Frame buffer分析 - fbcmap.c

 91 int fb_alloc_cmap(struct fb_cmap *cmap, int len, int transp)
 92 {
 93     int size = len*sizeof(u16);
 94
 95     if (cmap->len != len) {
 96     fb_dealloc_cmap(cmap);
 97     if (!len)
 98         return 0;
 99     if (!(cmap->red = kmalloc(size, GFP_ATOMIC)))
100         goto fail;
101     if (!(cmap->green = kmalloc(size, GFP_ATOMIC)))
102         goto fail;
103     if (!(cmap->blue = kmalloc(size, GFP_ATOMIC)))
104         goto fail;
105     if (transp) {
106         if (!(cmap->transp = kmalloc(size, GFP_ATOMIC)))
107         goto fail;
108     } else
109         cmap->transp = NULL;
110     }
111     cmap->start = 0;
112     cmap->len = len;
113     fb_copy_cmap(fb_default_cmap(len), cmap);
114     return 0;
115
116 fail:
117     fb_dealloc_cmap(cmap);
118     return -ENOMEM;
119 }

分配colormap, len是颜色分量的number

113使用缺省的colormap初始化颜色分量

149 int fb_copy_cmap(const struct fb_cmap *from, struct fb_cmap *to)
150 {
151     int tooff = 0, fromoff = 0;
152     int size;
153
154     if (to->start > from->start)
155         fromoff = to->start - from->start;
156     else
157         tooff = from->start - to->start;
158     size = to->len - tooff;
159     if (size > (int) (from->len - fromoff))
160         size = from->len - fromoff;
161     if (size <= 0)
162         return -EINVAL;
163     size *= sizeof(u16);
164
165     memcpy(to->red+tooff, from->red+fromoff, size);
166     memcpy(to->green+tooff, from->green+fromoff, size);
167     memcpy(to->blue+tooff, from->blue+fromoff, size);
168     if (from->transp && to->transp)
169         memcpy(to->transp+tooff, from->transp+fromoff, size);
170     return 0;
171 }
copy colormap @from 到@to

249 int fb_set_user_cmap(struct fb_cmap_user *cmap, struct fb_info *info)
250 {
251     int rc, size = cmap->len * sizeof(u16);
252     struct fb_cmap umap;
253
254     memset(&umap, 0, sizeof(struct fb_cmap));
255     rc = fb_alloc_cmap(&umap, cmap->len, cmap->transp != NULL);
256     if (rc)
257         return rc;
258     if (copy_from_user(umap.red, cmap->red, size) ||
259         copy_from_user(umap.green, cmap->green, size) ||
260         copy_from_user(umap.blue, cmap->blue, size) ||
261         (cmap->transp && copy_from_user(umap.transp, cmap->transp, size))) {
262         rc = -EFAULT;
263         goto out;
264     }
265     umap.start = cmap->start;
266     if (!lock_fb_info(info)) {
267         rc = -ENODEV;
268         goto out;
269     }
270     if (cmap->start < 0 || (!info->fbops->fb_setcolreg &&
271                 !info->fbops->fb_setcmap)) {
272         rc = -EINVAL;
273         goto out1;
274     }
275     rc = fb_set_cmap(&umap, info);
276 out1:
277     unlock_fb_info(info);
278 out:
279     fb_dealloc_cmap(&umap);
280     return rc;
281 }
先把fb_cmap_user类型的cmap内容复制到fb_cmap中，然后再调用fb_set_cmap

294 const struct fb_cmap *fb_default_cmap(int len)
295 {
296     if (len <= 2)
297     return &default_2_colors;
298     if (len <= 4)
299     return &default_4_colors;
300     if (len <= 8)
301     return &default_8_colors;
302     return &default_16_colors;
303 }

根据len，返回缺省的cmap

313 void fb_invert_cmaps(void)
314 {
315     u_int i;
316
317     for (i = 0; i < ARRAY_SIZE(red2); i++) {
318     red2[i] = ~red2[i];
319     green2[i] = ~green2[i];
320     blue2[i] = ~blue2[i];
321     }
322     for (i = 0; i < ARRAY_SIZE(red4); i++) {
323     red4[i] = ~red4[i];
324     green4[i] = ~green4[i];
325     blue4[i] = ~blue4[i];
326     }
327     for (i = 0; i < ARRAY_SIZE(red8); i++) {
328     red8[i] = ~red8[i];
329     green8[i] = ~green8[i];
330     blue8[i] = ~blue8[i];
331     }
332     for (i = 0; i < ARRAY_SIZE(red16); i++) {
333     red16[i] = ~red16[i];
334     green16[i] = ~green16[i];
335     blue16[i] = ~blue16[i];
336     }
337 }
invert cmap的颜色分量