Add support for LZ4 decompression algorithm

This patch adds support for LZ4-compressed FIT image contents. This
algorithm has a slightly worse compression ration than LZO while being
nearly twice as fast to decompress. When loading images from a fast
storage medium this usually results in a boot time win.

Sandbox-tested only since I don't have a U-Boot development system set
up right now. The code was imported unchanged from coreboot where it's
proven to work, though. I'm mostly interested in getting this recognized
by mkImage for use in a downstream project.

Signed-off-by: Julius Werner <jwerner@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>

1 files changed, 137 insertions, 0 deletions

diff --git a/lib/lz4_wrapper.c b/lib/lz4_wrapper.c
new file mode 100644
index 0000000..0739663
--- /dev/null
+++ b/lib/lz4_wrapper.c
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * SPDX-License-Identifier: GPL 2.0+ BSD-3-Clause
+ */
+
+#include <common.h>
+#include <compiler.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+static u16 LZ4_readLE16(const void *src) { return le16_to_cpu(*(u16 *)src); }
+static void LZ4_copy4(void *dst, const void *src) { *(u32 *)dst = *(u32 *)src; }
+static void LZ4_copy8(void *dst, const void *src) { *(u64 *)dst = *(u64 *)src; }
+
+typedef  uint8_t BYTE;
+typedef uint16_t U16;
+typedef uint32_t U32;
+typedef  int32_t S32;
+typedef uint64_t U64;
+
+#define FORCE_INLINE static inline __attribute__((always_inline))
+
+/* Unaltered (except removing unrelated code) from github.com/Cyan4973/lz4. */
+#include "lz4.c"	/* #include for inlining, do not link! */
+
+#define LZ4F_MAGIC 0x184D2204
+
+struct lz4_frame_header {
+	u32 magic;
+	union {
+		u8 flags;
+		struct {
+			u8 reserved0:2;
+			u8 has_content_checksum:1;
+			u8 has_content_size:1;
+			u8 has_block_checksum:1;
+			u8 independent_blocks:1;
+			u8 version:2;
+		};
+	};
+	union {
+		u8 block_descriptor;
+		struct {
+			u8 reserved1:4;
+			u8 max_block_size:3;
+			u8 reserved2:1;
+		};
+	};
+	/* + u64 content_size iff has_content_size is set */
+	/* + u8 header_checksum */
+} __packed;
+
+struct lz4_block_header {
+	union {
+		u32 raw;
+		struct {
+			u32 size:31;
+			u32 not_compressed:1;
+		};
+	};
+	/* + size bytes of data */
+	/* + u32 block_checksum iff has_block_checksum is set */
+} __packed;
+
+int ulz4fn(const void *src, size_t srcn, void *dst, size_t *dstn)
+{
+	const void *end = dst + *dstn;
+	const void *in = src;
+	void *out = dst;
+	int has_block_checksum;
+	int ret;
+	*dstn = 0;
+
+	{ /* With in-place decompression the header may become invalid later. */
+		const struct lz4_frame_header *h = in;
+
+		if (srcn < sizeof(*h) + sizeof(u64) + sizeof(u8))
+			return -EINVAL;	/* input overrun */
+
+		/* We assume there's always only a single, standard frame. */
+		if (le32_to_cpu(h->magic) != LZ4F_MAGIC || h->version != 1)
+			return -EPROTONOSUPPORT;	/* unknown format */
+		if (h->reserved0 || h->reserved1 || h->reserved2)
+			return -EINVAL;	/* reserved must be zero */
+		if (!h->independent_blocks)
+			return -EPROTONOSUPPORT; /* we can't support this yet */
+		has_block_checksum = h->has_block_checksum;
+
+		in += sizeof(*h);
+		if (h->has_content_size)
+			in += sizeof(u64);
+		in += sizeof(u8);
+	}
+
+	while (1) {
+		struct lz4_block_header b = { .raw = le32_to_cpu(*(u32 *)in) };
+		in += sizeof(struct lz4_block_header);
+
+		if (in - src + b.size > srcn) {
+			ret = -EINVAL;		/* input overrun */
+			break;
+		}
+
+		if (!b.size) {
+			ret = 0;	/* decompression successful */
+			break;
+		}
+
+		if (b.not_compressed) {
+			size_t size = min((ptrdiff_t)b.size, end - out);
+			memcpy(out, in, size);
+			out += size;
+			if (size < b.size) {
+				ret = -ENOBUFS;	/* output overrun */
+				break;
+			}
+		} else {
+			/* constant folding essential, do not touch params! */
+			ret = LZ4_decompress_generic(in, out, b.size,
+					end - out, endOnInputSize,
+					full, 0, noDict, out, NULL, 0);
+			if (ret < 0) {
+				ret = -EPROTO;	/* decompression error */
+				break;
+			}
+			out += ret;
+		}
+
+		in += b.size;
+		if (has_block_checksum)
+			in += sizeof(u32);
+	}
+
+	*dstn = out - dst;
+	return ret;
+}