See the JLS:. In a hexadecimal or binary literal, the integer is only denoted by the digits after the 0x or 0b characters and before any type suffix.

2012年10月20日 · >>>is the unsigned bitwise right-shift operator. 0x0F is a hexadecimal number which equals 15 in decimal. It represents the lower four bits and translates the the bit-pattern 0000 1111.

2012年9月20日 · Byte verflag = (Byte)(bIsAck & 0x0f) | ((version << 4) & 0xf0). Here I'm combining two values into a single Byte value to save space because it's being used in a packet header structure. bIsAck is a BOOL and version is a Byte whose value is very small. So both these values can be contained in a single Byte variable.

Copied out the Java reference manual: For example, the result of the expression: 0xff00 &amp; 0xf0f0 is: 0xf000 The result of the expression: 0xff00 ^ 0xf0f0 is: 0x0ff0 The

2012年8月1日 · tcp[12]&0xf0) refers to the first half of byte 12 (i.e. the 11th byte), which is the data offset field, which specifies the size of the TCP header in 32-bit words and as such, this is typically multiplied by 4 for such a calculation.

0xF0: 11110000 0x0F: 00001111 0xCC: 11001100 0x33: 00110011 0xAA: 10101010 0x55: 01010101 The first pair of numbers are used to mask out and swap the first 4 bits and the last 4 bits of a byte. The second pair masks out and swaps the first 2 bits and last 2 bits of a set of 4 bits. The third pair masks out and swap adjacent pairs of bits.

2011年8月7日 · Numbers can be represented in different ways. In C, you can use decimal (e.g. 243), octal (e.g. 0363) or hexadecimal (0xF3).

2012年2月10日 · a byte in your file that is >127 keeps its sign during &0xf0, and >> 4 is a signed shift which makes the bit-pattern keep the bit set in the most significant bit. then you compare >9 which is not the case because the sign-bit is still set

2016年9月22日 · tcp[((tcp[12] & 0xf0) >> 2)] = 0x16: a bit more tricky, let's detail this below; tcp[12] means capturing the 13th byte of the tcp packet, corresponding to first half being the offset, second half being reserved. The offset, once multiplied by 4 gives the byte count of the TCP header, meaning ((tcp[12] & 0xf0) >> 2) provides the size of the TCP ...

2010年10月12日 · An interesting aside by the way. You can classify bytes in a UTF-8 stream as follows: With the high bit set to 0, it's a single byte value.