zmalloc: kill unused __size parameter in update_zmalloc_stat_alloc() macro.

[redis.git] / src / ziplist.c

diff --git a/src/ziplist.c b/src/ziplist.c
index 7a3a8b01b5cc47e955b9b0cc6f97194f7608d95e..d4ac4f9b4bc3708a7faa7ffbae8521cb32215c75 100644 (file)
--- a/src/ziplist.c
+++ b/src/ziplist.c
@@ -1,17 +1,104 @@
-/* Memory layout of a ziplist, containing "foo", "bar", "quux":
- * <zlbytes><zllen><len>"foo"<len>"bar"<len>"quux"
+/* The ziplist is a specially encoded dually linked list that is designed
+ * to be very memory efficient. It stores both strings and integer values,
+ * where integers are encoded as actual integers instead of a series of
+ * characters. It allows push and pop operations on either side of the list
+ * in O(1) time. However, because every operation requires a reallocation of
+ * the memory used by the ziplist, the actual complexity is related to the
+ * amount of memory used by the ziplist.

  *
  *

- * <zlbytes> is an unsigned integer to hold the number of bytes that
- * the ziplist occupies. This is stored to not have to traverse the ziplist
- * to know the new length when pushing.
+ * ----------------------------------------------------------------------------

  *
  *

- * <zllen> is the number of items in the ziplist. When this value is
- * greater than 254, we need to traverse the entire list to know
- * how many items it holds.
+ * ZIPLIST OVERALL LAYOUT:
+ * The general layout of the ziplist is as follows:
+ * <zlbytes><zltail><zllen><entry><entry><zlend>

  *
  *

- * <len> is the number of bytes occupied by a single entry. When this
- * number is greater than 253, the length will occupy 5 bytes, where
- * the extra bytes contain an unsigned integer to hold the length.
+ * <zlbytes> is an unsigned integer to hold the number of bytes that the
+ * ziplist occupies. This value needs to be stored to be able to resize the
+ * entire structure without the need to traverse it first.
+ *
+ * <zltail> is the offset to the last entry in the list. This allows a pop
+ * operation on the far side of the list without the need for full traversal.
+ *
+ * <zllen> is the number of entries.When this value is larger than 2**16-2,
+ * we need to traverse the entire list to know how many items it holds.
+ *
+ * <zlend> is a single byte special value, equal to 255, which indicates the
+ * end of the list.
+ *
+ * ZIPLIST ENTRIES:
+ * Every entry in the ziplist is prefixed by a header that contains two pieces
+ * of information. First, the length of the previous entry is stored to be
+ * able to traverse the list from back to front. Second, the encoding with an
+ * optional string length of the entry itself is stored.
+ *
+ * The length of the previous entry is encoded in the following way:
+ * If this length is smaller than 254 bytes, it will only consume a single
+ * byte that takes the length as value. When the length is greater than or
+ * equal to 254, it will consume 5 bytes. The first byte is set to 254 to
+ * indicate a larger value is following. The remaining 4 bytes take the
+ * length of the previous entry as value.
+ *
+ * The other header field of the entry itself depends on the contents of the
+ * entry. When the entry is a string, the first 2 bits of this header will hold
+ * the type of encoding used to store the length of the string, followed by the
+ * actual length of the string. When the entry is an integer the first 2 bits
+ * are both set to 1. The following 2 bits are used to specify what kind of
+ * integer will be stored after this header. An overview of the different
+ * types and encodings is as follows:
+ *
+ * |00pppppp| - 1 byte
+ *      String value with length less than or equal to 63 bytes (6 bits).
+ * |01pppppp|qqqqqqqq| - 2 bytes
+ *      String value with length less than or equal to 16383 bytes (14 bits).
+ * |10______|qqqqqqqq|rrrrrrrr|ssssssss|tttttttt| - 5 bytes
+ *      String value with length greater than or equal to 16384 bytes.
+ * |11000000| - 1 byte
+ *      Integer encoded as int16_t (2 bytes).
+ * |11010000| - 1 byte
+ *      Integer encoded as int32_t (4 bytes).
+ * |11100000| - 1 byte
+ *      Integer encoded as int64_t (8 bytes).
+ * |11110000| - 1 byte
+ *      Integer encoded as 24 bit signed (3 bytes).
+ * |11111110| - 1 byte
+ *      Integer encoded as 8 bit signed (1 byte).
+ * |1111xxxx| - (with xxxx between 0000 and 1101) immediate 4 bit integer.
+ *      Unsigned integer from 0 to 12. The encoded value is actually from
+ *      1 to 13 because 0000 and 1111 can not be used, so 1 should be
+ *      subtracted from the encoded 4 bit value to obtain the right value.
+ * |11111111| - End of ziplist.
+ *
+ * All the integers are represented in little endian byte order.
+ *
+ * ----------------------------------------------------------------------------
+ *
+ * Copyright (c) 2009-2012, Pieter Noordhuis <pcnoordhuis at gmail dot com>
+ * Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *   * 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.
+ *   * Neither the name of Redis nor the names of its contributors may be used
+ *     to endorse or promote products derived from this software without
+ *     specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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 <stdio.h>
  */
 
 #include <stdio.h>


@@ -21,29 +108,35 @@
 #include <assert.h>
 #include <limits.h>
 #include "zmalloc.h"
 #include <assert.h>
 #include <limits.h>
 #include "zmalloc.h"

+#include "util.h"

 #include "ziplist.h"
 #include "ziplist.h"

+#include "endianconv.h"

 
 

-int ll2string(char *s, size_t len, long long value);
-
-/* Important note: the ZIP_END value is used to depict the end of the
- * ziplist structure. When a pointer contains an entry, the first couple
- * of bytes contain the encoded length of the previous entry. This length
- * is encoded as ZIP_ENC_RAW length, so the first two bits will contain 00
- * and the byte will therefore never have a value of 255. */

 #define ZIP_END 255
 #define ZIP_BIGLEN 254
 
 #define ZIP_END 255
 #define ZIP_BIGLEN 254
 

-/* Entry encoding */
-#define ZIP_ENC_RAW     0
-#define ZIP_ENC_INT16   1
-#define ZIP_ENC_INT32   2
-#define ZIP_ENC_INT64   3
-#define ZIP_ENCODING(p) ((p)[0] >> 6)
-
-/* Length encoding for raw entries */
-#define ZIP_LEN_INLINE  0
-#define ZIP_LEN_UINT16  1
-#define ZIP_LEN_UINT32  2
+/* Different encoding/length possibilities */
+#define ZIP_STR_MASK 0xc0
+#define ZIP_INT_MASK 0x30
+#define ZIP_STR_06B (0 << 6)
+#define ZIP_STR_14B (1 << 6)
+#define ZIP_STR_32B (2 << 6)
+#define ZIP_INT_16B (0xc0 | 0<<4)
+#define ZIP_INT_32B (0xc0 | 1<<4)
+#define ZIP_INT_64B (0xc0 | 2<<4)
+#define ZIP_INT_24B (0xc0 | 3<<4)
+#define ZIP_INT_8B 0xfe
+/* 4 bit integer immediate encoding */
+#define ZIP_INT_IMM_MASK 0x0f
+#define ZIP_INT_IMM_MIN 0xf1    /* 11110001 */
+#define ZIP_INT_IMM_MAX 0xfd    /* 11111101 */
+#define ZIP_INT_IMM_VAL(v) (v & ZIP_INT_IMM_MASK)
+
+#define INT24_MAX 0x7fffff
+#define INT24_MIN (-INT24_MAX - 1)
+
+/* Macro to determine type */
+#define ZIP_IS_STR(enc) (((enc) & ZIP_STR_MASK) < ZIP_STR_MASK)

 
 /* Utility macros */
 #define ZIPLIST_BYTES(zl)       (*((uint32_t*)(zl)))
 
 /* Utility macros */
 #define ZIPLIST_BYTES(zl)       (*((uint32_t*)(zl)))


