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1da177e4 LT |
1 | |
2 | SN9C10x PC Camera Controllers | |
3 | Driver for Linux | |
4 | ============================= | |
5 | ||
6 | - Documentation - | |
7 | ||
8 | ||
9 | Index | |
10 | ===== | |
11 | 1. Copyright | |
12 | 2. Disclaimer | |
13 | 3. License | |
14 | 4. Overview and features | |
15 | 5. Module dependencies | |
16 | 6. Module loading | |
17 | 7. Module parameters | |
18 | 8. Optional device control through "sysfs" | |
19 | 9. Supported devices | |
a966f3e7 LR |
20 | 10. Notes for V4L2 application developers |
21 | 11. Video frame formats | |
22 | 12. Contact information | |
23 | 13. Credits | |
1da177e4 LT |
24 | |
25 | ||
26 | 1. Copyright | |
27 | ============ | |
a966f3e7 | 28 | Copyright (C) 2004-2006 by Luca Risolia <luca.risolia@studio.unibo.it> |
1da177e4 LT |
29 | |
30 | ||
31 | 2. Disclaimer | |
32 | ============= | |
33 | SONiX is a trademark of SONiX Technology Company Limited, inc. | |
34 | This software is not sponsored or developed by SONiX. | |
35 | ||
36 | ||
37 | 3. License | |
38 | ========== | |
39 | This program is free software; you can redistribute it and/or modify | |
40 | it under the terms of the GNU General Public License as published by | |
41 | the Free Software Foundation; either version 2 of the License, or | |
42 | (at your option) any later version. | |
43 | ||
44 | This program is distributed in the hope that it will be useful, | |
45 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
46 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
47 | GNU General Public License for more details. | |
48 | ||
49 | You should have received a copy of the GNU General Public License | |
50 | along with this program; if not, write to the Free Software | |
51 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | |
52 | ||
53 | ||
54 | 4. Overview and features | |
55 | ======================== | |
a966f3e7 LR |
56 | This driver attempts to support the video interface of the devices mounting the |
57 | SONiX SN9C101, SN9C102 and SN9C103 PC Camera Controllers. | |
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58 | |
59 | It's worth to note that SONiX has never collaborated with the author during the | |
60 | development of this project, despite several requests for enough detailed | |
61 | specifications of the register tables, compression engine and video data format | |
62 | of the above chips. Nevertheless, these informations are no longer necessary, | |
63 | becouse all the aspects related to these chips are known and have been | |
64 | described in detail in this documentation. | |
65 | ||
66 | The driver relies on the Video4Linux2 and USB core modules. It has been | |
67 | designed to run properly on SMP systems as well. | |
68 | ||
69 | The latest version of the SN9C10x driver can be found at the following URL: | |
70 | http://www.linux-projects.org/ | |
71 | ||
72 | Some of the features of the driver are: | |
73 | ||
74 | - full compliance with the Video4Linux2 API (see also "Notes for V4L2 | |
75 | application developers" paragraph); | |
76 | - available mmap or read/poll methods for video streaming through isochronous | |
77 | data transfers; | |
78 | - automatic detection of image sensor; | |
a966f3e7 | 79 | - support for built-in microphone interface; |
1da177e4 LT |
80 | - support for any window resolutions and optional panning within the maximum |
81 | pixel area of image sensor; | |
82 | - image downscaling with arbitrary scaling factors from 1, 2 and 4 in both | |
83 | directions (see "Notes for V4L2 application developers" paragraph); | |
84 | - two different video formats for uncompressed or compressed data in low or | |
85 | high compression quality (see also "Notes for V4L2 application developers" | |
86 | and "Video frame formats" paragraphs); | |
87 | - full support for the capabilities of many of the possible image sensors that | |
