Question

Assembly language help:
Find the equivalent single instruction:
mov edx, 0
rcl eax, 1
jnc skip
dec edx
skip: rcr eax, 1

Answer 1

First `edx` is assigned to 0.
Then `eax` is left shifted once, i.e. multiplied by 2.
If the left shift operation causes over flow, then `edx` is decreased by 1.
After that `eax` right shifted, i.e. divided by 2.

I suppose you could do this with:
```
d = (e | (1 << 32)) ? -1 : 0;
```
This just checks of `e` has its highest order bit (32nd bit) set, and if so `d` is set to -1, otherwise d is set to 0.