loadable_extension.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see <http://www.gnu.org/licenses/>
 *
 * Additional note on redistribution: The copyright and license notices above
 * must be maintained in each individual source file that is a derivative work
 * of this source file; otherwise redistribution is prohibited.
 */

#ifndef _LOADABLE_EXTENSION_H
#define _LOADABLE_EXTENSION_H

#include <stdint.h>

/* 48 byte header-- containing a high degree of redundancy/verification
 * for sanity.  Payload immediately follows.
 */
struct loadable_extension {
#define LOADABLE_EXTENSION_MAGIC        0x58655264      /* 'dReX' little endian */
#define LOADABLE_EXTENSION_UNPROGRAMMED 0xffffffff
        uint32_t magic;           
        uint32_t length;          
        uint32_t reserved[2];     
#define LOADABLE_REQUIRE_VERSION_INVALID 0x00000000
#define LOADABLE_REQUIRE_VERSION_WIRED   0x00000001
        uint32_t require_version; 
        uint32_t ram_seg_len;     
        uint32_t ram_seg_copylen; 
        uint32_t ram_seg_copyoff; 
        uint32_t ram_seg_gotlen;  
        uint32_t entry_offset;    
        uint32_t header_crc;      
        uint32_t payload_crc;     
};

#define DECLARE_LOADABLE_EXTENSION(ent_func) \
extern char _sidata; \
extern char _eidata; \
 \
extern char _copylen; \
extern char _gotlen; \
extern char _ramlen; \
 \
const struct loadable_extension lext __attribute__((section (".extension_header"))) = { \
        .magic = LOADABLE_EXTENSION_MAGIC, \
        .length = (uint32_t) &_eidata, \
        .require_version = LOADABLE_REQUIRE_VERSION_WIRED, \
        .entry_offset = (uint32_t) ent_func, \
        .ram_seg_copyoff = (uint32_t) &_sidata, \
        /* These next & opers are lies, because they're lengths, not offsets */ \
        .ram_seg_len = (uint32_t) &_ramlen, \
        .ram_seg_copylen = (uint32_t) &_copylen, \
        .ram_seg_gotlen = (uint32_t) &_gotlen, \
}

#endif