I want to calculate length of the word, but I have error. I don’t understand why.

int new_strlen(char* word)
{
    int len = 0;
    __asm__  ("mov ecx, 100nt"
                          "mov esi, %1nt"
                          "mov al, 0nt"
                          "repne scasbnt"
                          "mov %0, 100nt"
                          "sub %0, ecxnt"
                        : "=a"(len)
                        : "r"(word)
                        : "%ecx","%esi", "%eax"
    );

    return len;
}

My error is “‘asm’ operand has impossible constraints”.

I attempted to use the __asm{} construct, but it is not available on the x64 architecture.I am compiling a program using the “-masm=intel” flag. My compiler is “g++”. Also I attempted to use “volatile” but it useless.
Do you have any thoughts on this matter? I would appreciate it if you could share your insights.
I am very grateful!

I try anything. Pls, help me