/* Bit operations.
*
* 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 "redis.h"
/* -----------------------------------------------------------------------------
* Helpers and low level bit functions.
* -------------------------------------------------------------------------- */
/* This helper function used by GETBIT / SETBIT parses the bit offset argument
* making sure an error is returned if it is negative or if it overflows
* Redis 512 MB limit for the string value. */
static int getBitOffsetFromArgument(redisClient *c, robj *o, size_t *offset) {
long long loffset;
char *err = "bit offset is not an integer or out of range";
if (getLongLongFromObjectOrReply(c,o,&loffset,err) != REDIS_OK)
return REDIS_ERR;
/* Limit offset to 512MB in bytes */
if ((loffset < 0) || ((unsigned long long)loffset >> 3) >= (512*1024*1024))
{
addReplyError(c,err);
return REDIS_ERR;
}
*offset = (size_t)loffset;
return REDIS_OK;
}
/* Count number of bits set in the binary array pointed by 's' and long
* 'count' bytes. The implementation of this function is required to
* work with a input string length up to 512 MB. */
size_t redisPopcount(void *s, long count) {
size_t bits = 0;
unsigned char *p = s;
uint32_t *p4;
static const unsigned char bitsinbyte[256] = {0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8};
/* Count initial bytes not aligned to 32 bit. */
while((unsigned long)p & 3 && count) {
bits += bitsinbyte[*p++];
count--;
}
/* Count bits 16 bytes at a time */
p4 = (uint32_t*)p;
while(count>=16) {
uint32_t aux1, aux2, aux3, aux4;
aux1 = *p4++;
aux2 = *p4++;
aux3 = *p4++;
aux4 = *p4++;
count -= 16;
aux1 = aux1 - ((aux1 >> 1) & 0x55555555);
aux1 = (aux1 & 0x33333333) + ((aux1 >> 2) & 0x33333333);
aux2 = aux2 - ((aux2 >> 1) & 0x55555555);
aux2 = (aux2 & 0x33333333) + ((aux2 >> 2) & 0x33333333);
aux3 = aux3 - ((aux3 >> 1) & 0x55555555);
aux3 = (aux3 & 0x33333333) + ((aux3 >> 2) & 0x33333333);
aux4 = aux4 - ((aux4 >> 1) & 0x55555555);
aux4 = (aux4 & 0x33333333) + ((aux4 >> 2) & 0x33333333);
bits += ((((aux1 + (aux1 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
((((aux2 + (aux2 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
((((aux3 + (aux3 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
((((aux4 + (aux4 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24);
}
/* Count the remaining bytes. */
p = (unsigned char*)p4;
while(count--) bits += bitsinbyte[*p++];
return bits;
}
/* Return the position of the first bit set to one (if 'bit' is 1) or
* zero (if 'bit' is 0) in the bitmap starting at 's' and long 'count' bytes.
*
* The function is guaranteed to return a value >= 0 if 'bit' is 0 since if
* no zero bit is found, it returns count*8 assuming the string is zero
* padded on the right. However if 'bit' is 1 it is possible that there is
* not a single set bit in the bitmap. In this special case -1 is returned. */
long redisBitpos(void *s, long count, int bit) {
unsigned long *l;
unsigned char *c;
unsigned long skipval, word = 0, one;
long pos = 0; /* Position of bit, to return to the caller. */
int j;
/* Process whole words first, seeking for first word that is not
* all ones or all zeros respectively if we are lookig for zeros
* or ones. This is much faster with large strings having contiguous
* blocks of 1 or 0 bits compared to the vanilla bit per bit processing.
*
* Note that if we start from an address that is not aligned
* to sizeof(unsigned long) we consume it byte by byte until it is
* aligned. */
/* Skip initial bits not aligned to sizeof(unsigned long) byte by byte. */
skipval = bit ? 0 : UCHAR_MAX;
c = (unsigned char*) s;
while((unsigned long)c & (sizeof(*l)-1) && count) {
if (*c != skipval) break;
c++;
count--;
pos += 8;
}
/* Skip bits with full word step. */
skipval = bit ? 0 : ULONG_MAX;
l = (unsigned long*) c;
while (count >= sizeof(*l)) {
if (*l != skipval) break;
l++;
count -= sizeof(*l);
pos += sizeof(*l)*8;
}
/* Load bytes into "word" considering the first byte as the most significant
* (we basically consider it as written in big endian, since we consider the
* string as a set of bits from left to right, with the first bit at position
* zero.
