1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657
//! Graphics output protocol.
//!
//! The UEFI GOP is meant to replace existing [VGA][vga] hardware interfaces.
//! It can be used in the boot environment as well as at runtime,
//! until a high-performance driver is loaded by the OS.
//!
//! The GOP provides access to a hardware frame buffer and allows UEFI apps
//! to draw directly to the graphics output device.
//!
//! The advantage of the GOP over legacy VGA is that it allows multiple GPUs
//! to exist and be used on the system. There is a GOP implementation for every
//! unique GPU in the system which supports UEFI.
//!
//! This protocol _can_ be used after boot services are exited.
//!
//! [vga]: https://en.wikipedia.org/wiki/Video_Graphics_Array
//!
//! # Definitions
//!
//! All graphics operations use a coordinate system where the top-left of the screen
//! is mapped to the point (0, 0), and `y` increases going down.
//!
//! Rectangles are defined by their top-left corner, and their width and height.
//!
//! The stride is understood as the length in bytes of a scan line / row of a buffer.
//! In theory, a buffer with a width of 640 should have (640 * 4) bytes per row,
//! but in practice there might be some extra padding used for efficiency.
//!
//! Frame buffers represent the graphics card's image buffers, backing the displays.
//!
//! Blits (**bl**ock **t**ransfer) can do high-speed memory copy between
//! the frame buffer and itself, or to and from some other buffers.
//!
//! # Blitting
//!
//! On certain hardware, the frame buffer is in a opaque format,
//! or cannot be accessed by the CPU. In those cases, it is not possible
//! to draw directly to the frame buffer. You must draw to another buffer
//! with a known pixel format, and then submit a blit command to copy that buffer
//! into the back buffer.
//!
//! Blitting can also copy a rectangle from the frame buffer to
//! another rectangle in the frame buffer, or move data out of the frame buffer
//! into a CPU-visible buffer. It can also do very fast color fills.
//!
//! The source and destination rectangles must always be of the same size:
//! no stretching / squashing will be done.
//!
//! # Animations
//!
//! UEFI does not mention if double buffering is used, nor how often
//! the frame buffer gets sent to the screen, but it's safe to assume that
//! the graphics card will re-draw the buffer at around the monitor's refresh rate.
//! You will have to implement your own double buffering if you want to
//! avoid tearing with animations.
use crate::proto::Protocol;
use crate::{unsafe_guid, Result, Status};
use core::marker::PhantomData;
use core::mem;
use core::ptr;
/// Provides access to the video hardware's frame buffer.
///
/// The GOP can be used to set the properties of the frame buffer,
/// and also allows the app to access the in-memory buffer.
#[repr(C)]
#[unsafe_guid("9042a9de-23dc-4a38-96fb-7aded080516a")]
#[derive(Protocol)]
pub struct GraphicsOutput<'boot> {
query_mode: extern "efiapi" fn(
&GraphicsOutput,
mode: u32,
info_sz: &mut usize,
&mut *const ModeInfo,
) -> Status,
set_mode: extern "efiapi" fn(&mut GraphicsOutput, mode: u32) -> Status,
// Clippy correctly complains that this is too complicated, but we can't change the spec.
#[allow(clippy::type_complexity)]
blt: unsafe extern "efiapi" fn(
this: &mut GraphicsOutput,
buffer: *mut BltPixel,
op: u32,
source_x: usize,
source_y: usize,
dest_x: usize,
dest_y: usize,
width: usize,
height: usize,
stride: usize,
) -> Status,
mode: &'boot ModeData<'boot>,
}
impl<'boot> GraphicsOutput<'boot> {
/// Returns information for an available graphics mode that the graphics
/// device and the set of active video output devices supports.
pub fn query_mode(&self, index: u32) -> Result<Mode> {
let mut info_sz = 0;
let mut info = ptr::null();
(self.query_mode)(self, index, &mut info_sz, &mut info).into_with_val(|| {
let info = unsafe { *info };
Mode {
index,
info_sz,
info,
}
})
}
/// Returns information about all available graphics modes.
pub fn modes(&'_ self) -> impl ExactSizeIterator<Item = Mode> + '_ {
ModeIter {
gop: self,
current: 0,
max: self.mode.max_mode,
}
}
/// Sets the video device into the specified mode, clearing visible portions
/// of the output display to black.
///
/// This function will invalidate the current framebuffer.
pub fn set_mode(&mut self, mode: &Mode) -> Result {
(self.set_mode)(self, mode.index).into()
}
/// Performs a blt (block transfer) operation on the frame buffer.
