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[edit | edit source]
Operating Modes[edit | edit source]
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[edit | edit source]
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 |