*
* Note that the loading is designed to work even when the bytes left
* (count) are less than a full word. We pad it with zero on the right. */
c = (unsigned char*)l;
for (j = 0; j < sizeof(*l); j++) {
word <<= 8;
if (count) {
word |= *c;
c++;
count--;
}
}
/* Special case:
* If bits in the string are all zero and we are looking for one,
* return -1 to signal that there is not a single "1" in the whole
* string. This can't happen when we are looking for "0" as we assume
* that the right of the string is zero padded. */
if (bit == 1 && word == 0) return -1;
/* Last word left, scan bit by bit. The first thing we need is to
* have a single "1" set in the most significant position in an
* unsigned long. We don't know the size of the long so we use a
* simple trick. */
one = ULONG_MAX; /* All bits set to 1.*/
one >>= 1; /* All bits set to 1 but the MSB. */
one = ~one; /* All bits set to 0 but the MSB. */
while(one) {
if (((one & word) != 0) == bit) return pos;
pos++;
one >>= 1;
}
/* If we reached this point, there is a bug in the algorithm, since
* the case of no match is handled as a special case before. */
redisPanic("End of redisBitpos() reached.");
return 0; /* Just to avoid warnings. */
}
/* -----------------------------------------------------------------------------
* Bits related string commands: GETBIT, SETBIT, BITCOUNT, BITOP.
* -------------------------------------------------------------------------- */
#define BITOP_AND 0
#define BITOP_OR 1
#define BITOP_XOR 2
#define BITOP_NOT 3
/* SETBIT key offset bitvalue */
void setbitCommand(redisClient *c) {
robj *o;
char *err = "bit is not an integer or out of range";
size_t bitoffset;
int byte, bit;
int byteval, bitval;
long on;
if (getBitOffsetFromArgument(c,c->argv[2],&bitoffset) != REDIS_OK)
return;
if (getLongFromObjectOrReply(c,c->argv[3],&on,err) != REDIS_OK)
return;
/* Bits can only be set or cleared... */
if (on & ~1) {
addReplyError(c,err);
return;
}
o = lookupKeyWrite(c->db,c->argv[1]);
if (o == NULL) {
o = createObject(REDIS_STRING,sdsempty());
dbAdd(c->db,c->argv[1],o);
} else {
if (checkType(c,o,REDIS_STRING)) return;
o = dbUnshareStringValue(c->db,c->argv[1],o);
}
/* Grow sds value to the right length if necessary */
byte = bitoffset >> 3;
o->ptr = sdsgrowzero(o->ptr,byte+1);
/* Get current values */
byteval = ((uint8_t*)o->ptr)[byte];
bit = 7 - (bitoffset & 0x7);
bitval = byteval & (1 << bit);
/* Update byte with new bit value and return original value */
byteval &= ~(1 << bit);
byteval |= ((on & 0x1) << bit);
((uint8_t*)o->ptr)[byte] = byteval;
signalModifiedKey(c->db,c->argv[1]);
notifyKeyspaceEvent(REDIS_NOTIFY_STRING,"setbit",c->argv[1],c->db->id);
server.dirty++;
addReply(c, bitval ? shared.cone : shared.czero);
}
/* GETBIT key offset */
void getbitCommand(redisClient *c) {
robj *o;
char llbuf[32];
size_t bitoffset;
size_t byte, bit;
size_t bitval = 0;
if (getBitOffsetFromArgument(c,c->argv[2],&bitoffset) != REDIS_OK)
return;
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,o,REDIS_STRING)) return;
byte = bitoffset >> 3;
bit = 7 - (bitoffset & 0x7);
if (sdsEncodedObject(o)) {
if (byte < sdslen(o->ptr))
bitval = ((uint8_t*)o->ptr)[byte] & (1 << bit);
} else {
if (byte < (size_t)ll2string(llbuf,sizeof(llbuf),(long)o->ptr))
bitval = llbuf[byte] & (1 << bit);
}
addReply(c, bitval ? shared.cone : shared.czero);
}
/* BITOP op_name target_key src_key1 src_key2 src_key3 ... src_keyN */
void bitopCommand(redisClient *c) {
char *opname = c->argv[1]->ptr;
robj *o, *targetkey = c->argv[2];
long op, j, numkeys;
robj **objects; /* Array of source objects. */
unsigned char **src; /* Array of source strings pointers. */
long *len, maxlen = 0; /* Array of length of src strings, and max len. */
long minlen = 0; /* Min len among the input keys. */
unsigned char *res = NULL; /* Resulting string. */
/* Parse the operation name. */
if ((opname[0] == 'a' || opname[0] == 'A') && !strcasecmp(opname,"and"))
