gfx: the console and the crash screen stop drawing on a driver by name
Same disease as the network stack, one subsystem over. kernel/dev/vga.c
was three things wearing one name: the owner of the framebuffer, a
bitmap drawing library, and the text console. Only the first is a
driver, and because they shared a file they shared a prefix -- so
panic.c drew the crash screen with vga_fill_rect, console.c printed with
vga_putc, /dev/fb0 handed out vga_fb_phys, and every one of those files
named a display driver it had no business knowing about.
Split three ways:
- kernel/drivers/gpu/vga/vga_fb.c owns the VBE framebuffer -- the mode
the loader programmed and handed over, the aperture, and the display
class vtable. It is a driver and now lives with the driver that
finds the card on the bus.
- kernel/dev/gfx.c draws: pixels, shapes, glyphs, the cursor, scroll,
the ANSI erase operations. It names no driver. The framebuffer
arrives through gfx_attach_scanout(), so a driver publishes what it
owns and this file draws on it without knowing what it is.
- include/gfx.h is the interface, and says why it is deliberately not
the display class: that one is about frames -- acquire, present,
vblank -- and the crash screen has to work when nothing else does.
main() no longer calls a display driver. platform_register_devices()
takes the framebuffer address and brings up whatever owns it, which is
where driver names belong; kernel/drivers/registry.c is the file whose
entire job is naming every driver in the kernel.
virtio-gpu got the e1000 treatment as well: instances in an array, the
instance hung on dev->priv by an `attached` hook, and every op reading
it rather than a file-static. It refused the second adapter outright
before, which is not hypothetical -- integrated plus discrete is an
ordinary laptop. The VGA driver deliberately has no such hook, and says
so: there is one framebuffer the loader programmed however many
VGA-class controllers the bus turns up, and a second one publishing the
same scanout is the truth rather than a bug.
Private headers moved next to their drivers: include/virtio.h and
include/xhci.h each had exactly one includer. include/ is for headers
the rest of the kernel needs.
Deleted rather than moved: consoleinit() programmed the sixteen ANSI
colours into the VGA DAC and disabled text-mode blink, by writing ports
0x3C0-0x3C9 from the console. The comment three lines above the colour
table already said this does nothing in a 32bpp linear mode -- there is
no palette to index -- so it was both dead and in the wrong file.
Verified, and this is a refactor so the evidence is that nothing moved:
- bootcheck -Fb -Net: 59 [ok], no failures. That covers the console
through every command, /dev/fb0's geometry, writing pixels through
write() and mapping the framebuffer through mmap.
- make crashshot: the crash screen renders exactly as before --
shapes, glyphs, logo and QR code -- which is the whole of gfx.c
exercised at once, in a panic, with the scanout attached by a driver.
- make schcom-test: five pixel assertions from the host oracle still
pass, so the display class and the compositor above it are unmoved.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Nexoniarz
parent
20cc673a41
commit
817d666068
22 changed files with 942 additions and 752 deletions
444
kernel/dev/gfx.c
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444
kernel/dev/gfx.c
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// Drawing and the text console, on whatever display is bound. See include/gfx.h
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// for why this is not a driver and does not name one.
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//
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// It was kernel/dev/vga.c, and the name was the problem: panic.c called
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// gfx_fill_rect, console.c called gfx_putc, /dev/fb0 called gfx_fb_phys. None
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// of this code is VGA-specific -- it is bitmap drawing over a linear
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// framebuffer -- and the one part that genuinely was is now the driver, in
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// kernel/drivers/gpu/vga/.
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//
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// The framebuffer arrives through gfx_attach_scanout() rather than being read
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// out of the boot block here. That is the whole of the inversion: a driver
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// publishes what it owns, and this file draws on it without knowing what it is.
