ww: import toolchain — C bootstrap + ww-side self-host (phases 0-10)

C bootstrap (phases 0-9):
  cmd/wwc, cmd/6c, cmd/6a, cmd/6l, cmd/ww, rt, lib/*.

ww-side self-host (phase 10):
  selfhost/cmd/wwc — ww-cgen frontend; bootstrap fixed point.
  selfhost/cmd/6a  — assembler; byte-identical to C 6a (test 991).
  selfhost/cmd/6l  — linker w/ archive (.a) support; byte-identical
                     to C 6l (test 992).
  selfhost/cmd/ww  — driver (build/run/version); byte-identical to
                     C ww (test 993).

make test: 15/15. make bootstrap: ww2.s == ww3.s, ww2.o == ww3.o,
ww2 == ww3 byte-identical, with the full ww-tooled chain.

lib/strings/strings.ww

@@ -0,0 +1,95 @@
+// strings — operations over the immutable str type ({ *u8, len }).
+
+use os;
+
+export fn len(s: str) i32 = {
+	return s.len;
+};
+
+export fn isempty(s: str) bool = {
+	return s.len == 0;
+};
+
+export fn equal(a: str, b: str) bool = {
+	if (a.len != b.len) { return false; };
+	let i: i32 = 0;
+	for (i < a.len) {
+		if (a[i] != b[i]) { return false; };
+		i += 1;
+	};
+	return true;
+};
+
+export fn hasprefix(s: str, p: str) bool = {
+	if (p.len > s.len) { return false; };
+	let i: i32 = 0;
+	for (i < p.len) {
+		if (s[i] != p[i]) { return false; };
+		i += 1;
+	};
+	return true;
+};
+
+export fn hassuffix(s: str, suf: str) bool = {
+	if (suf.len > s.len) { return false; };
+	let off: i32 = s.len - suf.len;
+	let i: i32 = 0;
+	for (i < suf.len) {
+		if (s[off + i] != suf[i]) { return false; };
+		i += 1;
+	};
+	return true;
+};
+
+// indexbyte — first index of `c` in `s`, or -1 if absent. Plan 9-
+// style sentinel return; callers that prefer a fallible shape can
+// wrap this in their own (i32 | str). No allocation.
+export fn indexbyte(s: str, c: u8) i32 = {
+	let i: i32 = 0;
+	for (i < s.len) {
+		if (s[i] == c) { return i; };
+		i += 1;
+	};
+	return -1;
+};
+
+// index — first index of `sub` in `s`, or -1. Naive scan; fine for
+// short patterns and small strings, which dominate config and CLI
+// parsing. Empty `sub` matches at 0.
+export fn index(s: str, sub: str) i32 = {
+	if (sub.len == 0) { return 0; };
+	if (sub.len > s.len) { return -1; };
+	let last: i32 = s.len - sub.len;
+	let i: i32 = 0;
+	for (i <= last) {
+		let j: i32 = 0;
+		let ok: bool = true;
+		for (j < sub.len) {
+			if (s[i + j] != sub[j]) { ok = false; j = sub.len; }
+			else { j += 1; };
+		};
+		if (ok) { return i; };
+		i += 1;
+	};
+	return -1;
+};
+
+export fn contains(s: str, sub: str) bool = {
+	return index(s, sub) >= 0;
+};
+
+// concat — joins two strings into a fresh str. Caller owns the
+// returned str's storage; release via `os.free(r.ptr, r.len)`. Mirrors
+// Hare's strings::concat shape.
+export fn concat(a: str, b: str) str = {
+	let total: i32 = a.len + b.len;
+	let buf: *u8 = os.alloc(total: u64): *u8;
+	let i: i32 = 0;
+	for (i < a.len) { buf[i] = a[i]; i += 1; };
+	let j: i32 = 0;
+	for (j < b.len) { buf[a.len + j] = b[j]; j += 1; };
+	let r: str;
+	r.ptr = buf;
+	r.len = total;
+	return r;
+};