eeb949a94f
It appears to work but more stress testing, and both unit tests and fuzzy testing, is needed in order to ensure the implementation is sane.
588 lines
21 KiB
C
588 lines
21 KiB
C
/* Bit operations.
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*
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* Copyright (c) 2009-2012, Salvatore Sanfilippo <antirez at gmail dot com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "redis.h"
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/* -----------------------------------------------------------------------------
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* Helpers and low level bit functions.
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* -------------------------------------------------------------------------- */
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/* This helper function used by GETBIT / SETBIT parses the bit offset argument
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* making sure an error is returned if it is negative or if it overflows
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* Redis 512 MB limit for the string value. */
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static int getBitOffsetFromArgument(redisClient *c, robj *o, size_t *offset) {
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long long loffset;
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char *err = "bit offset is not an integer or out of range";
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if (getLongLongFromObjectOrReply(c,o,&loffset,err) != REDIS_OK)
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return REDIS_ERR;
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/* Limit offset to 512MB in bytes */
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if ((loffset < 0) || ((unsigned long long)loffset >> 3) >= (512*1024*1024))
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{
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addReplyError(c,err);
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return REDIS_ERR;
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}
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*offset = (size_t)loffset;
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return REDIS_OK;
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}
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/* Count number of bits set in the binary array pointed by 's' and long
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* 'count' bytes. The implementation of this function is required to
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* work with a input string length up to 512 MB. */
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size_t redisPopcount(void *s, long count) {
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size_t bits = 0;
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unsigned char *p = s;
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uint32_t *p4;
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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};
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/* Count initial bytes not aligned to 32 bit. */
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while((unsigned long)p & 3 && count) {
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bits += bitsinbyte[*p++];
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count--;
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}
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/* Count bits 16 bytes at a time */
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p4 = (uint32_t*)p;
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while(count>=16) {
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uint32_t aux1, aux2, aux3, aux4;
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aux1 = *p4++;
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aux2 = *p4++;
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aux3 = *p4++;
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aux4 = *p4++;
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count -= 16;
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aux1 = aux1 - ((aux1 >> 1) & 0x55555555);
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aux1 = (aux1 & 0x33333333) + ((aux1 >> 2) & 0x33333333);
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aux2 = aux2 - ((aux2 >> 1) & 0x55555555);
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aux2 = (aux2 & 0x33333333) + ((aux2 >> 2) & 0x33333333);
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aux3 = aux3 - ((aux3 >> 1) & 0x55555555);
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aux3 = (aux3 & 0x33333333) + ((aux3 >> 2) & 0x33333333);
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aux4 = aux4 - ((aux4 >> 1) & 0x55555555);
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aux4 = (aux4 & 0x33333333) + ((aux4 >> 2) & 0x33333333);
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bits += ((((aux1 + (aux1 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
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((((aux2 + (aux2 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
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((((aux3 + (aux3 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24) +
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((((aux4 + (aux4 >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24);
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}
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/* Count the remaining bytes. */
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p = (unsigned char*)p4;
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while(count--) bits += bitsinbyte[*p++];
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return bits;
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}
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/* Return the position of the first bit set to one (if 'bit' is 1) or
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* zero (if 'bit' is 0) in the bitmap starting at 's' and long 'count' bytes.
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*
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* The function is guaranteed to return a value >= 0 if 'bit' is 0 since if
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* no zero bit is found, it returns count*8 assuming the string is zero
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* padded on the right. However if 'bit' is 1 it is possible that there is
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* not a single set bit in the bitmap. In this special case -1 is returned. */
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long redisBitpos(void *s, long count, int bit) {
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unsigned long *l;
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unsigned char *c;
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unsigned long skipval, word = 0, one;
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long pos = 0; /* Position of bit, to return to the caller. */
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int j;
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/* Process whole words first, seeking for first word that is not
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* all ones or all zeros respectively if we are lookig for zeros
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* or ones. This is much faster with large strings having contiguous
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* blocks of 1 or 0 bits compared to the vanilla bit per bit processing.