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#include "types.h"
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#include "x86.h"
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#include "memlayout.h"
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#include "defs.h"
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#include "theme.h"
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#include "font.h"
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#include "logo.h"
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#include "device.h"
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#include "display.h"
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#include "gfx.h"
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#define BACKSPACE 0x100
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#define CHAR_HEIGHT 16
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#define CHAR_WIDTH 8
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#define COLOR_BG SCH_BG
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// The scanout, as published by whichever driver owns the display. Zeroed until
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// one does, and every entry point checks `fb` before touching memory -- a
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// kernel that panics before any display driver has run still has to be able to
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// call in here and do nothing gracefully.
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static struct fb_info scanout;
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static volatile uchar *fb;
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static int cursor_x = 0;
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static int cursor_y = 0;
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// Current fill color for glyph backgrounds, backspace erase, and scroll --
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// normally COLOR_BG, but panic() switches this to paint the whole console a
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// solid color (e.g. PSOGM's purple) instead of leaving cream-colored boxes
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// around each character.
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static uint32 gfx_bg = COLOR_BG;
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void
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gfx_attach_scanout(const struct fb_info *info)
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{
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scanout = *info;
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fb = info->ptr;
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}
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const struct fb_info *
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gfx_scanout(void)
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{
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return fb ? &scanout : 0;
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}
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void
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gfx_set_bg(uint32 color)
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{
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gfx_bg = color;
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}
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// The mode that was actually set. Exported because the resolution is chosen at
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// boot now (press R -- see boot/bios/stage2.S), so nothing above may assume it.
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uint32
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gfx_width(void)
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{
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return scanout.width;
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}
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uint32
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gfx_height(void)
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{
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return scanout.height;
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}
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void
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gfx_draw_pixel(int x, int y, uint32 color)
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{
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if (!fb || x < 0 || x >= scanout.width || y < 0 || y >= scanout.height)
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return;
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uint32 offset = (y * scanout.stride) + (x * (scanout.bpp / 8));
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if (scanout.bpp == 32) {
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*(volatile uint32*)(fb + offset) = color;
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} else if (scanout.bpp == 24) {
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fb[offset] = color & 0xFF;
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fb[offset + 1] = (color >> 8) & 0xFF;
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fb[offset + 2] = (color >> 16) & 0xFF;
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} else if (scanout.bpp == 16) {
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uint16 c16 = (((color >> 19) & 0x1F) << 11) | (((color >> 10) & 0x3F) << 5) | ((color >> 3) & 0x1F);
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*(volatile uint16*)(fb + offset) = c16;
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}
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}
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void
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gfx_clear(uint32 color)
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{
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for (int y = 0; y < scanout.height; y++) {
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for (int x = 0; x < scanout.width; x++) {
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gfx_draw_pixel(x, y, color);
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}
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}
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}
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void
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gfx_draw_char(int x, int y, uchar c, uint32 color)
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{
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// No `c > 127` rejection any more: font_data holds 256 Latin-1 glyphs, and
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// a uchar cannot index past them.
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if (!fb) return;
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for (int row = 0; row < CHAR_HEIGHT; row++) {
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uchar row_data = font_data[c][row];
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for (int col = 0; col < CHAR_WIDTH; col++) {
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if (row_data & (0x80 >> col)) {
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gfx_draw_pixel(x + col, y + row, color);
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} else {
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gfx_draw_pixel(x + col, y + row, gfx_bg);
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}
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}
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}
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}
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void
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gfx_puts(int x, int y, char *s, uint32 color)
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{
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while (*s) {
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gfx_putc((uchar)*s, color);
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s++;
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}
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}
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void
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gfx_putc(int c, uint32 color)
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{
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if (!fb) return;
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if (c == BACKSPACE || c == 0x08 || c == '\b' || c == 127) {
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if (cursor_x >= CHAR_WIDTH) {
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cursor_x -= CHAR_WIDTH;
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for (int i = 0; i < CHAR_HEIGHT; i++) {
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for (int j = 0; j < CHAR_WIDTH; j++) {
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gfx_draw_pixel(cursor_x + j, cursor_y + i, gfx_bg);
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}
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}
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}
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return;
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}
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if (c == '\n') {
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cursor_x = 0;
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cursor_y += CHAR_HEIGHT;
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} else if (c == '\r') {
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cursor_x = 0;
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} else if (c == '\t') {
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// Advance to the next multiple of eight columns, erasing as it goes so a
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// tab overwrites rather than skipping over stale characters.
