all: add console and logging machinery

src/dev/fbconsole.zig

@@ -0,0 +1,193 @@
+const r = @import("root");
+const std = @import("std");
+const pl = r.pl;
+const ke = r.ke;
+const ex = r.ex;
+
+const PSF1_MAGIC: u16 = 0x0436;
+const PSF2_MAGIC: u32 = 0x864ab572;
+
+const Psf1Header = extern struct {
+    magic: u16,
+    mode: u8,
+    glyph_size: u8,
+};
+
+const Psf2Header = extern struct {
+    magic: u32,
+    version: u32,
+    header_size: u32,
+    flags: u32,
+    glyph_count: u32,
+    glyph_size: u32,
+    height: u32,
+    width: u32,
+};
+
+const FontInfo = struct {
+    header_size: usize,
+    glyph_size: usize,
+    width: usize,
+    height: usize,
+};
+
+const font_file = @embedFile("sun12x22.psfu");
+var font: FontInfo = undefined;
+var framebuffer: [*]u32 = undefined;
+var framebuffer_width: usize = 0;
+var framebuffer_height: usize = 0;
+
+const bg_color: u32 = 0xFFFFFFFF;
+const text_color: u32 = 0xFF000000;
+const window_padding: usize = 10;
+
+var content_x: usize = 0;
+var content_y: usize = 0;
+var content_w: usize = 0;
+var content_h: usize = 0;
+var visible_h: usize = 0;
+
+fn load_font() void {
+    if (font_file.len >= @sizeOf(Psf2Header)) {
+        const h2: *const Psf2Header = @ptrCast(@alignCast(font_file.ptr));
+        if (h2.magic == PSF2_MAGIC) {
+            font = .{
+                .header_size = h2.header_size,
+                .glyph_size = h2.glyph_size,
+                .width = h2.width,
+                .height = h2.height,
+            };
+            return;
+        }
+    }
+    if (font_file.len >= @sizeOf(Psf1Header)) {
+        const h1: *const Psf1Header = @ptrCast(@alignCast(font_file.ptr));
+        if (h1.magic == PSF1_MAGIC) {
+            font = .{
+                .header_size = @sizeOf(Psf1Header),
+                .glyph_size = h1.glyph_size,
+                .width = 8,
+                .height = h1.glyph_size,
+            };
+            return;
+        }
+    }
+    font = .{ .header_size = 0, .glyph_size = 0, .width = 0, .height = 0 };
+}
+
+fn plot_character(x: usize, y: usize, c: u8) void {
+    const bytes_per_row = font.glyph_size / font.height;
+    const glyph_offset = font.header_size + (@as(usize, c) * font.glyph_size);
+    const glyph_data = font_file[glyph_offset..(glyph_offset + font.glyph_size)];
+    for (0..font.height) |row| {
+        var row_data: u32 = 0;
+        for (0..bytes_per_row) |b| {
+            row_data = (row_data << 8) | @as(u32, glyph_data[row * bytes_per_row + b]);
+        }
+        const shift_base = bytes_per_row * 8;
+        for (0..font.width) |col| {
+            if ((row_data & (@as(u32, 1) << @intCast(shift_base - 1 - col))) != 0) {
+                framebuffer[(y + row) * framebuffer_width + (x + col)] = text_color;
+            }
+        }
+    }
+}
+
+var cursor_x: usize = 0;
+var cursor_y: usize = 0;
+
+fn clear_content_rows(y: usize, height: usize) void {
+    for (0..height) |row| {
+        const dst_y = content_y + y + row;
+        if (dst_y >= content_y + visible_h) break;
+
+        for (0..content_w) |col| {
+            framebuffer[dst_y * framebuffer_width + content_x + col] = bg_color;
+        }
+    }
+}
+
+fn scroll_up(pixels: usize) void {
+    if (pixels >= visible_h) {
+        clear_content_rows(0, visible_h);
+        return;
+    }
+
+    const remaining_h = visible_h - pixels;
+    for (0..remaining_h) |row| {
+        const dst_y = content_y + row;
+        const src_y = dst_y + pixels;
+
+        for (0..content_w) |col| {
+            framebuffer[dst_y * framebuffer_width + content_x + col] =
+                framebuffer[src_y * framebuffer_width + content_x + col];
+        }
+    }
+
+    clear_content_rows(remaining_h, pixels);
+}
+
+fn ensure_cursor_visible() void {
+    while (cursor_y + font.height > visible_h) {
+        scroll_up(font.height);
+        cursor_y -= font.height;
+    }
+}
+
+fn newline() void {
+    cursor_x = 0;
+    cursor_y += font.height;
+
+    while (cursor_y > visible_h) {
+        scroll_up(font.height);
+        cursor_y -= font.height;
+    }
+}
+
+fn write_char(c: u8) void {
+    if (font.width == 0 or font.height == 0 or content_w < font.width or visible_h < font.height) {
+        return;
+    }
+
+    if (c == '\n') {
+        newline();
+    } else if (c == '\r') {
+        cursor_x = 0;
+    } else {
+        if (cursor_x + font.width > content_w) {
+            newline();
+        }
+
+        ensure_cursor_visible();
+        plot_character(content_x + cursor_x, content_y + cursor_y, c);
+        cursor_x += font.width;
+    }
+}
+
+fn write(_: ?*anyopaque, s: []const u8) void {
+    for (s) |c| {
+        write_char(c);
+    }
+}
+
+var console: ex.Console = .{ .ctx = null, .link = undefined, .write = write };
+
+pub fn init(boot_info: *pl.BootInfo) void {
+    framebuffer = @ptrFromInt(boot_info.framebuffer.?.address);
+    framebuffer_width = boot_info.framebuffer.?.width;
+    framebuffer_height = boot_info.framebuffer.?.height;
+
+    load_font();
+
+    content_x = window_padding;
+    content_y = window_padding;
+    content_w = framebuffer_width - (window_padding * 2);
+    content_h = framebuffer_height - (window_padding * 2);
+    visible_h = if (font.height == 0) 0 else content_h - (content_h % font.height);
+
+    for (0..framebuffer_width * framebuffer_height) |i| {
+        framebuffer[i] = bg_color;
+    }
+
+    ex.console.register(&console);
+}