///
/// Every operation requires different parameters.
pub fn blt(&mut self, op: BltOp) -> Result {
// Demultiplex the operation type.
unsafe {
match op {
BltOp::VideoFill {
color,
dest: (dest_x, dest_y),
dims: (width, height),
} => {
self.check_framebuffer_region((dest_x, dest_y), (width, height));
(self.blt)(
self,
&color as *const _ as *mut _,
0,
0,
0,
dest_x,
dest_y,
width,
height,
0,
)
.into()
}
BltOp::VideoToBltBuffer {
buffer,
src: (src_x, src_y),
dest: dest_region,
dims: (width, height),
} => {
self.check_framebuffer_region((src_x, src_y), (width, height));
self.check_blt_buffer_region(dest_region, (width, height), buffer.len());
match dest_region {
BltRegion::Full => (self.blt)(
self,
buffer.as_mut_ptr(),
1,
src_x,
src_y,
0,
0,
width,
height,
0,
)
.into(),
BltRegion::SubRectangle {
coords: (dest_x, dest_y),
px_stride,
} => (self.blt)(
self,
buffer.as_mut_ptr(),
1,
src_x,
src_y,
dest_x,
dest_y,
width,
height,
px_stride * core::mem::size_of::<BltPixel>(),
)
.into(),
}
}
BltOp::BufferToVideo {
buffer,
src: src_region,
dest: (dest_x, dest_y),
dims: (width, height),
} => {
self.check_blt_buffer_region(src_region, (width, height), buffer.len());
self.check_framebuffer_region((dest_x, dest_y), (width, height));
match src_region {
BltRegion::Full => (self.blt)(
self,
buffer.as_ptr() as *mut _,
2,
0,
0,
dest_x,
dest_y,
width,
height,
0,
)
.into(),
BltRegion::SubRectangle {
coords: (src_x, src_y),
px_stride,
} => (self.blt)(
self,
buffer.as_ptr() as *mut _,
2,
src_x,
src_y,
dest_x,
dest_y,
width,
height,
px_stride * core::mem::size_of::<BltPixel>(),
)
.into(),
}
}
BltOp::VideoToVideo {
src: (src_x, src_y),
dest: (dest_x, dest_y),
dims: (width, height),
} => {
self.check_framebuffer_region((src_x, src_y), (width, height));
self.check_framebuffer_region((dest_x, dest_y), (width, height));
(self.blt)(
self,
ptr::null_mut(),
3,
src_x,
src_y,
dest_x,
dest_y,
width,
height,
0,
)
.into()
}
}
}
}
/// Memory-safety check for accessing a region of the framebuffer
fn check_framebuffer_region(&self, coords: (usize, usize), dims: (usize, usize)) {
let (width, height) = self.current_mode_info().resolution();
assert!(
coords.0.saturating_add(dims.0) <= width,
"Horizontal framebuffer coordinate out of bounds"
);
assert!(
coords.1.saturating_add(dims.1) <= height,
"Vertical framebuffer coordinate out of bounds"
);
}
/// Memory-safety check for accessing a region of a user-provided buffer
fn check_blt_buffer_region(&self, region: BltRegion, dims: (usize, usize), buf_length: usize) {
match region {
BltRegion::Full => assert!(
dims.1.saturating_mul(dims.0) <= buf_length,
"BltBuffer access out of bounds"
),
BltRegion::SubRectangle {
coords: (x, y),
px_stride,
} => {
assert!(
x.saturating_add(dims.0) <= px_stride,
"Horizontal BltBuffer coordinate out of bounds"
);
assert!(
y.saturating_add(dims.1).saturating_mul(px_stride) <= buf_length,
"Vertical BltBuffer coordinate out of bounds"
);
}
}
}
/// Returns the frame buffer information for the current mode.
pub fn current_mode_info(&self) -> ModeInfo {
*self.mode.info
}
/// Access the frame buffer directly
pub fn frame_buffer(&mut self) -> FrameBuffer {
assert!(
self.mode.info.format != PixelFormat::BltOnly,
"Cannot access the framebuffer in a Blt-only mode"
);
let base = self.mode.fb_address as *mut u8;
let size = self.mode.fb_size;
FrameBuffer {
base,
size,
_lifetime: PhantomData,
}
}
}
#[repr(C)]
struct ModeData<'info> {
// Number of modes which the GOP supports.
max_mode: u32,
// Current mode.
mode: u32,
// Information about the current mode.
info: &'info ModeInfo,
// Size of the above structure.
info_sz: usize,
// Physical address of the frame buffer.
fb_address: u64,
// Size in bytes. Equal to (pixel size) * height * stride.
fb_size: usize,
}
/// Represents the format of the pixels in a frame buffer.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[repr(u32)]
pub enum PixelFormat {
/// Each pixel is 32-bit long, with 24-bit RGB, and the last byte is reserved.