@@ -51,13 +144,15 @@ int ll2string(char *s, size_t len, long long value);
 #define ZIPLIST_LENGTH(zl)      (*((uint16_t*)((zl)+sizeof(uint32_t)*2)))
 #define ZIPLIST_HEADER_SIZE     (sizeof(uint32_t)*2+sizeof(uint16_t))
 #define ZIPLIST_ENTRY_HEAD(zl)  ((zl)+ZIPLIST_HEADER_SIZE)
 #define ZIPLIST_LENGTH(zl)      (*((uint16_t*)((zl)+sizeof(uint32_t)*2)))
 #define ZIPLIST_HEADER_SIZE     (sizeof(uint32_t)*2+sizeof(uint16_t))
 #define ZIPLIST_ENTRY_HEAD(zl)  ((zl)+ZIPLIST_HEADER_SIZE)

-#define ZIPLIST_ENTRY_TAIL(zl)  ((zl)+ZIPLIST_TAIL_OFFSET(zl))
-#define ZIPLIST_ENTRY_END(zl)   ((zl)+ZIPLIST_BYTES(zl)-1)
+#define ZIPLIST_ENTRY_TAIL(zl)  ((zl)+intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl)))
+#define ZIPLIST_ENTRY_END(zl)   ((zl)+intrev32ifbe(ZIPLIST_BYTES(zl))-1)

 
 /* We know a positive increment can only be 1 because entries can only be
  * pushed one at a time. */
 #define ZIPLIST_INCR_LENGTH(zl,incr) { \
 
 /* We know a positive increment can only be 1 because entries can only be
  * pushed one at a time. */
 #define ZIPLIST_INCR_LENGTH(zl,incr) { \

-    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) ZIPLIST_LENGTH(zl)+=incr; }
+    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) \
+        ZIPLIST_LENGTH(zl) = intrev16ifbe(intrev16ifbe(ZIPLIST_LENGTH(zl))+incr); \
+}

 
 typedef struct zlentry {
     unsigned int prevrawlensize, prevrawlen;
 
 typedef struct zlentry {
     unsigned int prevrawlensize, prevrawlen;


@@ -67,88 +162,90 @@ typedef struct zlentry {
     unsigned char *p;
 } zlentry;
 
     unsigned char *p;
 } zlentry;
 

+/* Extract the encoding from the byte pointed by 'ptr' and set it into
+ * 'encoding'. */
+#define ZIP_ENTRY_ENCODING(ptr, encoding) do {  \
+    (encoding) = (ptr[0]); \
+    if ((encoding) < ZIP_STR_MASK) (encoding) &= ZIP_STR_MASK; \
+} while(0)
+

 /* Return bytes needed to store integer encoded by 'encoding' */
 /* Return bytes needed to store integer encoded by 'encoding' */

-static unsigned int zipEncodingSize(unsigned char encoding) {
-    if (encoding == ZIP_ENC_INT16) {
-        return sizeof(int16_t);
-    } else if (encoding == ZIP_ENC_INT32) {
-        return sizeof(int32_t);
-    } else if (encoding == ZIP_ENC_INT64) {
-        return sizeof(int64_t);
+static unsigned int zipIntSize(unsigned char encoding) {
+    switch(encoding) {
+    case ZIP_INT_8B:  return 1;
+    case ZIP_INT_16B: return 2;
+    case ZIP_INT_24B: return 3;
+    case ZIP_INT_32B: return 4;
+    case ZIP_INT_64B: return 8;
+    default: return 0; /* 4 bit immediate */

     }
     assert(NULL);
     }
     assert(NULL);

-}
-
-/* Decode the encoded length pointed by 'p'. If a pointer to 'lensize' is
- * provided, it is set to the number of bytes required to encode the length. */
-static unsigned int zipDecodeLength(unsigned char *p, unsigned int *lensize) {
-    unsigned char encoding = ZIP_ENCODING(p), lenenc;
-    unsigned int len;
-
-    if (encoding == ZIP_ENC_RAW) {
-        lenenc = (p[0] >> 4) & 0x3;
-        if (lenenc == ZIP_LEN_INLINE) {
-            len = p[0] & 0xf;
-            if (lensize) *lensize = 1;
-        } else if (lenenc == ZIP_LEN_UINT16) {
-            len = p[1] | (p[2] << 8);
-            if (lensize) *lensize = 3;
-        } else {
-            len = p[1] | (p[2] << 8) | (p[3] << 16) | (p[4] << 24);
-            if (lensize) *lensize = 5;
-        }
-    } else {
-        len = zipEncodingSize(encoding);
-        if (lensize) *lensize = 1;
-    }
-    return len;
+    return 0;

 }
 
 /* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
  * the amount of bytes required to encode such a length. */
 }
 
 /* Encode the length 'l' writing it in 'p'. If p is NULL it just returns
  * the amount of bytes required to encode such a length. */

-static unsigned int zipEncodeLength(unsigned char *p, char encoding, unsigned int rawlen) {
-    unsigned char len = 1, lenenc, buf[5];
-    if (encoding == ZIP_ENC_RAW) {
-        if (rawlen <= 0xf) {
+static unsigned int zipEncodeLength(unsigned char *p, unsigned char encoding, unsigned int rawlen) {
+    unsigned char len = 1, buf[5];
+
+    if (ZIP_IS_STR(encoding)) {
+        /* Although encoding is given it may not be set for strings,
+         * so we determine it here using the raw length. */
+        if (rawlen <= 0x3f) {

             if (!p) return len;
             if (!p) return len;

-            lenenc = ZIP_LEN_INLINE;
-            buf[0] = rawlen;
-        } else if (rawlen <= 0xffff) {
-            len += 2;
+            buf[0] = ZIP_STR_06B | rawlen;
+        } else if (rawlen <= 0x3fff) {
+            len += 1;

             if (!p) return len;
             if (!p) return len;

-            lenenc = ZIP_LEN_UINT16;
-            buf[1] = (rawlen     ) & 0xff;
-            buf[2] = (rawlen >> 8) & 0xff;
+            buf[0] = ZIP_STR_14B | ((rawlen >> 8) & 0x3f);
+            buf[1] = rawlen & 0xff;

         } else {
             len += 4;
             if (!p) return len;
         } else {
             len += 4;
             if (!p) return len;

-            lenenc = ZIP_LEN_UINT32;
-            buf[1] = (rawlen      ) & 0xff;
-            buf[2] = (rawlen >>  8) & 0xff;
-            buf[3] = (rawlen >> 16) & 0xff;
-            buf[4] = (rawlen >> 24) & 0xff;
+            buf[0] = ZIP_STR_32B;
+            buf[1] = (rawlen >> 24) & 0xff;
+            buf[2] = (rawlen >> 16) & 0xff;
+            buf[3] = (rawlen >> 8) & 0xff;
+            buf[4] = rawlen & 0xff;

         }
         }

-        buf[0] = (lenenc << 4) | (buf[0] & 0xf);
+    } else {
+        /* Implies integer encoding, so length is always 1. */
+        if (!p) return len;
+        buf[0] = encoding;

     }
     }

-    if (!p) return len;

 
 

