signature.h

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/* $Id: signature_8h_source.html,v 1.1.1.7 2022/01/29 09:22:01 joerg_wunsch Exp $ */

/* avr/signature.h - Signature API */

#ifndef _AVR_SIGNATURE_H_
#define _AVR_SIGNATURE_H_ 1

/** \file */
/** \defgroup avr_signature <avr/signature.h>: Signature Support

    \par Introduction

    The <avr/signature.h> header file allows the user to automatically
    and easily include the device's signature data in a special section of
    the final linked ELF file.
    
    This value can then be used by programming software to compare the on-device
    signature with the signature recorded in the ELF file to look for a match
    before programming the device.
    
    \par API Usage Example

    Usage is very simple; just include the header file:
    
    \code
    #include <avr/signature.h>
    \endcode
    
    This will declare a constant unsigned char array and it is initialized with
    the three signature bytes, MSB first, that are defined in the device I/O
    header file. This array is then placed in the .signature section in the
    resulting linked ELF file.
    
    The three signature bytes that are used to initialize the array are 
    these defined macros in the device I/O header file, from MSB to LSB:
    SIGNATURE_2, SIGNATURE_1, SIGNATURE_0.
    
    This header file should only be included once in an application.
*/

#ifndef __ASSEMBLER__

#include <avr/io.h>

#if defined(SIGNATURE_0) && defined(SIGNATURE_1) && defined(SIGNATURE_2)

const unsigned char __signature[3]
__attribute__((__used__, __section__(".signature"))) =
        { SIGNATURE_2, SIGNATURE_1, SIGNATURE_0 };

#endif  /* defined(SIGNATURE_0) && defined(SIGNATURE_1) && defined(SIGNATURE_2) */

#endif  /* __ASSEMBLER__ */

#endif  /* _AVR_SIGNATURE_H_ */