Question about assembly in set bit function for x86 architecture

Greetings All, I am wondering what the below code in the asm modifier does: static inline void set_bit(int nr, void *addr) { asm("btsl %1,%0" : "+m" (*(u32 *)addr) : "Ir" (nr)); } This would be very helpful as I am new to x86 assembly and don't even known what register(s)/instruction(s) this touches and therefore this is impossible for me to look up in the Intel Manuals. If someone either tells me the registers/instructions this uses or explains the code that would be very helpful. Nick