xref: /system/core/adb/framebuffer_service.c

/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

#include "fdevent.h"
#include "adb.h"

#include <linux/fb.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

/* TODO:
** - sync with vsync to avoid tearing
*/

void framebuffer_service(int fd, void *cookie)
{
    struct fb_var_screeninfo vinfo;
    int fb, offset;
    char x[256];

    unsigned fbinfo[4];
    unsigned i, bytespp;

    fb = open("/dev/graphics/fb0", O_RDONLY);
    if(fb < 0) goto done;

    if(ioctl(fb, FBIOGET_VSCREENINFO, &vinfo) < 0) goto done;
    fcntl(fb, F_SETFD, FD_CLOEXEC);

    bytespp = vinfo.bits_per_pixel / 8;

    fbinfo[0] = vinfo.bits_per_pixel;
    fbinfo[1] = vinfo.xres * vinfo.yres * bytespp;
    fbinfo[2] = vinfo.xres;
    fbinfo[3] = vinfo.yres;

    /* HACK: for several of our 3d cores a specific alignment
     * is required so the start of the fb may not be an integer number of lines
     * from the base.  As a result we are storing the additional offset in
     * xoffset. This is not the correct usage for xoffset, it should be added
     * to each line, not just once at the beginning */
    offset = vinfo.xoffset * bytespp;

    offset += vinfo.xres * vinfo.yoffset * bytespp;

    if(writex(fd, fbinfo, sizeof(fbinfo))) goto done;

    lseek(fb, offset, SEEK_SET);
    for(i = 0; i < fbinfo[1]; i += 256) {
      if(readx(fb, &x, 256)) goto done;
      if(writex(fd, &x, 256)) goto done;
    }

    if(readx(fb, &x, fbinfo[1] % 256)) goto done;
    if(writex(fd, &x, fbinfo[1] % 256)) goto done;

done:
    if(fb >= 0) close(fb);
    close(fd);
}