88 | can be connected to the SN9C10x bridges, including, for istance, red, green, | |
89 | blue and global gain adjustments and exposure (see "Supported devices" | |
90 | paragraph for details); | |
91 | - use of default color settings for sunlight conditions; | |
92 | - dynamic I/O interface for both SN9C10x and image sensor control and | |
93 | monitoring (see "Optional device control through 'sysfs'" paragraph); | |
94 | - dynamic driver control thanks to various module parameters (see "Module | |
95 | parameters" paragraph); | |
96 | - up to 64 cameras can be handled at the same time; they can be connected and | |
97 | disconnected from the host many times without turning off the computer, if | |
a966f3e7 | 98 | the system supports hotplugging; |
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99 | - no known bugs. |
100 | ||
101 | ||
102 | 5. Module dependencies | |
103 | ====================== | |
104 | For it to work properly, the driver needs kernel support for Video4Linux and | |
105 | USB. | |
106 | ||
107 | The following options of the kernel configuration file must be enabled and | |
108 | corresponding modules must be compiled: | |
109 | ||
110 | # Multimedia devices | |
111 | # | |
112 | CONFIG_VIDEO_DEV=m | |
113 | ||
114 | # USB support | |
115 | # | |
116 | CONFIG_USB=m | |
117 | ||
118 | In addition, depending on the hardware being used, the modules below are | |
119 | necessary: | |
120 | ||
121 | # USB Host Controller Drivers | |
122 | # | |
123 | CONFIG_USB_EHCI_HCD=m | |
124 | CONFIG_USB_UHCI_HCD=m | |
125 | CONFIG_USB_OHCI_HCD=m | |
126 | ||
a966f3e7 LR |
127 | The SN9C103 controller also provides a built-in microphone interface. It is |
128 | supported by the USB Audio driver thanks to the ALSA API: | |
129 | ||
130 | # Sound | |
131 | # | |
132 | CONFIG_SOUND=y | |
133 | ||
134 | # Advanced Linux Sound Architecture | |
135 | # | |
136 | CONFIG_SND=m | |
137 | ||
138 | # USB devices | |
139 | # | |
140 | CONFIG_SND_USB_AUDIO=m | |
141 | ||
1da177e4 LT |
142 | And finally: |
143 | ||
144 | # USB Multimedia devices | |
145 | # | |
146 | CONFIG_USB_SN9C102=m | |
147 | ||
148 | ||
149 | 6. Module loading | |
150 | ================= | |
151 | To use the driver, it is necessary to load the "sn9c102" module into memory | |
152 | after every other module required: "videodev", "usbcore" and, depending on | |
153 | the USB host controller you have, "ehci-hcd", "uhci-hcd" or "ohci-hcd". | |
154 | ||
155 | Loading can be done as shown below: | |
156 | ||
157 | [root@localhost home]# modprobe sn9c102 | |
158 | ||
159 | At this point the devices should be recognized. You can invoke "dmesg" to | |
160 | analyze kernel messages and verify that the loading process has gone well: | |
161 | ||
162 | [user@localhost home]$ dmesg | |
163 | ||
164 | ||
165 | 7. Module parameters | |
166 | ==================== | |
167 | Module parameters are listed below: | |
168 | ------------------------------------------------------------------------------- | |
169 | Name: video_nr | |
a966f3e7 | 170 | Type: short array (min = 0, max = 64) |
1da177e4 LT |
171 | Syntax: <-1|n[,...]> |
172 | Description: Specify V4L2 minor mode number: | |
173 | -1 = use next available | |
174 | n = use minor number n | |
175 | You can specify up to 64 cameras this way. | |
176 | For example: | |
177 | video_nr=-1,2,-1 would assign minor number 2 to the second | |
178 | recognized camera and use auto for the first one and for every | |
179 | other camera. | |
180 | Default: -1 | |
181 | ------------------------------------------------------------------------------- | |
a966f3e7 | 182 | Name: force_munmap |
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183 | Type: bool array (min = 0, max = 64) |
184 | Syntax: <0|1[,...]> | |
185 | Description: Force the application to unmap previously mapped buffer memory | |
186 | before calling any VIDIOC_S_CROP or VIDIOC_S_FMT ioctl's. Not | |
187 | all the applications support this feature. This parameter is | |
