X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/29b14d5face8a434810794f524c8449581166adf..6435c76772bfc846c4f336d07f56668aef33a38b:/ziplist.c?ds=sidebyside

diff --git a/ziplist.c b/ziplist.c
index a45ae339..e54f3211 100644
--- a/ziplist.c
+++ b/ziplist.c
@@ -22,26 +22,215 @@
 #include "zmalloc.h"
 #include "sds.h"
 #include "ziplist.h"
-#include "zip.c"
 
+/* 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
+
+/* Entry encoding */
+#define ZIP_ENC_RAW     0
+#define ZIP_ENC_SHORT   1
+#define ZIP_ENC_INT     2
+#define ZIP_ENC_LLONG   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
+
+/* Utility macros */
 #define ZIPLIST_BYTES(zl) (*((unsigned int*)(zl)))
-#define ZIPLIST_LENGTH(zl) (*((zl)+sizeof(unsigned int)))
-#define ZIPLIST_HEADER_SIZE (sizeof(unsigned int)+1)
+#define ZIPLIST_TAIL_OFFSET(zl) (*((zl)+sizeof(unsigned int)))
+#define ZIPLIST_LENGTH(zl) (*((zl)+2*sizeof(unsigned int)))
+#define ZIPLIST_HEADER_SIZE (2*sizeof(unsigned int)+1)
 #define ZIPLIST_INCR_LENGTH(zl,incr) { \
-    if (ZIPLIST_LENGTH(zl) < (ZIP_END-1)) ZIPLIST_LENGTH(zl)+=incr; }
+    if (ZIPLIST_LENGTH(zl) < ZIP_BIGLEN) ZIPLIST_LENGTH(zl)+=incr; }
+
+typedef struct zlentry {
+    unsigned int prevrawlensize, prevrawlen;
+    unsigned int lensize, len;
+    unsigned int headersize;
+    unsigned char encoding;
+    unsigned char *p;
+} zlentry;
+
+/* Return bytes needed to store integer encoded by 'encoding' */
+static unsigned int zipEncodingSize(char encoding) {
+    if (encoding == ZIP_ENC_SHORT) {
+        return sizeof(short int);
+    } else if (encoding == ZIP_ENC_INT) {
+        return sizeof(int);
+    } else if (encoding == ZIP_ENC_LLONG) {
+        return sizeof(long long);
+    }
+    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;
+}
+
+/* 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) {
+            if (!p) return len;
+            lenenc = ZIP_LEN_INLINE;
+            buf[0] = rawlen;
+        } else if (rawlen <= 0xffff) {
+            len += 2;
+            if (!p) return len;
+            lenenc = ZIP_LEN_UINT16;
+            buf[1] = (rawlen     ) & 0xff;
+            buf[2] = (rawlen >> 8) & 0xff;
+        } 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] = (lenenc << 4) | (buf[0] & 0xf);
+    }
+    if (!p) return len;
+
+    /* Apparently we need to store the length in 'p' */
+    buf[0] = (encoding << 6) | (buf[0] & 0x3f);
+    memcpy(p,buf,len);
+    return len;
+}
+
+/* Return the difference in number of bytes needed to store the new length
+ * "len" on the entry pointed to by "p". */
+static int zipPrevLenByteDiff(unsigned char *p, unsigned int len) {
+    unsigned int prevlensize;
+    zipDecodeLength(p,&prevlensize);
+    return zipEncodeLength(NULL,ZIP_ENC_RAW,len)-prevlensize;
+}
+
+/* Check if string pointed to by 'entry' can be encoded as an integer.
+ * Stores the integer value in 'v' and its encoding in 'encoding'.
+ * Warning: this function requires a NULL-terminated string! */
+static int zipTryEncoding(unsigned char *entry, long long *v, char *encoding) {
+    long long value;
+    char *eptr;
+
+    if (entry[0] == '-' || (entry[0] >= '0' && entry[0] <= '9')) {
+        value = strtoll((char*)entry,&eptr,10);
+        if (eptr[0] != '\0') return 0;
+        if (value >= SHRT_MIN && value <= SHRT_MAX) {
+            *encoding = ZIP_ENC_SHORT;
+        } else if (value >= INT_MIN && value <= INT_MAX) {
+            *encoding = ZIP_ENC_INT;
+        } else {
+            *encoding = ZIP_ENC_LLONG;
+        }
+        *v = value;
+        return 1;
+    }
+    return 0;
+}
+
+/* Store integer 'value' at 'p', encoded as 'encoding' */
+static void zipSaveInteger(unsigned char *p, long long value, char encoding) {
+    short int s;
+    int i;
+    long long l;
+    if (encoding == ZIP_ENC_SHORT) {
+        s = value;
+        memcpy(p,&s,sizeof(s));
+    } else if (encoding == ZIP_ENC_INT) {
+        i = value;
+        memcpy(p,&i,sizeof(i));
+    } else if (encoding == ZIP_ENC_LLONG) {
+        l = value;
+        memcpy(p,&l,sizeof(l));
+    } else {
+        assert(NULL);
+    }
+}
+
+/* Read integer encoded as 'encoding' from 'p' */
+static long long zipLoadInteger(unsigned char *p, char encoding) {
+    short int s;
+    int i;
+    long long l, ret;
+    if (encoding == ZIP_ENC_SHORT) {
+        memcpy(&s,p,sizeof(s));
+        ret = s;
+    } else if (encoding == ZIP_ENC_INT) {
+        memcpy(&i,p,sizeof(i));
+        ret = i;
+    } else if (encoding == ZIP_ENC_LLONG) {
+        memcpy(&l,p,sizeof(l));
+        ret = l;
+    } else {
+        assert(NULL);
+    }
+    return ret;
+}
+
+/* Return a struct with all information about an entry. */
+static zlentry zipEntry(unsigned char *p) {
+    zlentry e;
+    e.prevrawlen = zipDecodeLength(p,&e.prevrawlensize);
+    e.len = zipDecodeLength(p+e.prevrawlensize,&e.lensize);
+    e.headersize = e.prevrawlensize+e.lensize;
+    e.encoding = ZIP_ENCODING(p+e.prevrawlensize);
+    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);
     ZIPLIST_BYTES(zl) = bytes;
+    ZIPLIST_TAIL_OFFSET(zl) = ZIPLIST_HEADER_SIZE;
     ZIPLIST_LENGTH(zl) = 0;
     zl[bytes-1] = ZIP_END;
     return zl;
 }
 
