colormap.c

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/***************************************************************************
 * colormap.c
 * 
 * Provide utilities for manipulating framebuffer colormaps.
 * 
 * See <kernel-source-dir>/include/linux/fb.h for framebuffer data
 * structures.
 ***************************************************************************/
#include <asm/types.h>
#include <stdlib.h>

#include "colormap.h"

struct fb_cmap *new_fb_cmap(int ncolors)
{
  __u8           *temp_array;
  struct fb_cmap *cmap;

  /* Allocate memory for the cmap structure and the color arrays. */
  temp_array =
    (__u8 *)malloc(sizeof(struct fb_cmap) + 4*ncolors*sizeof(__u16));

  if(!temp_array){
    return NULL;
  }else{
    /* Fill in the colormap structure using the new memory. */
    cmap = (struct fb_cmap *)&temp_array[0];
    cmap->start  = 0;
    cmap->len    = ncolors;
    cmap->red    = (__u16 *)&temp_array[sizeof(struct fb_cmap)];
    cmap->green  = &cmap->red[ncolors];
    cmap->blue   = &cmap->red[2*ncolors];
    cmap->transp = &cmap->red[3*ncolors];

    return cmap;
  }
}

void free_fb_cmap(struct fb_cmap *cmap)
{
  /* Since the cmap structure was the first item in the allocated memory, we
   * can use its address for the free call. */
  free((void *)cmap);
}