Assembly Language Learning Notes (ix) Principle of transfer instruction

1.8086 Transfer Instruction Classification:
Unconditional Jump instruction: JMP
Conditional Transfer directives:
Loop command: Loop
Procedure (function equivalent to C)
Interrupt ()

The operator offset is a compiler-processed symbol in assembly language, and his function is to get the offset address of the label
Start:mov ax,offset start; equivalent to mov ax,0

JMP unconditionally jumps, can only modify IP, can also modify CS and IP
JMP Short Designator (intra-segment -128~127): Transfer to label instruction
(IP) = (IP) + 8-bit displacement
JMP near PTR designator (intra-segment transfer -32769~32767)
(IP) = (IP) + 16-bit displacement
Complement...
JMP far PTR designator (inter-segment transfer)

To transfer an address in a register with the JMP directive:
Instruction format: jmp 16 Register
JMP Word PTR memory cell address: Intra-segment transfer
JMP DWORD PTR memory Unit Address: transfer between segments

2.JCXZ command: Conditional jump instruction; All conditional instructions are short-shifted
JCXZ Marking:
If cx=0, then turn to the label, otherwise do not jump
When cx=0, (IP) = (IP) + 8-bit displacement

3.loop instruction, all circular instructions are short transfer, if cx=0 does not jump

4. The meaning of transfer according to displacement: