In C

For a function with prototype

long decode4(long x, long y, long z);

gcc generates the following assembly code:

decode4: addq %rsi, %rdx movq %rdx, %rax salq $8, %rax imulq %rdi, %rax orq %rdx, %rax ret

Parameters x, y, and z are passed in registers %rdi, %rsi, and %rdx. The code stores the return value in register %rax. Reverse-engineer decode4: write C code for decode4 that will have an effect equivalent to the assembly code shown.