working minimal capnp_c test case

5 files changed, 1851 insertions, 23 deletions

diff --git a/src/app/prototest/Makefile.inc b/src/app/prototest/Makefile.inc
index a3477e6..4658af6 100644
--- a/src/app/prototest/Makefile.inc
+++ b/src/app/prototest/Makefile.inc
@@ -21,6 +21,15 @@ ifeq (${prototest_arduinojson}, 1)
 	COMMON_FLAGS += -DPROTOTEST_ARDUINOJSON
 endif
 
+ifeq (${prototest_capnproto_c}, 1)
+	COMMON_FLAGS += -DPROTOTEST_CAPNPROTO_C
+	CXX_TARGETS += src/app/prototest/capnp_c_bench.capnp.cc
+	CXX_TARGETS += src/lib/capnp-c/capn.c
+	CXX_TARGETS += src/lib/capnp-c/capn-malloc.c
+	CXX_TARGETS += src/lib/capnp-c/capn-stream.c
+	INCLUDES += -Iinclude/lib/capnp-c
+endif
+
 ifeq (${prototest_modernjson}, 1)
 	COMMON_FLAGS += -DPROTOTEST_MODERNJSON
 	ostream = 1
@@ -50,8 +59,19 @@ ifeq (${prototest_xdr}, 1)
 	CXX_TARGETS += src/os/object/xdrstream.cc src/os/object/xdrinput.cc
 endif
 
+# Don't try to make .capnp from .capnp.c
+%.capnp: ;
+
+# Don't try to make .proto from .proto.c
+%.proto: ;
+
 %.pb.cc: %.proto
 	protoc --plugin=protoc-gen-nanopb=${HOME}/var/ess/protocol-modeling/nanopb/generator/protoc-gen-nanopb --nanopb_out=. src/app/prototest/nanopbbench.proto
 	mv src/app/prototest/nanopbbench.pb.c src/app/prototest/nanopbbench.pb.cc
 	sed -i 's!src/app/prototest/!!' src/app/prototest/nanopbbench.pb.cc
 	sed -i 's!\#include "src/app/prototest/nanopb.pb.h"!!' src/app/prototest/nanopbbench.pb.h
+
+%.capnp.cc: %.capnp
+	capnp compile -oc $<
+	mv $<.c $<.cc
+	cp $<.cc /tmp
diff --git a/src/app/prototest/main.cc b/src/app/prototest/main.cc
index b4d2254..ee907ab 100644
--- a/src/app/prototest/main.cc
+++ b/src/app/prototest/main.cc
@@ -6,6 +6,10 @@
 #ifdef PROTOTEST_ARDUINOJSON
 #include "lib/ArduinoJson.h"
 #endif
+#ifdef PROTOTEST_CAPNPROTO_C
+#include <capnp_c.h>
+#include "capnp_c_bench.capnp.h"
+#endif
 #ifdef PROTOTEST_MODERNJSON
 #include "lib/modernjson/json.h"
 #endif
@@ -40,6 +44,19 @@ char buf[256];
 char buf[256];
 #endif
 
+#ifdef PROTOTEST_NANOPB
+bool encode_hurr(pb_ostream_t *stream, const pb_field_t *field, void * const *arg)
+{
+if (!pb_encode_tag_for_field(stream, field)) return false;
+return pb_encode_string(stream, (uint8_t*)"durr", 4);
+}
+bool encode_sensor(pb_ostream_t *stream, const pb_field_t *field, void * const *arg)
+{
+if (!pb_encode_tag_for_field(stream, field)) return false;
+return pb_encode_string(stream, (uint8_t*)"gps", 3);
+}
+#endif
+
 // TODOs
 //
 // Code -> JSON
@@ -91,29 +108,65 @@ kout << "\"sensor\":\"gps\"" << ",";
 kout << "\"time\":" << dec << ts;
 kout << "}" << endl;
 
+#ifdef PROTOTEST_CAPNPROTO_C
+	uint8_t buf[1024];
+	for (unsigned int i = 0; i < sizeof(buf); i++) {
+		buf[i] = 0;
+	}
+	struct capn c;
+	capn_init_malloc(&c);
+	capn_ptr cr = capn_root(&c);
+	struct capn_segment *cs = cr.seg;
 
-#ifdef PROTOTEST_XDR
-	BufferOutput<XDRStream> foostream(buf);
-	XDRInput input(buf);
+	struct Benchmark benchmark;
+	//struct Benchmark_Nesting benchmark_nesting;
+	//struct Benchmark_Nesting_Foo benchmark_nesting_foo;
+	benchmark.time = ts + 1;
+
+	//benchmark.nesting = new_Benchmark_Nesting(cs);
+	//benchmark_nesting.foo = new_Benchmark_Nesting_Foo(cs);
 
-	char test[] = "Obai World!";
+	//write_Benchmark_Nesting_Foo(&benchmark_nesting_foo, benchmark_nesting.foo);
+	//write_Benchmark_Nesting(&benchmark_nesting, benchmark.nesting);
 
-	//counter.start();
-	foostream << (uint32_t)123 << (int16_t)-2 << ts << (uint16_t)0 << (uint64_t)4294967296 << (uint16_t)0;
-	foostream.setNextArrayLen(3);
-	foostream << variable << "Hai";
-	foostream.setNextArrayLen(sizeof(test));
-	foostream << variable << (char const *)test;
+	Benchmark_ptr benchmark_ptr = new_Benchmark(cs);
+	write_Benchmark(&benchmark, benchmark_ptr);
 
-	//tmp = counter.stop();
-	//kout << "XDR serialization took " << tmp << " >" << counter.overflowed << " cycles" << endl;
-	kout << "foostream is " << hex;
+	capn_write_mem(&c, buf, sizeof(buf), 0 /* packed */);
+	capn_free(&c);
+
+	kout << "capnproto is " << hex;
+	for (unsigned int i = 0; i < sizeof(buf); i++) {
+		kout << buf[i];
+	}
+	kout << endl;
+#endif
+
+#ifdef PROTOTEST_XDR
+	BufferOutput<XDRStream> xdrstream(buf);
+	xdrstream.setNextArrayLen(2);
+	xdrstream << 48.75608;
+	xdrstream << 2.302038;
+	xdrstream.setNextArrayLen(3);
+	xdrstream.setNextArrayLen(1);
+	xdrstream << 1;
+	xdrstream.setNextArrayLen(2);
+	xdrstream << 2;
+	xdrstream << 2;
+	xdrstream.setNextArrayLen(4);
+	xdrstream << variable << "durr";
+	xdrstream.setNextArrayLen(3);
+	xdrstream << variable << "gps";
+	xdrstream << ts;
+
+	kout << "xdrstream is " << hex;
 	for (unsigned int i = 0; i < 64; i += 4) {
 		kout << (unsigned char)buf[i] << (unsigned char)buf[i+1];
 		kout << (unsigned char)buf[i+2] << (unsigned char)buf[i+3] << " ";
 	}
 	kout << endl;
 
+	XDRInput input(buf);
 	kout << dec;
 	kout << "foostream = " << input.get_uint32() << " = " << 123;
 	kout << ", " << input.get_int32() << " = " << -2;
@@ -233,10 +286,15 @@ kout << "}" << endl;
 	bool status;
 
 	{
-		TestMessage msg = TestMessage_init_zero;
+		Benchmark msg = Benchmark_init_zero;
 		pb_ostream_t stream = pb_ostream_from_buffer(buf, sizeof(buf));
-		msg.number = 423;
-		status = pb_encode(&stream, TestMessage_fields, &msg);
+		msg.data[0] = 48.75608;
+		msg.data[1] = 2.302038;
+		msg.nesting.foo.hurr.funcs.encode = encode_hurr;
+		msg.nesting.foo.qwop = 9001;
+		msg.sensor.funcs.encode = encode_sensor;
+		msg.time = ts;
+		status = pb_encode(&stream, Benchmark_fields, &msg);
 		len = stream.bytes_written;
 		kout << len << " bytes written" << endl;
 	}
@@ -254,17 +312,26 @@ kout << "}" << endl;
 	}
 	mpack_writer_t writer;
 	mpack_writer_init(&writer, buf, sizeof(buf));
-
-	start = uptime.get_cycles();
-	mpack_start_map(&writer, 2);
-	stop = uptime.get_cycles();
-	kout << stop - start << endl;
-	mpack_write_cstr(&writer, "gps");
-	mpack_write_uint(&writer, ts);
+	mpack_start_map(&writer, 4);
+	mpack_write_cstr(&writer, "data");
 	mpack_start_array(&writer, 2);
 	mpack_write_float(&writer, 48.756080);
 	mpack_write_float(&writer, 2.302038);
 	mpack_finish_array(&writer);
+	mpack_write_cstr(&writer, "nesting");
+	mpack_start_map(&writer, 1);
+	mpack_write_cstr(&writer, "foo");
+	mpack_start_map(&writer, 2);
+	mpack_write_cstr(&writer, "hurr");
+	mpack_write_cstr(&writer, "durr");
+	mpack_write_cstr(&writer, "qwop");
+	mpack_write_uint(&writer, 9001);
+	mpack_finish_map(&writer);
+	mpack_finish_map(&writer);
+	mpack_write_cstr(&writer, "sensor");
+	mpack_write_cstr(&writer, "gps");
+	mpack_write_cstr(&writer, "time");
+	mpack_write_uint(&writer, ts);
 	mpack_finish_map(&writer);
 
 	if (mpack_writer_destroy(&writer) != mpack_ok) {
diff --git a/src/lib/capnp-c/capn-malloc.c b/src/lib/capnp-c/capn-malloc.c
new file mode 100644
index 0000000..7308061
--- /dev/null
+++ b/src/lib/capnp-c/capn-malloc.c
@@ -0,0 +1,409 @@
+/* vim: set sw=8 ts=8 sts=8 noet: */
+/* capn-malloc.c
+ *
+ * Copyright (C) 2013 James McKaskill
+ * Copyright (C) 2014 Steve Dee
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-Wunused-parameter"
+#endif
+
+#include "capnp_c.h"
+#include "capnp_priv.h"
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <errno.h>
+
+/*
+ * 8 byte alignment is required for struct capn_segment.
