Atomically testing and setting or clearing one or more bits stored in a memory location

摘要

Logic and method for or atomically testing and setting one or more bits stored in a memory location, in a single operation: disables one or more interrupts (100); access a number stored in a memory location, copies the number from the memory location to a working register (102); tests a particular bit of the number copied from the memory location (104); sets (108) or clears (110) a bit flag to reflect the state of the particular bit copied from the memory location; forces the particular bit of the number copied from the memory location to a predetermined digital state (112); and copies the number from the working register to the memory location (114). The bit flag is preferably in a processor status register used to control later conditional operations.