Changes

Usage during [[Syscalls|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 preserve rsp,rbp, rbx, r12, r13, r14, and r15 but may trample any other registers.

These instructions are sufficient to complete the [[SPO600 Assembler Lab]](GAS syntax):  add %r10,%r11 // add r10 and r11, put result in r11 cmp %r10,%r11 // compare register r10 with register r11. The comparison sets flags in the processor status register which affect conditional jumps. cmp $99,%r11 // compare the number 99 with register r11. The comparison sets flags in the processor status register which affect conditional jumps. 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 je ''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 syscall // invoke a syscall (in 32-bit mode, use "int $0x80" instead) Note the syntax:* [[Register]] names are prefixed by %* [[Immediate Value|Immediate values]] are prefixed by $* Indirect memory access is indicated by (parenthesis).* Hexadecimal values are indicated by a 0x prefix.* Character values are indicated by quotation marks. Escapes (such as '\n') are permitted.* Data sources are given as the first argument (mov %r10,%r11 moves FROM r10 INTO r11).

add %r10,%r11 // add r10 and r11, put result in r11 cmp %r10,%r11 // compare register r10 with register r11 cmp $99,%r11 // compare For the number 99 with register r11MOV instruction: div $r10 // divide rax by * You can append a suffix indicating the given register amount of data to be moved -- e.g., q for quadword (r1064 bits), places quotient into rax and remainder into rdx d for doubleword (rdx must be zero before this instruction32 bits) 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,w for word (%r11) // move data from r10 to address pointed to by r11 mov (%r1016 bits),%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 syscall // invoke a syscall or b for byte (in 32-bit mode, use "int $0x80" instead8 bits).

== References Resources ==

* CPU Designer's Instruction Set and Software Developer Manuals