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

arch/x86_64/boot/extractor.zig

@@ -0,0 +1,46 @@
+const std = @import("std");
+const BootParams = @import("params.zig").BootParams;
+const early_serial_console = @import("early_serial_console.zig");
+const Cmdline = @import("cmdline.zig").Cmdline;
+const payload = @import("payload.zig");
+const multiboot = @import("multiboot.zig");
+const Decompress = std.compress.flate.Decompress;
+const relocate = @import("relocate.zig");
+const ident_map = @import("ident_map.zig");
+
+comptime {
+    @export(&relocate.relocateSelf, .{
+        .name = "relocateSelf",
+    });
+}
+fn decompress(target_addr: [*]u8) !void {
+    var data_reader = std.Io.Reader.fixed(payload.getCompressedKernelData());
+    var work_buffer: [std.compress.flate.max_window_len]u8 = undefined;
+    var decompressor = Decompress.init(&data_reader, .gzip, &work_buffer);
+    var decompressor_reader = &decompressor.reader;
+    var decompress_buf = target_addr;
+    while (true) {
+        const read_bytes = try decompressor_reader.readSliceShort(decompress_buf[0..4096]);
+        if (read_bytes == 0) break;
+        decompress_buf = decompress_buf[read_bytes..];
+        if ((@intFromPtr(decompress_buf) - @intFromPtr(target_addr) ) % 10240 == 0) {
+            early_serial_console.dprint("Decompressed {d} bytes...\n", .{@intFromPtr(decompress_buf) - @intFromPtr(target_addr)});
+        }
+    }
+}
+export fn extractKernel(multiboot_info: *u8, 
+                        target_addr: usize) callconv(.c) noreturn {
+    const params = multiboot.parseMultibootInfo(multiboot_info);
+    const cmdline = Cmdline.init(params.cmdline);
+    early_serial_console.earlyConsoleInit(&cmdline);
+    early_serial_console.dprint("Starting kernel extraction...\n", .{});
+    early_serial_console.dprint("Kernel compressed size {d} bytes\n", .{payload.getCompressedKernelData().len});
+    early_serial_console.dprint("Kernel uncompressed size {d} bytes\n", .{payload.getUncompressedKernelSize()});
+    decompress(@ptrFromInt(target_addr)) catch |err| {
+        early_serial_console.dprint("Kernel decompression failed: {s}\n", .{@errorName(err)});
+        while(true){}
+    };
+    early_serial_console.dprint("Kernel extraction completed.\n", .{});
+    
+    while(true){}
+}