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Compiler Reference Guide

Preface armclang Command-line Options Compiler-specific Keywords and Operators Compiler-specific Function, Variable, and Type Att Function attributes __attribute__((always_inline)) function attribute __attribute__((cmse_nonsecure_call)) function attr __attribute__((cmse_nonsecure_entry)) function att __attribute__((const)) function attribute __attribute__((constructor(priority))) function at __attribute__((format_arg(string-index))) function __attribute__((interrupt("type"))) function attrib __attribute__((malloc)) function attribute __attribute__((naked)) function attribute __attribute__((noinline)) function attribute __attribute__((nonnull)) function attribute __attribute__((noreturn)) function attribute __attribute__((nothrow)) function attribute __attribute__((pcs("calling_convention"))) functio __attribute__((pure)) function attribute __attribute__((section("name"))) function attribut __attribute__((unused)) function attribute __attribute__((used)) function attribute __attribute__((value_in_regs)) function attribute __attribute__((visibility("visibility_type"))) fun __attribute__((weak)) function attribute __attribute__((weakref("target"))) function attrib Type attributes __attribute__((aligned)) type attribute __attribute__((packed)) type attribute __attribute__((transparent_union)) type attribute Variable attributes __attribute__((alias)) variable attribute __attribute__((aligned)) variable attribute __attribute__((deprecated)) variable attribute __attribute__((packed)) variable attribute __attribute__((section("name"))) variable attribut __attribute__((unused)) variable attribute __attribute__((used)) variable attribute __attribute__((visibility("visibility_type"))) var __attribute__((weak)) variable attribute __attribute__((weakref("target"))) variable attrib Compiler-specific Intrinsics Compiler-specific Pragmas Other Compiler-specific Features Standard C Implementation Definition Standard C++ Implementation Definition armclang Integrated Assembler armclang Inline Assembler

__attribute__((naked)) function attribute

3.10 __attribute__((naked)) function attribute

This attribute tells the compiler that the function is an embedded assembly function. You can write the body of the function entirely in assembly code using __asm statements.

The compiler does not generate prologue and epilogue sequences for functions with __attribute__((naked)).

The compiler only supports basic __asm statements in __attribute__((naked)) functions. Using extended assembly, parameter references or mixing C code with __asm statements might not work reliably.

Example 3-1 Examples

__attribute__((naked)) int add(int i, int j); /* Declaring a function with __attribute__((naked)). */

__attribute__((naked)) int add(int i, int j)
{
    __asm("ADD r0, r1, #1"); /* Basic assembler statements are supported. */

/*  Parameter references are not supported inside naked functions: */
/*  __asm (
    "ADD r0, %[input_i], %[input_j]"       /* Assembler statement with parameter references */
    :                                      /* Output operand parameter */
    : [input_i] "r" (i), [input_j] "r" (j) /* Input operand parameter */
    );
*/

/*  Mixing C code is not supported inside naked functions: */
/*  int res = 0;
    return res; 
*/

}
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