jcxz instruction
The jcxz instruction is a conditional transfer instruction, all conditional transfer instructions are short transfers,
Include the shifted displacement in the corresponding machine code, not the destination address. The range of IP modification is -128~127.
Instruction format: jcxz label (if (cx)=0, transfer to the label for execution.)
When (cx) = 0, (IP) = (IP) + 8-bit shift
8-bit displacement = the address at the "label"-the address of the first byte after the jcxz instruction;
The range of 8-bit displacement is -128~127, expressed in complement;
The 8-bit displacement is calculated by the compiler at compile time.
When (cx)!=0, do nothing (the program is executed downward)
Reference: <<Assembly Language>> Wang Shuang