+ * This struct check_segment_alignment verifies this at compile time.
+ *
+ * Unless capn_segment is defined with 8 byte alignment, check_segment_alignment
+ * fails to compile in x86 mode (or on another CPU with 32-bit pointers),
+ * as (sizeof(struct capn_segment)&7) -> (44 & 7) evaluates to 4.
+ * It compiles in x64 mode (or on another CPU with 64-bit pointers),
+ * as (sizeof(struct capn_segment)&7) -> (80 & 7) evaluates to 0.
+ */
+struct check_segment_alignment {
+	unsigned int foo : (sizeof(struct capn_segment)&7) ? -1 : 1;
+};
+
+static struct capn_segment *create(void *u, uint32_t id, int sz) {
+	struct capn_segment *s;
+	sz += sizeof(*s);
+	if (sz < 4096) {
+		sz = 4096;
+	} else {
+		sz = (sz + 4095) & ~4095;
+	}
+	s = (struct capn_segment*) calloc(1, sz);
+	s->data = (char*) (s+1);
+	s->cap = sz - sizeof(*s);
+	s->user = s;
+	return s;
+}
+
+static struct capn_segment *create_local(void *u, int sz) {
+	return create(u, 0, sz);
+}
+
+void capn_init_malloc(struct capn *c) {
+	memset(c, 0, sizeof(*c));
+	c->create = &create;
+	c->create_local = &create_local;
+}
+
+void capn_free(struct capn *c) {
+	struct capn_segment *s = c->seglist;
+	while (s != NULL) {
+		struct capn_segment *n = s->next;
+		free(s->user);
+		s = n;
+	}
+	capn_reset_copy(c);
+}
+
+void capn_reset_copy(struct capn *c) {
+	struct capn_segment *s = c->copylist;
+	while (s != NULL) {
+		struct capn_segment *n = s->next;
+		free(s->user);
+		s = n;
+	}
+	c->copy = NULL;
+	c->copylist = NULL;
+}
+
+#define ZBUF_SZ 4096
+
+static int read_fp(void *p, size_t sz, FILE *f, struct capn_stream *z, uint8_t* zbuf, int packed) {
+	if (f && packed) {
+		z->next_out = (uint8_t*) p;
+		z->avail_out = sz;
+
+		while (z->avail_out && capn_inflate(z) == CAPN_NEED_MORE) {
+			int r;
+			memmove(zbuf, z->next_in, z->avail_in);
+			r = fread(zbuf+z->avail_in, 1, ZBUF_SZ - z->avail_in, f);
+			if (r <= 0)
+				return -1;
+			z->avail_in += r;
+		}
+		return 0;
+
+	} else if (f && !packed) {
+		return fread(p, sz, 1, f) != 1;
+
+	} else if (packed) {
+		z->next_out = (uint8_t*) p;
+		z->avail_out = sz;
+		return capn_inflate(z) != 0;
+
+	} else {
+		if (z->avail_in < sz)
+			return -1;
+		memcpy(p, z->next_in, sz);
+		z->next_in += sz;
+		z->avail_in -= sz;
+		return 0;
+	}
+}
+
+static int init_fp(struct capn *c, FILE *f, struct capn_stream *z, int packed) {
+	/*
+	 * Initialize 'c' from the contents of 'f', assuming the message has been
+	 * serialized with the standard framing format. From https://capnproto.org/encoding.html:
+	 *
+	 * When transmitting over a stream, the following should be sent. All integers are unsigned and little-endian.
+	 *   (4 bytes) The number of segments, minus one (since there is always at least one segment).
+	 *   (N * 4 bytes) The size of each segment, in words.
+	 *   (0 or 4 bytes) Padding up to the next word boundary.
+	 *   The content of each segment, in order.
