* 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.
- * |1100____| - 1 byte
+ * |11000000| - 1 byte
* Integer encoded as int16_t (2 bytes).
- * |1101____| - 1 byte
+ * |11010000| - 1 byte
* Integer encoded as int32_t (4 bytes).
- * |1110____| - 1 byte
+ * |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.
*/
#include <stdio.h>
#include "zmalloc.h"
#include "util.h"
#include "ziplist.h"
-#include "endian.h"
+#include "endianconv.h"
#define ZIP_END 255
#define ZIP_BIGLEN 254
/* 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's to determine type */
-#define ZIP_IS_STR(enc) (((enc) & 0xc0) < 0xc0)
-#define ZIP_IS_INT(enc) (!ZIP_IS_STR(enc) && ((enc) & 0x30) < 0x30)
+/* 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)))
unsigned char *p;
} zlentry;
-/* Return the encoding pointer to by 'p'. */
-static unsigned int zipEntryEncoding(unsigned char *p) {
- /* String encoding: 2 MSBs */
- unsigned char b = p[0] & 0xc0;
- if (b < 0xc0) {
- return b;
- } else {
- /* Integer encoding: 4 MSBs */
- return p[0] & 0xf0;
- }
- assert(NULL);
- return 0;
-}
+/* 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' */
static unsigned int zipIntSize(unsigned char encoding) {
switch(encoding) {
- case ZIP_INT_16B: return sizeof(int16_t);
- case ZIP_INT_32B: return sizeof(int32_t);
- case ZIP_INT_64B: return sizeof(int64_t);
+ 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);
return 0;
}
-/* 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 = zipEntryEncoding(p);
- unsigned int len = 0;
-
- if (ZIP_IS_STR(encoding)) {
- switch(encoding) {
- case ZIP_STR_06B:
- len = p[0] & 0x3f;
- if (lensize) *lensize = 1;
- break;
- case ZIP_STR_14B:
- len = ((p[0] & 0x3f) << 8) | p[1];
- if (lensize) *lensize = 2;
- break;
- case ZIP_STR_32B:
- len = (p[1] << 24) | (p[2] << 16) | (p[3] << 8) | p[4];
- if (lensize) *lensize = 5;
- break;
- default:
- assert(NULL);
- }
- } else {
- len = zipIntSize(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, unsigned char encoding, unsigned int rawlen) {
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));
- memrev32ifbe(&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. */
memrev32ifbe(p+1);
}
-/* Return the difference in number of bytes needed to store the new length
- * "len" on the entry pointed to by "p". */
+/* 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;
- 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.
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. */
- if (value >= INT16_MIN && value <= INT16_MAX) {
+ 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) {
*encoding = ZIP_INT_32B;
} else {
int16_t i16;
int32_t i32;
int64_t i64;
- if (encoding == ZIP_INT_16B) {
+ if (encoding == ZIP_INT_8B) {
+ ((char*)p)[0] = (char)value;
+ } else if (encoding == ZIP_INT_16B) {
i16 = value;
memcpy(p,&i16,sizeof(i16));
memrev16ifbe(p);
+ } else if (encoding == ZIP_INT_24B) {
+ i32 = value<<8;
+ memrev32ifbe(&i32);
+ memcpy(p,((unsigned char*)&i32)+1,sizeof(i32)-sizeof(int8_t));
} else if (encoding == ZIP_INT_32B) {
i32 = value;
memcpy(p,&i32,sizeof(i32));
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);
}
int16_t i16;
int32_t i32;
int64_t i64, ret = 0;
- if (encoding == ZIP_INT_16B) {
+ if (encoding == ZIP_INT_8B) {
+ ret = ((char*)p)[0];
+ } else if (encoding == ZIP_INT_16B) {
memcpy(&i16,p,sizeof(i16));
memrev16ifbe(&i16);
ret = i16;
memcpy(&i32,p,sizeof(i32));
memrev32ifbe(&i32);
ret = i32;
+ } else if (encoding == ZIP_INT_24B) {
+ i32 = 0;
+ memcpy(((unsigned char*)&i32)+1,p,sizeof(i32)-sizeof(int8_t));
+ memrev32ifbe(&i32);
+ ret = i32>>8;
} else if (encoding == ZIP_INT_64B) {
memcpy(&i64,p,sizeof(i64));
memrev64ifbe(&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);
}
/* 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 = zipEntryEncoding(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;
}
-/* 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;
* 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 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 specified entry can be encoded */
+ if (vencoding == 0) {
+ /* UINT_MAX when the entry CANNOT be encoded */
+ if (!zipTryEncoding(vstr, vlen, &vll, &vencoding)) {
+ vencoding = UCHAR_MAX;
+ }
+
+ /* Must be non-zero by now */
+ assert(vencoding);
+ }
+
+ /* Compare current entry with specified entry */
+ if (encoding == vencoding) {
+ 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;
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