-    /* Apparently we need to store the length in 'p' */
-    buf[0] = (encoding << 6) | (buf[0] & 0x3f);
+    /* Store this length at p */

     memcpy(p,buf,len);
     return len;
 }
 
     memcpy(p,buf,len);
     return len;
 }
 

-/* Decode the length of the previous element stored at "p". */
-static unsigned int zipPrevDecodeLength(unsigned char *p, unsigned int *lensize) {
-    unsigned int len = *p;
-    if (len < ZIP_BIGLEN) {
-        if (lensize) *lensize = 1;
-    } else {
-        if (lensize) *lensize = 1+sizeof(len);
-        memcpy(&len,p+1,sizeof(len));
-    }
-    return len;
-}
+/* Decode the length encoded in 'ptr'. The 'encoding' variable will hold the
+ * entries encoding, the 'lensize' variable will hold the number of bytes
+ * required to encode the entries length, and the 'len' variable will hold the
+ * entries length. */
+#define ZIP_DECODE_LENGTH(ptr, encoding, lensize, len) do {                    \
+    ZIP_ENTRY_ENCODING((ptr), (encoding));                                     \
+    if ((encoding) < ZIP_STR_MASK) {                                           \
+        if ((encoding) == ZIP_STR_06B) {                                       \
+            (lensize) = 1;                                                     \
+            (len) = (ptr)[0] & 0x3f;                                           \
+        } else if ((encoding) == ZIP_STR_14B) {                                \
+            (lensize) = 2;                                                     \
+            (len) = (((ptr)[0] & 0x3f) << 8) | (ptr)[1];                       \
+        } else if (encoding == ZIP_STR_32B) {                                  \
+            (lensize) = 5;                                                     \
+            (len) = ((ptr)[1] << 24) |                                         \
+                    ((ptr)[2] << 16) |                                         \
+                    ((ptr)[3] <<  8) |                                         \
+                    ((ptr)[4]);                                                \
+        } else {                                                               \
+            assert(NULL);                                                      \
+        }                                                                      \
+    } else {                                                                   \
+        (lensize) = 1;                                                         \
+        (len) = zipIntSize(encoding);                                          \
+    }                                                                          \
+} while(0);

 
 /* Encode the length of the previous entry and write it to "p". Return the
  * number of bytes needed to encode this length if "p" is NULL. */
 
 /* Encode the length of the previous entry and write it to "p". Return the
  * number of bytes needed to encode this length if "p" is NULL. */


@@ -162,47 +259,81 @@ static unsigned int zipPrevEncodeLength(unsigned char *p, unsigned int len) {
         } else {
             p[0] = ZIP_BIGLEN;
             memcpy(p+1,&len,sizeof(len));
         } else {
             p[0] = ZIP_BIGLEN;
             memcpy(p+1,&len,sizeof(len));

+            memrev32ifbe(p+1);

             return 1+sizeof(len);
         }
     }
 }
 
             return 1+sizeof(len);
         }
     }
 }
 

-/* Return the difference in number of bytes needed to store the new length
- * "len" on the entry pointed to by "p". */
+/* Encode the length of the previous entry and write it to "p". This only
+ * uses the larger encoding (required in __ziplistCascadeUpdate). */
+static void zipPrevEncodeLengthForceLarge(unsigned char *p, unsigned int len) {
+    if (p == NULL) return;
+    p[0] = ZIP_BIGLEN;
+    memcpy(p+1,&len,sizeof(len));
+    memrev32ifbe(p+1);
+}
+
+/* Decode the number of bytes required to store the length of the previous
+ * element, from the perspective of the entry pointed to by 'ptr'. */
+#define ZIP_DECODE_PREVLENSIZE(ptr, prevlensize) do {                          \
+    if ((ptr)[0] < ZIP_BIGLEN) {                                               \
+        (prevlensize) = 1;                                                     \
+    } else {                                                                   \
+        (prevlensize) = 5;                                                     \
+    }                                                                          \
+} while(0);
+
+/* Decode the length of the previous element, from the perspective of the entry
+ * pointed to by 'ptr'. */
+#define ZIP_DECODE_PREVLEN(ptr, prevlensize, prevlen) do {                     \
+    ZIP_DECODE_PREVLENSIZE(ptr, prevlensize);                                  \
+    if ((prevlensize) == 1) {                                                  \
+        (prevlen) = (ptr)[0];                                                  \
+    } else if ((prevlensize) == 5) {                                           \
+        assert(sizeof((prevlensize)) == 4);                                    \
+        memcpy(&(prevlen), ((char*)(ptr)) + 1, 4);                             \
+        memrev32ifbe(&prevlen);                                                \
+    }                                                                          \
+} while(0);
+
+/* Return the difference in number of bytes needed to store the length of the
+ * previous element 'len', in the entry pointed to by 'p'. */

 static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
     unsigned int prevlensize;
 static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
     unsigned int prevlensize;

-    zipPrevDecodeLength(p,&prevlensize);
-    return zipPrevEncodeLength(NULL,len)-prevlensize;
+    ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+    return zipPrevEncodeLength(NULL, len) - prevlensize;
+}
+
+/* Return the total number of bytes used by the entry pointed to by 'p'. */
+static unsigned int zipRawEntryLength(unsigned char *p) {
+    unsigned int prevlensize, encoding, lensize, len;
+    ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+    ZIP_DECODE_LENGTH(p + prevlensize, encoding, lensize, len);
+    return prevlensize + lensize + len;

 }
 
 /* Check if string pointed to by 'entry' can be encoded as an integer.
  * Stores the integer value in 'v' and its encoding in 'encoding'. */
 static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) {
     long long value;
 }
 
 /* Check if string pointed to by 'entry' can be encoded as an integer.
  * Stores the integer value in 'v' and its encoding in 'encoding'. */
 static int zipTryEncoding(unsigned char *entry, unsigned int entrylen, long long *v, unsigned char *encoding) {
     long long value;

-    char *eptr;
-    char buf[32];

 
     if (entrylen >= 32 || entrylen == 0) return 0;
 
     if (entrylen >= 32 || entrylen == 0) return 0;

-    if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) {
-        int slen;
-
-        /* Perform a back-and-forth conversion to make sure that
-         * the string turned into an integer is not losing any info. */
-        memcpy(buf,entry,entrylen);
-        buf[entrylen] = '\0';
-        value = strtoll(buf,&eptr,10);
-        if (eptr[0] != '\0') return 0;
-        slen = ll2string(buf,32,value);
-        if (entrylen != (unsigned)slen || memcmp(buf,entry,slen)) return 0;
-
+    if (string2ll((char*)entry,entrylen,&value)) {

         /* Great, the string can be encoded. Check what's the smallest
          * of our encoding types that can hold this value. */
         /* Great, the string can be encoded. Check what's the smallest
          * of our encoding types that can hold this value. */

-        if (value >= INT16_MIN && value <= INT16_MAX) {
-            *encoding = ZIP_ENC_INT16;
+        if (value >= 0 && value <= 12) {
+            *encoding = ZIP_INT_IMM_MIN+value;
+        } else if (value >= INT8_MIN && value <= INT8_MAX) {
+            *encoding = ZIP_INT_8B;
+        } else if (value >= INT16_MIN && value <= INT16_MAX) {
+            *encoding = ZIP_INT_16B;
+        } else if (value >= INT24_MIN && value <= INT24_MAX) {
+            *encoding = ZIP_INT_24B;

         } else if (value >= INT32_MIN && value <= INT32_MAX) {
         } else if (value >= INT32_MIN && value <= INT32_MAX) {

-            *encoding = ZIP_ENC_INT32;
+            *encoding = ZIP_INT_32B;

         } else {
         } else {

-            *encoding = ZIP_ENC_INT64;
+            *encoding = ZIP_INT_64B;

         }
         *v = value;
         return 1;
         }
         *v = value;
         return 1;


@@ -215,15 +346,26 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi
     int16_t i16;
     int32_t i32;
     int64_t i64;
     int16_t i16;
     int32_t i32;
     int64_t i64;

-    if (encoding == ZIP_ENC_INT16) {
+    if (encoding == ZIP_INT_8B) {
+        ((int8_t*)p)[0] = (int8_t)value;
+    } else if (encoding == ZIP_INT_16B) {

         i16 = value;
         memcpy(p,&i16,sizeof(i16));
         i16 = value;
         memcpy(p,&i16,sizeof(i16));

-    } else if (encoding == ZIP_ENC_INT32) {
+        memrev16ifbe(p);
+    } else if (encoding == ZIP_INT_24B) {
+        i32 = value<<8;
+        memrev32ifbe(&i32);
+        memcpy(p,((uint8_t*)&i32)+1,sizeof(i32)-sizeof(uint8_t));
+    } else if (encoding == ZIP_INT_32B) {

         i32 = value;
         memcpy(p,&i32,sizeof(i32));
         i32 = value;
         memcpy(p,&i32,sizeof(i32));

