AMD64
From Leo's Notes
Last edited on 30 December 2021, at 02:13.
The AMD64 (x86-64, x86_64) is the 64bit version of the Intel x86 instruction set.
Overview
Operating Modes
There are 3 modes of operation:
- Real/Unreal mode: Earliest x86 processors; initial mode on power on.
- Legacy mode (protected mode, virtual 8086 mode): Runs protected mode operating systems in either 32 or 16bit.
- Long mode: Primary mode for 64bit processors. Can also run 32 or 16bit compatibility mode.
Registers
There are 16 64bit general registers. While considered these are considered for "general use", some have specific behavior; see notes for more information.
| Register | Higher Byte | Lower Byte | Lower Word (2 byte) | Lower Dword (4 byte) | Note |
|---|---|---|---|---|---|
| rax | ah | al | ax | eax | accumulator |
| rbx | bh | bl | bx | ebx | |
| rcx | ch | cl | cx | ecx | |
| rdx | dh | dl | dx | edx | |
| rsp | spl | sp | esp | Stack pointer | |
| rsi | sil | si | esi | source index | |
| rdi | dil | di | edi | destination index | |
| rbp | bpl | bp | ebp | ||
| r8 | r8b | r8w | r8d | ||
| r9 | r9b | r9w | r9d | ||
| r10 | r10b | r10w | r10d | ||
| r11 | r11b | r11w | r11d | ||
| r12 | r12b | r12w | r12d | ||
| r13 | r13b | r13w | r13d | ||
| r14 | r14b | r14w | r14d | ||
| r15 | r15b | r15w | r15d |