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*
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* Note that if we start from an address that is not aligned
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* to sizeof(unsigned long) we consume it byte by byte until it is
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* aligned. */
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/* Skip initial bits not aligned to sizeof(unsigned long) byte by byte. */
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skipval = bit ? 0 : UCHAR_MAX;
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c = (unsigned char*) s;
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while((unsigned long)c & (sizeof(*l)-1) && count) {
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if (*c != skipval) break;
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c++;
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count--;
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pos += 8;
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}
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/* Skip bits with full word step. */
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skipval = bit ? 0 : ULONG_MAX;
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l = (unsigned long*) c;
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while (count >= sizeof(*l)) {
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if (*l != skipval) break;
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l++;
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count -= sizeof(*l);
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pos += sizeof(*l)*8;
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}
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/* Load bytes into "word" considering the first byte as the most significant
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* (we basically consider it as written in big endian, since we consider the
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* string as a set of bits from left to right, with the first bit at position
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* zero.
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*
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* Note that the loading is designed to work even when the bytes left
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* (count) are less than a full word. We pad it with zero on the right. */
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c = (unsigned char*)l;
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for (j = 0; j < sizeof(*l); j++) {
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word <<= 8;
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if (count) {
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word |= *c;
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c++;
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count--;
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}
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}
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/* Special case:
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* If bits in the string are all zero and we are looking for one,
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* return -1 to signal that there is not a single "1" in the whole
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* string. This can't happen when we are looking for "0" as we assume
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* that the right of the string is zero padded. */
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if (bit == 1 && word == 0) return -1;
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/* Last word left, scan bit by bit. The first thing we need is to
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* have a single "1" set in the most significant position in an
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* unsigned long. We don't know the size of the long so we use a
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* simple trick. */
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one = ULONG_MAX; /* All bits set to 1.*/
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one >>= 1; /* All bits set to 1 but the MSB. */
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one = ~one; /* All bits set to 0 but the MSB. */
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while(one) {
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if (((one & word) != 0) == bit) return pos;
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pos++;
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one >>= 1;
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}
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/* If we reached this point, there is a bug in the algorithm, since
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* the case of no match is handled as a special case before. */
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redisPanic("End of redisBitpos() reached.");
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return 0; /* Just to avoid warnigns. */
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}
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/* -----------------------------------------------------------------------------
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* Bits related string commands: GETBIT, SETBIT, BITCOUNT, BITOP.
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* -------------------------------------------------------------------------- */
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#define BITOP_AND 0
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#define BITOP_OR 1
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#define BITOP_XOR 2
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#define BITOP_NOT 3
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/* SETBIT key offset bitvalue */
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void setbitCommand(redisClient *c) {
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robj *o;
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char *err = "bit is not an integer or out of range";
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size_t bitoffset;
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int byte, bit;
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int byteval, bitval;
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long on;
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if (getBitOffsetFromArgument(c,c->argv[2],&bitoffset) != REDIS_OK)
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return;
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if (getLongFromObjectOrReply(c,c->argv[3],&on,err) != REDIS_OK)
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return;
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/* Bits can only be set or cleared... */
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if (on & ~1) {
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addReplyError(c,err);
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return;
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}
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o = lookupKeyWrite(c->db,c->argv[1]);
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if (o == NULL) {
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o = createObject(REDIS_STRING,sdsempty());
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dbAdd(c->db,c->argv[1],o);
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} else {
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if (checkType(c,o,REDIS_STRING)) return;
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/* Create a copy when the object is shared or encoded. */
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if (o->refcount != 1 || o->encoding != REDIS_ENCODING_RAW) {
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robj *decoded = getDecodedObject(o);
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o = createRawStringObject(decoded->ptr, sdslen(decoded->ptr));