-    } else if (encoding == ZIP_ENC_INT64) {
+        memrev32ifbe(p);
+    } else if (encoding == ZIP_INT_64B) {

         i64 = value;
         memcpy(p,&i64,sizeof(i64));
         i64 = value;
         memcpy(p,&i64,sizeof(i64));

+        memrev64ifbe(p);
+    } else if (encoding >= ZIP_INT_IMM_MIN && encoding <= ZIP_INT_IMM_MAX) {
+        /* Nothing to do, the value is stored in the encoding itself. */

     } else {
         assert(NULL);
     }
     } else {
         assert(NULL);
     }


@@ -233,16 +375,28 @@ static void zipSaveInteger(unsigned char *p, int64_t value, unsigned char encodi
 static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
     int16_t i16;
     int32_t i32;
 static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
     int16_t i16;
     int32_t i32;

-    int64_t i64, ret;
-    if (encoding == ZIP_ENC_INT16) {
+    int64_t i64, ret = 0;
+    if (encoding == ZIP_INT_8B) {
+        ret = ((int8_t*)p)[0];
+    } else if (encoding == ZIP_INT_16B) {

         memcpy(&i16,p,sizeof(i16));
         memcpy(&i16,p,sizeof(i16));

+        memrev16ifbe(&i16);

         ret = i16;
         ret = i16;

-    } else if (encoding == ZIP_ENC_INT32) {
+    } else if (encoding == ZIP_INT_32B) {

         memcpy(&i32,p,sizeof(i32));
         memcpy(&i32,p,sizeof(i32));

+        memrev32ifbe(&i32);

         ret = i32;
         ret = i32;

-    } else if (encoding == ZIP_ENC_INT64) {
+    } else if (encoding == ZIP_INT_24B) {
+        i32 = 0;
+        memcpy(((uint8_t*)&i32)+1,p,sizeof(i32)-sizeof(uint8_t));
+        memrev32ifbe(&i32);
+        ret = i32>>8;
+    } else if (encoding == ZIP_INT_64B) {

         memcpy(&i64,p,sizeof(i64));
         memcpy(&i64,p,sizeof(i64));

+        memrev64ifbe(&i64);

         ret = i64;
         ret = i64;

+    } else if (encoding >= ZIP_INT_IMM_MIN && encoding <= ZIP_INT_IMM_MAX) {
+        ret = (encoding & ZIP_INT_IMM_MASK)-1;

     } else {
         assert(NULL);
     }
     } else {
         assert(NULL);
     }


@@ -252,26 +406,20 @@ static int64_t zipLoadInteger(unsigned char *p, unsigned char encoding) {
 /* Return a struct with all information about an entry. */
 static zlentry zipEntry(unsigned char *p) {
     zlentry e;
 /* Return a struct with all information about an entry. */
 static zlentry zipEntry(unsigned char *p) {
     zlentry e;

-    e.prevrawlen = zipPrevDecodeLength(p,&e.prevrawlensize);
-    e.len = zipDecodeLength(p+e.prevrawlensize,&e.lensize);
-    e.headersize = e.prevrawlensize+e.lensize;
-    e.encoding = ZIP_ENCODING(p+e.prevrawlensize);
+
+    ZIP_DECODE_PREVLEN(p, e.prevrawlensize, e.prevrawlen);
+    ZIP_DECODE_LENGTH(p + e.prevrawlensize, e.encoding, e.lensize, e.len);
+    e.headersize = e.prevrawlensize + e.lensize;

     e.p = p;
     return e;
 }
 
     e.p = p;
     return e;
 }
 

-/* Return the total number of bytes used by the entry at "p". */
-static unsigned int zipRawEntryLength(unsigned char *p) {
-    zlentry e = zipEntry(p);
-    return e.headersize + e.len;
-}
-

 /* Create a new empty ziplist. */
 unsigned char *ziplistNew(void) {
     unsigned int bytes = ZIPLIST_HEADER_SIZE+1;
     unsigned char *zl = zmalloc(bytes);
 /* Create a new empty ziplist. */
 unsigned char *ziplistNew(void) {
     unsigned int bytes = ZIPLIST_HEADER_SIZE+1;
     unsigned char *zl = zmalloc(bytes);

-    ZIPLIST_BYTES(zl) = bytes;
-    ZIPLIST_TAIL_OFFSET(zl) = ZIPLIST_HEADER_SIZE;
+    ZIPLIST_BYTES(zl) = intrev32ifbe(bytes);
+    ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(ZIPLIST_HEADER_SIZE);

     ZIPLIST_LENGTH(zl) = 0;
     zl[bytes-1] = ZIP_END;
     return zl;
     ZIPLIST_LENGTH(zl) = 0;
     zl[bytes-1] = ZIP_END;
     return zl;


@@ -280,16 +428,100 @@ unsigned char *ziplistNew(void) {
 /* Resize the ziplist. */
 static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
     zl = zrealloc(zl,len);
 /* Resize the ziplist. */
 static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
     zl = zrealloc(zl,len);

-    ZIPLIST_BYTES(zl) = len;
+    ZIPLIST_BYTES(zl) = intrev32ifbe(len);

     zl[len-1] = ZIP_END;
     return zl;
 }
 
     zl[len-1] = ZIP_END;
     return zl;
 }
 

+/* When an entry is inserted, we need to set the prevlen field of the next
+ * entry to equal the length of the inserted entry. It can occur that this
+ * length cannot be encoded in 1 byte and the next entry needs to be grow
+ * a bit larger to hold the 5-byte encoded prevlen. This can be done for free,
+ * because this only happens when an entry is already being inserted (which
+ * causes a realloc and memmove). However, encoding the prevlen may require
+ * that this entry is grown as well. This effect may cascade throughout
+ * the ziplist when there are consecutive entries with a size close to
+ * ZIP_BIGLEN, so we need to check that the prevlen can be encoded in every
+ * consecutive entry.
+ *
+ * Note that this effect can also happen in reverse, where the bytes required
+ * to encode the prevlen field can shrink. This effect is deliberately ignored,
+ * because it can cause a "flapping" effect where a chain prevlen fields is
+ * first grown and then shrunk again after consecutive inserts. Rather, the
+ * field is allowed to stay larger than necessary, because a large prevlen
+ * field implies the ziplist is holding large entries anyway.
+ *
+ * The pointer "p" points to the first entry that does NOT need to be
+ * updated, i.e. consecutive fields MAY need an update. */
+static unsigned char *__ziplistCascadeUpdate(unsigned char *zl, unsigned char *p) {
+    size_t curlen = intrev32ifbe(ZIPLIST_BYTES(zl)), rawlen, rawlensize;
+    size_t offset, noffset, extra;
+    unsigned char *np;
+    zlentry cur, next;
+
+    while (p[0] != ZIP_END) {
+        cur = zipEntry(p);
+        rawlen = cur.headersize + cur.len;
+        rawlensize = zipPrevEncodeLength(NULL,rawlen);
+
+        /* Abort if there is no next entry. */
+        if (p[rawlen] == ZIP_END) break;
+        next = zipEntry(p+rawlen);
+
+        /* Abort when "prevlen" has not changed. */
+        if (next.prevrawlen == rawlen) break;
+
+        if (next.prevrawlensize < rawlensize) {
+            /* The "prevlen" field of "next" needs more bytes to hold
+             * the raw length of "cur". */
+            offset = p-zl;
+            extra = rawlensize-next.prevrawlensize;
+            zl = ziplistResize(zl,curlen+extra);
+            p = zl+offset;
+
+            /* Current pointer and offset for next element. */
+            np = p+rawlen;
+            noffset = np-zl;
+
+            /* Update tail offset when next element is not the tail element. */
+            if ((zl+intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))) != np) {
+                ZIPLIST_TAIL_OFFSET(zl) =
+                    intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+extra);
+            }
+
+            /* Move the tail to the back. */
+            memmove(np+rawlensize,
+                np+next.prevrawlensize,
+                curlen-noffset-next.prevrawlensize-1);
+            zipPrevEncodeLength(np,rawlen);
+
+            /* Advance the cursor */
+            p += rawlen;
+            curlen += extra;
+        } else {
+            if (next.prevrawlensize > rawlensize) {
+                /* This would result in shrinking, which we want to avoid.
+                 * So, set "rawlen" in the available bytes. */
+                zipPrevEncodeLengthForceLarge(p+rawlen,rawlen);
+            } else {
+                zipPrevEncodeLength(p+rawlen,rawlen);
+            }
+
+            /* Stop here, as the raw length of "next" has not changed. */
+            break;
+        }
+    }
+    return zl;
+}
+

