text: /*
   * Copyright 2015 Google Inc.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. The name of the author may not be used to endorse or promote products
   *    derived from this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <endian.h>
  #include <libpayload.h>
  #include <lz4.h>
  
  /* LZ4 comes with its own supposedly portable memory access functions, but they
   * seem to be very inefficient in practice (at least on ARM64). Since libpayload
   * knows about endinaness and allows some basic assumptions (such as unaligned
   * access support), we can easily write the ones we need ourselves. */
  static uint16_t LZ4_readLE16(const void *src)
  {
  	return le16toh(*(uint16_t *)src);
  }
  static void LZ4_copy8(void *dst, const void *src)
  {
  /* ARM32 needs to be a special snowflake to prevent GCC from coalescing the
   * access into LDRD/STRD (which don't support unaligned accesses). */
  #ifdef __arm__
  	uint32_t x0, x1;
  	asm volatile (
  		"ldr %[x0], [%[src]]\n\t"
  		"ldr %[x1], [%[src], #4]\n\t"
  		"str %[x0], [%[dst]]\n\t"
  		"str %[x1], [%[dst], #4]\n\t"
  		: [x0]"=r"(x0), [x1]"=r"(x1)
  		: [src]"r"(src), [dst]"r"(dst)
  		: "memory" );
  #else
  	*(uint64_t *)dst = *(const uint64_t *)src;
  #endif
  }
  
  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))
  #define likely(expr) __builtin_expect((expr) != 0, 1)
  #define unlikely(expr) __builtin_expect((expr) != 0, 0)
  
  /* Unaltered (just removed unrelated code) from github.com/Cyan4973/lz4/dev. */
  #include "lz4.c.inc"	/* #include for inlining, do not link! */
  
  #define LZ4F_MAGICNUMBER 0x184D2204
  
  struct lz4_frame_header {
  	uint32_t magic;
  	union {
  		uint8_t flags;
  		struct {
  			uint8_t reserved0		: 2;
  			uint8_t has_content_checksum	: 1;
  			uint8_t has_content_size	: 1;
  			uint8_t has_block_checksum	: 1;
  			uint8_t independent_blocks	: 1;
  			uint8_t version			: 2;
  		};
  	};
  	union {
  		uint8_t block_descriptor;
  		struct {
  			uint8_t reserved1		: 4;
  			uint8_t max_block_size		: 3;
  			uint8_t reserved2		: 1;
  		};
  	};
  	/* + uint64_t content_size iff has_content_size is set */
  	/* + uint8_t header_checksum */
  } __packed;
  
  struct lz4_block_header {
  	union {
  		uint32_t raw;
  		struct {
  			uint32_t size		: 31;
  			uint32_t not_compressed	: 1;
  		};
  	};
  	/* + size bytes of data */
  	/* + uint32_t block_checksum iff has_block_checksum is set */
  } __packed;
  
  size_t ulz4fn(const void *src, size_t srcn, void *dst, size_t dstn)
  {
  	const void *in = src;
  	void *out = dst;
  	size_t out_size = 0;
  	int has_block_checksum;
  
  	{ /* With in-place decompression the header may become invalid later. */
  		const struct lz4_frame_header *h = in;
  
  		if (srcn < sizeof(*h) + sizeof(uint64_t) + sizeof(uint8_t))
  			return 0;	/* input overrun */
  
  		/* We assume there's always only a single, standard frame. */
  		if (le32toh(h->magic) != LZ4F_MAGICNUMBER || h->version != 1)
  			return 0;	/* unknown format */
  		if (h->reserved0 || h->reserved1 || h->reserved2)
  			return 0;	/* reserved must be zero */
  		if (!h->independent_blocks)
  			return 0;	/* we don't support block dependency */
  		has_block_checksum = h->has_block_checksum;
  
  		in += sizeof(*h);
  		if (h->has_content_size)
  			in += sizeof(uint64_t);
  		in += sizeof(uint8_t);
  	}
  
  	while (1) {
  		if ((size_t)(in - src) + sizeof(struct lz4_block_header) > srcn)
  			break;          /* input overrun */
  
  		struct lz4_block_header b = { .raw = le32toh(*(uint32_t *)in) };
  		in += sizeof(struct lz4_block_header);
  
  		if ((size_t)(in - src) + b.size > srcn)
  			break;			/* input overrun */
  
  		if (!b.size) {
  			out_size = out - dst;
  			break;			/* decompression successful */
  		}
  
  		if (b.not_compressed) {
  			size_t size = MIN((uint32_t)b.size, dst + dstn - out);
  			memcpy(out, in, size);
  			if (size < b.size)
  				break;		/* output overrun */
  			else
  				out += size;
  		} else {
  			/* constant folding essential, do not touch params! */
  			int ret = LZ4_decompress_generic(in, out, b.size,
  					dst + dstn - out, endOnInputSize,
  					full, 0, noDict, out, NULL, 0);
  			if (ret < 0)
  				break;		/* decompression error */
  			else
  				out += ret;
  		}
  
  		in += b.size;
  		if (has_block_checksum)
  			in += sizeof(uint32_t);
  	}
  
  	return out_size;
  }
  
  size_t ulz4f(const void *src, void *dst)
  {
  	/* LZ4 uses signed size parameters, so can't just use ((u32)-1) here. */
  	return ulz4fn(src, 1*GiB, dst, 1*GiB);
  }
  