A quick reference please sei()

Using Arduino Programming Questions
1

Hello,
If anyone can provide a quick reference..........
Is sei() an AVR assembler macro ?

2

It enables interrupts.

3

reference from AVR LibC

http://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html

#define sei ( )

Enables interrupts by setting the global interrupt mask. This function actually compiles into a single line of assembly, so there is no function call overhead. However, the macro also implies a memory barrier which can cause additional loss of optimization.

In order to implement atomic access to multi-byte objects, consider using the macros from <util/atomic.h>, rather than implementing them manually with cli() and sei().

4

GoForSmoke:
reference from AVR LibC

avr-libc: <avr/interrupt.h>: Interrupts

Many thanks, exactly what I was trying to locate