 /* Delete "num" entries, starting at "p". Returns pointer to the ziplist. */
 static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsigned int num) {
     unsigned int i, totlen, deleted = 0;
 /* Delete "num" entries, starting at "p". Returns pointer to the ziplist. */
 static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsigned int num) {
     unsigned int i, totlen, deleted = 0;

+    size_t offset;

     int nextdiff = 0;
     int nextdiff = 0;

-    zlentry first = zipEntry(p);
+    zlentry first, tail;
+
+    first = zipEntry(p);

     for (i = 0; p[0] != ZIP_END && i < num; i++) {
         p += zipRawEntryLength(p);
         deleted++;
     for (i = 0; p[0] != ZIP_END && i < num; i++) {
         p += zipRawEntryLength(p);
         deleted++;


@@ -298,57 +530,81 @@ static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, unsig
     totlen = p-first.p;
     if (totlen > 0) {
         if (p[0] != ZIP_END) {
     totlen = p-first.p;
     if (totlen > 0) {
         if (p[0] != ZIP_END) {

-            /* Tricky: storing the prevlen in this entry might reduce or
-             * increase the number of bytes needed, compared to the current
-             * prevlen. Note that we can always store this length because
-             * it was previously stored by an entry that is being deleted. */
+            /* Storing `prevrawlen` in this entry may increase or decrease the
+             * number of bytes required compare to the current `prevrawlen`.
+             * There always is room to store this, because it was previously
+             * stored by an entry that is now being deleted. */

             nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
             nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);

-            zipPrevEncodeLength(p-nextdiff,first.prevrawlen);
+            p -= nextdiff;
+            zipPrevEncodeLength(p,first.prevrawlen);

 
             /* Update offset for tail */
 
             /* Update offset for tail */

-            ZIPLIST_TAIL_OFFSET(zl) -= totlen+nextdiff;
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))-totlen);
+
+            /* When the tail contains more than one entry, we need to take
+             * "nextdiff" in account as well. Otherwise, a change in the
+             * size of prevlen doesn't have an effect on the *tail* offset. */
+            tail = zipEntry(p);
+            if (p[tail.headersize+tail.len] != ZIP_END) {
+                ZIPLIST_TAIL_OFFSET(zl) =
+                   intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+nextdiff);
+            }

 
             /* Move tail to the front of the ziplist */
 
             /* Move tail to the front of the ziplist */

-            memmove(first.p,p-nextdiff,ZIPLIST_BYTES(zl)-(p-zl)-1+nextdiff);
+            memmove(first.p,p,
+                intrev32ifbe(ZIPLIST_BYTES(zl))-(p-zl)-1);

         } else {
             /* The entire tail was deleted. No need to move memory. */
         } else {
             /* The entire tail was deleted. No need to move memory. */

-            ZIPLIST_TAIL_OFFSET(zl) = (first.p-zl)-first.prevrawlen;
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe((first.p-zl)-first.prevrawlen);

         }
 
         /* Resize and update length */
         }
 
         /* Resize and update length */

-        zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen+nextdiff);
+        offset = first.p-zl;
+        zl = ziplistResize(zl, intrev32ifbe(ZIPLIST_BYTES(zl))-totlen+nextdiff);

         ZIPLIST_INCR_LENGTH(zl,-deleted);
         ZIPLIST_INCR_LENGTH(zl,-deleted);

+        p = zl+offset;
+
+        /* When nextdiff != 0, the raw length of the next entry has changed, so
+         * we need to cascade the update throughout the ziplist */
+        if (nextdiff != 0)
+            zl = __ziplistCascadeUpdate(zl,p);

     }
     return zl;
 }
 
 /* Insert item at "p". */
 static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {
     }
     return zl;
 }
 
 /* Insert item at "p". */
 static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char *s, unsigned int slen) {

-    unsigned int curlen = ZIPLIST_BYTES(zl), reqlen, prevlen = 0;
-    unsigned int offset, nextdiff = 0;
-    unsigned char *tail;
-    unsigned char encoding = ZIP_ENC_RAW;
-    long long value;
-    zlentry entry;
+    size_t curlen = intrev32ifbe(ZIPLIST_BYTES(zl)), reqlen, prevlen = 0;
+    size_t offset;
+    int nextdiff = 0;
+    unsigned char encoding = 0;
+    long long value = 123456789; /* initialized to avoid warning. Using a value
+                                    that is easy to see if for some reason
+                                    we use it uninitialized. */
+    zlentry entry, tail;

 
     /* Find out prevlen for the entry that is inserted. */
     if (p[0] != ZIP_END) {
         entry = zipEntry(p);
         prevlen = entry.prevrawlen;
     } else {
 
     /* Find out prevlen for the entry that is inserted. */
     if (p[0] != ZIP_END) {
         entry = zipEntry(p);
         prevlen = entry.prevrawlen;
     } else {

-        tail = ZIPLIST_ENTRY_TAIL(zl);
-        if (tail[0] != ZIP_END) {
-            prevlen = zipRawEntryLength(tail);
+        unsigned char *ptail = ZIPLIST_ENTRY_TAIL(zl);
+        if (ptail[0] != ZIP_END) {
+            prevlen = zipRawEntryLength(ptail);

         }
     }
 
     /* See if the entry can be encoded */
     if (zipTryEncoding(s,slen,&value,&encoding)) {
         }
     }
 
     /* See if the entry can be encoded */
     if (zipTryEncoding(s,slen,&value,&encoding)) {

-        reqlen = zipEncodingSize(encoding);
+        /* 'encoding' is set to the appropriate integer encoding */
+        reqlen = zipIntSize(encoding);

     } else {
     } else {

+        /* 'encoding' is untouched, however zipEncodeLength will use the
+         * string length to figure out how to encode it. */

         reqlen = slen;
     }
         reqlen = slen;
     }

-

     /* We need space for both the length of the previous entry and
      * the length of the payload. */
     reqlen += zipPrevEncodeLength(NULL,prevlen);
     /* We need space for both the length of the previous entry and
      * the length of the payload. */
     reqlen += zipPrevEncodeLength(NULL,prevlen);


@@ -368,22 +624,42 @@ static unsigned char *__ziplistInsert(unsigned char *zl, unsigned char *p, unsig
     if (p[0] != ZIP_END) {
         /* Subtract one because of the ZIP_END bytes */
         memmove(p+reqlen,p-nextdiff,curlen-offset-1+nextdiff);
     if (p[0] != ZIP_END) {
         /* Subtract one because of the ZIP_END bytes */
         memmove(p+reqlen,p-nextdiff,curlen-offset-1+nextdiff);

+

         /* Encode this entry's raw length in the next entry. */
         zipPrevEncodeLength(p+reqlen,reqlen);
         /* Encode this entry's raw length in the next entry. */
         zipPrevEncodeLength(p+reqlen,reqlen);

+

         /* Update offset for tail */
         /* Update offset for tail */

-        ZIPLIST_TAIL_OFFSET(zl) += reqlen+nextdiff;
+        ZIPLIST_TAIL_OFFSET(zl) =
+            intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+reqlen);
+
+        /* When the tail contains more than one entry, we need to take
+         * "nextdiff" in account as well. Otherwise, a change in the
+         * size of prevlen doesn't have an effect on the *tail* offset. */
+        tail = zipEntry(p+reqlen);
+        if (p[reqlen+tail.headersize+tail.len] != ZIP_END) {
+            ZIPLIST_TAIL_OFFSET(zl) =
+                intrev32ifbe(intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl))+nextdiff);
+        }