188 | specific for each detected camera. | |
a966f3e7 LR |
189 | 0 = do not force memory unmapping |
190 | 1 = force memory unmapping (save memory) | |
1da177e4 LT |
191 | Default: 0 |
192 | ------------------------------------------------------------------------------- | |
193 | Name: debug | |
a966f3e7 | 194 | Type: ushort |
1da177e4 LT |
195 | Syntax: <n> |
196 | Description: Debugging information level, from 0 to 3: | |
197 | 0 = none (use carefully) | |
198 | 1 = critical errors | |
199 | 2 = significant informations | |
200 | 3 = more verbose messages | |
201 | Level 3 is useful for testing only, when only one device | |
202 | is used. It also shows some more informations about the | |
203 | hardware being detected. This parameter can be changed at | |
a966f3e7 | 204 | runtime thanks to the /sys filesystem interface. |
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205 | Default: 2 |
206 | ------------------------------------------------------------------------------- | |
207 | ||
208 | ||
209 | 8. Optional device control through "sysfs" [1] | |
210 | ========================================== | |
211 | It is possible to read and write both the SN9C10x and the image sensor | |
212 | registers by using the "sysfs" filesystem interface. | |
213 | ||
214 | Every time a supported device is recognized, a write-only file named "green" is | |
215 | created in the /sys/class/video4linux/videoX directory. You can set the green | |
216 | channel's gain by writing the desired value to it. The value may range from 0 | |
217 | to 15 for SN9C101 or SN9C102 bridges, from 0 to 127 for SN9C103 bridges. | |
218 | Similarly, only for SN9C103 controllers, blue and red gain control files are | |
219 | available in the same directory, for which accepted values may range from 0 to | |
220 | 127. | |
221 | ||
222 | There are other four entries in the directory above for each registered camera: | |
223 | "reg", "val", "i2c_reg" and "i2c_val". The first two files control the | |
224 | SN9C10x bridge, while the other two control the sensor chip. "reg" and | |
225 | "i2c_reg" hold the values of the current register index where the following | |
226 | reading/writing operations are addressed at through "val" and "i2c_val". Their | |
227 | use is not intended for end-users. Note that "i2c_reg" and "i2c_val" will not | |
228 | be created if the sensor does not actually support the standard I2C protocol or | |
229 | its registers are not 8-bit long. Also, remember that you must be logged in as | |
230 | root before writing to them. | |
231 | ||
232 | As an example, suppose we were to want to read the value contained in the | |
233 | register number 1 of the sensor register table - which is usually the product | |
234 | identifier - of the camera registered as "/dev/video0": | |
235 | ||
236 | [root@localhost #] cd /sys/class/video4linux/video0 | |
237 | [root@localhost #] echo 1 > i2c_reg | |
238 | [root@localhost #] cat i2c_val | |
239 | ||
240 | Note that "cat" will fail if sensor registers cannot be read. | |
241 | ||
242 | Now let's set the green gain's register of the SN9C101 or SN9C102 chips to 2: | |
243 | ||
244 | [root@localhost #] echo 0x11 > reg | |
245 | [root@localhost #] echo 2 > val | |
246 | ||
247 | Note that the SN9C10x always returns 0 when some of its registers are read. | |
248 | To avoid race conditions, all the I/O accesses to the above files are | |
249 | serialized. | |
250 | ||
251 | The sysfs interface also provides the "frame_header" entry, which exports the | |
252 | frame header of the most recent requested and captured video frame. The header | |
a966f3e7 | 253 | is always 18-bytes long and is appended to every video frame by the SN9C10x |
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254 | controllers. As an example, this additional information can be used by the user |
255 | application for implementing auto-exposure features via software. | |
256 | ||
