law zb_zero

lawful-words@0.1.0.0 · LAWS.bend:456

import Base
import lawful-words@0.1.0.0/defs.bend as D

456# The zero-byte test: zb(v) is zero exactly when no byte of v is zero. (Only
457# this whole-word statement holds: a flag above a zero byte can be set even
458# though that byte is not zero, e.g. v = 0x01010100 flags all four bytes.)
459law zb_zero:
460  for v: U32
461  {U32.is_zero(D.zb(v)) == (U32.is_ne(D.byte(v, 0n), 0) && (U32.is_ne(D.byte(v, 1n), 0) && (U32.is_ne(D.byte(v, 2n), 0) && U32.is_ne(D.byte(v, 3n), 0)))) : Bool}