counting cycle

.section .data
cycle_str:
        .asciz "cycle count is: %lu\n"
long:
        .quad   5

.section .text
.globl   _start
_start:
        # measure base = mov + rdtsc
        xorq    %rax, %rax
        rdtsc              # write time stamp to rax
        movq    %rax, %rcx # %rcx = %rax
        rdtsc              # write time stamp to rax
        subq    %rcx, %rax # %rax = %rax -%rcx

        movq    %rax, %rsi
        movq    $cycle_str, %rdi
        movq    $0, %rax
        call    printf

        # measure base + xchgq
        xorq    %rax, %rax
        rdtsc              # write time stamp to rax
        movq    %rax, %rcx # %rcx = %rax
        xchgq   long, %rdx
        rdtsc              # write time stamp to rax
        subq    %rcx, %rax # %rax = %rax -%rcx

        # print %rax
        movq    %rax, %rsi
        movq    $cycle_str, %rdi
        movq    $0, %rax
        call    printf

        # exit
        movq $1,%rax # syscall id: sys_exit
        movq $0,%rbx # exit code 0
        int  $0x80

all:
        as -o hello.o hello.S
        ld -o hello hello.o -lc  --dynamic-linker /lib64/ld-linux-x86-64.so.2
        ./hello
clean:
        rm *.o hello

https://docs.microsoft.com/en-us/cpp/intrinsics/rdtsc?view=msvc-160

https://cs.brown.edu/courses/cs033/docs/guides/x64_cheatsheet.pdf

https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/ia-32-ia-64-benchmark-code-execution-paper.pdf