+	 */
+
+	struct capn_segment *s = NULL;
+	uint32_t i, segnum, total = 0;
+	uint32_t hdr[1024];
+	uint8_t zbuf[ZBUF_SZ];
+	char *data = NULL;
+
+	capn_init_malloc(c);
+
+	/* Read the first four bytes to know how many headers we have */
+	if (read_fp(&segnum, 4, f, z, zbuf, packed))
+		goto err;
+
+	segnum = capn_flip32(segnum);
+	if (segnum > 1023)
+		goto err;
+	segnum++; /* The wire encoding was zero-based */
+
+	/* Read the header list */
+	if (read_fp(hdr, 8 * (segnum/2) + 4, f, z, zbuf, packed))
+		goto err;
+
+	for (i = 0; i < segnum; i++) {
+		uint32_t n = capn_flip32(hdr[i]);
+		if (n > INT_MAX/8 || n > UINT32_MAX/8 || UINT32_MAX - total < n*8)
+			goto err;
+		hdr[i] = n*8;
+		total += hdr[i];
+	}
+
+	/* Allocate space for the data and the capn_segment structs */
+	s = (struct capn_segment*) calloc(1, total + (sizeof(*s) * segnum));
+	if (!s)
+		goto err;
+
+	/* Now read the data and setup the capn_segment structs */
+	data = (char*) (s+segnum);
+	if (read_fp(data, total, f, z, zbuf, packed))
+		goto err;
+
+	for (i = 0; i < segnum; i++) {
+		s[i].len = s[i].cap = hdr[i];
+		s[i].data = data;
+		data += s[i].len;
+		capn_append_segment(c, &s[i]);
+	}
+
+    /* Set the entire region to be freed on the last segment */
+	s[segnum-1].user = s;
+
+	return 0;
+
+err:
+	memset(c, 0, sizeof(*c));
+	free(s);
+	return -1;
+}
+
+int capn_init_fp(struct capn *c, FILE *f, int packed) {
+	struct capn_stream z;
+	memset(&z, 0, sizeof(z));
+	return init_fp(c, f, &z, packed);
+}
+
+int capn_init_mem(struct capn *c, const uint8_t *p, size_t sz, int packed) {
+	struct capn_stream z;
+	memset(&z, 0, sizeof(z));
+	z.next_in = p;
+	z.avail_in = sz;
+	return init_fp(c, NULL, &z, packed);
+}
+
+static void header_calc(struct capn *c, uint32_t *headerlen, size_t *headersz)
+{
+	/* segnum == 1:
+	 *   [segnum][segsiz]
+	 * segnum == 2:
+	 *   [segnum][segsiz][segsiz][zeroes]
+	 * segnum == 3:
+	 *   [segnum][segsiz][segsiz][segsiz]
+	 * segnum == 4:
+	 *   [segnum][segsiz][segsiz][segsiz][segsiz][zeroes]
+	 */
+	*headerlen = ((2 + c->segnum) / 2) * 2;
+	*headersz = 4 * *headerlen;
+}
+
+static int header_render(struct capn *c, struct capn_segment *seg, uint32_t *header, uint32_t headerlen, size_t *datasz)
+{
+	size_t i;
+
+	header[0] = capn_flip32(c->segnum - 1);
+	header[headerlen-1] = 0; /* Zero out the spare position in the header sizes */
+	for (i = 0; i < c->segnum; i++, seg = seg->next) {
+		if (0 == seg)
+			return -1;
+		*datasz += seg->len;
+		header[1 + i] = capn_flip32(seg->len / 8);
+	}
+	if (0 != seg)
+		return -1;
+
+	return 0;
+}
+
+static int capn_write_mem_packed(struct capn *c, uint8_t *p, size_t sz)
+{
+	struct capn_segment *seg;
+	struct capn_ptr root;
+	uint32_t headerlen;
+	size_t headersz, datasz = 0;
+	uint32_t *header;
+	struct capn_stream z;
+	int ret;
+
+	root = capn_root(c);
+	header_calc(c, &headerlen, &headersz);
+	header = (uint32_t*) (p + headersz + 2); /* must reserve two bytes for worst case expansion */
+
+	if (sz < headersz*2 + 2) /* We must have space for temporary writing of header to deflate */
+		return -1;
+
+	ret = header_render(c, root.seg, header, headerlen, &datasz);
+	if (ret != 0)
+		return -1;
+
+	memset(&z, 0, sizeof(z));
+	z.next_in = (uint8_t *)header;
+	z.avail_in = headersz;
+	z.next_out = p;
+	z.avail_out = sz;
+
+	// pack the headers
+	ret = capn_deflate(&z);
+	if (ret != 0 || z.avail_in != 0)
+		return -1;
+
+	for (seg = root.seg; seg; seg = seg->next) {
+		z.next_in = (uint8_t *)seg->data;
+		z.avail_in = seg->len;
+		ret = capn_deflate(&z);
+		if (ret != 0 || z.avail_in != 0)
+			return -1;
+	}
+
+	return sz - z.avail_out;
+}
+
+int
+capn_write_mem(struct capn *c, uint8_t *p, size_t sz, int packed)
+{
+	struct capn_segment *seg;
+	struct capn_ptr root;
+	uint32_t headerlen;
+	size_t headersz, datasz = 0;
+	uint32_t *header;
+	int ret;
+
+	if (c->segnum == 0)
+		return -1;
+
+	if (packed)
+		return capn_write_mem_packed(c, p, sz);
+
+	root = capn_root(c);
+	header_calc(c, &headerlen, &headersz);
+	header = (uint32_t*) p;
+
+	if (sz < headersz)
+		return -1;
+
+	ret = header_render(c, root.seg, header, headerlen, &datasz);
+	if (ret != 0)
+		return -1;
+
+	if (sz < headersz + datasz)
+		return -1;
+
+	p += headersz;
+
+	for (seg = root.seg; seg; seg = seg->next) {
+		memcpy(p, seg->data, seg->len);
+		p += seg->len;
+	}
+
+	return headersz+datasz;
+}
+
+static int _write_fd(ssize_t (*write_fd)(int fd, const void *p, size_t count), int fd, void *p, size_t count)
+{
+	ssize_t ret;
+	size_t sent = 0;
+
+	while (sent < count) {
+		ret = write_fd(fd, ((uint8_t*)p)+sent, count-sent);
+		if (ret < 0) {
+			if (errno == EAGAIN || errno == EINTR)
+				continue;
+			else
+				return -1;
+		}
+		sent += ret;
+	}
+
+	return 0;
+}
+
+int capn_write_fd(struct capn *c, ssize_t (*write_fd)(int fd, const void *p, size_t count), int fd, int packed)
+{
+	unsigned char buf[4096];
+	struct capn_segment *seg;
+	struct capn_ptr root;
+	uint32_t headerlen;
+	size_t headersz, datasz = 0;
+	int ret;
+	struct capn_stream z;
+	unsigned char *p;
+
+	if (c->segnum == 0)
+		return -1;
+
+	root = capn_root(c);
+	header_calc(c, &headerlen, &headersz);
+
+	if (sizeof(buf) < headersz)
+		return -1;
+
+	ret = header_render(c, root.seg, (uint32_t*)buf, headerlen, &datasz);
+	if (ret != 0)
+		return -1;
+
+	if (packed) {
+		const int headerrem = sizeof(buf) - headersz;
+		const int maxpack = headersz + 2;
+		if (headerrem < maxpack)
+			return -1;
+
+		memset(&z, 0, sizeof(z));
+		z.next_in = buf;
+		z.avail_in = headersz;
+		z.next_out = buf + headersz;
+		z.avail_out = headerrem;
+		ret = capn_deflate(&z);
+		if (ret != 0)
+			return -1;
+
+		p = buf + headersz;
+		headersz = headerrem - z.avail_out;
+	} else {
+		p = buf;
+	}
+
+	ret = _write_fd(write_fd, fd, p, headersz);
+	if (ret < 0)
+		return -1;
+
+	datasz = headersz;
+	for (seg = root.seg; seg; seg = seg->next) {
+		size_t bufsz;
+		if (packed) {
+			memset(&z, 0, sizeof(z));
+			z.next_in = (uint8_t*)seg->data;
+			z.avail_in = seg->len;
+			z.next_out = buf;
+			z.avail_out = sizeof(buf);
+			ret = capn_deflate(&z);
+			if (ret != 0)
+				return -1;
+			p = buf;
+			bufsz = sizeof(buf) - z.avail_out;
+		} else {
+			p = (uint8_t*)seg->data;
+			bufsz = seg->len;
+		}
+		ret = _write_fd(write_fd, fd, p, bufsz);