+/* Resize the ziplist. */
 static unsigned char *ziplistResize(unsigned char *zl, unsigned int len) {
-    zl = zipResize(zl,len);
+    zl = zrealloc(zl,len);
     ZIPLIST_BYTES(zl) = len;
     zl[len-1] = ZIP_END;
     return zl;
@@ -59,48 +248,119 @@ static unsigned char *ziplistTail(unsigned char *zl) {
         p += zipRawEntryLength(p);
     }
     return q;
+
+/* Delete "num" entries, starting at "p". Returns pointer to the ziplist. */
+static unsigned char *__ziplistDelete(unsigned char *zl, unsigned char *p, int num) {
+    unsigned int i, totlen, deleted = 0;
+    int nextdiff = 0;
+    zlentry first = zipEntry(p);
+    for (i = 0; p[0] != ZIP_END && i < num; i++) {
+        p += zipRawEntryLength(p);
+        deleted++;
+    }
+
+    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. */
+            nextdiff = zipPrevLenByteDiff(p,first.prevrawlen);
+            zipEncodeLength(p-nextdiff,ZIP_ENC_RAW,first.prevrawlen);
+
+            /* Update offset for tail */
+            ZIPLIST_TAIL_OFFSET(zl) -= totlen+nextdiff;
+
+            /* Move tail to the front of the ziplist */
+            memmove(first.p,p-nextdiff,ZIPLIST_BYTES(zl)-(p-zl)-1+nextdiff);
+        } else {
+            /* The entire tail was deleted. No need to move memory. */
+            ZIPLIST_TAIL_OFFSET(zl) = (first.p-zl)-first.prevrawlen;
+        }
+
+        /* Resize and update length */
+        zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen+nextdiff);
+        ZIPLIST_INCR_LENGTH(zl,-deleted);
+    }
+    return zl;
 }
 
