teensy-core-4.1/include/irq.h

#pragma once

#ifndef   __ASM
  #define __ASM                                  __asm
#endif
#ifndef   __STATIC_FORCEINLINE
  #define __STATIC_FORCEINLINE                   __attribute__((always_inline)) static inline
#endif

/**
  \brief   Enable IRQ Interrupts
  \details Enables IRQ interrupts by clearing the I-bit in the CPSR.
           Can only be executed in Privileged modes.
 */
__STATIC_FORCEINLINE void __enable_irq(void)
{
  __ASM volatile ("cpsie i" : : : "memory");
}


/**
  \brief   Disable IRQ Interrupts
  \details Disables IRQ interrupts by setting the I-bit in the CPSR.
           Can only be executed in Privileged modes.
 */
__STATIC_FORCEINLINE void __disable_irq(void)
{
  __ASM volatile ("cpsid i" : : : "memory");
}