+		if (ret < 0)
+			return -1;
+		datasz += bufsz;
+	}
+
+	return datasz;
+}
diff --git a/src/lib/capnp-c/capn-stream.c b/src/lib/capnp-c/capn-stream.c
new file mode 100644
index 0000000..135d1b2
--- /dev/null
+++ b/src/lib/capnp-c/capn-stream.c
@@ -0,0 +1,217 @@
+/* vim: set sw=8 ts=8 sts=8 noet: */
+/* capn-stream.c
+ *
+ * Copyright (C) 2013 James McKaskill
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+#include "capnp_c.h"
+#include "capnp_priv.h"
+#include <string.h>
+
+#ifndef min
+static unsigned min(unsigned a, unsigned b) { return (a < b) ? a : b; }
+#endif
+
+int capn_deflate(struct capn_stream* s) {
+	if (s->avail_in % 8) {
+		return CAPN_MISALIGNED;
+	}
+
+	while (s->avail_in) {
+		int i;
+		size_t sz;
+		uint8_t hdr = 0;
+		uint8_t *p;
+
+		if (!s->avail_out)
+			return CAPN_NEED_MORE;
+
+		if (s->raw > 0) {
+			sz = min(s->raw, min(s->avail_in, s->avail_out));
+			memcpy(s->next_out, s->next_in, sz);
+			s->next_out += sz;
+			s->next_in += sz;
+			s->avail_out -= sz;
+			s->avail_in -= sz;
+			s->raw -= sz;
+			continue;
+		}
+
+		if (s->avail_in < 8)
+			return CAPN_NEED_MORE;
+
+		sz = 0;
+		for (i = 0; i < 8; i++) {
+			if (s->next_in[i]) {
+				sz ++;
+				hdr |= 1 << i;
+			}
+		}
+
+		switch (sz) {
+		case 0:
+			if (s->avail_out < 2)
+				return CAPN_NEED_MORE;
+
+			s->next_out[0] = 0;
+			for (sz = 1; sz < min(s->avail_in/8, 256); sz++) {
+				if (((uint64_t*) s->next_in)[sz] != 0) {
+					break;
+				}
+			}
+
+			s->next_out[1] = (uint8_t) (sz-1);
+			s->next_in += sz*8;
+			s->avail_in -= sz*8;
+			s->next_out += 2;
+			s->avail_out -= 2;
+			continue;
+
+		case 8:
+			if (s->avail_out < 10)
+				return CAPN_NEED_MORE;
+
+			s->next_out[0] = 0xFF;
+			memcpy(s->next_out+1, s->next_in, 8);
+			s->next_in += 8;
+			s->avail_in -= 8;
+
+			s->raw = min(s->avail_in, 256*8);
+			if ((p = (uint8_t*) memchr(s->next_in, 0, s->raw)) != NULL) {
+				s->raw = (p - s->next_in) & ~7;
+			}
+
+			s->next_out[9] = (uint8_t) (s->raw/8);
+			s->next_out += 10;
+			s->avail_out -= 10;
+			continue;
+
+		default:
+			if (s->avail_out < 1U + sz)
+				return CAPN_NEED_MORE;
+
+			*(s->next_out++) = hdr;
+			for (i = 0; i < 8; i++) {
+				if (s->next_in[i]) {
+					*(s->next_out++) = s->next_in[i];
+				}
+			}
+			s->avail_out -= sz + 1;
+			s->next_in += 8;
+			s->avail_in -= 8;
+			continue;
+		}
+	}
+
+	return 0;
+}
+
+int capn_inflate(struct capn_stream* s) {
+	while (s->avail_out) {
+		int i;
+		size_t sz;
+		uint8_t hdr;
+		uint8_t *wr;
+
+		if (s->avail_buf && s->avail_out >= s->avail_buf) {
+			memcpy(s->next_out, s->inflate_buf, s->avail_buf);
+			s->next_out += s->avail_buf;
+			s->avail_out -= s->avail_buf;
+			s->avail_buf = 0;
+			if (!s->avail_out)
+				return 0;
+		}
+		if (s->avail_buf && s->avail_out < s->avail_buf) {
+			memcpy(s->next_out, s->inflate_buf, s->avail_out);
+			memmove(s->inflate_buf, s->inflate_buf + s->avail_out,
+					s->avail_buf - s->avail_out);
+			s->avail_buf -= s->avail_out;
+			s->avail_out = 0;
+			return 0;
+		}
+
+		if (s->zeros > 0) {
+			sz = min(s->avail_out, s->zeros);
+			memset(s->next_out, 0, sz);
+			s->next_out += sz;
+			s->avail_out -= sz;
+			s->zeros -= sz;
+			continue;
+		}
+
+		if (s->raw > 0) {
+			if (s->avail_in == 0)
+				return CAPN_NEED_MORE;
+
+			sz = min(min(s->avail_out, s->raw), s->avail_in);
+			memcpy(s->next_out, s->next_in, sz);
+			s->next_in += sz;
+			s->next_out += sz;
+			s->avail_in -= sz;
+			s->avail_out -= sz;
+			s->raw -= sz;
+			continue;
+		}
+
+		if (s->avail_in == 0)
+			return 0;
+		else if (s->avail_in < 2)
+			return CAPN_NEED_MORE;
+
+		switch (s->next_in[0]) {
+		case 0xFF:
+			/* 0xFF is followed by 8 bytes raw, followed by
+			 * a byte with length in words to read raw */
+			if (s->avail_in < 10)
+				return CAPN_NEED_MORE;
+
+			memcpy(s->inflate_buf, s->next_in+1, 8);
+			s->avail_buf = 8;
+
+			s->raw = s->next_in[9] * 8;
+			s->next_in += 10;
+			s->avail_in -= 10;
+			continue;
+
+		case 0x00:
+			/* 0x00 is followed by a single byte indicating
+			 * the count of consecutive zero value words
+			 * minus 1 */
+			s->zeros = (s->next_in[1] + 1) * 8;
+			s->next_in += 2;
+			s->avail_in -= 2;
+			continue;
+
+		default:
+			hdr = s->next_in[0];
+			sz = 0;
+			for (i = 0; i < 8; i++) {
+				if (hdr & (1 << i))
+					sz++;
+			}
+			if (s->avail_in < 1U + sz)
+				return CAPN_NEED_MORE;
+
+			s->next_in += 1;
+
+			wr = s->inflate_buf;
+			for (i = 0; i < 8; i++) {
+				if (hdr & (1 << i)) {
+					*wr++ = *s->next_in++;
+				} else {
+					*wr++ = 0;
+				}
+			}
+
+			s->avail_buf = 8;
+			s->avail_in -= 1 + sz;
+			continue;
+		}
+	}
+
+	return 0;
+}
+
diff --git a/src/lib/capnp-c/capn.c b/src/lib/capnp-c/capn.c
new file mode 100644
index 0000000..6e0f196
--- /dev/null
+++ b/src/lib/capnp-c/capn.c
@@ -0,0 +1,1115 @@
+/* vim: set sw=8 ts=8 sts=8 noet: */
+/* capn.c
+ *
+ * Copyright (C) 2013 James McKaskill
+ *
+ * This software may be modified and distributed under the terms
+ * of the MIT license.  See the LICENSE file for details.
+ */
+
+#ifdef __GNUC__
+#pragma GCC diagnostic ignored "-Wmissing-field-initializers"
+#endif
+
+#include "capnp_c.h"
+
+#include <stdlib.h>
+#include <string.h>
+#ifndef _MSC_VER
+#include <sys/param.h>
+#endif
+
+#define STRUCT_PTR 0
+#define LIST_PTR 1
+#define FAR_PTR 2
+#define DOUBLE_PTR 6
+
+#define VOID_LIST 0
+#define BIT_1_LIST 1
+#define BYTE_1_LIST 2
+#define BYTE_2_LIST 3
+#define BYTE_4_LIST 4
+#define BYTE_8_LIST 5
+#define PTR_LIST 6
+#define COMPOSITE_LIST 7
+
+#define U64(val) ((uint64_t) (val))
+#define I64(val) ((int64_t) (val))
+#define U32(val) ((uint32_t) (val))
+#define I32(val) ((int32_t) (val))
+#define U16(val) ((uint16_t) (val))
+#define I16(val) ((int16_t) (val))
+
+#ifndef min
+static int min(int a, int b) { return (a < b) ? a : b; }
+#endif
+
+#ifdef BYTE_ORDER
+#define CAPN_LITTLE (BYTE_ORDER == LITTLE_ENDIAN)
+#elif defined(__BYTE_ORDER)
+#define CAPN_LITTLE (__BYTE_ORDER == __LITTLE_ENDIAN)
+#else
+#define CAPN_LITTLE 0
+#endif
+
+struct capn_tree *capn_tree_insert(struct capn_tree *root, struct capn_tree *n) {
+	n->red = 1;
+	n->link[0] = n->link[1] = NULL;
+
+	for (;;) {
+		/* parent, uncle, grandparent, great grandparent link */
+		struct capn_tree *p, *u, *g, **gglink;
+		int dir;
+
+		/* Case 1: N is root */