-unsigned char *ziplistPush(unsigned char *zl, unsigned char *entry, unsigned int elen, int where) {
-    unsigned int curlen = ZIPLIST_BYTES(zl), reqlen;
-    unsigned char *p;
+/* 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;
     char encoding = ZIP_ENC_RAW;
     long long value;
+    zlentry entry;
+
+    /* Find out prevlen for the entry that is inserted. */
+    if (p[0] != ZIP_END) {
+        entry = zipEntry(p);
+        prevlen = entry.prevrawlen;
+    } else {
+        tail = ziplistTail(zl);
+        if (tail[0] != ZIP_END) {
+            prevlen = zipRawEntryLength(tail);
+        }
+    }
 
     /* See if the entry can be encoded */
-    if (zipTryEncoding(entry,&value,&encoding)) {
+    if (zipTryEncoding(s,&value,&encoding)) {
         reqlen = zipEncodingSize(encoding);
     } else {
-        reqlen = elen;
+        reqlen = slen;
     }
-    reqlen += zipEncodeLength(NULL,encoding,elen);
-
-    /* Resize the ziplist and move if needed */
-    zl = ziplistResize(zl,curlen+reqlen);
-    if (where == ZIPLIST_HEAD) {
-        p = zl+ZIPLIST_HEADER_SIZE;
-        if (*p != ZIP_END) {
-            /* Subtract one because of the ZIP_END bytes */
-            memmove(p+reqlen,p,curlen-ZIPLIST_HEADER_SIZE-1);
-        }
+
+    /* We need space for both the length of the previous entry and
+     * the length of the payload. */
+    reqlen += zipEncodeLength(NULL,ZIP_ENC_RAW,prevlen);
+    reqlen += zipEncodeLength(NULL,encoding,slen);
+
+    /* When the insert position is not equal to the tail, we need to
+     * make sure that the next entry can hold this entry's length in
+     * its prevlen field. */
+    nextdiff = p[0] != ZIP_END ? zipPrevLenByteDiff(p,reqlen) : 0;
+
+    /* Store offset because a realloc may change the address of zl. */
+    offset = p-zl;
+    zl = ziplistResize(zl,curlen+reqlen+nextdiff);
+    p = zl+offset;
+
+    /* Apply memory move when necessary and update tail offset. */
+    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. */
+        zipEncodeLength(p+reqlen,ZIP_ENC_RAW,reqlen);
+        /* Update offset for tail */
+        ZIPLIST_TAIL_OFFSET(zl) += reqlen+nextdiff;
     } else {
-        p = zl+curlen-1;
+        /* This element will be the new tail. */
+        ZIPLIST_TAIL_OFFSET(zl) = p-zl;
     }
 
     /* Write the entry */
-    p += zipEncodeLength(p,encoding,elen);
+    p += zipEncodeLength(p,ZIP_ENC_RAW,prevlen);
+    p += zipEncodeLength(p,encoding,slen);
     if (encoding != ZIP_ENC_RAW) {
         zipSaveInteger(p,value,encoding);
     } else {
-        memcpy(p,entry,elen);
+        memcpy(p,s,slen);
     }
     ZIPLIST_INCR_LENGTH(zl,1);
     return zl;
 }
 
+unsigned char *ziplistPush(unsigned char *zl, unsigned char *s, unsigned int slen, int where) {
+    unsigned char *p;
+    p = (where == ZIPLIST_HEAD) ? ziplistHead(zl) : (zl+ZIPLIST_BYTES(zl)-1);
+    return __ziplistInsert(zl,p,s,slen);
+}
+
 unsigned char *ziplistPop(unsigned char *zl, sds *target, int where) {
-    unsigned int curlen = ZIPLIST_BYTES(zl), rawlen;
-    unsigned int len, lensize;
+    zlentry entry;
     unsigned char *p;
     long long value;
     if (target) *target = NULL;
@@ -108,25 +368,18 @@ unsigned char *ziplistPop(unsigned char *zl, sds *target, int where) {
     /* Get pointer to element to remove */
     p = (where == ZIPLIST_HEAD) ? ziplistHead(zl) : ziplistTail(zl);
     if (*p == ZIP_END) return zl;
-    len = zipDecodeLength(p,&lensize);
+
+    entry = zipEntry(p);
     if (target) {
-        if (ZIP_ENCODING(p) == ZIP_ENC_RAW) {
-            *target = sdsnewlen(p+lensize,len);
+        if (entry.encoding == ZIP_ENC_RAW) {
+            *target = sdsnewlen(p+entry.headersize,entry.len);
         } else {
-            value = zipLoadInteger(p+lensize,ZIP_ENCODING(p));
+            value = zipLoadInteger(p+entry.headersize,entry.encoding);
             *target = sdscatprintf(sdsempty(), "%lld", value);
         }
     }
 
