feat(loader, kernel): impl part of loader and initialize kernel structure

arch/x86_64/boot/build_tool/compress_kernel.zig

@@ -0,0 +1,57 @@
+const std = @import("std");
+const Compress = std.compress.flate.Compress;
+const Dir = std.Io.Dir;
+const SIZE_ALIGN: usize = 0x200;
+pub fn main(init: std.process.Init) !void {
+    const args = try init.minimal.args.toSlice(init.arena.allocator());
+
+    if (args.len != 4) {
+        std.debug.print("Usage: {s} <kernel_bin> <output_file> <assembly_file>\n", .{args[0]});
+        std.process.exit(1);
+    }
+    const kernel_bin_path = args[1];
+    const output_path = args[2];
+    const assembly_path = args[3];
+    std.debug.print("Compressing kernel: {s} -> {s}\n", .{kernel_bin_path, output_path});
+
+    const kernel_file = try Dir.cwd().openFile(init.io, kernel_bin_path, .{});
+    defer kernel_file.close(init.io);
+    
+    const compressed_file = try Dir.cwd().createFile(init.io, output_path, .{ .truncate = true });
+    defer compressed_file.close(init.io);
+
+    var read_buffer: [4096]u8 = undefined;
+    var write_buffer: [4096]u8 = undefined;
+    var work_buffer: [std.compress.flate.max_window_len]u8 = undefined;
+    
+    var writer = compressed_file.writer(init.io, &write_buffer);
+    var reader = kernel_file.reader(init.io, &[0]u8{});
+    var compressor = try Compress.init(&writer.interface, &work_buffer, .gzip, .best);
+    var compressor_writer = &compressor.writer;
+    var total_read: usize = 0;
+    while (true) {
+        const read_bytes = try reader.interface.readSliceShort(&read_buffer);
+        if (read_bytes == 0) break;
+        total_read += read_bytes;
+        try compressor_writer.writeAll(read_buffer[0..read_bytes]);
+    }
+    try compressor_writer.flush();
+    const aligned_size = (total_read + SIZE_ALIGN - 1) & ~(SIZE_ALIGN - 1);
+    var assembly_file = try Dir.cwd().createFile(init.io, assembly_path, .{ .truncate = true });
+    defer assembly_file.close(init.io);
+    var assembly_writer = assembly_file.writer(init.io, &[0]u8{});
+    try assembly_writer.interface.print(
+        \\/* Auto-generated compressed kernel data */
+        \\    .section .rodata.compressed,"a"
+        \\    .global compressed_kernel_data
+        \\compressed_kernel_data:
+        \\    .incbin "{s}"
+        \\compressed_end:
+        \\    .set compressed_kernel_size, compressed_end - compressed_kernel_data
+        \\    .set uncompressed_kernel_size, {d}
+        \\    .global compressed_kernel_size
+        \\    .global uncompressed_kernel_size
+    , .{output_path, aligned_size});
+    try assembly_writer.interface.flush();
+    std.debug.print("Uncompressed aligned size: 0x{x} bytes\n", .{aligned_size});
+}