     } else {
         /* This element will be the new tail. */
     } else {
         /* This element will be the new tail. */

-        ZIPLIST_TAIL_OFFSET(zl) = p-zl;
+        ZIPLIST_TAIL_OFFSET(zl) = intrev32ifbe(p-zl);
+    }
+
+    /* When nextdiff != 0, the raw length of the next entry has changed, so
+     * we need to cascade the update throughout the ziplist */
+    if (nextdiff != 0) {
+        offset = p-zl;
+        zl = __ziplistCascadeUpdate(zl,p+reqlen);
+        p = zl+offset;

     }
 
     /* Write the entry */
     p += zipPrevEncodeLength(p,prevlen);
     p += zipEncodeLength(p,encoding,slen);
     }
 
     /* Write the entry */
     p += zipPrevEncodeLength(p,prevlen);
     p += zipEncodeLength(p,encoding,slen);

-    if (encoding != ZIP_ENC_RAW) {
-        zipSaveInteger(p,value,encoding);
-    } else {
+    if (ZIP_IS_STR(encoding)) {

         memcpy(p,s,slen);
         memcpy(p,s,slen);

+    } else {
+        zipSaveInteger(p,value,encoding);

     }
     ZIPLIST_INCR_LENGTH(zl,1);
     return zl;
     }
     ZIPLIST_INCR_LENGTH(zl,1);
     return zl;


@@ -420,7 +696,12 @@ unsigned char *ziplistIndex(unsigned char *zl, int index) {
     return (p[0] == ZIP_END || index > 0) ? NULL : p;
 }
 
     return (p[0] == ZIP_END || index > 0) ? NULL : p;
 }
 

-/* Return pointer to next entry in ziplist. */
+/* Return pointer to next entry in ziplist.
+ *
+ * zl is the pointer to the ziplist
+ * p is the pointer to the current element
+ *
+ * The element after 'p' is returned, otherwise NULL if we are at the end. */

 unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) {
     ((void) zl);
 
 unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) {
     ((void) zl);
 


@@ -429,10 +710,14 @@ unsigned char *ziplistNext(unsigned char *zl, unsigned char *p) {
      * when the *next* element is ZIP_END (there is no next entry). */
     if (p[0] == ZIP_END) {
         return NULL;
      * when the *next* element is ZIP_END (there is no next entry). */
     if (p[0] == ZIP_END) {
         return NULL;

-    } else {
-        p = p+zipRawEntryLength(p);
-        return (p[0] == ZIP_END) ? NULL : p;

     }
     }

+
+    p += zipRawEntryLength(p);
+    if (p[0] == ZIP_END) {
+        return NULL;
+    }
+
+    return p;

 }
 
 /* Return pointer to previous entry in ziplist. */
 }
 
 /* Return pointer to previous entry in ziplist. */


@@ -449,6 +734,7 @@ unsigned char *ziplistPrev(unsigned char *zl, unsigned char *p) {
         return NULL;
     } else {
         entry = zipEntry(p);
         return NULL;
     } else {
         entry = zipEntry(p);

+        assert(entry.prevrawlen > 0);

         return p-entry.prevrawlen;
     }
 }
         return p-entry.prevrawlen;
     }
 }


@@ -463,7 +749,7 @@ unsigned int ziplistGet(unsigned char *p, unsigned char **sstr, unsigned int *sl
     if (sstr) *sstr = NULL;
 
     entry = zipEntry(p);
     if (sstr) *sstr = NULL;
 
     entry = zipEntry(p);

-    if (entry.encoding == ZIP_ENC_RAW) {
+    if (ZIP_IS_STR(entry.encoding)) {

         if (sstr) {
             *slen = entry.len;
             *sstr = p+entry.headersize;
         if (sstr) {
             *slen = entry.len;
             *sstr = p+entry.headersize;


@@ -485,7 +771,7 @@ unsigned char *ziplistInsert(unsigned char *zl, unsigned char *p, unsigned char
  * Also update *p in place, to be able to iterate over the
  * ziplist, while deleting entries. */
 unsigned char *ziplistDelete(unsigned char *zl, unsigned char **p) {
  * Also update *p in place, to be able to iterate over the
  * ziplist, while deleting entries. */
 unsigned char *ziplistDelete(unsigned char *zl, unsigned char **p) {

-    unsigned int offset = *p-zl;
+    size_t offset = *p-zl;

     zl = __ziplistDelete(zl,*p,1);
 
     /* Store pointer to current element in p, because ziplistDelete will
     zl = __ziplistDelete(zl,*p,1);
 
     /* Store pointer to current element in p, because ziplistDelete will


@@ -510,7 +796,7 @@ unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int
     if (p[0] == ZIP_END) return 0;
 
     entry = zipEntry(p);
     if (p[0] == ZIP_END) return 0;
 
     entry = zipEntry(p);

-    if (entry.encoding == ZIP_ENC_RAW) {
+    if (ZIP_IS_STR(entry.encoding)) {

         /* Raw compare */
         if (entry.len == slen) {
             return memcmp(p+entry.headersize,sstr,slen) == 0;
         /* Raw compare */
         if (entry.len == slen) {
             return memcmp(p+entry.headersize,sstr,slen) == 0;


@@ -518,22 +804,82 @@ unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int
             return 0;
         }
     } else {
             return 0;
         }
     } else {

-        /* Try to compare encoded values */
+        /* Try to compare encoded values. Don't compare encoding because
+         * different implementations may encoded integers differently. */

         if (zipTryEncoding(sstr,slen,&sval,&sencoding)) {
         if (zipTryEncoding(sstr,slen,&sval,&sencoding)) {

-            if (entry.encoding == sencoding) {
-                zval = zipLoadInteger(p+entry.headersize,entry.encoding);
-                return zval == sval;
-            }
+          zval = zipLoadInteger(p+entry.headersize,entry.encoding);
+          return zval == sval;

         }
     }
     return 0;
 }
 
         }
     }
     return 0;
 }
 

+/* Find pointer to the entry equal to the specified entry. Skip 'skip' entries
+ * between every comparison. Returns NULL when the field could not be found. */
+unsigned char *ziplistFind(unsigned char *p, unsigned char *vstr, unsigned int vlen, unsigned int skip) {
+    int skipcnt = 0;
+    unsigned char vencoding = 0;
+    long long vll = 0;
+
+    while (p[0] != ZIP_END) {
+        unsigned int prevlensize, encoding, lensize, len;
+        unsigned char *q;
+
+        ZIP_DECODE_PREVLENSIZE(p, prevlensize);
+        ZIP_DECODE_LENGTH(p + prevlensize, encoding, lensize, len);
+        q = p + prevlensize + lensize;
+
+        if (skipcnt == 0) {
+            /* Compare current entry with specified entry */
+            if (ZIP_IS_STR(encoding)) {
+                if (len == vlen && memcmp(q, vstr, vlen) == 0) {
+                    return p;
+                }
+            } else {
+                /* Find out if the searched field can be encoded. Note that
+                 * we do it only the first time, once done vencoding is set
+                 * to non-zero and vll is set to the integer value. */
+                if (vencoding == 0) {
+                    if (!zipTryEncoding(vstr, vlen, &vll, &vencoding)) {
+                        /* If the entry can't be encoded we set it to
+                         * UCHAR_MAX so that we don't retry again the next
+                         * time. */
+                        vencoding = UCHAR_MAX;
+                    }
+                    /* Must be non-zero by now */
+                    assert(vencoding);
+                }
+
+                /* Compare current entry with specified entry, do it only
+                 * if vencoding != UCHAR_MAX because if there is no encoding
+                 * possible for the field it can't be a valid integer. */
+                if (vencoding != UCHAR_MAX) {
+                    long long ll = zipLoadInteger(q, encoding);
+                    if (ll == vll) {
+                        return p;
+                    }
+                }
+            }
+
+            /* Reset skip count */
+            skipcnt = skip;
+        } else {
+            /* Skip entry */
+            skipcnt--;
+        }
+
+        /* Move to next entry */
+        p = q + len;
+    }
+
+    return NULL;
+}
+