-    /* Move list to front when popping from the head */
-    rawlen = lensize+len;
-    if (where == ZIPLIST_HEAD) {
-        memmove(p,p+rawlen,curlen-ZIPLIST_HEADER_SIZE-len);
-    }
-
-    /* Resize and update length */
-    zl = ziplistResize(zl,curlen-rawlen);
-    ZIPLIST_INCR_LENGTH(zl,-1);
+    zl = __ziplistDelete(zl,p,1);
     return zl;
 }
 
@@ -141,81 +394,120 @@ unsigned char *ziplistIndex(unsigned char *zl, unsigned int index) {
     return p;
 }
 
-/* Store entry at current position in sds *value and return pointer
- * to the next entry. */
-unsigned char *ziplistNext(unsigned char *p, unsigned char **q, unsigned char **entry, unsigned int *elen) {
-    unsigned int lensize;
-    if (*p == ZIP_END) return NULL;
-    if (entry) {
-        *elen = zipDecodeLength(p,&lensize);
-        *entry = p+lensize;
+/* Return pointer to next entry in ziplist. */
+unsigned char *ziplistNext(unsigned char *p) {
+    return *p == ZIP_END ? p : p+zipRawEntryLength(p);
+}
+
+/* Get entry pointer to by 'p' and store in either 'e' or 'v' depending
+ * on the encoding of the entry. 'e' is always set to NULL to be able
+ * to find out whether the string pointer or the integer value was set.
+ * Return 0 if 'p' points to the end of the zipmap, 1 otherwise. */
+unsigned int ziplistGet(unsigned char *p, unsigned char **sstr, unsigned int *slen, long long *sval) {
+    zlentry entry;
+    if (*p == ZIP_END) return 0;
+    if (sstr) *sstr = NULL;
+
+    entry = zipEntry(p);
+    if (entry.encoding == ZIP_ENC_RAW) {
+        if (sstr) {
+            *slen = entry.len;
+            *sstr = p+entry.headersize;
+        }
+    } else {
+        if (sval) {
+            *sval = zipLoadInteger(p+entry.headersize,entry.encoding);
+        }
     }
-    if (q != NULL) *q = p;
-    p += zipRawEntryLength(p);
-    return p;
+    return 1;
 }
 
 /* Delete a range of entries from the ziplist. */
 unsigned char *ziplistDeleteRange(unsigned char *zl, unsigned int index, unsigned int num) {
-    unsigned char *p, *first = ziplistIndex(zl, index);
-    unsigned int i, deleted = 0, totlen, newlen;
-    for (p = first, i = 0; *p != ZIP_END && i < num; i++) {
-        p += zipRawEntryLength(p);
-        deleted++;
-    }
-
-    totlen = p-first;
-    if (totlen > 0) {
-        /* Move current tail to the new tail when there *is* a tail */
-        if (*p != ZIP_END) memmove(first,p,ZIPLIST_BYTES(zl)-(p-zl)-1);
-
-        /* Resize and update length */
-        zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-totlen);
-        ZIPLIST_INCR_LENGTH(zl,-deleted);
-    }
-    return zl;
+    unsigned char *p = ziplistIndex(zl,index);
+    return __ziplistDelete(zl,p,num);
 }
 
 /* Delete a single entry from the ziplist, pointed to by *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, tail, len;
-    len = zipRawEntryLength(*p);
-    tail = ZIPLIST_BYTES(zl)-offset-len-1;
+    unsigned int offset = *p-zl;
+    zl = __ziplistDelete(zl,*p,1);
 
-    /* Move current tail to the new tail when there *is* a tail */
-    if (tail > 0) memmove(*p,*p+len,tail);
-
-    /* Resize and update length */
-    zl = ziplistResize(zl, ZIPLIST_BYTES(zl)-len);
-    ZIPLIST_INCR_LENGTH(zl,-1);
-
-    /* Store new pointer to current element in p.
-     * This needs to be done because zl can change on realloc. */
+    /* Store pointer to current element in p, because ziplistDelete will
+     * do a realloc which might result in a different "zl"-pointer. */
     *p = zl+offset;
     return zl;
 }
 
