Enhacnementsand toolchain

linker/linker.v

@@ -0,0 +1,61 @@
+// linker.v — links one or more VROBJ object files into a VRBIN executable.
+//
+// Code sections are concatenated, symbol entries are rebased, and call-site
+// relocations are patched with the final code offsets. Duplicate or unresolved
+// symbols are link errors.
+module linker
+
+import obj
+
+pub fn link(paths []string, out string) ! {
+	if paths.len == 0 {
+		return error('no object files to link')
+	}
+	mut code := []u8{}
+	mut strings := []string{}
+	mut symbols := map[string]int{}
+	mut relocs := []obj.Reloc{}
+	for p in paths {
+		o := obj.read(p)!
+		base := code.len
+		for s in o.symbols {
+			if s.name in symbols {
+				return error('duplicate symbol "${s.name}" (in ${p})')
+			}
+			symbols[s.name] = base + s.entry
+		}
+		code << o.code
+		for r in o.relocs {
+			relocs << obj.Reloc{ offset: r.offset + u32(base), name: r.name, kind: r.kind }
+		}
+	}
+	// resolve relocations
+	for r in relocs {
+		if r.kind == 1 {
+			// string constant: rebase to its index in the merged table
+			idx := intern_str(mut strings, r.name)
+			obj.patch_i64(mut code, r.offset, i64(idx))
+			continue
+		}
+		entry := symbols[r.name] or {
+			return error('unresolved symbol "${r.name}" (no such function)')
+		}
+		obj.patch_i64(mut code, r.offset, i64(entry))
+	}
+	// build the executable
+	mut fns := []obj.BinFn{}
+	for name, entry in symbols {
+		fns << obj.BinFn{ name: name, entry: entry }
+	}
+	obj.write_bin(out, obj.Bin{ fns: fns, strings: strings, code: code })!
+}
+
+fn intern_str(mut table []string, s string) int {
+	for i, t in table {
+		if t == s {
+			return i
+		}
+	}
+	table << s
+	return table.len - 1
+}