 /* Return length of ziplist. */
 unsigned int ziplistLen(unsigned char *zl) {
     unsigned int len = 0;
 /* Return length of ziplist. */
 unsigned int ziplistLen(unsigned char *zl) {
     unsigned int len = 0;

-    if (ZIPLIST_LENGTH(zl) < UINT16_MAX) {
-        len = ZIPLIST_LENGTH(zl);
+    if (intrev16ifbe(ZIPLIST_LENGTH(zl)) < UINT16_MAX) {
+        len = intrev16ifbe(ZIPLIST_LENGTH(zl));

     } else {
         unsigned char *p = zl+ZIPLIST_HEADER_SIZE;
         while (*p != ZIP_END) {
     } else {
         unsigned char *p = zl+ZIPLIST_HEADER_SIZE;
         while (*p != ZIP_END) {


@@ -542,39 +888,75 @@ unsigned int ziplistLen(unsigned char *zl) {
         }
 
         /* Re-store length if small enough */
         }
 
         /* Re-store length if small enough */

-        if (len < UINT16_MAX) ZIPLIST_LENGTH(zl) = len;
+        if (len < UINT16_MAX) ZIPLIST_LENGTH(zl) = intrev16ifbe(len);

     }
     return len;
 }
 
     }
     return len;
 }
 

-/* Return size in bytes of ziplist. */
-unsigned int ziplistSize(unsigned char *zl) {
-    return ZIPLIST_BYTES(zl);
+/* Return ziplist blob size in bytes. */
+size_t ziplistBlobLen(unsigned char *zl) {
+    return intrev32ifbe(ZIPLIST_BYTES(zl));

 }
 
 void ziplistRepr(unsigned char *zl) {
     unsigned char *p;
 }
 
 void ziplistRepr(unsigned char *zl) {
     unsigned char *p;

+    int index = 0;

     zlentry entry;
 
     zlentry entry;
 

-    printf("{total bytes %d} {length %u}\n",ZIPLIST_BYTES(zl), ZIPLIST_LENGTH(zl));
+    printf(
+        "{total bytes %d} "
+        "{length %u}\n"
+        "{tail offset %u}\n",
+        intrev32ifbe(ZIPLIST_BYTES(zl)),
+        intrev16ifbe(ZIPLIST_LENGTH(zl)),
+        intrev32ifbe(ZIPLIST_TAIL_OFFSET(zl)));

     p = ZIPLIST_ENTRY_HEAD(zl);
     while(*p != ZIP_END) {
         entry = zipEntry(p);
     p = ZIPLIST_ENTRY_HEAD(zl);
     while(*p != ZIP_END) {
         entry = zipEntry(p);

-        printf("{offset %ld, header %u, payload %u} ",p-zl,entry.headersize,entry.len);
+        printf(
+            "{"
+                "addr 0x%08lx, "
+                "index %2d, "
+                "offset %5ld, "
+                "rl: %5u, "
+                "hs %2u, "
+                "pl: %5u, "
+                "pls: %2u, "
+                "payload %5u"
+            "} ",
+            (long unsigned)p,
+            index,
+            (unsigned long) (p-zl),
+            entry.headersize+entry.len,
+            entry.headersize,
+            entry.prevrawlen,
+            entry.prevrawlensize,
+            entry.len);

         p += entry.headersize;
         p += entry.headersize;

-        if (entry.encoding == ZIP_ENC_RAW) {
-            fwrite(p,entry.len,1,stdout);
+        if (ZIP_IS_STR(entry.encoding)) {
+            if (entry.len > 40) {
+                if (fwrite(p,40,1,stdout) == 0) perror("fwrite");
+                printf("...");
+            } else {
+                if (entry.len &&
+                    fwrite(p,entry.len,1,stdout) == 0) perror("fwrite");
+            }

         } else {
             printf("%lld", (long long) zipLoadInteger(p,entry.encoding));
         }
         printf("\n");
         p += entry.len;
         } else {
             printf("%lld", (long long) zipLoadInteger(p,entry.encoding));
         }
         printf("\n");
         p += entry.len;

+        index++;

     }
     printf("{end}\n\n");
 }
 
 #ifdef ZIPLIST_TEST_MAIN
 #include <sys/time.h>
     }
     printf("{end}\n\n");
 }
 
 #ifdef ZIPLIST_TEST_MAIN
 #include <sys/time.h>

+#include "adlist.h"
+#include "sds.h"
+
+#define debug(f, ...) { if (DEBUG) printf(f, __VA_ARGS__); }

 
 unsigned char *createList() {
     unsigned char *zl = ziplistNew();
 
 unsigned char *createList() {
     unsigned char *zl = ziplistNew();


@@ -628,7 +1010,7 @@ void stress(int pos, int num, int maxsize, int dnum) {
             zl = ziplistDeleteRange(zl,0,1);
         }
         printf("List size: %8d, bytes: %8d, %dx push+pop (%s): %6lld usec\n",
             zl = ziplistDeleteRange(zl,0,1);
         }
         printf("List size: %8d, bytes: %8d, %dx push+pop (%s): %6lld usec\n",

-            i,ZIPLIST_BYTES(zl),num,posstr[pos],usec()-start);
+            i,intrev32ifbe(ZIPLIST_BYTES(zl)),num,posstr[pos],usec()-start);

         zfree(zl);
     }
 }
         zfree(zl);
     }
 }


@@ -646,7 +1028,7 @@ void pop(unsigned char *zl, int where) {
             printf("Pop tail: ");
 
         if (vstr)
             printf("Pop tail: ");
 
         if (vstr)

-            fwrite(vstr,vlen,1,stdout);
+            if (vlen && fwrite(vstr,vlen,1,stdout) == 0) perror("fwrite");

         else
             printf("%lld", vlong);
 
         else
             printf("%lld", vlong);
 


@@ -658,12 +1040,57 @@ void pop(unsigned char *zl, int where) {
     }
 }
 
     }
 }
 

+int randstring(char *target, unsigned int min, unsigned int max) {
+    int p, len = min+rand()%(max-min+1);
+    int minval, maxval;
+    switch(rand() % 3) {
+    case 0:
+        minval = 0;
+        maxval = 255;
+    break;
+    case 1:
+        minval = 48;
+        maxval = 122;
+    break;
+    case 2:
+        minval = 48;
+        maxval = 52;
+    break;
+    default:
+        assert(NULL);
+    }
+
+    while(p < len)
+        target[p++] = minval+rand()%(maxval-minval+1);
+    return len;
+}
+
+void verify(unsigned char *zl, zlentry *e) {
+    int i;
+    int len = ziplistLen(zl);
+    zlentry _e;
+
+    for (i = 0; i < len; i++) {
+        memset(&e[i], 0, sizeof(zlentry));
+        e[i] = zipEntry(ziplistIndex(zl, i));
+
+        memset(&_e, 0, sizeof(zlentry));
+        _e = zipEntry(ziplistIndex(zl, -len+i));
+
+        assert(memcmp(&e[i], &_e, sizeof(zlentry)) == 0);
+    }
+}
+

 int main(int argc, char **argv) {
     unsigned char *zl, *p;
     unsigned char *entry;
     unsigned int elen;
     long long value;
 
 int main(int argc, char **argv) {
     unsigned char *zl, *p;
     unsigned char *entry;
     unsigned int elen;
     long long value;
 

+    /* If an argument is given, use it as the random seed. */
+    if (argc == 2)
+        srand(atoi(argv[1]));
+

     zl = createIntList();
     ziplistRepr(zl);
 
     zl = createIntList();
     ziplistRepr(zl);
 


@@ -691,7 +1118,7 @@ int main(int argc, char **argv) {
             return 1;
         }
         if (entry) {
             return 1;
         }
         if (entry) {

