Replacing the x86 bswap Assembly Instruction

Symptom

Compilation error: Error: unknown mnemonic 'bswap'-- 'bswap x3'

Possible Cause

bswap is the reverse byte order instruction of x86 and needs to be replaced with the rev instruction of Arm64.

Solution

bswap instruction on x86:

inline uint32_t bswap(uint32_t val) {  
  __asm__("bswap %0" : "=r" (val) : "0" (val)); 
    retrun val;  
}

Alternative on Arm64:

inline uint32_t bswap(uint32_t val) {  
   __asm__("rev %w[dst], %w[src]" : [dst]"=r"(val) : [src]"r"(val));  
}