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//
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// There was no tab case at all, so '\t' fell through to gfx_draw_char and
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// was drawn as glyph 9 -- which in CP437 is a hollow circle. Pressing Tab
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// printed a circle. Same for every other control character: the font has
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// a picture for each of them, and none of those pictures is what the
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// character means.
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int col = cursor_x / CHAR_WIDTH;
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int stop = (col + 8) & ~7;
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while (col < stop && cursor_x < (int)scanout.width) {
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for (int i = 0; i < CHAR_HEIGHT; i++)
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for (int j = 0; j < CHAR_WIDTH; j++)
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gfx_draw_pixel(cursor_x + j, cursor_y + i, gfx_bg);
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cursor_x += CHAR_WIDTH;
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col++;
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}
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} else if (c < 32) {
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return; // any other control character: not a glyph
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} else {
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gfx_draw_char(cursor_x, cursor_y, (uchar)c, color);
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cursor_x += CHAR_WIDTH;
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}
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if (cursor_x >= scanout.width) {
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cursor_x = 0;
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cursor_y += CHAR_HEIGHT;
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}
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if (cursor_y > (scanout.height - CHAR_HEIGHT)) {
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uint32 line_size = scanout.stride * CHAR_HEIGHT;
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uint32 total_size = scanout.stride * scanout.height;
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uint32 copy_size = total_size - line_size;
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memmove((void*)fb, (void*)(fb + line_size), copy_size);
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for (int y = scanout.height - CHAR_HEIGHT; y < scanout.height; y++) {
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for (int x = 0; x < scanout.width; x++) {
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gfx_draw_pixel(x, y, gfx_bg);
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}
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}
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cursor_y = scanout.height - CHAR_HEIGHT;
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}
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}
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void
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gfx_screen_reset(void)
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{
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gfx_bg = COLOR_BG;
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gfx_clear(COLOR_BG);
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cursor_x = 0;
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cursor_y = 0;
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}
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/* ------------------------------------------------------------------ */
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/* Drawing primitives for the crash screen */
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/* */
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/* The crash screen lays itself out rather than printing, which needs */
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/* two things the console never did: filled shapes, and text at an */
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/* absolute position that leaves the cursor alone. */
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/* ------------------------------------------------------------------ */
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int
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gfx_ready(void)
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{
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return fb != 0;
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}
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void
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gfx_dims(int *w, int *h)
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{
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if (w) *w = (int)scanout.width;
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if (h) *h = (int)scanout.height;
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}
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int gfx_char_w(void) { return CHAR_WIDTH; }
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int gfx_char_h(void) { return CHAR_HEIGHT; }
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/* ------------------------------------------------------------------ */
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/* Framebuffer geometry */
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/* */
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/* Whatever the attached scanout says, rather than anything read from */
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/* the boot block here -- the driver that owns the display is the only */
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/* thing that knows where the pixels are. See kernel/dev/fb.c for the */
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/* device these back. */
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/* ------------------------------------------------------------------ */
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uint64 gfx_fb_phys(void) { return scanout.phys; }
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// Bytes of framebuffer, measured in scanlines rather than as
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// width * height * bpp/8 -- the two differ whenever the card pads its rows,
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// and it is the stride that says how far apart two rows really are.