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decrRefCount(decoded);
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dbOverwrite(c->db,c->argv[1],o);
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}
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}
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/* Grow sds value to the right length if necessary */
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byte = bitoffset >> 3;
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o->ptr = sdsgrowzero(o->ptr,byte+1);
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/* Get current values */
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byteval = ((uint8_t*)o->ptr)[byte];
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bit = 7 - (bitoffset & 0x7);
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bitval = byteval & (1 << bit);
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/* Update byte with new bit value and return original value */
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byteval &= ~(1 << bit);
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byteval |= ((on & 0x1) << bit);
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((uint8_t*)o->ptr)[byte] = byteval;
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signalModifiedKey(c->db,c->argv[1]);
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notifyKeyspaceEvent(REDIS_NOTIFY_STRING,"setbit",c->argv[1],c->db->id);
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server.dirty++;
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addReply(c, bitval ? shared.cone : shared.czero);
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}
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/* GETBIT key offset */
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void getbitCommand(redisClient *c) {
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robj *o;
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char llbuf[32];
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size_t bitoffset;
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size_t byte, bit;
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size_t bitval = 0;
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if (getBitOffsetFromArgument(c,c->argv[2],&bitoffset) != REDIS_OK)
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return;
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if ((o = lookupKeyReadOrReply(c,c->argv[1],shared.czero)) == NULL ||
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checkType(c,o,REDIS_STRING)) return;
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byte = bitoffset >> 3;
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bit = 7 - (bitoffset & 0x7);
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if (sdsEncodedObject(o)) {
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if (byte < sdslen(o->ptr))
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bitval = ((uint8_t*)o->ptr)[byte] & (1 << bit);
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} else {
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if (byte < (size_t)ll2string(llbuf,sizeof(llbuf),(long)o->ptr))
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bitval = llbuf[byte] & (1 << bit);
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}
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addReply(c, bitval ? shared.cone : shared.czero);
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}
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/* BITOP op_name target_key src_key1 src_key2 src_key3 ... src_keyN */
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void bitopCommand(redisClient *c) {
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char *opname = c->argv[1]->ptr;
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robj *o, *targetkey = c->argv[2];
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long op, j, numkeys;
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robj **objects; /* Array of source objects. */
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unsigned char **src; /* Array of source strings pointers. */
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long *len, maxlen = 0; /* Array of length of src strings, and max len. */
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long minlen = 0; /* Min len among the input keys. */
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unsigned char *res = NULL; /* Resulting string. */
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/* Parse the operation name. */
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if ((opname[0] == 'a' || opname[0] == 'A') && !strcasecmp(opname,"and"))
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op = BITOP_AND;
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else if((opname[0] == 'o' || opname[0] == 'O') && !strcasecmp(opname,"or"))
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op = BITOP_OR;
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else if((opname[0] == 'x' || opname[0] == 'X') && !strcasecmp(opname,"xor"))
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op = BITOP_XOR;
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else if((opname[0] == 'n' || opname[0] == 'N') && !strcasecmp(opname,"not"))
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op = BITOP_NOT;
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else {
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addReply(c,shared.syntaxerr);
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return;
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}
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/* Sanity check: NOT accepts only a single key argument. */
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if (op == BITOP_NOT && c->argc != 4) {
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addReplyError(c,"BITOP NOT must be called with a single source key.");
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return;
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}
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/* Lookup keys, and store pointers to the string objects into an array. */
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numkeys = c->argc - 3;
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src = zmalloc(sizeof(unsigned char*) * numkeys);
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len = zmalloc(sizeof(long) * numkeys);
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objects = zmalloc(sizeof(robj*) * numkeys);
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for (j = 0; j < numkeys; j++) {
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o = lookupKeyRead(c->db,c->argv[j+3]);
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/* Handle non-existing keys as empty strings. */
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if (o == NULL) {
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objects[j] = NULL;
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src[j] = NULL;
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len[j] = 0;
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minlen = 0;
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continue;
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}
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/* Return an error if one of the keys is not a string. */
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if (checkType(c,o,REDIS_STRING)) {
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for (j = j-1; j >= 0; j--) {
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if (objects[j])
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decrRefCount(objects[j]);
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}
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zfree(src);
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zfree(len);
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zfree(objects);
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return;
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}
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objects[j] = getDecodedObject(o);