Rgb = 0,
/// Each pixel is 32-bit long, with 24-bit BGR, and the last byte is reserved.
Bgr,
/// Custom pixel format, check the associated bitmask.
Bitmask,
/// The graphics mode does not support drawing directly to the frame buffer.
///
/// This means you will have to use the `blt` function which will
/// convert the graphics data to the device's internal pixel format.
BltOnly,
// SAFETY: UEFI also defines a PixelFormatMax variant, and states that all
// valid enum values are guaranteed to be smaller. Since that is the
// case, adding a new enum variant would be a breaking change, so it
// is safe to model this C enum as a Rust enum.
}
/// Bitmask used to indicate which bits of a pixel represent a given color.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
#[repr(C)]
pub struct PixelBitmask {
/// The bits indicating the red channel.
pub red: u32,
/// The bits indicating the green channel.
pub green: u32,
/// The bits indicating the blue channel.
pub blue: u32,
/// The reserved bits, which are ignored by the video hardware.
pub reserved: u32,
}
/// Represents a graphics mode compatible with a given graphics device.
pub struct Mode {
index: u32,
info_sz: usize,
info: ModeInfo,
}
impl Mode {
/// The size of the info structure in bytes.
///
/// Newer versions of the spec might add extra information, in a backwards compatible way.
pub fn info_size(&self) -> usize {
self.info_sz
}
/// Returns a reference to the mode info structure.
pub fn info(&self) -> &ModeInfo {
&self.info
}
}
/// Information about a graphics output mode.
#[derive(Debug, Copy, Clone)]
#[repr(C)]
pub struct ModeInfo {
// The only known version, associated with the current spec, is 0.
version: u32,
hor_res: u32,
ver_res: u32,
format: PixelFormat,
mask: PixelBitmask,
stride: u32,
}
impl ModeInfo {
/// Returns the (horizontal, vertical) resolution.
///
/// On desktop monitors, this usually means (width, height).
pub fn resolution(&self) -> (usize, usize) {
(self.hor_res as usize, self.ver_res as usize)
}
/// Returns the format of the frame buffer.
pub fn pixel_format(&self) -> PixelFormat {
self.format
}
/// Returns the bitmask of the custom pixel format, if available.
pub fn pixel_bitmask(&self) -> Option<PixelBitmask> {
match self.format {
PixelFormat::Bitmask => Some(self.mask),
_ => None,
}
}
/// Returns the number of pixels per scanline.
///
/// Due to performance reasons, the stride might not be equal to the width,
/// instead the stride might be bigger for better alignment.
pub fn stride(&self) -> usize {
self.stride as usize
}
}
/// Iterator for graphics modes.
struct ModeIter<'gop> {
gop: &'gop GraphicsOutput<'gop>,
current: u32,
max: u32,
}
impl<'gop> Iterator for ModeIter<'gop> {
type Item = Mode;
fn next(&mut self) -> Option<Self::Item> {
let index = self.current;
if index < self.max {
let m = self.gop.query_mode(index);
self.current += 1;
m.ok().or_else(|| self.next())
} else {
None
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let size = (self.max - self.current) as usize;
(size, Some(size))
}
}
impl ExactSizeIterator for ModeIter<'_> {}
/// Format of pixel data used for blitting.
///
/// This is a BGR 24-bit format with an 8-bit padding, to keep each pixel 32-bit in size.
#[allow(missing_docs)]
#[derive(Debug, Copy, Clone)]
#[repr(C)]
pub struct BltPixel {
pub blue: u8,
pub green: u8,
pub red: u8,
_reserved: u8,
}
impl BltPixel {
/// Create a new pixel from RGB values.
pub fn new(red: u8, green: u8, blue: u8) -> Self {
Self {
red,
green,
blue,
_reserved: 0,
}
}
}
impl From<u32> for BltPixel {
fn from(color: u32) -> Self {
Self {
blue: (color & 0x00_00_FF) as u8,
green: ((color & 0x00_FF_00) >> 8) as u8,
red: ((color & 0xFF_00_00) >> 16) as u8,
_reserved: 0,
}
}
}
/// Region of the `BltBuffer` which we are operating on
///
/// Some `Blt` operations can operate on either the full `BltBuffer` or a
/// sub-rectangle of it, but require the stride to be known in the latter case.
#[derive(Clone, Copy, Debug)]
pub enum BltRegion {
/// Operate on the full `BltBuffer`
Full,
/// Operate on a sub-rectangle of the `BltBuffer`
SubRectangle {
/// Coordinate of the rectangle in the `BltBuffer`
coords: (usize, usize),
/// Stride (length of each row of the `BltBuffer`) in **pixels**
px_stride: usize,
},
}
/// Blit operation to perform.
