contrib/loaders/flash/cc26xx/startup.c

   1 /* SPDX-License-Identifier: BSD-3-Clause */
   2
   3 /******************************************************************************
   4 *
   5 * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
   6 *
   7 ******************************************************************************/
   8
   9 #include <stdint.h>
  10
  11 /******************************************************************************
  12 *
  13 * The entry point for the application startup code.
  14 *
  15 ******************************************************************************/
  16 extern int main(void);
  17
  18 /******************************************************************************
  19 *
  20 * Reserve space for the system stack.
  21 *
  22 ******************************************************************************/
  23 __attribute__ ((section(".stack")))
  24 static uint32_t stack[100];
  25 const uint32_t stack_pntr = (uint32_t)stack + sizeof(stack);
  26
  27 /******************************************************************************
  28 *
  29 * The following are constructs created by the linker indicating where
  30 * the "bss" and "ebss" segments reside in memory.
  31 *
  32 ******************************************************************************/
  33 extern uint32_t _bss;
  34 extern uint32_t _ebss;
  35
  36 /******************************************************************************
  37 *
  38 * This is the entry point that handles setting the stack within the allowed
  39 * workspace, initializing the .bss segment, and then jumping to main.
  40 *
  41 ******************************************************************************/
  42 __attribute__ ((section(".entry")))
  43 void entry(void)
  44 {
  45         /* Workaround for ITT instructions. */
  46         __asm("         NOP");
  47         __asm("         NOP");
  48         __asm("         NOP");
  49         __asm("         NOP");
  50
  51         /* Initialize stack pointer */
  52         __asm("         ldr             sp, =stack_pntr");
  53
  54         /* Zero fill the bss segment. */
  55         __asm("         ldr     r0, =_bss\n"
  56                   "             ldr     r1, =_ebss\n"
  57                   "             mov     r2, #0\n"
  58                   "             .thumb_func\n"
  59                   "     zero_loop:\n"
  60                   "             cmp             r0, r1\n"
  61                   "             it              lt\n"
  62                   "             strlt   r2, [r0], #4\n"
  63                   "             blt             zero_loop");
  64
  65         /* Call the application's entry point. */
  66         main();
  67
  68         /* If we ever return, enter an infinite loop */
  69         while (1)
  70                 ;
  71 }