即时通讯之输入流中读取基本数据

来源：互联网发布：人工智能论文网站编辑：程序博客网时间：2024/05/21 17:04

相应的和写入一样，下面将读取的接口陈列如下：

读取 1 byte

- (int8_t)readChar;{    int8_t v;    [data getBytes:&v range:NSMakeRange(len, 1)];    len++;    return (v & 0x0FF);}

读取 2 byte

- (int16_t)readShort;{    int32_t ch1 = [self read];    int32_t ch2 = [self read];    if ((ch1 | ch2) < 0) {        @throw [NSException exceptionWithName:@"Exception" reason:@"EOFException" userInfo:nil];    }    return (int16_t)((ch1 << 8) + (ch2 << 0));}

读取 4 byte

- (int32_t)readInt;{    int32_t ch1 = [self read];    int32_t ch2 = [self read];    int32_t ch3 = [self read];    int32_t ch4 = [self read];    if ((ch1 | ch2 | ch3 | ch4) < 0){        @throw [NSException exceptionWithName:@"Exception" reason:@"EOFException" userInfo:nil];    }    return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));}

读取 8 byte

- (int64_t)readLong;{    int8_t ch[8];    [data getBytes:&ch range:NSMakeRange(len,8)];    len += 8;    return (((int64_t)ch[0] << 56) +            ((int64_t)(ch[1] & 255) << 48) +            ((int64_t)(ch[2] & 255) << 40) +            ((int64_t)(ch[3] & 255) << 32) +            ((int64_t)(ch[4] & 255) << 24) +            ((ch[5] & 255) << 16) +            ((ch[6] & 255) <<  8) +            ((ch[7] & 255) <<  0));}

BCD时钟转换

- (BDSTime)readBCDTime{    struct BDSTime bcdTime;    Byte year[2];    Byte month[1], day[1], hour[1], min[1], sec[1];    [data getBytes:&year range:NSMakeRange(len, sizeof(year))];    len += sizeof(year);    [data getBytes:&month range:NSMakeRange(len, sizeof(month))];    len += sizeof(month);    [data getBytes:&day range:NSMakeRange(len, sizeof(day))];    len += sizeof(day);    [data getBytes:&hour range:NSMakeRange(len, sizeof(hour))];    len += sizeof(hour);    [data getBytes:&min range:NSMakeRange(len, sizeof(min))];    len += sizeof(min);    [data getBytes:&sec range:NSMakeRange(len, sizeof(sec))];    len += sizeof(sec);    bcdTime.year = [self readBCDToYear:year];    bcdTime.month = bcdToInt(month, sizeof(month));    bcdTime.day = bcdToInt(day, sizeof(day));    bcdTime.hour = bcdToInt(hour, sizeof(hour));    bcdTime.min = bcdToInt(min, sizeof(min));    bcdTime.sec = bcdToInt(sec, sizeof(sec));    return bcdTime;}///bcd转intunsigned int  bcdToInt(const unsigned char *bcd, int length){    int tmp;    unsigned int dec = 0;    for(int i = 0; i < length; i++)    {        tmp = ((bcd[i] >> 4) & 0x0F) * 10 + (bcd[i] & 0x0F);        dec += tmp * pow(100, length - 1 - i);    }    return dec;}- (int16_t)readBCDToYear:(Byte *)dt{    Byte *year = dt;    Byte y_high = year[0];    Byte y_low = year[1];    int16_t high = bcdToInt(&y_high, sizeof(y_high));    int16_t low = bcdToInt(&y_low, sizeof(y_low));    return high*100+low;}

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