257 | The following table describes the frame header: | |
258 | ||
259 | Byte # Value Description | |
260 | ------ ----- ----------- | |
261 | 0x00 0xFF Frame synchronisation pattern. | |
262 | 0x01 0xFF Frame synchronisation pattern. | |
263 | 0x02 0x00 Frame synchronisation pattern. | |
264 | 0x03 0xC4 Frame synchronisation pattern. | |
265 | 0x04 0xC4 Frame synchronisation pattern. | |
266 | 0x05 0x96 Frame synchronisation pattern. | |
a966f3e7 LR |
267 | 0x06 0xXX Unknown meaning. The exact value depends on the chip; |
268 | possible values are 0x00, 0x01 and 0x20. | |
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269 | 0x07 0xXX Variable value, whose bits are ff00uzzc, where ff is a |
270 | frame counter, u is unknown, zz is a size indicator | |
271 | (00 = VGA, 01 = SIF, 10 = QSIF) and c stands for | |
272 | "compression enabled" (1 = yes, 0 = no). | |
273 | 0x08 0xXX Brightness sum inside Auto-Exposure area (low-byte). | |
274 | 0x09 0xXX Brightness sum inside Auto-Exposure area (high-byte). | |
275 | For a pure white image, this number will be equal to 500 | |
276 | times the area of the specified AE area. For images | |
277 | that are not pure white, the value scales down according | |
278 | to relative whiteness. | |
279 | 0x0A 0xXX Brightness sum outside Auto-Exposure area (low-byte). | |
280 | 0x0B 0xXX Brightness sum outside Auto-Exposure area (high-byte). | |
281 | For a pure white image, this number will be equal to 125 | |
282 | times the area outside of the specified AE area. For | |
283 | images that are not pure white, the value scales down | |
284 | according to relative whiteness. | |
a966f3e7 LR |
285 | according to relative whiteness. |
286 | ||
287 | The following bytes are used by the SN9C103 bridge only: | |
288 | ||
289 | 0x0C 0xXX Unknown meaning | |
290 | 0x0D 0xXX Unknown meaning | |
291 | 0x0E 0xXX Unknown meaning | |
292 | 0x0F 0xXX Unknown meaning | |
293 | 0x10 0xXX Unknown meaning | |
294 | 0x11 0xXX Unknown meaning | |
1da177e4 LT |
295 | |
296 | The AE area (sx, sy, ex, ey) in the active window can be set by programming the | |
297 | registers 0x1c, 0x1d, 0x1e and 0x1f of the SN9C10x controllers, where one unit | |
298 | corresponds to 32 pixels. | |
299 | ||
a966f3e7 LR |
300 | [1] Part of the meaning of the frame header has been documented by Bertrik |
301 | Sikken. | |
1da177e4 LT |
302 | |
303 | ||
304 | 9. Supported devices | |
305 | ==================== | |
306 | None of the names of the companies as well as their products will be mentioned | |
307 | here. They have never collaborated with the author, so no advertising. | |
308 | ||
309 | From the point of view of a driver, what unambiguously identify a device are | |
310 | its vendor and product USB identifiers. Below is a list of known identifiers of | |
311 | devices mounting the SN9C10x PC camera controllers: | |
312 | ||
313 | Vendor ID Product ID | |
314 | --------- ---------- | |
315 | 0x0c45 0x6001 | |
316 | 0x0c45 0x6005 | |
317 | 0x0c45 0x6009 | |
318 | 0x0c45 0x600d | |
319 | 0x0c45 0x6024 | |
320 | 0x0c45 0x6025 | |
321 | 0x0c45 0x6028 | |
322 | 0x0c45 0x6029 | |
323 | 0x0c45 0x602a | |
324 | 0x0c45 0x602b | |
325 | 0x0c45 0x602c | |
b9df978f | 326 | 0x0c45 0x602d |
a966f3e7 | 327 | 0x0c45 0x602e |
1da177e4 LT |
328 | 0x0c45 0x6030 |
329 | 0x0c45 0x6080 | |
330 | 0x0c45 0x6082 | |
331 | 0x0c45 0x6083 | |
332 | 0x0c45 0x6088 | |
333 | 0x0c45 0x608a | |
334 | 0x0c45 0x608b | |
335 | 0x0c45 0x608c | |
336 | 0x0c45 0x608e | |
337 | 0x0c45 0x608f | |
338 | 0x0c45 0x60a0 | |
339 | 0x0c45 0x60a2 | |
340 | 0x0c45 0x60a3 | |
341 | 0x0c45 0x60a8 | |
342 | 0x0c45 0x60aa | |
343 | 0x0c45 0x60ab | |
344 | 0x0c45 0x60ac | |
345 | 0x0c45 0x60ae | |
346 | 0x0c45 0x60af | |
347 | 0x0c45 0x60b0 | |
348 | 0x0c45 0x60b2 | |
349 | 0x0c45 0x60b3 | |
350 | 0x0c45 0x60b8 | |
351 | 0x0c45 0x60ba | |
352 | 0x0c45 0x60bb | |
353 | 0x0c45 0x60bc | |
354 | 0x0c45 0x60be | |
355 | ||