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uint64 gfx_fb_size(void)
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{
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if (!fb)
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return 0;
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return (uint64)scanout.stride * (uint64)scanout.height;
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}
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uint32 gfx_fb_stride(void) { return scanout.stride; }
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uint32 gfx_fb_bpp(void) { return scanout.bpp; }
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volatile uchar *gfx_fb_ptr(void) { return fb; }
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/* ------------------------------------------------------------------ */
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/* Cursor addressing and erasing */
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/* */
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/* What an ANSI escape parser needs and gfx_putc alone cannot give it: */
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/* the ability to put the cursor somewhere specific and to erase a */
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/* region without writing spaces over it. See kernel/core/console.c. */
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/* ------------------------------------------------------------------ */
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int gfx_cols(void) { return scanout.width ? (int)(scanout.width / CHAR_WIDTH) : 0; }
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int gfx_rows(void) { return scanout.height ? (int)(scanout.height / CHAR_HEIGHT) : 0; }
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void
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gfx_cursor_get(int *col, int *row)
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{
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if (col) *col = cursor_x / CHAR_WIDTH;
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if (row) *row = cursor_y / CHAR_HEIGHT;
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}
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// Clamped rather than validated: an escape sequence is untrusted input that
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// arrives from any program that can write to the terminal, and "CUP to row
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// 9999" should put the cursor on the last row, not off the end of the
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// framebuffer.
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void
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gfx_cursor_set(int col, int row)
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{
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int maxc = gfx_cols(), maxr = gfx_rows();
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if (maxc <= 0 || maxr <= 0)
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return;
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if (col < 0) col = 0;
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if (row < 0) row = 0;
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if (col >= maxc) col = maxc - 1;
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if (row >= maxr) row = maxr - 1;
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cursor_x = col * CHAR_WIDTH;
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cursor_y = row * CHAR_HEIGHT;
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}
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// Fill a run of character cells with the background colour.
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static void
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erase_cells(int col, int row, int count)
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{
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int maxc = gfx_cols();
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while (count-- > 0) {
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int x = col * CHAR_WIDTH, y = row * CHAR_HEIGHT;
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for (int i = 0; i < CHAR_HEIGHT; i++)
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for (int j = 0; j < CHAR_WIDTH; j++)
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gfx_draw_pixel(x + j, y + i, gfx_bg);
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if (++col >= maxc) { col = 0; row++; }
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}
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}
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// ED -- erase in display. 0: cursor to end, 1: start to cursor, 2: all.
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void
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gfx_erase_display(int mode)
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{
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int col, row, maxc = gfx_cols(), maxr = gfx_rows();
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gfx_cursor_get(&col, &row);
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switch (mode) {
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case 0: erase_cells(col, row, (maxr - row) * maxc - col); break;
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case 1: erase_cells(0, 0, row * maxc + col + 1); break;
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default: gfx_clear(gfx_bg); break;
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}
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}
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// EL -- erase in line. Same three modes, bounded to the current row.
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void
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gfx_erase_line(int mode)
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{
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int col, row, maxc = gfx_cols();
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gfx_cursor_get(&col, &row);
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switch (mode) {
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case 0: erase_cells(col, row, maxc - col); break;
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case 1: erase_cells(0, row, col + 1); break;
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default: erase_cells(0, row, maxc); break;
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}
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}
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// Row pointer computed once per row rather than per pixel. The crash screen
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// paints a solid card behind the QR symbol, and at 8 pixels per module that is
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// tens of thousands of writes going through gfx_draw_pixel's bounds check and
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// multiply.
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void
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gfx_fill_rect(int x0, int y0, int w, int h, uint32 color)
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{
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if (!fb)
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return;
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if (x0 < 0) { w += x0; x0 = 0; }
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if (y0 < 0) { h += y0; y0 = 0; }
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if (x0 + w > (int)scanout.width) w = (int)scanout.width - x0;
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if (y0 + h > (int)scanout.height) h = (int)scanout.height - y0;
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if (w <= 0 || h <= 0)
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return;
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// Only the 32bpp case gets the fast path; anything else is rare enough that
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// correctness through gfx_draw_pixel is the better trade.