+/* Compare entry pointer to by 'p' with 'entry'. Return 1 if equal. */
+unsigned int ziplistCompare(unsigned char *p, unsigned char *sstr, unsigned int slen) {
+    zlentry entry;
+    unsigned char sencoding;
+    long long val, sval;
+    if (*p == ZIP_END) return 0;
+
+    entry = zipEntry(p);
+    if (entry.encoding == ZIP_ENC_RAW) {
+        /* Raw compare */
+        if (entry.len == slen) {
+            return memcmp(p+entry.headersize,sstr,slen) == 0;
+        } else {
+            return 0;
+        }
+    } else {
+        /* Try to compare encoded values */
+        if (zipTryEncoding(sstr,&sval,&sencoding)) {
+            if (entry.encoding == sencoding) {
+                val = zipLoadInteger(p+entry.headersize,entry.encoding);
+                return val == sval;
+            }
+        }
+    }
+    return 0;
+}
+
+/* Return length of ziplist. */
+unsigned int ziplistLen(unsigned char *zl) {
+    unsigned int len = 0;
+    if (ZIPLIST_LENGTH(zl) < ZIP_BIGLEN) {
+        len = ZIPLIST_LENGTH(zl);
+    } else {
+        unsigned char *p = zl+ZIPLIST_HEADER_SIZE;
+        while (*p != ZIP_END) {
+            p += zipRawEntryLength(p);
+            len++;
+        }
+
+        /* Re-store length if small enough */
+        if (len < ZIP_BIGLEN) ZIPLIST_LENGTH(zl) = len;
+    }
+    return len;
+}
+
+/* Return size in bytes of ziplist. */
+unsigned int ziplistSize(unsigned char *zl) {
+    return ZIPLIST_BYTES(zl);
+}
+
 void ziplistRepr(unsigned char *zl) {
-    unsigned char *p, encoding;
-    unsigned int l, lsize;
-    long long value;
+    unsigned char *p;
+    zlentry entry;
 
     printf("{total bytes %d} {length %u}\n",ZIPLIST_BYTES(zl), ZIPLIST_LENGTH(zl));
     p = ziplistHead(zl);
     while(*p != ZIP_END) {
-        l = zipDecodeLength(p,&lsize);
-        printf("{header %u, payload %u} ",lsize,l);
-        encoding = ZIP_ENCODING(p);
-        p += lsize;
-        if (encoding == ZIP_ENC_RAW) {
-            fwrite(p,l,1,stdout);
+        entry = zipEntry(p);
+        printf("{offset %ld, header %u, payload %u} ",p-zl,entry.headersize,entry.len);
+        p += entry.headersize;
+        if (entry.encoding == ZIP_ENC_RAW) {
+            fwrite(p,entry.len,1,stdout);
         } else {
-            printf("%lld", zipLoadInteger(p,encoding));
+            printf("%lld", zipLoadInteger(p,entry.encoding));
         }
         printf("\n");
-        p += l;
+        p += entry.len;
     }
     printf("{end}\n\n");
 }
@@ -227,6 +519,7 @@ unsigned char *createList() {
     zl = ziplistPush(zl, (unsigned char*)"foo", 3, ZIPLIST_TAIL);
     zl = ziplistPush(zl, (unsigned char*)"quux", 4, ZIPLIST_TAIL);
     zl = ziplistPush(zl, (unsigned char*)"hello", 5, ZIPLIST_HEAD);
+    zl = ziplistPush(zl, (unsigned char*)"1024", 4, ZIPLIST_TAIL);
     return zl;
 }
 
@@ -252,6 +545,7 @@ unsigned char *createIntList() {
 int main(int argc, char **argv) {
     unsigned char *zl, *p, *q, *entry;
     unsigned int elen;
+    long long value;
     sds s;
 
     zl = createIntList();
@@ -268,14 +562,27 @@ int main(int argc, char **argv) {
     printf("Pop head: %s (length %ld)\n", s, sdslen(s));
     ziplistRepr(zl);
 
