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gnif/Makefile

Last active Jan 12, 2020
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Proof of concept: Create Pixmap via DRI3 from shared memory via udmabuf
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <sys/mman.h>
#include <linux/udmabuf.h>
#include <xcb/xcb.h>
#include <xcb/dri3.h>
#include <xcb/present.h>
struct App
{
int size;
int devFd, memFd, dmaFd;
void * mem;
xcb_connection_t * xcb;
xcb_screen_t * screen;
xcb_window_t window;
int fd;
xcb_pixmap_t pixmap;
};
struct App app = { 0 };
static int get_udmabuf(const int size)
{
int ret;
app.size = size;
app.devFd = open("/dev/udmabuf", O_RDWR);
if (app.devFd < 0)
{
perror("open /dev/udmabuf failed");
return app.devFd;
}
app.memFd = memfd_create("udmabuf-test", MFD_ALLOW_SEALING);
if (app.memFd < 0)
{
perror("memfd_create failed");
return app.memFd;
}
app.mem = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, app.memFd, 0);
if (!app.mem)
{
perror("mmap failed");
return -1;
}
ret = fcntl(app.memFd, F_ADD_SEALS, F_SEAL_SHRINK);
if (ret < 0)
{
perror("fcntl");
return ret;
}
ret = ftruncate(app.memFd, size);
if (ret == -1)
{
perror("ftruncate failed");
return ret;
}
struct udmabuf_create create = {
.memfd = app.memFd,
.offset = 0,
.size = size
};
app.dmaFd = ioctl(app.devFd, UDMABUF_CREATE, &create);
if (app.dmaFd < 0)
{
perror("UDMABUF_CREATE failed");
return -1;
}
return 0;
}
static void close_udmabuf()
{
if (app.mem ) munmap(app.mem, app.size);
if (app.dmaFd >= 0 ) close(app.dmaFd);
if (app.memFd >= 0) close(app.memFd );
if (app.devFd >= 0) close(app.devFd );
}
static int dri3_open()
{
xcb_dri3_open_cookie_t c =
xcb_dri3_open(app.xcb, app.window, 0);
xcb_dri3_open_reply_t * r =
xcb_dri3_open_reply(app.xcb, c, NULL);
if (!r)
{
printf("failed to open dri3\n");
return -1;
}
if (r->nfd != 1)
{
free(r);
printf("nfd != 1\n");
return -1;
}
int fd = xcb_dri3_open_reply_fds(app.xcb, r)[0];
if (fd < 0)
{
free(r);
return fd;
}
fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
free(r);
return fd;
}
int main()
{
const uint32_t width = 200;
const uint32_t height = 200;
const uint32_t bpp = 24;
const uint32_t pitch = 32;
const int size = (width * height * (pitch << 3) + (getpagesize() - 1)) & ~(getpagesize() - 1);
if (!get_udmabuf(size) == 0)
return -1;
app.xcb = xcb_connect(NULL, NULL);
app.screen = xcb_setup_roots_iterator(xcb_get_setup(app.xcb)).data;
const uint32_t values[2] = {
app.screen->white_pixel,
XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS
};
app.window = xcb_generate_id(app.xcb);
xcb_create_window(
app.xcb,
XCB_COPY_FROM_PARENT,
app.window,
app.screen->root,
0, 0, 240, 240,
0,
XCB_WINDOW_CLASS_INPUT_OUTPUT,
app.screen->root_visual,
XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK,
values
);
xcb_map_window(app.xcb, app.window);
xcb_flush(app.xcb);
app.fd = dri3_open();
if (app.fd < 0)
{
close_udmabuf();
return app.fd;
}
app.pixmap = xcb_generate_id(app.xcb);
{
xcb_void_cookie_t c =
xcb_dri3_pixmap_from_buffer_checked(
app.xcb,
app.pixmap,
app.window,
width * height * (pitch >> 3),
width,
height,
width * (bpp >> 3),
24,
32,
app.dmaFd
);
xcb_generic_error_t *error;
if ((error = xcb_request_check(app.xcb, c)))
{
printf("dri3_pixmap_from_buffer failure: code=%d value=%d\n",
error->error_code, error->resource_id);
free(error);
goto exit;
}
}
int id = 0;
while(1)
{
xcb_generic_event_t * e;
if ((e = xcb_poll_for_event(app.xcb)) != NULL)
{
switch(e->response_type)
{
case XCB_KEY_PRESS:
{
xcb_key_release_event_t *ev = (xcb_key_release_event_t *)e;
if (ev->detail == 9)
{
free(e);
goto exit;
}
}
case XCB_EXPOSE:
break;
}
free(e);
}
memset(app.mem, id, app.size);
xcb_present_pixmap(
app.xcb,
app.window,
app.pixmap,
++id,
0, // valid
0, // dirty
20, // x
20, // y
0,
0,
0,
XCB_PRESENT_OPTION_COPY,
0, 0, 0, 0,
NULL
);
xcb_flush(app.xcb);
}
exit:
close(app.fd);
xcb_disconnect(app.xcb);
close_udmabuf();
return 0;
}
all:
gcc -D_GNU_SOURCE main.c -Wall -Werror -g -Og -o test -lX11-xcb -lX11 -lxcb -lxcb-dri3 -lxcb-present
@gnif

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@gnif gnif commented Jan 12, 2020

Epilepsy Warning: Puts a rapidly fading square on screen.

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