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src[j] = objects[j]->ptr;
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len[j] = sdslen(objects[j]->ptr);
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if (len[j] > maxlen) maxlen = len[j];
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if (j == 0 || len[j] < minlen) minlen = len[j];
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}
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/* Compute the bit operation, if at least one string is not empty. */
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if (maxlen) {
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res = (unsigned char*) sdsnewlen(NULL,maxlen);
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unsigned char output, byte;
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long i;
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/* Fast path: as far as we have data for all the input bitmaps we
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* can take a fast path that performs much better than the
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* vanilla algorithm. */
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j = 0;
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if (minlen && numkeys <= 16) {
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unsigned long *lp[16];
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unsigned long *lres = (unsigned long*) res;
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/* Note: sds pointer is always aligned to 8 byte boundary. */
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memcpy(lp,src,sizeof(unsigned long*)*numkeys);
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memcpy(res,src[0],minlen);
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/* Different branches per different operations for speed (sorry). */
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if (op == BITOP_AND) {
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while(minlen >= sizeof(unsigned long)*4) {
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for (i = 1; i < numkeys; i++) {
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lres[0] &= lp[i][0];
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lres[1] &= lp[i][1];
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lres[2] &= lp[i][2];
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lres[3] &= lp[i][3];
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lp[i]+=4;
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}
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lres+=4;
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j += sizeof(unsigned long)*4;
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minlen -= sizeof(unsigned long)*4;
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}
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} else if (op == BITOP_OR) {
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while(minlen >= sizeof(unsigned long)*4) {
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for (i = 1; i < numkeys; i++) {
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lres[0] |= lp[i][0];
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lres[1] |= lp[i][1];
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lres[2] |= lp[i][2];
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lres[3] |= lp[i][3];
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lp[i]+=4;
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}
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lres+=4;
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j += sizeof(unsigned long)*4;
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minlen -= sizeof(unsigned long)*4;
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}
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} else if (op == BITOP_XOR) {
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while(minlen >= sizeof(unsigned long)*4) {
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for (i = 1; i < numkeys; i++) {
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lres[0] ^= lp[i][0];
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lres[1] ^= lp[i][1];
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lres[2] ^= lp[i][2];
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lres[3] ^= lp[i][3];
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lp[i]+=4;
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}
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lres+=4;
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j += sizeof(unsigned long)*4;
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minlen -= sizeof(unsigned long)*4;
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}
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} else if (op == BITOP_NOT) {
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while(minlen >= sizeof(unsigned long)*4) {
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lres[0] = ~lres[0];
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lres[1] = ~lres[1];
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lres[2] = ~lres[2];
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lres[3] = ~lres[3];
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lres+=4;
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j += sizeof(unsigned long)*4;
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minlen -= sizeof(unsigned long)*4;
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}
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}
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}
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/* j is set to the next byte to process by the previous loop. */
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for (; j < maxlen; j++) {
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output = (len[0] <= j) ? 0 : src[0][j];
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if (op == BITOP_NOT) output = ~output;
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for (i = 1; i < numkeys; i++) {
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byte = (len[i] <= j) ? 0 : src[i][j];
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switch(op) {
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case BITOP_AND: output &= byte; break;
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case BITOP_OR: output |= byte; break;
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case BITOP_XOR: output ^= byte; break;
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}
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}
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res[j] = output;
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}
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}
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for (j = 0; j < numkeys; j++) {
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if (objects[j])
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decrRefCount(objects[j]);
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}
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zfree(src);
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zfree(len);
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|
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];
|
|
|
|
/* 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 == 5) {
|
|
if (getLongFromObjectOrReply(c,c->argv[3],&start,NULL) != REDIS_OK)
|
|
return;
|
|
if (getLongFromObjectOrReply(c,c->argv[4],&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 == 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 our range does not includes
|
|
* the end of the string, but terminates before, we can't consider the
|
|
* right of the range as zero padded.
|
|
*
|
|
* so if redisBitpos() returns the first bit outside the string,
|
|
* we return -1 to the caller, to mean, in the specified range there
|
|
* is not a single "0" bit. */
|
|
if (end != strlen-1 && bit == 0 && pos == bytes*8) {
|
|
addReplyLongLong(c,-1);
|
|
return;
|
|
}
|
|
if (pos != -1) pos += start*8; /* Adjust for the bytes we skipped. */
|
|
addReplyLongLong(c,pos);
|
|
}
|
|
}
|