356 | The list above does not imply that all those devices work with this driver: up | |
357 | until now only the ones that mount the following image sensors are supported; | |
358 | kernel messages will always tell you whether this is the case: | |
359 | ||
360 | Model Manufacturer | |
361 | ----- ------------ | |
362 | HV7131D Hynix Semiconductor, Inc. | |
363 | MI-0343 Micron Technology, Inc. | |
b9df978f | 364 | OV7630 OmniVision Technologies, Inc. |
1da177e4 LT |
365 | PAS106B PixArt Imaging, Inc. |
366 | PAS202BCB PixArt Imaging, Inc. | |
367 | TAS5110C1B Taiwan Advanced Sensor Corporation | |
368 | TAS5130D1B Taiwan Advanced Sensor Corporation | |
369 | ||
370 | All the available control settings of each image sensor are supported through | |
371 | the V4L2 interface. | |
372 | ||
373 | Donations of new models for further testing and support would be much | |
374 | appreciated. Non-available hardware will not be supported by the author of this | |
375 | driver. | |
376 | ||
377 | ||
a966f3e7 | 378 | 10. Notes for V4L2 application developers |
1da177e4 LT |
379 | ========================================= |
380 | This driver follows the V4L2 API specifications. In particular, it enforces two | |
381 | rules: | |
382 | ||
383 | - exactly one I/O method, either "mmap" or "read", is associated with each | |
384 | file descriptor. Once it is selected, the application must close and reopen the | |
385 | device to switch to the other I/O method; | |
386 | ||
387 | - although it is not mandatory, previously mapped buffer memory should always | |
388 | be unmapped before calling any "VIDIOC_S_CROP" or "VIDIOC_S_FMT" ioctl's. | |
389 | The same number of buffers as before will be allocated again to match the size | |
390 | of the new video frames, so you have to map the buffers again before any I/O | |
391 | attempts on them. | |
392 | ||
393 | Consistently with the hardware limits, this driver also supports image | |
394 | downscaling with arbitrary scaling factors from 1, 2 and 4 in both directions. | |
395 | However, the V4L2 API specifications don't correctly define how the scaling | |
396 | factor can be chosen arbitrarily by the "negotiation" of the "source" and | |
397 | "target" rectangles. To work around this flaw, we have added the convention | |
398 | that, during the negotiation, whenever the "VIDIOC_S_CROP" ioctl is issued, the | |
399 | scaling factor is restored to 1. | |
400 | ||
401 | This driver supports two different video formats: the first one is the "8-bit | |
402 | Sequential Bayer" format and can be used to obtain uncompressed video data | |
403 | from the device through the current I/O method, while the second one provides | |
404 | "raw" compressed video data (without frame headers not related to the | |
405 | compressed data). The compression quality may vary from 0 to 1 and can be | |
406 | selected or queried thanks to the VIDIOC_S_JPEGCOMP and VIDIOC_G_JPEGCOMP V4L2 | |
407 | ioctl's. For maximum flexibility, both the default active video format and the | |
408 | default compression quality depend on how the image sensor being used is | |
409 | initialized (as described in the documentation of the API for the image sensors | |
410 | supplied by this driver). | |
411 | ||
412 | ||
a966f3e7 | 413 | 11. Video frame formats [1] |
1da177e4 LT |
414 | ======================= |
415 | The SN9C10x PC Camera Controllers can send images in two possible video | |
416 | formats over the USB: either native "Sequential RGB Bayer" or Huffman | |
417 | compressed. The latter is used to achieve high frame rates. The current video | |
418 | format may be selected or queried from the user application by calling the | |
419 | VIDIOC_S_FMT or VIDIOC_G_FMT ioctl's, as described in the V4L2 API | |
420 | specifications. | |
421 | ||
422 | The name "Sequential Bayer" indicates the organization of the red, green and | |
423 | blue pixels in one video frame. Each pixel is associated with a 8-bit long | |
