_t width, uint32_t height,
		   uint32_t format, uint32_t flags)
{
   return gbm->surface_create(gbm, width, height, format, flags, NULL, 0);
}

GBM_EXPORT struct gbm_surface *
gbm_surface_create_with_modifiers(struct gbm_device *gbm,
                                  uint32_t width, uint32_t height,
                                  uint32_t format,
                                  const uint64_t *modifiers,
                                  const unsigned int count)
{
   if ((count && !modifiers) || (modifiers && !count)) {
      errno = EINVAL;
      return NULL;
   }

   return gbm->surface_create(gbm, width, height, format, 0,
                              modifiers, count);
}

/**
 * Destroys the given surface and frees all resources associated with
 * it.
 *
 * All buffers locked with gbm_surface_lock_front_buffer() should be
 * released prior to calling this function.
 *
 * \param surf The surface
 */
GBM_EXPORT void
gbm_surface_destroy(struct gbm_surface *surf)
{
   surf->gbm->surface_destroy(surf);
}

/**
 * Lock the surface's current front buffer
 *
 * Lock rendering to the surface's current front buffer until it is
 * released with gbm_surface_release_buffer().
 *
 * This function must be called exactly once after calling
 * eglSwapBuffers.  Calling it before any eglSwapBuffer has happened
 * on the surface or two or more times after eglSwapBuffers is an
 * error.  A new bo representing the new front buffer is returned.  On
 * multiple invocations, all the returned bos must be released in
 * order to release the actual surface buffer.
 *
 * \param surf The surface
 *
 * \return A buffer object that should be released with
 * gbm_surface_release_buffer() when no longer needed.  The implementation
 * is free to reuse buffers released with gbm_surface_release_buffer() so
 * this bo should not be destroyed using gbm_bo_destroy().  If an error
 * occurs this function returns %NULL.
 */
GBM_EXPORT struct gbm_bo *
gbm_surface_lock_front_buffer(struct gbm_surface *surf)
{
   return surf->gbm->surface_lock_front_buffer(surf);
}

/**
 * Release a locked buffer obtained with gbm_surface_lock_front_buffer()
 *
 * Returns the underlying buffer to the gbm surface.  Releasing a bo
 * will typically make gbm_surface_has_free_buffer() return 1 and thus
 * allow rendering the next frame, but not always. The implementation
 * may choose to destroy the bo immediately or reuse it, in which case
 * the user data associated with it is unchanged.
 *
 * \param surf The surface
 * \param bo The buffer object
 */
GBM_EXPORT void
gbm_surface_release_buffer(struct gbm_surface *surf, struct gbm_bo *bo)
{
   surf->gbm->surface_release_buffer(surf, bo);
}

/**
 * Return whether or not a surface has free (non-locked) buffers
 *
 * Before starting a new frame, the surface must have a buffer
 * available for rendering.  Initially, a gbm surface will have a free
 * buffer, but after one or more buffers have been locked (\sa
 * gbm_surface_lock_front_buffer()), the application must check for a
 * free buffer before rendering.
 *
 * If a surface doesn't have a free buffer, the application must
 * return a buffer to the surface using gbm_surface_release_buffer()
 * and after that, the application can query for free buffers again.
 *
 * \param surf The surface
 * \return 1 if the surface has free buffers, 0 otherwise
 */
GBM_EXPORT int
gbm_surface_has_free_buffers(struct gbm_surface *surf)
{
   return surf->gbm->surface_has_free_buffers(surf);
}

/* The two GBM_BO_FORMAT_[XA]RGB8888 formats alias the GBM_FORMAT_*
 * formats of the same name. We want to accept them whenever someone
 * has a GBM format, but never return them to the user. */
uint32_t
gbm_format_canonicalize(uint32_t gbm_format)
{
   switch (gbm_format) {
   case GBM_BO_FORMAT_XRGB8888:
      return GBM_FORMAT_XRGB8888;
   case GBM_BO_FORMAT_ARGB8888:
      return GBM_FORMAT_ARGB8888;
   default:
      return gbm_format;
   }
}

/**
 * Returns a string representing the fourcc format name.
 *
 * \param desc Caller-provided storage for the format name string.
 * \return String containing the fourcc of the format.
 */
GBM_EXPORT char *
gbm_format_get_name(uint32_t gbm_format, struct gbm_format_name_desc *desc)
{
   gbm_format = gbm_format_canonicalize(gbm_format);

   desc->name[0] = gbm_format;
   desc->name[1] = gbm_format >> 8;
   desc->name[2] = gbm_format >> 16;
   desc->name[3] = gbm_format >> 24;
   desc->name[4] = 0;

   return desc->name;
}