+    zl = ziplistPop(zl, &s, ZIPLIST_TAIL);
+    printf("Pop tail: %s (length %ld)\n", s, sdslen(s));
+    ziplistRepr(zl);
+
+    zl = ziplistPop(zl, &s, ZIPLIST_TAIL);
+    printf("Pop tail: %s (length %ld)\n", s, sdslen(s));
+    ziplistRepr(zl);
+
     printf("Iterate list from 0 to end:\n");
     {
         zl = createList();
         p = ziplistIndex(zl, 0);
-        while ((p = ziplistNext(p, NULL, &entry, &elen)) != NULL) {
+        while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
-            fwrite(entry,elen,1,stdout);
-            printf(" (length %d)\n", elen);
+            if (entry) {
+                fwrite(entry,elen,1,stdout);
+            } else {
+                printf("%lld", value);
+            }
+            p = ziplistNext(p);
+            printf("\n");
         }
         printf("\n");
     }
@@ -284,10 +591,15 @@ int main(int argc, char **argv) {
     {
         zl = createList();
         p = ziplistIndex(zl, 1);
-        while ((p = ziplistNext(p, NULL, &entry, &elen)) != NULL) {
+        while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
-            fwrite(entry,elen,1,stdout);
-            printf(" (length %d)\n", elen);
+            if (entry) {
+                fwrite(entry,elen,1,stdout);
+            } else {
+                printf("%lld", value);
+            }
+            p = ziplistNext(p);
+            printf("\n");
         }
         printf("\n");
     }
@@ -296,10 +608,15 @@ int main(int argc, char **argv) {
     {
         zl = createList();
         p = ziplistIndex(zl, 2);
-        while ((p = ziplistNext(p, NULL, &entry, &elen)) != NULL) {
+        while (ziplistGet(p, &entry, &elen, &value)) {
             printf("Entry: ");
-            fwrite(entry,elen,1,stdout);
-            printf(" (length %d)\n", elen);
+            if (entry) {
+                fwrite(entry,elen,1,stdout);
+            } else {
+                printf("%lld", value);
+            }
+            p = ziplistNext(p);
+            printf("\n");
         }
         printf("\n");
     }
@@ -307,8 +624,8 @@ int main(int argc, char **argv) {
     printf("Iterate starting out of range:\n");
     {
         zl = createList();
-        p = ziplistIndex(zl, 3);
-        if (ziplistNext(p, &entry, NULL, &elen) == NULL) {
+        p = ziplistIndex(zl, 4);
+        if (!ziplistGet(p, &entry, &elen, &value)) {
             printf("No entry\n");
         } else {
             printf("ERROR\n");
@@ -355,20 +672,48 @@ int main(int argc, char **argv) {
     {
         zl = createList();
         p = ziplistIndex(zl, 0);
-        while ((p = ziplistNext(p, &q, &entry, &elen)) != NULL) {
-            if (strncmp("foo", entry, elen) == 0) {
+        while (ziplistGet(p, &entry, &elen, &value)) {
+            if (entry && strncmp("foo", entry, elen) == 0) {
                 printf("Delete foo\n");
-                zl = ziplistDelete(zl, &q);
-                p = q;
+                zl = ziplistDelete(zl, &p);
             } else {
                 printf("Entry: ");
-                fwrite(entry,elen,1,stdout);
-                printf(" (length %d)\n", elen);
+                if (entry) {
+                    fwrite(entry,elen,1,stdout);
+                } else {
+                    printf("%lld", value);
+                }
+                p = ziplistNext(p);
+                printf("\n");
             }
         }
         printf("\n");
         ziplistRepr(zl);
-        printf("\n");
+    }
+
+    printf("Compare strings with ziplist entries:\n");
+    {
+        zl = createList();
+        p = ziplistIndex(zl, 0);
+        if (!ziplistCompare(p,"hello",5)) {
+            printf("ERROR: not \"hello\"\n");
+            return;
+        }
+        if (ziplistCompare(p,"hella",5)) {
+            printf("ERROR: \"hella\"\n");
+            return;
+        }
+
+        p = ziplistIndex(zl, 3);
+        if (!ziplistCompare(p,"1024",4)) {
+            printf("ERROR: not \"1024\"\n");
+            return;
+        }
+        if (ziplistCompare(p,"1025",4)) {
+            printf("ERROR: \"1025\"\n");
+            return;
+        }
+        printf("SUCCESS\n");
     }
 
     return 0;