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setbit命令

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This commit is contained in:
LingZhaoHui 2020-11-14 19:56:01 +08:00
parent 22f73b0644
commit 8f7d6a4c97
1 changed files with 6 additions and 6 deletions
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12
src/bitops.c
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@ -545,14 +545,14 @@ void setbitCommand(client *c) {
if ((o = lookupStringForBitCommand(c,bitoffset)) == NULL) return;
/* Get current values */
byte = bitoffset >> 3;
byteval = ((uint8_t*)o->ptr)[byte];
bit = 7 - (bitoffset & 0x7);
bitval = byteval & (1 << bit);
byte = bitoffset >> 3; //一个字节是8位，现在需要除以8，以定位到第byte个字节上
byteval = ((uint8_t*)o->ptr)[byte]; //取出第byte个字节
bit = 7 - (bitoffset & 0x7); //offset对8取模
bitval = byteval & (1 << bit); //1<<bit位表示将1从低位向左移bit位，获取到第bit位
/* Update byte with new bit value and return original value */
byteval &= ~(1 << bit);
byteval |= ((on & 0x1) << bit);
byteval &= ~(1 << bit); //1左移bit位，取反与原值相与，即将原值的低bit位赋值为0
byteval |= ((on & 0x1) << bit); //on&0x1的值为要修改后的值，左移bit位，与原值相或
((uint8_t*)o->ptr)[byte] = byteval;
signalModifiedKey(c,c->db,c->argv[1]);
notifyKeyspaceEvent(NOTIFY_STRING,"setbit",c->argv[1],c->db->id);