2 files changed, 65 insertions, 9 deletions

diff --git a/src/codegen.zig b/src/codegen.zig
new file mode 100644
index 0000000..da1acd2
--- /dev/null
+++ b/src/codegen.zig
@@ -0,0 +1,51 @@
+const std = @import("std");
+const elf = std.elf;
+const Allocator = std.mem.Allocator;
+const root = @import("root");
+const Block = root.Block;
+
+pub fn create_elf(allocator: Allocator, block: Block) ![]u8 {
+    _ = block;
+
+    const base_addr = 0x10000000;
+    const elf_header: elf.Elf64_Ehdr = .{
+        .e_ident = elf.MAGIC.* ++ [_]u8{
+            elf.ELFCLASS64, // EI_CLASS
+            elf.ELFDATA2LSB, // EI_DATA
+            1, // EI_VERSION
+            @intFromEnum(elf.OSABI.NONE), // EI_OSABI
+            0, // EI_ABIVERSION
+        } ++ [1]u8{0} ** 7, // EI_PAD
+        .e_type = .EXEC,
+        .e_machine = elf.EM.RISCV,
+        .e_version = 1,
+        .e_entry = base_addr + @sizeOf(elf.Elf64_Ehdr) + @sizeOf(elf.Elf64_Phdr), // we place the code directly after the headers
+        .e_phoff = @sizeOf(elf.Elf64_Ehdr), // we place the program header(s) directly after the elf header
+        .e_shoff = 0,
+        .e_flags = 0, // ?
+        .e_ehsize = @sizeOf(elf.Elf64_Ehdr),
+        .e_phentsize = @sizeOf(elf.Elf64_Phdr),
+        .e_phnum = 1,
+        .e_shentsize = @sizeOf(elf.Elf64_Shdr),
+        .e_shnum = 0,
+        .e_shstrndx = 0,
+    };
+    const program_header: elf.Elf64_Phdr = .{
+        .p_type = elf.PT_LOAD,
+        .p_flags = elf.PF_R | elf.PF_X,
+        .p_offset = 0,
+        .p_vaddr = base_addr,
+        .p_paddr = base_addr,
+        .p_filesz = @sizeOf(elf.Elf64_Ehdr) + @sizeOf(elf.Elf64_Phdr) + 40,
+        .p_memsz = @sizeOf(elf.Elf64_Ehdr) + @sizeOf(elf.Elf64_Phdr) + 40,
+        .p_align = 0x1000,
+    };
+
+    var output_buffer: std.ArrayList(u8) = .init(allocator);
+    errdefer output_buffer.deinit();
+    const output = output_buffer.writer();
+    try output.writeAll(std.mem.asBytes(&elf_header));
+    try output.writeAll(std.mem.asBytes(&program_header));
+    for (0..10) |_| try output.writeAll(&std.mem.toBytes(@as(u32, 0x13)));
+    return output_buffer.toOwnedSlice();
+}
diff --git a/src/main.zig b/src/main.zig
index d938d9b..a7874d8 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -2,19 +2,23 @@ const std = @import("std");
 const parse = @import("./parse.zig");
 const peek = @import("./peek.zig");
 const compile = @import("./compile.zig");
+const codegen = @import("./codegen.zig");
 
 pub const peekable = peek.peekable;
 pub const Peekable = peek.Peekable;
 pub const Expr = parse.Expr;
 pub const Lexer = @import("./lexer.zig");
+pub const Block = compile.Block;
 
 pub fn main() !void {
     var arena: std.heap.ArenaAllocator = .init(std.heap.smp_allocator);
     defer arena.deinit();
     const allocator = arena.allocator();
 
-    var bw = std.io.bufferedWriter(std.io.getStdOut().writer());
-    const stdout = bw.writer();
+    var args = std.process.args();
+    _ = args.next();
+    const out_file = if (args.next()) |path| try std.fs.cwd().createFile(path, .{}) else std.io.getStdOut();
+    const output = out_file.writer();
 
     // var br = std.io.bufferedReader(std.io.getStdIn().reader());
     // const stdin = br.reader();
@@ -33,22 +37,23 @@ pub fn main() !void {
     // var lexer = Lexer{ .source = source };
     // while (true) {
     //     const token = lexer.next().?;
-    //     try stdout.print("{}\n", .{token});
+    //     std.debug.print("{}\n", .{token});
     //     if (token.type == .Eof) break;
     // }
-    // try stdout.print("\n", .{});
+    // std.debug.print("\n", .{});
     var lexer = peekable(Lexer{ .source = source });
     const expr = try parse.expression(allocator, &lexer);
-    try stdout.print("{}\n", .{expr});
+    std.debug.print("{}\n", .{expr});
     if (lexer.next()) |token| if (token.type != .eof) {
-        try stdout.print("Unexpected token {}, expected end of file\n", .{token});
+        std.debug.print("Unexpected token {}, expected end of file\n", .{token});
     };
     const block = try compile.compile(allocator, expr);
     for (block.instrs) |instr| {
-        try stdout.print("{}\n", .{instr});
+        std.debug.print("{}\n", .{instr});
     }
-
-    try bw.flush(); // Don't forget to flush!
+    const elf = try codegen.create_elf(allocator, block);
+    try output.writeAll(elf);
+    // try stdout.print("{x}\n", .{elf});
 }
 
 test {