Module interrupt 

Interrupt control: the IME master switch and the IE / IF masks.

Two gates stand between the hardware and a handler. IME is the CPU’s master switch, flipped by enable and disable; IE picks which of the five sources may fire, and set_enabled writes it. Both must be open. The runtime enters main with IME off, so a program sees no interrupt until it opens them.

Handlers are not installed here: write one with #[gb::rt::interrupt], which binds it straight to a vector.

Turning interrupts on is unsafe throughout, since it introduces preemption that the surrounding code may have been written to rule out. With the critical-section-impl feature these functions are also the only sanctioned way to change IME, which the implementation mirrors in HRAM.

Structs

CriticalSection

Critical section token.

Functions

disable

Clear IME with di: interrupts stop being serviced.

enable^⚠

Set IME with ei, effective after the next instruction.

enable_and_halt^⚠

Sleep until an interrupt arrives, then service it.

enabled

Read IE: the interrupts that may fire.

free^⚠

Run f with interrupts disabled, handing it proof of that.

halt

Sleep until an interrupt arrives. Never returns if no enabled interrupt can fire.

pending

Read IF: the interrupts that have been requested.

set_enabled^⚠

Replace IE with mask.