op = BITOP_AND;
else if((opname[0] == 'o' || opname[0] == 'O') && !strcasecmp(opname,"or"))
op = BITOP_OR;
else if((opname[0] == 'x' || opname[0] == 'X') && !strcasecmp(opname,"xor"))
op = BITOP_XOR;
else if((opname[0] == 'n' || opname[0] == 'N') && !strcasecmp(opname,"not"))
op = BITOP_NOT;
else {
addReply(c,shared.syntaxerr);
return;
}
/* Sanity check: NOT accepts only a single key argument. */
if (op == BITOP_NOT && c->argc != 4) {
addReplyError(c,"BITOP NOT must be called with a single source key.");
return;
}
/* Lookup keys, and store pointers to the string objects into an array. */
numkeys = c->argc - 3;
src = zmalloc(sizeof(unsigned char*) * numkeys);
len = zmalloc(sizeof(long) * numkeys);
objects = zmalloc(sizeof(robj*) * numkeys);
for (j = 0; j < numkeys; j++) {
o = lookupKeyRead(c->db,c->argv[j+3]);
/* Handle non-existing keys as empty strings. */
if (o == NULL) {
objects[j] = NULL;
src[j] = NULL;
len[j] = 0;
minlen = 0;
continue;
}
/* Return an error if one of the keys is not a string. */
if (checkType(c,o,REDIS_STRING)) {
for (j = j-1; j >= 0; j--) {
if (objects[j])
decrRefCount(objects[j]);
}
zfree(src);
zfree(len);
zfree(objects);
return;
}
objects[j] = getDecodedObject(o);
src[j] = objects[j]->ptr;
len[j] = sdslen(objects[j]->ptr);
if (len[j] > maxlen) maxlen = len[j];
if (j == 0 || len[j] < minlen) minlen = len[j];
}
/* Compute the bit operation, if at least one string is not empty. */
if (maxlen) {
res = (unsigned char*) sdsnewlen(NULL,maxlen);
unsigned char output, byte;
long i;
/* Fast path: as far as we have data for all the input bitmaps we
* can take a fast path that performs much better than the
* vanilla algorithm. */
j = 0;
if (minlen && numkeys <= 16) {
unsigned long *lp[16];
unsigned long *lres = (unsigned long*) res;
/* Note: sds pointer is always aligned to 8 byte boundary. */
memcpy(lp,src,sizeof(unsigned long*)*numkeys);
memcpy(res,src[0],minlen);
/* Different branches per different operations for speed (sorry). */
if (op == BITOP_AND) {
while(minlen >= sizeof(unsigned long)*4) {
for (i = 1; i < numkeys; i++) {
lres[0] &= lp[i][0];
lres[1] &= lp[i][1];
lres[2] &= lp[i][2];
lres[3] &= lp[i][3];
lp[i]+=4;
}
lres+=4;
j += sizeof(unsigned long)*4;
minlen -= sizeof(unsigned long)*4;
}
} else if (op == BITOP_OR) {
while(minlen >= sizeof(unsigned long)*4) {
for (i = 1; i < numkeys; i++) {
lres[0] |= lp[i][0];
lres[1] |= lp[i][1];
lres[2] |= lp[i][2];
lres[3] |= lp[i][3];
lp[i]+=4;
}
lres+=4;
j += sizeof(unsigned long)*4;
minlen -= sizeof(unsigned long)*4;
}
} else if (op == BITOP_XOR) {
while(minlen >= sizeof(unsigned long)*4) {
for (i = 1; i < numkeys; i++) {
lres[0] ^= lp[i][0];
lres[1] ^= lp[i][1];
lres[2] ^= lp[i][2];
lres[3] ^= lp[i][3];
lp[i]+=4;
}
lres+=4;
j += sizeof(unsigned long)*4;
minlen -= sizeof(unsigned long)*4;
}
} else if (op == BITOP_NOT) {
while(minlen >= sizeof(unsigned long)*4) {
lres[0] = ~lres[0];
lres[1] = ~lres[1];
lres[2] = ~lres[2];
lres[3] = ~lres[3];
lres+=4;
j += sizeof(unsigned long)*4;
minlen -= sizeof(unsigned long)*4;
}
}
}
/* j is set to the next byte to process by the previous loop. */
for (; j < maxlen; j++) {
output = (len[0] <= j) ? 0 : src[0][j];
if (op == BITOP_NOT) output = ~output;
for (i = 1; i < numkeys; i++) {
byte = (len[i] <= j) ? 0 : src[i][j];
switch(op) {
case BITOP_AND: output &= byte; break;
case BITOP_OR: output |= byte; break;
case BITOP_XOR: output ^= byte; break;
}
}
res[j] = output;
}
}
for (j = 0; j < numkeys; j++) {
if (objects[j])
decrRefCount(objects[j]);
}
zfree(src);
zfree(len);
zfree(objects);
/* Store the computed value into the target key */
if (maxlen) {
o = createObject(REDIS_STRING,res);
setKey(c->db,targetkey,o);
notifyKeyspaceEvent(REDIS_NOTIFY_STRING,"set",targetkey,c->db->id);
decrRefCount(o);
} else if (dbDelete(c->db,targetkey)) {
signalModifiedKey(c->db,targetkey);
notifyKeyspaceEvent(REDIS_NOTIFY_GENERIC,"del",targetkey,c->db->id);
}
