JCXZ performs a short jump (with maximum range 128 bytes) if and
only if the contents of the CX register is 0. JECXZ does the
same thing, but with ECX.
jcxz
8086 and laterJump if CX/ECX Zero
jcxz imm8 {near|short} | jcxz imm8 {near|short}, cx | jcxz imm8 {near|short}, ecx | jcxz imm8 {near|short}, rcxNo example here: this instruction either stops the program, or belongs to a mode this emulator does not run.
Forms
Every form of jcxz the assembler accepts, from NASM's own instruction table.
The second column is the processor that introduced the form; a badge marks a form that needs
an extension, that is lockable, or that long mode dropped.
| Form | Since | Notes |
|---|---|---|
| jcxz imm8 {near|short} | 8086 | nolong |
| jcxz imm8 {near|short}, cx | 8086 | nolong |
| jcxz imm8 {near|short}, ecx | 386 | |
| jcxz imm8 {near|short}, rcx | x86-64 | long |