+		p = n->parent;
+		if (!p) {
+			n->red = 0;
+			root = n;
+			break;
+		}
+
+		/* Case 2: p is black */
+		if (!p->red) {
+			break;
+		}
+
+		g = p->parent;
+		dir = (p == g->link[1]);
+
+		/* Case 3: P and U are red, switch g to red, but must
+		 * loop as G could be root or have a red parent
+		 *     g    to   G
+		 *    / \       / \
+		 *   P   U     p   u
+		 *  /         /
+		 * N         N
+		 */
+		u = g->link[!dir];
+		if (u != NULL && u->red) {
+			p->red = 0;
+			u->red = 0;
+			g->red = 1;
+			n = g;
+			continue;
+		}
+
+		if (!g->parent) {
+			gglink = &root;
+		} else if (g->parent->link[1] == g) {
+			gglink = &g->parent->link[1];
+		} else {
+			gglink = &g->parent->link[0];
+		}
+
+		if (dir != (n == p->link[1])) {
+			/* Case 4: rotate on P, then on g
+			 * here dir is /
+			 *     g    to   g   to   n
+			 *    / \       / \      / \
+			 *   P   u     N   u    P   G
+			 *  / \       / \      /|  / \
+			 * 1   N     P   3    1 2 3   u
+			 *    / \   / \
+			 *   2   3 1   2
+			 */
+			struct capn_tree *two = n->link[dir];
+			struct capn_tree *three = n->link[!dir];
+			p->link[!dir] = two;
+			g->link[dir] = three;
+			n->link[dir] = p;
+			n->link[!dir] = g;
+			*gglink = n;
+			n->parent = g->parent;
+			p->parent = n;
+			g->parent = n;
+			if (two)
+				two->parent = p;
+			if (three)
+				three->parent = g;
+			n->red = 0;
+			g->red = 1;
+		} else {
+			/* Case 5: rotate on g
+			 * here dir is /
+			 *       g   to   p
+			 *      / \      / \
+			 *     P   u    N   G
+			 *    / \      /|  / \
+			 *   N   3    1 2 3   u
+			 *  / \
+			 * 1   2
+			 */
+			struct capn_tree *three = p->link[!dir];
+			g->link[dir] = three;
+			p->link[!dir] = g;
+			*gglink = p;
+			p->parent = g->parent;
+			g->parent = p;
+			if (three)
+				three->parent = g;
+			g->red = 1;
+			p->red = 0;
+		}
+
+		break;
+	}
+
+	return root;
+}
+
+void capn_append_segment(struct capn *c, struct capn_segment *s) {
+	s->id = c->segnum++;
+	s->capn = c;
+	s->next = NULL;
+
+	if (c->lastseg) {
+		c->lastseg->next = s;
+		c->lastseg->hdr.link[1] = &s->hdr;
+		s->hdr.parent = &c->lastseg->hdr;
+	} else {
+		c->seglist = s;
+		s->hdr.parent = NULL;
+	}
+
+	c->lastseg = s;
+	c->segtree = capn_tree_insert(c->segtree, &s->hdr);
+}
+
+static char *new_data(struct capn *c, int sz, struct capn_segment **ps) {
+	struct capn_segment *s;
+
+	/* find a segment with sufficient data */
+	for (s = c->seglist; s != NULL; s = s->next) {
+		if (s->len + sz <= s->cap) {
+			goto end;
+		}
+	}
+
+	s = c->create ? c->create(c->user, c->segnum, sz) : NULL;
+	if (!s) {
+		*ps = NULL;
+		return NULL;
+	}
+
+	capn_append_segment(c, s);
+end:
+	*ps = s;
+	s->len += sz;
+	return s->data + s->len - sz;
+}
+
+static struct capn_segment *lookup_segment(struct capn* c, struct capn_segment *s, uint32_t id) {
+	struct capn_tree **x;
+	struct capn_segment *y = NULL;
+
+	if (s && s->id == id)
+		return s;
+	if (!c)
+		return NULL;
+
+	if (id < c->segnum) {
+		x = &c->segtree;
+		while (*x) {
+			y = (struct capn_segment*) *x;
+			if (id == y->id) {
+				return y;
+			} else if (id < y->id) {
+				x = &y->hdr.link[0];
+			} else {
+				x = &y->hdr.link[1];
+			}
+		}
+	} else {
+		/* Otherwise `x` may be uninitialized */
+		return NULL;
+	}
+
+	s = c->lookup ? c->lookup(c->user, id) : NULL;
+	if (!s)
+		return NULL;
+
+	if (id < c->segnum) {
+		s->id = id;
+		s->capn = c;
+		s->next = c->seglist;
+		c->seglist = s;
+		s->hdr.parent = &y->hdr;
+		*x = &s->hdr;
+		c->segtree = capn_tree_insert(c->segtree, &s->hdr);
+	} else {
+		c->segnum = id;
+		capn_append_segment(c, s);
+	}
+
+	return s;
+}
+
+static uint64_t lookup_double(struct capn_segment **s, char **d, uint64_t val) {
+	uint64_t far, tag;
+	size_t off = (U32(val) >> 3) * 8;
+	char *p;
+
+	if ((*s = lookup_segment((*s)->capn, *s, U32(val >> 32))) == NULL) {
+		return 0;
+	}
+
+	p = (*s)->data + off;
+	if (off + 16 > (*s)->len) {
+		return 0;
+	}
+
+	far = capn_flip64(*(uint64_t*) p);
+	tag = capn_flip64(*(uint64_t*) (p+8));
+
+	/* the far tag should not be another double, and the tag
+	 * should be struct/list and have no offset */
+	if ((far&7) != FAR_PTR || U32(tag) > LIST_PTR) {
+		return 0;
+	}
+
+	if ((*s = lookup_segment((*s)->capn, *s, U32(far >> 32))) == NULL) {
+		return 0;
+	}
+
+	/* -8 because far pointers reference from the start of
+	 * the segment, but offsets reference the end of the
+	 * pointer data. Here *d points to where an equivalent
+	 * ptr would be.
+	 */
+	*d = (*s)->data - 8;
+	return U64(U32(far) >> 3 << 2) | tag;
+}
+
+static uint64_t lookup_far(struct capn_segment **s, char **d, uint64_t val) {
+	size_t off = (U32(val) >> 3) * 8;
+
+	if ((*s = lookup_segment((*s)->capn, *s, U32(val >> 32))) == NULL) {
+		return 0;
+	}
+
+	if (off + 8 > (*s)->len) {
+		return 0;
+	}
+
+	*d = (*s)->data + off;
+	return capn_flip64(*(uint64_t*)*d);
+}
+
+static char *struct_ptr(struct capn_segment *s, char *d, int minsz) {
+	uint64_t val = capn_flip64(*(uint64_t*)d);
+	uint16_t datasz;
+
+	switch (val&7) {
+	case FAR_PTR:
+		val = lookup_far(&s, &d, val);
+		break;
+	case DOUBLE_PTR:
+		val = lookup_double(&s, &d, val);
+		break;
+	}
+
+	datasz = U16(val >> 32);
+	d += (I32(U32(val)) << 1) + 8;
+
+	if (val != 0 && (val&3) != STRUCT_PTR && datasz >= minsz && s->data <= d && d < s->data + s->len) {
+		return d;
+	}
+
+	return NULL;
+}
+
+static capn_ptr read_ptr(struct capn_segment *s, char *d) {
+	capn_ptr ret = {CAPN_NULL};
+	uint64_t val;
+	char *e = 0;
+
+	val = capn_flip64(*(uint64_t*) d);
+
+	switch (val&7) {
+	case FAR_PTR:
+		val = lookup_far(&s, &d, val);
+		ret.has_ptr_tag = (U32(val) >> 2) == 0;
+		break;
+	case DOUBLE_PTR:
+		val = lookup_double(&s, &d, val);
+		break;
+	}
+
+	d += (I32(U32(val)) >> 2) * 8 + 8;
+
+	if (d < s->data) {
+		goto err;
+	}
+
+	switch (val & 3) {
+	case STRUCT_PTR:
+		ret.type = val ? CAPN_STRUCT : CAPN_NULL;
+		goto struct_common;
+
+	struct_common:
+		ret.datasz = U32(U16(val >> 32)) * 8;
+		ret.ptrs = U32(U16(val >> 48));
+		e = d + ret.datasz + 8 * ret.ptrs;
+		break;
+
+	case LIST_PTR:
+		ret.type = CAPN_LIST;
+		ret.len = val >> 35;
+
+		switch ((val >> 32) & 7) {
+		case VOID_LIST:
+			e = d;
+			break;
+		case BIT_1_LIST:
+			ret.type = CAPN_BIT_LIST;
+			ret.datasz = (ret.len+7)/8;
