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path: root/example-fs-bb48/first-pages.c
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/*
 * first-pages.c - First pages for MKL27Z256.
 *
 * Copyright (C) 2016 Flying Stone Technology
 * Author: NIIBE Yutaka <gniibe@fsij.org>
 *
 * Copying and distribution of this file, with or without modification,
 * are permitted in any medium without royalty provided the copyright
 * notice and this notice are preserved.  This file is offered as-is,
 * without any warranty.
 *
 *
 * First two pages of Flash ROM is difficult to use because of
 * predefined purposes.  It's defined as a default vector page and
 * a flash configuration page.
 *
 * We put something useful to those two pages, together with the
 * data for predefined purposes.
 */


#include <stdint.h>

extern uint8_t __main_stack_end__;

static void __attribute__ ((naked,section(".flash_config_page")))
reset (void)
{
  uint32_t r3 = 0xe000ed08;

  asm volatile ("str	%2, [%0]\n\t"	  /* Set SCR->VTOR     */
		"ldr	%0, [%2, #4]\n\t" /* Jump to the entry */
		"bx	%0\n\t"
		".align	2\n"
		: "=r" (r3)
		: "0" (r3), "r" (0x00000800)
		: "memory");

  /* Never reach here. */
}


static uint32_t
stack_entry[] __attribute__ ((section(".first_page.first_words"),used)) = {
  (uint32_t)(&__main_stack_end__ - 32),
  (uint32_t)reset,
};

/*
 * NOTE: We don't use backdoor comparison key.  The area is used by
 * CRC32 table.
 */
static uint32_t
flash_config[] __attribute__ ((section(".flash_config"),used)) = {
  0xffffffff, /* Protection bytes */
  0xffff3ffe, /* FSEC=0xfe, FOPT=0x3f */
  /* FOPT=0x3f:
   * BOOTSRC_SEL=00: Boot from flash
   */
  /* FSEC=0xfe:
   * unsecure
   */
};


/*
 * CRC32 calculation routines.
 */

/*
 * Table of CRC32, generated by gen_crc_table.py
 */
static unsigned int
crc32_table[256] __attribute__ ((section(".first_page"))) = {
  0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 
  0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 
  0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2, 
  0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 
  0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 
  0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 
  0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c, 
  0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, 
  0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 
  0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 
  0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106, 
  0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, 
  0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 
  0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 
  0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950, 
  0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, 
  0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 
  0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 
  0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 
  0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, 
  0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 
  0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 
  0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84, 
  0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 
  0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 
  0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 
  0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e, 
  0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, 
  0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 
  0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 
  0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28, 
  0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, 
  0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 
  0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 
  0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242, 
  0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, 
  0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 
  0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 
  0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 
  0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, 
  0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 
  0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 
  0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
};

static unsigned int crc_reg;

__attribute__ ((section(".flash_config_page")))
void
crc32_init (void)
{
  crc_reg = 0xffffffff;
}

__attribute__ ((section(".flash_config_page")))
unsigned int
crc32_value (void)
{
  return crc_reg;
}

__attribute__ ((section(".flash_config_page")))
void
crc32_u8 (unsigned char bits_eight)
{
  crc_reg = crc32_table[(crc_reg & 0xff) ^ bits_eight] ^ (crc_reg >> 8);
}

__attribute__ ((section(".flash_config_page")))
void
crc32_u32 (unsigned int u)
{
  crc32_u8 (u & 0xff);
  crc32_u8 ((u >> 8)& 0xff);
  crc32_u8 ((u >> 16)& 0xff);
  crc32_u8 ((u >> 24)& 0xff);
}