#[derive(Debug)]
pub enum BltOp<'buf> {
/// Fills a rectangle of video display with a pixel color.
VideoFill {
/// The color to fill with.
color: BltPixel,
/// The X / Y coordinates of the destination rectangle.
dest: (usize, usize),
/// The width / height of the rectangle.
dims: (usize, usize),
},
/// Reads data from the video display to the buffer.
VideoToBltBuffer {
/// Buffer into which to copy data.
buffer: &'buf mut [BltPixel],
/// Coordinates of the source rectangle, in the frame buffer.
src: (usize, usize),
/// Location of the destination rectangle in the user-provided buffer
dest: BltRegion,
/// Width / height of the rectangles.
dims: (usize, usize),
},
/// Write data from the buffer to the video rectangle.
/// Delta must be the stride (count of bytes in a row) of the buffer.
BufferToVideo {
/// Buffer from which to copy data.
buffer: &'buf [BltPixel],
/// Location of the source rectangle in the user-provided buffer.
src: BltRegion,
/// Coordinates of the destination rectangle, in the frame buffer.
dest: (usize, usize),
/// Width / height of the rectangles.
dims: (usize, usize),
},
/// Copy from the source rectangle in video memory to
/// the destination rectangle, also in video memory.
VideoToVideo {
/// Coordinates of the source rectangle, in the frame buffer.
src: (usize, usize),
/// Coordinates of the destination rectangle, also in the frame buffer.
dest: (usize, usize),
/// Width / height of the rectangles.
dims: (usize, usize),
},
}
/// Direct access to a memory-mapped frame buffer
pub struct FrameBuffer<'gop> {
base: *mut u8,
size: usize,
_lifetime: PhantomData<&'gop mut u8>,
}
impl<'gop> FrameBuffer<'gop> {
/// Access the raw framebuffer pointer
///
/// To use this pointer safely and correctly, you must...
/// - Honor the pixel format and stride specified by the mode info
/// - Keep memory accesses in bound
/// - Use volatile reads and writes
/// - Make sure that the pointer does not outlive the FrameBuffer
pub fn as_mut_ptr(&mut self) -> *mut u8 {
self.base
}
/// Query the framebuffer size in bytes
pub fn size(&self) -> usize {
self.size
}
/// Modify the i-th byte of the frame buffer
///
/// # Safety
///
/// This operation is unsafe because...
/// - You must honor the pixel format and stride specified by the mode info
/// - There is no bound checking on memory accesses in release mode
#[inline]
pub unsafe fn write_byte(&mut self, index: usize, value: u8) {
debug_assert!(index < self.size, "Frame buffer accessed out of bounds");
self.base.add(index).write_volatile(value)
}
/// Read the i-th byte of the frame buffer
///
/// # Safety
///
/// This operation is unsafe because...
/// - You must honor the pixel format and stride specified by the mode info
/// - There is no bound checking on memory accesses in release mode
#[inline]
pub unsafe fn read_byte(&self, index: usize) -> u8 {
debug_assert!(index < self.size, "Frame buffer accessed out of bounds");
self.base.add(index).read_volatile()
}
/// Write a value in the frame buffer, starting at the i-th byte
///
/// We only recommend using this method with [u8; N] arrays. Once Rust has
/// const generics, it will be deprecated and replaced with a write_bytes()
/// method that only accepts [u8; N] input.
///
/// # Safety
///
/// This operation is unsafe because...
/// - It is your reponsibility to make sure that the value type makes sense
/// - You must honor the pixel format and stride specified by the mode info
/// - There is no bound checking on memory accesses in release mode
#[inline]
pub unsafe fn write_value<T>(&mut self, index: usize, value: T) {
debug_assert!(
index.saturating_add(mem::size_of::<T>()) <= self.size,
"Frame buffer accessed out of bounds"
);
(self.base.add(index) as *mut T).write_volatile(value)
}
/// Read a value from the frame buffer, starting at the i-th byte
///
/// We only recommend using this method with [u8; N] arrays. Once Rust has
/// const generics, it will be deprecated and replaced with a read_bytes()
/// method that only accepts [u8; N] input.
///
/// # Safety
///
/// This operation is unsafe because...
/// - It is your reponsibility to make sure that the value type makes sense
/// - You must honor the pixel format and stride specified by the mode info
/// - There is no bound checking on memory accesses in release mode
#[inline]
pub unsafe fn read_value<T>(&self, index: usize) -> T {
debug_assert!(
index.saturating_add(mem::size_of::<T>()) <= self.size,
"Frame buffer accessed out of bounds"
);
(self.base.add(index) as *const T).read_volatile()
}
}