+			e = d + ret.datasz;
+			break;
+		case BYTE_1_LIST:
+			ret.datasz = 1;
+			e = d + ret.len;
+			break;
+		case BYTE_2_LIST:
+			ret.datasz = 2;
+			e = d + ret.len * 2;
+			break;
+		case BYTE_4_LIST:
+			ret.datasz = 4;
+			e = d + ret.len * 4;
+			break;
+		case BYTE_8_LIST:
+			ret.datasz = 8;
+			e = d + ret.len * 8;
+			break;
+		case PTR_LIST:
+			ret.type = CAPN_PTR_LIST;
+			e = d + ret.len * 8;
+			break;
+		case COMPOSITE_LIST:
+			if ((size_t)((d+8) - s->data) > s->len) {
+				goto err;
+			}
+
+			val = capn_flip64(*(uint64_t*) d);
+
+			d += 8;
+			e = d + ret.len * 8;
+
+			ret.datasz = U32(U16(val >> 32)) * 8;
+			ret.ptrs = U32(U16(val >> 48));
+			ret.len = U32(val) >> 2;
+			ret.is_composite_list = 1;
+
+			if ((ret.datasz + 8*ret.ptrs) * ret.len != e - d) {
+				goto err;
+			}
+			break;
+		}
+		break;
+
+	default:
+		goto err;
+	}
+
+	if ((size_t)(e - s->data) > s->len)
+		goto err;
+
+	ret.data = d;
+	ret.seg = s;
+	return ret;
+err:
+	memset(&ret, 0, sizeof(ret));
+	return ret;
+}
+
+void capn_resolve(capn_ptr *p) {
+	if (p->type == CAPN_FAR_POINTER) {
+		*p = read_ptr(p->seg, p->data);
+	}
+}
+
+/* TODO: should this handle CAPN_BIT_LIST? */
+capn_ptr capn_getp(capn_ptr p, int off, int resolve) {
+	capn_ptr ret = {CAPN_FAR_POINTER};
+	ret.seg = p.seg;
+
+	capn_resolve(&p);
+
+	switch (p.type) {
+	case CAPN_LIST:
+		/* Return an inner pointer */
+		if (off < p.len) {
+			capn_ptr ret = {CAPN_STRUCT};
+			ret.is_list_member = 1;
+			ret.data = p.data + off * (p.datasz + 8*p.ptrs);
+			ret.seg = p.seg;
+			ret.datasz = p.datasz;
+			ret.ptrs = p.ptrs;
+			return ret;
+		} else {
+			goto err;
+		}
+
+	case CAPN_STRUCT:
+		if (off >= p.ptrs) {
+			goto err;
+		}
+		ret.data = p.data + p.datasz + 8*off;
+		break;
+
+	case CAPN_PTR_LIST:
+		if (off >= p.len) {
+			goto err;
+		}
+		ret.data = p.data + 8*off;
+		break;
+
+	default:
+		goto err;
+	}
+
+	if (resolve) {
+		ret = read_ptr(ret.seg, ret.data);
+	}
+
+	return ret;
+
+err:
+	memset(&p, 0, sizeof(p));
+	return p;
+}
+
+static void write_ptr_tag(char *d, capn_ptr p, int off) {
+	uint64_t val = U64(U32(I32(off/8) << 2));
+
+	switch (p.type) {
+	case CAPN_STRUCT:
+		val |= STRUCT_PTR | (U64(p.datasz/8) << 32) | (U64(p.ptrs) << 48);
+		break;
+
+	case CAPN_LIST:
+		if (p.is_composite_list) {
+			val |= LIST_PTR | (U64(COMPOSITE_LIST) << 32) | (U64(p.len * (p.datasz/8 + p.ptrs)) << 35);
+		} else {
+			val |= LIST_PTR | (U64(p.len) << 35);
+
+			switch (p.datasz) {
+			case 8:
+				val |= (U64(BYTE_8_LIST) << 32);
+				break;
+			case 4:
+				val |= (U64(BYTE_4_LIST) << 32);
+				break;
+			case 2:
+				val |= (U64(BYTE_2_LIST) << 32);
+				break;
+			case 1:
+				val |= (U64(BYTE_1_LIST) << 32);
+				break;
+			case 0:
+				val |= (U64(VOID_LIST) << 32);
+				break;
+			}
+		}
+		break;
+
+	case CAPN_BIT_LIST:
+		val |= LIST_PTR | (U64(BIT_1_LIST) << 32) | (U64(p.len) << 35);
+		break;
+
+	case CAPN_PTR_LIST:
+		val |= LIST_PTR | (U64(PTR_LIST) << 32) | (U64(p.len) << 35);
+		break;
+
+	default:
+		val = 0;
+		break;
+	}
+
+	*(uint64_t*) d = capn_flip64(val);
+}
+
+static void write_far_ptr(char *d, struct capn_segment *s, char *tgt) {
+	*(uint64_t*) d = capn_flip64(FAR_PTR | U64(tgt - s->data) | (U64(s->id) << 32));
+}
+
+static void write_double_far(char *d, struct capn_segment *s, char *tgt) {
+	*(uint64_t*) d = capn_flip64(DOUBLE_PTR | U64(tgt - s->data) | (U64(s->id) << 32));
+}
+
+#define NEED_TO_COPY 1
+
+static int write_ptr(struct capn_segment *s, char *d, capn_ptr p) {
+	/* note p.seg can be NULL if its a ptr to static data */
+	char *pdata = p.data - 8*p.is_composite_list;
+
+	if (p.type == CAPN_NULL || (p.type == CAPN_STRUCT && p.datasz == 0 && p.ptrs == 0)) {
+		write_ptr_tag(d, p, 0);
+		return 0;
+
+	} else if (!p.seg || p.seg->capn != s->capn || p.is_list_member) {
+		return NEED_TO_COPY;
+
+	} else if (p.seg == s) {
+		write_ptr_tag(d, p, pdata - d - 8);
+		return 0;
+
+	} else if (p.has_ptr_tag) {
+		/* By lucky chance, the data has a tag in front
+		 * of it. This happens when new_object had to move
+		 * the data to a new segment. */
+		write_far_ptr(d, p.seg, pdata-8);
+		return 0;
+
+	} else if (p.seg->len + 8 <= p.seg->cap) {
+		/* The target segment has enough room for tag */
+		char *t = p.seg->data + p.seg->len;
+		write_ptr_tag(t, p, pdata - t - 8);
+		write_far_ptr(d, p.seg, t);
+		p.seg->len += 8;
+		return 0;
+
+	} else {
+		/* have to allocate room for a double far
+		 * pointer */
+		char *t;
+
+		if (s->len + 16 <= s->cap) {
+			/* Try and allocate in the src segment
+			 * first. This should improve lookup on
+			 * read. */
+			t = s->data + s->len;
+			s->len += 16;
+		} else {
+			t = new_data(s->capn, 16, &s);
+			if (!t) return -1;
+		}
+
+		write_far_ptr(t, p.seg, pdata);
+		write_ptr_tag(t+8, p, 0);
+		write_double_far(d, s, t);
+		return 0;
+	}
+}
+
+struct copy {
+	struct capn_tree hdr;
+	struct capn_ptr to, from;
+	char *fbegin, *fend;
+};
+
+static capn_ptr new_clone(struct capn_segment *s, capn_ptr p) {
+	switch (p.type) {
+	case CAPN_STRUCT:
+		return capn_new_struct(s, p.datasz, p.ptrs);
+	case CAPN_PTR_LIST:
+		return capn_new_ptr_list(s, p.len);
+	case CAPN_BIT_LIST:
+		return capn_new_list1(s, p.len).p;
+	case CAPN_LIST:
+		return capn_new_list(s, p.len, p.datasz, p.ptrs);
+	default:
+		return p;
+	}
+}
+
+static int is_ptr_equal(const struct capn_ptr *a, const struct capn_ptr *b) {
+	return a->data == b->data
+		&& a->type == b->type
+		&& a->len == b->len
+		&& a->datasz == b->datasz
+		&& a->ptrs == b->ptrs;
+}
+
+static int data_size(struct capn_ptr p) {
+	switch (p.type) {
+	case CAPN_BIT_LIST:
+		return p.datasz;
+	case CAPN_PTR_LIST:
+		return p.len*8;
+	case CAPN_STRUCT:
+		return p.datasz + 8*p.ptrs;
+	case CAPN_LIST:
+		return p.len * (p.datasz + 8*p.ptrs) + 8*p.is_composite_list;
+	default:
+		return 0;
+	}
+}
+
+static int copy_ptr(struct capn_segment *seg, char *data, struct capn_ptr *t, struct capn_ptr *f, int *dep) {
+	struct capn *c = seg->capn;
+	struct copy *cp = NULL;
+	struct capn_tree **xcp;
+	char *fbegin = f->data - 8*f->is_composite_list;
+	char *fend = fbegin + data_size(*f);
+	int zero_sized = (fend == fbegin);
+
+	/* We always copy list members as it would otherwise be an
+	 * overlapped pointer (the data is owned by the enclosing list).
