X86 64 Register and Instruction Quick Start
Revision as of 09:57, 24 January 2014 by Chris Tyler (talk | contribs)
Contents
Registers
General-Purpose Registers
The 64-bit versions of the 'original' x86 registers are named:
- rax - register a extended
- rbx - register b extended
- rcx - register c extended
- rdx - register d extended
- rbp - register base pointer (start of stack)
- rsp - register stack pointer (current location in stack, growing downwards)
- rsi - register source index (source for data copies)
- rdi - register destination index (destination for data copies)
The registers added for 64-bit mode are named:
- r8 - register 8
- r9 - register 9
- r10 - register 10
- r11 - register 11
- r12 - register 12
- r13 - register 13
- r14 - register 14
- r15 - register 15
These may be accessed as:
- 64-bit registers using the 'r' prefix: rax, r15
- 32-bit registers using the 'e' prefix (original registers: e_x) or 'd' suffix (added registers: r__d): eax, r15d
- 16-bit registers using no prefix (original registers: _x) or a 'd' suffix (added registers: r__d): ax, r15d
- 8-bit registers using 'h' suffix (original registers - bits 8-15: _h): ah, bh
- 8-bit registers using 'l' suffix (original registers - bits 0-7: _l) or 'b' suffix (added registers: r__b): al, bl, r15b
Usage during syscall/function call:
- First six arguments are in rdi, rsi, rdx, rcx, r8d, r9d; remaining arguments are on the stack
- For syscalls, the syscall number is in rax
- Return value is in rax
- The called routine is expected to save rsp,rbp, rbx, r12, r13, r14, and r15 but may trample any other registers
Floating-Point and SIMD Registers
x86_64 also defines a set of large registers for floating-point and single-instruction/multiple-data (SIMD) operations. For details, refer to the Intel or AMD documentation.
Instructions
Starter Kit
These instructions are sufficient to complete the SPO600 Assembler Lab:
add %r10,%r11 // add r10 and r11, put result in r11 cmp %r10,%r11 // compare register r10 with register r11 cmp $99,%r11 // compare the number 99 with register r11 div $r10 // divide rax by the given register (r10), places quotient into rax and remainder into rdx (rdx must be zero before this instruction) inc %r10 // increment r10 jmp label // jump to label jeq label // jump to label if equal jne label // jump to label if not equal jl label // jump to label if less jg label // jump to label if greater mov %r10,%r11 // move data from r10 to r11 mov $99,%r10 // put the immediate value 99 into r10 mov %r10,(%r11) // move data from r10 to address pointed to by r11 mov (%r10),%r11 // move data from address pointed to by r10 to r10 mul $r10 // multiplies rax by r10, places result in rax and overflow in rdx push %r10 // push r10 onto the stack pop %r10 // pop r10 off the stack
References
- CPU Designer's Instruction Set and Software Developer Manuals