-            fwrite(entry,elen,1,stdout);
+            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             printf("\n");
         } else {
             printf("%lld\n", value);
             printf("\n");
         } else {
             printf("%lld\n", value);


@@ -721,7 +1148,7 @@ int main(int argc, char **argv) {
             return 1;
         }
         if (entry) {
             return 1;
         }
         if (entry) {

-            fwrite(entry,elen,1,stdout);
+            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             printf("\n");
         } else {
             printf("%lld\n", value);
             printf("\n");
         } else {
             printf("%lld\n", value);


@@ -738,7 +1165,7 @@ int main(int argc, char **argv) {
             return 1;
         }
         if (entry) {
             return 1;
         }
         if (entry) {

-            fwrite(entry,elen,1,stdout);
+            if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             printf("\n");
         } else {
             printf("%lld\n", value);
             printf("\n");
         } else {
             printf("%lld\n", value);


@@ -766,7 +1193,7 @@ int main(int argc, char **argv) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {

-                fwrite(entry,elen,1,stdout);
+                if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             } else {
                 printf("%lld", value);
             }
             } else {
                 printf("%lld", value);
             }


@@ -783,7 +1210,7 @@ int main(int argc, char **argv) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {

-                fwrite(entry,elen,1,stdout);
+                if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             } else {
                 printf("%lld", value);
             }
             } else {
                 printf("%lld", value);
             }


@@ -800,7 +1227,7 @@ int main(int argc, char **argv) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {

-                fwrite(entry,elen,1,stdout);
+                if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             } else {
                 printf("%lld", value);
             }
             } else {
                 printf("%lld", value);
             }


@@ -829,7 +1256,7 @@ int main(int argc, char **argv) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {

-                fwrite(entry,elen,1,stdout);
+                if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             } else {
                 printf("%lld", value);
             }
             } else {
                 printf("%lld", value);
             }


@@ -846,7 +1273,7 @@ int main(int argc, char **argv) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {
         while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
             if (entry) {

-                fwrite(entry,elen,1,stdout);
+                if (elen && fwrite(entry,elen,1,stdout) == 0) perror("fwrite");

             } else {
                 printf("%lld", value);
             }
             } else {
                 printf("%lld", value);
             }


@@ -903,7 +1330,8 @@ int main(int argc, char **argv) {
             } else {
                 printf("Entry: ");
                 if (entry) {
             } else {
                 printf("Entry: ");
                 if (entry) {

-                    fwrite(entry,elen,1,stdout);
+                    if (elen && fwrite(entry,elen,1,stdout) == 0)
+                        perror("fwrite");

                 } else {
                     printf("%lld",value);
                 }
                 } else {
                     printf("%lld",value);
                 }


@@ -915,6 +1343,62 @@ int main(int argc, char **argv) {
         ziplistRepr(zl);
     }
 
         ziplistRepr(zl);
     }
 

+    printf("Regression test for >255 byte strings:\n");
+    {
+        char v1[257],v2[257];
+        memset(v1,'x',256);
+        memset(v2,'y',256);
+        zl = ziplistNew();
+        zl = ziplistPush(zl,(unsigned char*)v1,strlen(v1),ZIPLIST_TAIL);
+        zl = ziplistPush(zl,(unsigned char*)v2,strlen(v2),ZIPLIST_TAIL);
+
+        /* Pop values again and compare their value. */
+        p = ziplistIndex(zl,0);
+        assert(ziplistGet(p,&entry,&elen,&value));
+        assert(strncmp(v1,(char*)entry,elen) == 0);
+        p = ziplistIndex(zl,1);
+        assert(ziplistGet(p,&entry,&elen,&value));
+        assert(strncmp(v2,(char*)entry,elen) == 0);
+        printf("SUCCESS\n\n");
+    }
+
+    printf("Regression test deleting next to last entries:\n");
+    {
+        char v[3][257];
+        zlentry e[3];
+        int i;
+
+        for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
+            memset(v[i], 'a' + i, sizeof(v[0]));
+        }
+
+        v[0][256] = '\0';
+        v[1][  1] = '\0';
+        v[2][256] = '\0';
+
+        zl = ziplistNew();
+        for (i = 0; i < (sizeof(v)/sizeof(v[0])); i++) {
+            zl = ziplistPush(zl, (unsigned char *) v[i], strlen(v[i]), ZIPLIST_TAIL);
+        }
+
+        verify(zl, e);
+
+        assert(e[0].prevrawlensize == 1);
+        assert(e[1].prevrawlensize == 5);
+        assert(e[2].prevrawlensize == 1);
+
+        /* Deleting entry 1 will increase `prevrawlensize` for entry 2 */
+        unsigned char *p = e[1].p;
+        zl = ziplistDelete(zl, &p);
+
+        verify(zl, e);
+
+        assert(e[0].prevrawlensize == 1);
+        assert(e[1].prevrawlensize == 5);
+
+        printf("SUCCESS\n\n");
+    }
+

     printf("Create long list and check indices:\n");
     {
         zl = ziplistNew();
     printf("Create long list and check indices:\n");
     {
         zl = ziplistNew();


@@ -958,7 +1442,84 @@ int main(int argc, char **argv) {
             printf("ERROR: \"1025\"\n");
             return 1;
         }
             printf("ERROR: \"1025\"\n");
             return 1;
         }

-        printf("SUCCESS\n");
+        printf("SUCCESS\n\n");
+    }
+
+    printf("Stress with random payloads of different encoding:\n");
+    {
+        int i,j,len,where;
+        unsigned char *p;
+        char buf[1024];
+        int buflen;
+        list *ref;
+        listNode *refnode;
+
+        /* Hold temp vars from ziplist */
+        unsigned char *sstr;
+        unsigned int slen;
+        long long sval;
+
+        for (i = 0; i < 20000; i++) {
+            zl = ziplistNew();
+            ref = listCreate();
+            listSetFreeMethod(ref,sdsfree);
+            len = rand() % 256;
+
+            /* Create lists */
+            for (j = 0; j < len; j++) {
+                where = (rand() & 1) ? ZIPLIST_HEAD : ZIPLIST_TAIL;
+                if (rand() % 2) {
+                    buflen = randstring(buf,1,sizeof(buf)-1);
+                } else {
+                    switch(rand() % 3) {
+                    case 0:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()) >> 20);
+                        break;
+                    case 1:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()));
+                        break;
+                    case 2:
+                        buflen = sprintf(buf,"%lld",(0LL + rand()) << 20);
+                        break;
+                    default:
+                        assert(NULL);
+                    }
+                }
+
+                /* Add to ziplist */
+                zl = ziplistPush(zl, (unsigned char*)buf, buflen, where);
+
+                /* Add to reference list */
+                if (where == ZIPLIST_HEAD) {
+                    listAddNodeHead(ref,sdsnewlen(buf, buflen));
+                } else if (where == ZIPLIST_TAIL) {
+                    listAddNodeTail(ref,sdsnewlen(buf, buflen));
+                } else {
+                    assert(NULL);
+                }
+            }
+
+            assert(listLength(ref) == ziplistLen(zl));
+            for (j = 0; j < len; j++) {
+                /* Naive way to get elements, but similar to the stresser
+                 * executed from the Tcl test suite. */
+                p = ziplistIndex(zl,j);
+                refnode = listIndex(ref,j);
+
+                assert(ziplistGet(p,&sstr,&slen,&sval));
+                if (sstr == NULL) {
+                    buflen = sprintf(buf,"%lld",sval);
+                } else {
+                    buflen = slen;
+                    memcpy(buf,sstr,buflen);
+                    buf[buflen] = '\0';
+                }
+                assert(memcmp(buf,listNodeValue(refnode),buflen) == 0);
+            }
+            zfree(zl);
+            listRelease(ref);
+        }
+        printf("SUCCESS\n\n");

     }
 
     printf("Stress with variable ziplist size:\n");
     }
 
     printf("Stress with variable ziplist size:\n");