424 | value and is disposed in memory according to the pattern shown below: | |
425 | ||
426 | B[0] G[1] B[2] G[3] ... B[m-2] G[m-1] | |
427 | G[m] R[m+1] G[m+2] R[m+2] ... G[2m-2] R[2m-1] | |
428 | ... | |
429 | ... B[(n-1)(m-2)] G[(n-1)(m-1)] | |
430 | ... G[n(m-2)] R[n(m-1)] | |
431 | ||
432 | The above matrix also represents the sequential or progressive read-out mode of | |
433 | the (n, m) Bayer color filter array used in many CCD/CMOS image sensors. | |
434 | ||
435 | One compressed video frame consists of a bitstream that encodes for every R, G, | |
436 | or B pixel the difference between the value of the pixel itself and some | |
437 | reference pixel value. Pixels are organised in the Bayer pattern and the Bayer | |
438 | sub-pixels are tracked individually and alternatingly. For example, in the | |
439 | first line values for the B and G1 pixels are alternatingly encoded, while in | |
440 | the second line values for the G2 and R pixels are alternatingly encoded. | |
441 | ||
442 | The pixel reference value is calculated as follows: | |
443 | - the 4 top left pixels are encoded in raw uncompressed 8-bit format; | |
444 | - the value in the top two rows is the value of the pixel left of the current | |
445 | pixel; | |
446 | - the value in the left column is the value of the pixel above the current | |
447 | pixel; | |
448 | - for all other pixels, the reference value is the average of the value of the | |
449 | pixel on the left and the value of the pixel above the current pixel; | |
450 | - there is one code in the bitstream that specifies the value of a pixel | |
451 | directly (in 4-bit resolution); | |
452 | - pixel values need to be clamped inside the range [0..255] for proper | |
453 | decoding. | |
454 | ||
455 | The algorithm purely describes the conversion from compressed Bayer code used | |
456 | in the SN9C10x chips to uncompressed Bayer. Additional steps are required to | |
457 | convert this to a color image (i.e. a color interpolation algorithm). | |
458 | ||
459 | The following Huffman codes have been found: | |
460 | 0: +0 (relative to reference pixel value) | |
461 | 100: +4 | |
462 | 101: -4? | |
463 | 1110xxxx: set absolute value to xxxx.0000 | |
464 | 1101: +11 | |
465 | 1111: -11 | |
466 | 11001: +20 | |
467 | 110000: -20 | |
468 | 110001: ??? - these codes are apparently not used | |
469 | ||
470 | [1] The Huffman compression algorithm has been reverse-engineered and | |
471 | documented by Bertrik Sikken. | |
472 | ||
473 | ||
a966f3e7 | 474 | 12. Contact information |
1da177e4 LT |
475 | ======================= |
476 | The author may be contacted by e-mail at <luca.risolia@studio.unibo.it>. | |
477 | ||
478 | GPG/PGP encrypted e-mail's are accepted. The GPG key ID of the author is | |
479 | 'FCE635A4'; the public 1024-bit key should be available at any keyserver; | |
480 | the fingerprint is: '88E8 F32F 7244 68BA 3958 5D40 99DA 5D2A FCE6 35A4'. | |
481 | ||
482 | ||
a966f3e7 | 483 | 13. Credits |
1da177e4 LT |
484 | =========== |
485 | Many thanks to following persons for their contribute (listed in alphabetical | |
486 | order): | |
487 | ||
488 | - Luca Capello for the donation of a webcam; | |
489 | - Joao Rodrigo Fuzaro, Joao Limirio, Claudio Filho and Caio Begotti for the | |
490 | donation of a webcam; | |
b9df978f | 491 | - Jon Hollstrom for the donation of a webcam; |
1da177e4 LT |
492 | - Carlos Eduardo Medaglia Dyonisio, who added the support for the PAS202BCB |
493 | image sensor; | |
494 | - Stefano Mozzi, who donated 45 EU; | |
b9df978f | 495 | - Andrew Pearce for the donation of a webcam; |
1da177e4 LT |
496 | - Bertrik Sikken, who reverse-engineered and documented the Huffman compression |
497 | algorithm used in the SN9C10x controllers and implemented the first decoder; | |
498 | - Mizuno Takafumi for the donation of a webcam; | |
a966f3e7 | 499 | - an "anonymous" donator (who didn't want his name to be revealed) for the |
1da177e4 | 500 | donation of a webcam. |