---
name: "avr_builtins"
section: "3avr"
platform: "linux"
package: "avr-libc"
version: "1:2.2.1-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/avr_builtins"
---

# avr\_builtins(3avr)

\<avr/builtins.h\>: avr-gcc builtins documentation

## NAME

avr\_builtins - \<avr/builtins.h\>: avr-gcc builtins documentation

## SYNOPSIS

### Functions

void **\_\_builtin\_avr\_sei** (void)\
 void **\_\_builtin\_avr\_cli** (void)\
 void **\_\_builtin\_avr\_sleep** (void)\
 void **\_\_builtin\_avr\_wdr** (void)\
 **uint8\_t** **\_\_builtin\_avr\_swap** (**uint8\_t** \_\_b)\
 **uint16\_t** **\_\_builtin\_avr\_fmul** (**uint8\_t** \_\_a, **uint8\_t** \_\_b)\
 **int16\_t** **\_\_builtin\_avr\_fmuls** (**int8\_t** \_\_a, **int8\_t** \_\_b)\
 **int16\_t** **\_\_builtin\_avr\_fmulsu** (**int8\_t** \_\_a, **uint8\_t** \_\_b)\

## Detailed Description

```
#include <avr/builtins.h>
```

**Note**

This file only documents some avr-gcc builtins. For functions built-in in the compiler, there should be no prototype declarations.

See also the `GCC documentation` for a full list of avr-gcc builtins.

## Function Documentation

### void \_\_builtin\_avr\_cli (void)` [extern]`

Disables all interrupts by clearing the global interrupt mask.

### uint16\_t \_\_builtin\_avr\_fmul (uint8\_t \_\_a, uint8\_t \_\_b)` [extern]`

Emits an FMUL (fractional multiply unsigned) instruction.

### int16\_t \_\_builtin\_avr\_fmuls (int8\_t \_\_a, int8\_t \_\_b)` [extern]`

Emits an FMUL (fractional multiply signed) instruction.

### int16\_t \_\_builtin\_avr\_fmulsu (int8\_t \_\_a, uint8\_t \_\_b)` [extern]`

Emits an FMUL (fractional multiply signed with unsigned) instruction.

### void \_\_builtin\_avr\_sei (void)` [extern]`

Enables interrupts by setting the global interrupt mask.

### void \_\_builtin\_avr\_sleep (void)` [extern]`

Emits a `SLEEP` instruction.

### uint8\_t \_\_builtin\_avr\_swap (uint8\_t \_\_b)` [extern]`

Emits a SWAP (nibble swap) instruction on \_\_b.

### void \_\_builtin\_avr\_wdr (void)` [extern]`

Emits a WDR (watchdog reset) instruction.

## Author

Generated automatically by Doxygen for AVR-LibC from the source code.