+	 * We do not bother with the overlapped lookup for zero sized
+	 * structures/lists as they never overlap. Nor do we add them to
+	 * the copy list as there is no data to be shared by multiple
+	 * pointers.
+	 */
+
+	xcp = &c->copy;
+	while (*xcp && !zero_sized) {
+		cp = (struct copy*) *xcp;
+		if (fend <= cp->fbegin) {
+			xcp = &cp->hdr.link[0];
+		} else if (cp->fend <= fbegin) {
+			xcp = &cp->hdr.link[1];
+		} else if (is_ptr_equal(f, &cp->from)) {
+			/* we already have a copy so just point to that */
+			return write_ptr(seg, data, cp->to);
+		} else {
+			/* pointer to overlapped data */
+			return -1;
+		}
+	}
+
+	/* no copy found - have to create a new copy */
+	*t = new_clone(seg, *f);
+
+	if (write_ptr(seg, data, *t))
+		return -1;
+
+	/* add the copy to the copy tree so we can look for overlapping
+	 * source pointers and handle recursive structures */
+	if (!zero_sized) {
+		struct copy *n;
+		struct capn_segment *cs = c->copylist;
+
+		/* need to allocate a struct copy */
+		if (!cs || cs->len + (int)sizeof(*n) > cs->cap) {
+			cs = c->create_local ? c->create_local(c->user, sizeof(*n)) : NULL;
+			if (!cs) {
+				/* can't allocate a copy structure */
+				return -1;
+			}
+			cs->next = c->copylist;
+			c->copylist = cs;
+		}
+
+		n = (struct copy*) (cs->data + cs->len);
+		cs->len += sizeof(*n);
+
+		n->from = *f;
+		n->to = *t;
+		n->fbegin = fbegin;
+		n->fend = fend;
+
+		*xcp = &n->hdr;
+		n->hdr.parent = &cp->hdr;
+
+		c->copy = capn_tree_insert(c->copy, &n->hdr);
+	}
+
+	/* minimize the number of types the main copy routine has to
+	 * deal with to just CAPN_LIST and CAPN_PTR_LIST. ptr list only
+	 * needs t->type, t->len, t->data, t->seg, f->data, f->seg to
+	 * be valid */
+	switch (t->type) {
+	case CAPN_STRUCT:
+		if (t->datasz) {
+			memcpy(t->data, f->data, t->datasz);
+			t->data += t->datasz;
+			f->data += t->datasz;
+		}
+		if (t->ptrs) {
+			t->type = CAPN_PTR_LIST;
+			t->len = t->ptrs;
+			(*dep)++;
+		}
+		return 0;
+
+	case CAPN_BIT_LIST:
+		memcpy(t->data, f->data, t->datasz);
+		return 0;
+
+	case CAPN_LIST:
+		if (!t->len) {
+			/* empty list - nothing to copy */
+		} else if (t->ptrs && t->datasz) {
+			(*dep)++;
+		} else if (t->datasz) {
+			memcpy(t->data, f->data, t->len * t->datasz);
+		} else if (t->ptrs) {
+			t->type = CAPN_PTR_LIST;
+			t->len *= t->ptrs;
+			(*dep)++;
+		}
+		return 0;
+
+	case CAPN_PTR_LIST:
+		if (t->len) {
+			(*dep)++;
+		}
+		return 0;
+
+	default:
+		return -1;
+	}
+}
+
+static void copy_list_member(capn_ptr* t, capn_ptr *f, int *dep) {
+	/* copy struct data */
+	int sz = min(t->datasz, f->datasz);
+	memcpy(t->data, f->data, sz);
+	memset(t->data + sz, 0, t->datasz - sz);
+	t->data += t->datasz;
+	f->data += f->datasz;
+
+	/* reset excess pointers */
+	sz = min(t->ptrs, f->ptrs);
+	memset(t->data + sz, 0, 8*(t->ptrs - sz));
+
+	/* create a pointer list for the main loop to copy */
+	if (t->ptrs) {
+		t->type = CAPN_PTR_LIST;
+		t->len = t->ptrs;
+		(*dep)++;
+	}
+}
+
+#define MAX_COPY_DEPTH 32
+
+/* TODO: handle CAPN_BIT_LIST and setting from an inner bit list member */
+int capn_setp(capn_ptr p, int off, capn_ptr tgt) {
+	struct capn_ptr to[MAX_COPY_DEPTH], from[MAX_COPY_DEPTH];
+	char *data;
+	int err, dep = 0;
+
+	capn_resolve(&p);
+
+	if (tgt.type == CAPN_FAR_POINTER && tgt.seg->capn == p.seg->capn) {
+		uint64_t val = capn_flip64(*(uint64_t*) tgt.data);
+		if ((val & 3) == FAR_PTR) {
+			*(uint64_t*) p.data = *(uint64_t*) tgt.data;
+			return 0;
+		}
+	}
+
+	capn_resolve(&tgt);
+
+	switch (p.type) {
+	case CAPN_LIST:
+		if (off >= p.len || tgt.type != CAPN_STRUCT)
+			return -1;
+
+		to[0] = p;
+		to[0].data += off * (p.datasz + 8*p.ptrs);
+		from[0] = tgt;
+		copy_list_member(to, from, &dep);
+		break;
+
+	case CAPN_PTR_LIST:
+		if (off >= p.len)
+			return -1;
+		data = p.data + 8*off;
+		goto copy_ptr;
+
+	case CAPN_STRUCT:
+		if (off >= p.ptrs)
+			return -1;
+		data = p.data + p.datasz + 8*off;
+		goto copy_ptr;
+
+	copy_ptr:
+		err = write_ptr(p.seg, data, tgt);
+		if (err != NEED_TO_COPY)
+			return err;
+
+		/* Depth first copy the source whilst using a pointer stack to
+		 * maintain the ptr to set and size left to copy at each level.
+		 * We also maintain a rbtree (capn->copy) of the copies indexed
+		 * by the source data. This way we can detect overlapped
+		 * pointers in the source (and bail) and recursive structures
+		 * (and point to the previous copy).