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if (scanout.bpp != 32) {
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for (int y = y0; y < y0 + h; y++)
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for (int x = x0; x < x0 + w; x++)
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gfx_draw_pixel(x, y, color);
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return;
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}
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for (int y = y0; y < y0 + h; y++) {
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volatile uint32 *row = (volatile uint32 *)(fb + y * scanout.stride) + x0;
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for (int x = 0; x < w; x++)
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row[x] = color;
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}
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}
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void
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gfx_fill_circle(int cx, int cy, int r, uint32 color)
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{
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for (int dy = -r; dy <= r; dy++)
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for (int dx = -r; dx <= r; dx++)
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if (dx * dx + dy * dy <= r * r)
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gfx_draw_pixel(cx + dx, cy + dy, color);
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}
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// Text at an absolute position, leaving the console cursor alone. The crash
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// screen lays itself out, so gfx_putc's cursor tracking and scrolling are
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// exactly what it does not want.
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void
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gfx_text_at(int x, int y, const char *s, uint32 color)
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{
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for (int i = 0; s[i]; i++)
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gfx_draw_char(x + i * CHAR_WIDTH, y, (uchar)s[i], color);
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}
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// --- Logo ------------------------------------------------------------------
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//
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// The boot splash's logo is drawn by the *loader*, not here -- see splash() in
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// boot/bios/stage2main.c. It has to be, because the kernel does not reach gfx_init()
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// until roughly the last 300ms of a 2.8s boot: drawing it here put the logo on
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// screen for one frame before console_takeover() wiped it, which is worse than
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// not having one.
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//
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// What lives here is the same drawing code against the same mask, for the
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// things that want the mark *after* boot -- the crash screen, and eventually
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// whatever schinit shows. Keeping one copy of the compositing logic is why this
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// is not simply deleted.
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||||
// Blend `fg` over `bg` by coverage a (0..255). Per-channel, integer only: this
|
||||
// runs before any floating point is safe to touch.
|
||||
static uint32
|
||||
blend(uint32 bg, uint32 fg, uint a)
|
||||
{
|
||||
uint32 r = (((fg >> 16) & 0xFF) * a + ((bg >> 16) & 0xFF) * (255 - a)) / 255;
|
||||
uint32 g = (((fg >> 8) & 0xFF) * a + ((bg >> 8) & 0xFF) * (255 - a)) / 255;
|
||||
uint32 b = (((fg ) & 0xFF) * a + ((bg ) & 0xFF) * (255 - a)) / 255;
|
||||
return (r << 16) | (g << 8) | b;
|
||||
}
|
||||
|
||||
void
|
||||
gfx_draw_logo(int x, int y, uint32 color, uint32 bg)
|
||||
{
|
||||
if (!fb)
|
||||
return;
|
||||
for (int dy = 0; dy < LOGO_H; dy++) {
|
||||
for (int dx = 0; dx < LOGO_W; dx++) {
|
||||
uint a = LOGO_INK(dy * LOGO_W + dx);
|
||||
// Skip the background rather than painting it. The mask is a square but
|
||||
// the mark is a circle, so most of it is empty -- and drawing that empty
|
||||
// area in bg would stamp a visible box over whatever is underneath.
|
||||
if (a == 0)
|
||||
continue;
|
||||
gfx_draw_pixel(x + dx, y + dy, a == 255 ? color : blend(bg, color, a));
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// Centred, for callers that own the whole screen.
|
||||
void
|
||||
gfx_logo_centered(int cy, uint32 color, uint32 bg)
|
||||
{
|
||||
if (!fb || scanout.width < LOGO_W)
|
||||
return;
|
||||
gfx_draw_logo(((int)scanout.width - LOGO_W) / 2, cy - LOGO_H / 2, color, bg);
|
||||
}
|
||||
Loading…
Reference in a new issue