Implemented an assembler

src/linker/WriteFile.go

@@ -0,0 +1,49 @@
+package linker
+
+import (
+	"os"
+
+	"git.urbach.dev/cli/q/src/asm"
+	"git.urbach.dev/cli/q/src/build"
+	"git.urbach.dev/cli/q/src/core"
+	"git.urbach.dev/cli/q/src/data"
+	"git.urbach.dev/cli/q/src/elf"
+)
+
+// WriteFile writes an executable file to disk.
+func WriteFile(executable string, b *build.Build, env *core.Environment) error {
+	file, err := os.Create(executable)
+
+	if err != nil {
+		return err
+	}
+
+	init := env.Functions["core.init"]
+	traversed := make(map[*core.Function]bool, len(env.Functions))
+
+	final := asm.Assembler{
+		Instructions: make([]asm.Instruction, 0, 8),
+		Data:         make(data.Data, 32),
+	}
+
+	// This will place the main function immediately after the entry point
+	// and also add everything the main function calls recursively.
+	init.EachDependency(traversed, func(f *core.Function) {
+		final.Merge(&f.Assembler)
+	})
+
+	code, data := final.Compile(b)
+
+	switch b.OS {
+	case build.Linux:
+		elf.Write(file, b, code, data)
+	}
+
+	err = file.Close()
+
+	if err != nil {
+		return err
+	}
+
+	return os.Chmod(executable, 0755)
+}