+		 */
+
+		from[0] = tgt;
+		if (copy_ptr(p.seg, data, to, from, &dep))
+			return -1;
+		break;
+
+	default:
+		return -1;
+	}
+
+	while (dep) {
+		struct capn_ptr *tc = &to[dep-1], *tn = &to[dep];
+		struct capn_ptr *fc = &from[dep-1], *fn = &from[dep];
+
+		if (dep+1 == MAX_COPY_DEPTH) {
+			return -1;
+		}
+
+		if (!tc->len) {
+			dep--;
+			continue;
+		}
+
+		if (tc->type == CAPN_LIST) {
+			*fn = capn_getp(*fc, 0, 1);
+			*tn = capn_getp(*tc, 0, 1);
+
+			copy_list_member(tn, fn, &dep);
+
+			fc->data += fc->datasz + 8*fc->ptrs;
+			tc->data += tc->datasz + 8*tc->ptrs;
+			tc->len--;
+
+		} else { /* CAPN_PTR_LIST */
+			*fn = read_ptr(fc->seg, fc->data);
+
+			if (fn->type && copy_ptr(tc->seg, tc->data, tn, fn, &dep))
+				return -1;
+
+			fc->data += 8;
+			tc->data += 8;
+			tc->len--;
+		}
+	}
+
+	return 0;
+}
+
+/* TODO: handle CAPN_LIST, CAPN_PTR_LIST for bit lists */
+
+int capn_get1(capn_list1 l, int off) {
+	return l.p.type == CAPN_BIT_LIST
+		&& off < l.p.len
+		&& (l.p.data[off/8] & (1 << (off%8))) != 0;
+}
+
+int capn_set1(capn_list1 l, int off, int val) {
+	if (l.p.type != CAPN_BIT_LIST || off >= l.p.len)
+		return -1;
+	if (val) {
+		l.p.data[off/8] |= 1 << (off%8);
+	} else {
+		l.p.data[off/8] &= ~(1 << (off%8));
+	}
+	return 0;
+}
+
+int capn_getv1(capn_list1 l, int off, uint8_t *data, int sz) {
+	/* Note we only support aligned reads */
+	int bsz;
+	capn_ptr p;
+	capn_resolve(&l.p);
+	p = l.p;
+	if (p.type != CAPN_BIT_LIST || (off & 7) != 0)
+		return -1;
+
+	bsz = (sz + 7) / 8;
+	off /= 8;
+
+	if (off + sz > p.datasz) {
+		memcpy(data, p.data + off, p.datasz - off);
+		return p.len - off*8;
+	} else {
+		memcpy(data, p.data + off, bsz);
+		return sz;
+	}
+}
+
+int capn_setv1(capn_list1 l, int off, const uint8_t *data, int sz) {
+	/* Note we only support aligned writes */
+	int bsz;
+	capn_ptr p = l.p;
+	if (p.type != CAPN_BIT_LIST || (off & 7) != 0)
+		return -1;
+
+	bsz = (sz + 7) / 8;
+	off /= 8;
+
+	if (off + sz > p.datasz) {
+		memcpy(p.data + off, data, p.datasz - off);
+		return p.len - off*8;
+	} else {
+		memcpy(p.data + off, data, bsz);
+		return sz;
+	}
+}
+
+/* pull out whether we add a tag or not as a define so the unit test can
+ * test double far pointers by not creating tags */
+#ifndef ADD_TAG
+#define ADD_TAG 1
+#endif
+
+static void new_object(capn_ptr *p, int bytes) {
+	struct capn_segment *s = p->seg;
+
+	if (!s) {
+		memset(p, 0, sizeof(*p));
+		return;
+	}
+
+	/* pointer needs to be initialised to get a valid offset on write */
+	if (!bytes) {
+		p->data = s->data + s->len;
+		return;
+	}
+
+	/* all allocations are 8 byte aligned */
+	bytes = (bytes + 7) & ~7;
+
+	if (s->len + bytes <= s->cap) {
+		p->data = s->data + s->len;
+		s->len += bytes;
+		return;
+	}
+
+	/* add a tag whenever we switch segments so that write_ptr can
+	 * use it */
+	p->data = new_data(s->capn, bytes + ADD_TAG*8, &p->seg);
+	if (!p->data) {
+		memset(p, 0, sizeof(*p));
+		return;
+	}
+
+	if (ADD_TAG) {
+		write_ptr_tag(p->data, *p, 0);
+		p->data += 8;
+		p->has_ptr_tag = 1;
+	}
+}
+
+capn_ptr capn_root(struct capn *c) {
+	capn_ptr r = {CAPN_PTR_LIST};
+	r.seg = lookup_segment(c, NULL, 0);
+	r.data = r.seg ? r.seg->data : new_data(c, 8, &r.seg);
+	r.len = 1;
+
+	if (!r.seg || r.seg->cap < 8) {
+		memset(&r, 0, sizeof(r));
+	} else if (r.seg->len < 8) {
+		r.seg->len = 8;
+	}
+
+	return r;
+}
+
+capn_ptr capn_new_struct(struct capn_segment *seg, int datasz, int ptrs) {
+	capn_ptr p = {CAPN_STRUCT};
+	p.seg = seg;
+	p.datasz = (datasz + 7) & ~7;
+	p.ptrs = ptrs;
+	new_object(&p, p.datasz + 8*p.ptrs);
+	return p;
+}
+
+capn_ptr capn_new_list(struct capn_segment *seg, int sz, int datasz, int ptrs) {
+	capn_ptr p = {CAPN_LIST};
+	p.seg = seg;
+	p.len = sz;
+
+	if (ptrs || datasz > 8) {
+		p.is_composite_list = 1;
+		p.datasz = (datasz + 7) & ~7;
+		p.ptrs = ptrs;
+		new_object(&p, p.len * (p.datasz + 8*p.ptrs) + 8);
+		if (p.data) {
+			uint64_t hdr = STRUCT_PTR | (U64(p.len) << 2) | (U64(p.datasz/8) << 32) | (U64(ptrs) << 48);
+			*(uint64_t*) p.data = capn_flip64(hdr);
+			p.data += 8;
+		}
+	} else if (datasz > 4) {
+		p.datasz = 8;
+		new_object(&p, p.len * 8);
+	} else if (datasz > 2) {
+		p.datasz = 4;
+		new_object(&p, p.len * 4);
+	} else {
+		p.datasz = datasz;
+		new_object(&p, p.len * datasz);
+	}
+
+	return p;
+}
+
+capn_list1 capn_new_list1(struct capn_segment *seg, int sz) {
+	capn_list1 l = {{CAPN_BIT_LIST}};
+	l.p.seg = seg;
+	l.p.datasz = (sz+7)/8;
+	l.p.len = sz;
+	new_object(&l.p, l.p.datasz);
+	return l;
+}
+
+capn_ptr capn_new_ptr_list(struct capn_segment *seg, int sz) {
+	capn_ptr p = {CAPN_PTR_LIST};
+	p.seg = seg;
+	p.len = sz;
+	p.ptrs = 0;
+	p.datasz = 0;
+	new_object(&p, sz*8);
+	return p;
+}
+
+capn_ptr capn_new_string(struct capn_segment *seg, const char *str, ssize_t sz) {
+	capn_ptr p = {CAPN_LIST};
+	p.seg = seg;
+	p.len = ((sz >= 0) ? (size_t)sz : strlen(str)) + 1;
+	p.datasz = 1;
+	new_object(&p, p.len);
+	if (p.data) {
+		memcpy(p.data, str, p.len - 1);
+		p.data[p.len - 1] = '\0';
+	}
+	return p;
+}
+
+capn_text capn_get_text(capn_ptr p, int off, capn_text def) {
+	capn_ptr m = capn_getp(p, off, 1);
+	capn_text ret = def;
+	if (m.type == CAPN_LIST && m.datasz == 1 && m.len && m.data[m.len - 1] == 0) {
+		ret.seg = m.seg;
+		ret.str = m.data;
+		ret.len = m.len - 1;
+	}
+	return ret;
+}
+
+int capn_set_text(capn_ptr p, int off, capn_text tgt) {
+	capn_ptr m = {CAPN_NULL};
+	if (tgt.seg) {
+		m.type = CAPN_LIST;
+		m.seg = tgt.seg;
+		m.data = (char*)tgt.str;
+		m.len = tgt.len + 1;
+		m.datasz = 1;
+	} else if (tgt.str) {
+		m = capn_new_string(p.seg, tgt.str, tgt.len);
+	}
+	return capn_setp(p, off, m);
+}
+
+capn_data capn_get_data(capn_ptr p, int off) {
+	capn_data ret;
+	ret.p = capn_getp(p, off, 1);
+	if (ret.p.type != CAPN_LIST || ret.p.datasz != 1) {
+		memset(&ret, 0, sizeof(ret));
+	}
+	return ret;
+}
+
+#define SZ 8
+#include "capn-list.inc"
+#undef SZ
+
+#define SZ 16
+#include "capn-list.inc"
+#undef SZ
+
+#define SZ 32
+#include "capn-list.inc"
+#undef SZ
+
+#define SZ 64
+#include "capn-list.inc"
+#undef SZ