LXR linux-old/drivers/usb/pwc-uncompress.c

   1/* Linux driver for Philips webcam 
   2   Decompression frontend.
   3   (C) 1999-2003 Nemosoft Unv. (webcam@smcc.demon.nl)
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License
  16   along with this program; if not, write to the Free Software
  17   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18*/
  19/*
  20   This is where the decompression routines register and unregister 
  21   themselves. It also has a decompressor wrapper function.
  22*/
  23
  24#include <asm/types.h>
  25
  26#include "pwc.h"
  27#include "pwc-uncompress.h"
  28
  29
  30/* This contains a list of all registered decompressors */
  31static LIST_HEAD(pwc_decompressor_list);
  32
  33/* Should the pwc_decompress structure ever change, we increase the 
  34   version number so that we don't get nasty surprises, or can 
  35   dynamically adjust our structure.
  36 */
  37const int pwc_decompressor_version = PWC_MAJOR;
  38
  39/* Add decompressor to list, ignoring duplicates */
  40void pwc_register_decompressor(struct pwc_decompressor *pwcd)
  41{
  42        if (pwc_find_decompressor(pwcd->type) == NULL) {
  43                Trace(TRACE_PWCX, "Adding decompressor for model %d.\n", pwcd->type);
  44                list_add_tail(&pwcd->pwcd_list, &pwc_decompressor_list);
  45        }
  46}
  47
  48/* Remove decompressor from list */
  49void pwc_unregister_decompressor(int type)
  50{
  51        struct pwc_decompressor *find;
  52        
  53        find = pwc_find_decompressor(type);
  54        if (find != NULL) {
  55                Trace(TRACE_PWCX, "Removing decompressor for model %d.\n", type);
  56                list_del(&find->pwcd_list);
  57        }
  58}
  59
  60/* Find decompressor in list */
  61struct pwc_decompressor *pwc_find_decompressor(int type)
  62{
  63        struct list_head *tmp;
  64        struct pwc_decompressor *pwcd;
  65
  66        list_for_each(tmp, &pwc_decompressor_list) {
  67                pwcd  = list_entry(tmp, struct pwc_decompressor, pwcd_list);
  68                if (pwcd->type == type)
  69                        return pwcd;
  70        }
  71        return NULL;
  72}
  73
  74
  75
  76int pwc_decompress(struct pwc_device *pdev)
  77{
  78        struct pwc_frame_buf *fbuf;
  79        int n, line, col, stride;
  80        void *yuv, *image;
  81        u16 *src;
  82        u16 *dsty, *dstu, *dstv;
  83
  84        
  85        if (pdev == NULL)
  86                return -EFAULT;
  87#if defined(__KERNEL__) && defined(PWC_MAGIC)
  88        if (pdev->magic != PWC_MAGIC) {
  89                Err("pwc_decompress(): magic failed.\n");
  90                return -EFAULT;
  91        }
  92#endif
  93
  94        fbuf = pdev->read_frame;
  95        if (fbuf == NULL)
  96                return -EFAULT;
  97        image = pdev->image_ptr[pdev->fill_image];
  98        if (!image)
  99                return -EFAULT;
 100        
 101        yuv = fbuf->data + pdev->frame_header_size;  /* Skip header */
 102        if (pdev->vbandlength == 0) { 
 103                /* Uncompressed mode. We copy the data into the output buffer,
 104                   using the viewport size (which may be larger than the image
 105                   size). Unfortunately we have to do a bit of byte stuffing
 106                   to get the desired output format/size.
 107                 */
 108                        /* 
 109                         * We do some byte shuffling here to go from the 
 110                         * native format to YUV420P.
 111                         */
 112                        src = (u16 *)yuv;
 113                        n = pdev->view.x * pdev->view.y;
 114
 115                        /* offset in Y plane */
 116                        stride = pdev->view.x * pdev->offset.y + pdev->offset.x;
 117                        dsty = (u16 *)(image + stride);
 118
 119                        /* offsets in U/V planes */
 120                        stride = pdev->view.x * pdev->offset.y / 4 + pdev->offset.x / 2;
 121                        dstu = (u16 *)(image + n +         stride);
 122                        dstv = (u16 *)(image + n + n / 4 + stride);
 123
 124                        /* increment after each line */
 125                        stride = (pdev->view.x - pdev->image.x) / 2; /* u16 is 2 bytes */
 126
 127                        for (line = 0; line < pdev->image.y; line++) {
 128                                for (col = 0; col < pdev->image.x; col += 4) {
 129                                        *dsty++ = *src++;
 130                                        *dsty++ = *src++;
 131                                        if (line & 1)
 132                                                *dstv++ = *src++;
 133                                        else
 134                                                *dstu++ = *src++;
 135                                }
 136                                dsty += stride;
 137                                if (line & 1)
 138                                        dstv += (stride >> 1);
 139                                else
 140                                        dstu += (stride >> 1);
 141                        }
 142        }
 143        else { 
 144                /* Compressed; the decompressor routines will write the data 
 145                   in planar format immediately.
 146                 */
 147                if (pdev->decompressor)
 148                        pdev->decompressor->decompress(
 149                                &pdev->image, &pdev->view, &pdev->offset,
 150                                yuv, image,
 151                                1,
 152                                pdev->decompress_data, pdev->vbandlength);
 153                else
 154                        return -ENXIO; /* No such device or address: missing decompressor */
 155        }
 156        return 0;
 157}
 158
 159/* Make sure these functions are available for the decompressor plugin
 160   both when this code is compiled into the kernel or as as module.
 161 */
 162
 163EXPORT_SYMBOL_NOVERS(pwc_decompressor_version);
 164EXPORT_SYMBOL(pwc_register_decompressor);
 165EXPORT_SYMBOL(pwc_unregister_decompressor);
 166