contrib/loaders/flash/cc26xx/startup.c

   1 /******************************************************************************
   2 *
   3 * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
   4 *
   5 * Redistribution and use in source and binary forms, with or without
   6 * modification, are permitted provided that the following conditions
   7 * are met:
   8 *
   9 *  Redistributions of source code must retain the above copyright
  10 *  notice, this list of conditions and the following disclaimer.
  11 *
  12 *  Redistributions in binary form must reproduce the above copyright
  13 *  notice, this list of conditions and the following disclaimer in the
  14 *  documentation and/or other materials provided with the
  15 *  distribution.
  16 *
  17 *  Neither the name of Texas Instruments Incorporated nor the names of
  18 *  its contributors may be used to endorse or promote products derived
  19 *  from this software without specific prior written permission.
  20 *
  21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  25 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  26 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  27 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32 *
  33 ******************************************************************************/
  34
  35 #include <stdint.h>
  36
  37 /******************************************************************************
  38 *
  39 * The entry point for the application startup code.
  40 *
  41 ******************************************************************************/
  42 extern int main(void);
  43
  44 /******************************************************************************
  45 *
  46 * Reserve space for the system stack.
  47 *
  48 ******************************************************************************/
  49 __attribute__ ((section(".stack")))
  50 static uint32_t stack[100];
  51 const uint32_t stack_pntr = (uint32_t)stack + sizeof(stack);
  52
  53 /******************************************************************************
  54 *
  55 * The following are constructs created by the linker indicating where the
  56 * the "bss" and "ebss" segments reside in memory.
  57 *
  58 ******************************************************************************/
  59 extern uint32_t _bss;
  60 extern uint32_t _ebss;
  61
  62 /******************************************************************************
  63 *
  64 * This is the entry point that handles setting the stack within the allowed
  65 * workspace, initializing the .bss segment, and then jumping to main.
  66 *
  67 ******************************************************************************/
  68 __attribute__ ((section(".entry")))
  69 void entry(void)
  70 {
  71         /* Workaround for ITT instructions. */
  72         __asm("         NOP");
  73         __asm("         NOP");
  74         __asm("         NOP");
  75         __asm("         NOP");
  76
  77         /* Initialize stack pointer */
  78         __asm("         ldr             sp, =stack_pntr");
  79
  80         /* Zero fill the bss segment. */
  81         __asm("         ldr     r0, =_bss\n"
  82                   "             ldr     r1, =_ebss\n"
  83                   "             mov     r2, #0\n"
  84                   "             .thumb_func\n"
  85                   "     zero_loop:\n"
  86                   "             cmp             r0, r1\n"
  87                   "             it              lt\n"
  88                   "             strlt   r2, [r0], #4\n"
  89                   "             blt             zero_loop");
  90
  91         /* Call the application's entry point. */
  92         main();
  93
  94         /* If we ever return, enter an infinite loop */
  95         while (1)
  96                 ;
  97 }