server.dirty++;
addReplyLongLong(c,maxlen); /* Return the output string length in bytes. */
}
/* BITCOUNT key [start end] */
void bitcountCommand(redisClient *c) {
robj *o;
long start, end, strlen;
unsigned char *p;
char llbuf[32];
/* Lookup, check for type, and return 0 for non existing keys. */
if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
checkType(c,o,REDIS_STRING)) return;
/* Set the 'p' pointer to the string, that can be just a stack allocated
* array if our string was integer encoded. */
if (o->encoding == REDIS_ENCODING_INT) {
p = (unsigned char*) llbuf;
strlen = ll2string(llbuf,sizeof(llbuf),(long)o->ptr);
} else {
p = (unsigned char*) o->ptr;
strlen = sdslen(o->ptr);
}
/* Parse start/end range if any. */
if (c->argc == 4) {
if (getLongFromObjectOrReply(c,c->argv[2],&start,NULL) != REDIS_OK)
return;
if (getLongFromObjectOrReply(c,c->argv[3],&end,NULL) != REDIS_OK)
return;
/* Convert negative indexes */
if (start < 0) start = strlen+start;
if (end < 0) end = strlen+end;
if (start < 0) start = 0;
if (end < 0) end = 0;
if (end >= strlen) end = strlen-1;
} else if (c->argc == 2) {
/* The whole string. */
start = 0;
end = strlen-1;
} else {
/* Syntax error. */
addReply(c,shared.syntaxerr);
return;
}
/* Precondition: end >= 0 && end < strlen, so the only condition where
* zero can be returned is: start > end. */
if (start > end) {
addReply(c,shared.czero);
} else {
long bytes = end-start+1;
addReplyLongLong(c,redisPopcount(p+start,bytes));
}
}
/* BITPOS key bit [start [end]] */
void bitposCommand(redisClient *c) {
robj *o;
long bit, start, end, strlen;
unsigned char *p;
char llbuf[32];
int end_given = 0;
/* Parse the bit argument to understand what we are looking for, set
* or clear bits. */
if (getLongFromObjectOrReply(c,c->argv[2],&bit,NULL) != REDIS_OK)
return;
if (bit != 0 && bit != 1) {
addReplyError(c, "The bit argument must be 1 or 0.");
return;
}
/* If the key does not exist, from our point of view it is an infinite
* array of 0 bits. If the user is looking for the fist clear bit return 0,
* If the user is looking for the first set bit, return -1. */
if ((o = lookupKeyRead(c->db,c->argv[1])) == NULL) {
addReplyLongLong(c, bit ? -1 : 0);
return;
}
if (checkType(c,o,REDIS_STRING)) return;
/* Set the 'p' pointer to the string, that can be just a stack allocated
* array if our string was integer encoded. */
if (o->encoding == REDIS_ENCODING_INT) {
p = (unsigned char*) llbuf;
strlen = ll2string(llbuf,sizeof(llbuf),(long)o->ptr);
} else {
p = (unsigned char*) o->ptr;
strlen = sdslen(o->ptr);
}
/* Parse start/end range if any. */
if (c->argc == 4 || c->argc == 5) {
if (getLongFromObjectOrReply(c,c->argv[3],&start,NULL) != REDIS_OK)
return;
if (c->argc == 5) {
if (getLongFromObjectOrReply(c,c->argv[4],&end,NULL) != REDIS_OK)
return;
end_given = 1;
} else {
end = strlen-1;
}
/* Convert negative indexes */
if (start < 0) start = strlen+start;
if (end < 0) end = strlen+end;
if (start < 0) start = 0;
if (end < 0) end = 0;
if (end >= strlen) end = strlen-1;
} else if (c->argc == 3) {
/* The whole string. */
start = 0;
end = strlen-1;
} else {
/* Syntax error. */
addReply(c,shared.syntaxerr);
return;
}
/* For empty ranges (start > end) we return -1 as an empty range does
* not contain a 0 nor a 1. */
if (start > end) {
addReplyLongLong(c, -1);
} else {
long bytes = end-start+1;
long pos = redisBitpos(p+start,bytes,bit);
/* If we are looking for clear bits, and the user specified an exact
* range with start-end, we can't consider the right of the range as
* zero padded (as we do when no explicit end is given).
*
* So if redisBitpos() returns the first bit outside the range,
* we return -1 to the caller, to mean, in the specified range there
* is not a single "0" bit. */
if (end_given && bit == 0 && pos == bytes*8) {
addReplyLongLong(c,-1);
return;
}
if (pos != -1) pos += start*8; /* Adjust for the bytes we skipped. */
addReplyLongLong(c,pos);
}
}