/* Linker script for ATSAMD21G17D – no bootloader (flash starts at 0x00000000)
 *
 * Symbol names match Arduino SAMD core 1.8.14 (cortex_handlers.c / Reset.cpp):
 *   __StackTop, __data_start__, __data_end__, __etext,
 *   __bss_start__, __bss_end__, __text_start__, end
 */

OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
SEARCH_DIR(.)

MEMORY
{
  rom    (rx)  : ORIGIN = 0x00000000, LENGTH = 0x0001FE00  /* 127.5K – Firmware */
  config (rx)  : ORIGIN = 0x0001FE00, LENGTH = 0x00000200  /* 512B   – NVM Config (2 Rows) */
  ram    (rwx) : ORIGIN = 0x20000000, LENGTH = 0x00004000  /* 16K  */
}

/* Initial stack pointer = top of RAM */
__StackTop   = ORIGIN(ram) + LENGTH(ram);   /* 0x20004000 */
__StackLimit = __StackTop - 0x1000;         /* 4 KB minimum stack */

SECTIONS
{
  .text :
  {
    __text_start__ = .;
    . = ALIGN(4);
    KEEP(*(.isr_vector))
    KEEP(*(.vectors .vectors.*))
    *(.text .text.* .gnu.linkonce.t.*)
    *(.glue_7t) *(.glue_7)
    *(.rodata .rodata* .gnu.linkonce.r.*)
    *(.ARM.extab* .gnu.linkonce.armextab.*)

    . = ALIGN(4);
    KEEP(*(.init))
    __preinit_array_start = .;
    KEEP(*(.preinit_array))
    __preinit_array_end = .;

    __init_array_start = .;
    KEEP(*(SORT(.init_array.*)))
    KEEP(*(.init_array))
    __init_array_end = .;

    KEEP(*crtbegin.o(.ctors))
    KEEP(*(EXCLUDE_FILE(*crtend.o) .ctors))
    KEEP(*(SORT(.ctors.*)))
    KEEP(*crtend.o(.ctors))

    . = ALIGN(4);
    KEEP(*(.fini))
    __fini_array_start = .;
    KEEP(*(.fini_array))
    KEEP(*(SORT(.fini_array.*)))
    __fini_array_end = .;

    KEEP(*crtbegin.o(.dtors))
    KEEP(*(EXCLUDE_FILE(*crtend.o) .dtors))
    KEEP(*(SORT(.dtors.*)))
    KEEP(*crtend.o(.dtors))

    . = ALIGN(4);
  } > rom

  PROVIDE_HIDDEN(__exidx_start = .);
  .ARM.exidx :
  {
    *(.ARM.exidx* .gnu.linkonce.armexidx.*)
  } > rom
  PROVIDE_HIDDEN(__exidx_end = .);

  . = ALIGN(4);
  __etext = .;   /* LMA of .data – where initialized data lives in flash */
  _etext  = .;   /* legacy alias */

  .data : AT(__etext)
  {
    . = ALIGN(4);
    __data_start__ = .;
    _srelocate    = .;   /* legacy alias */
    *(.ramfunc .ramfunc.*);
    *(.data .data.*);
    . = ALIGN(4);
    __data_end__ = .;
    _erelocate   = .;   /* legacy alias */
  } > ram

  .bss (NOLOAD) :
  {
    . = ALIGN(4);
    __bss_start__ = .;
    _sbss  = .;   /* legacy alias */
    _szero = .;   /* legacy alias */
    *(.bss .bss.*)
    *(COMMON)
    . = ALIGN(4);
    __bss_end__ = .;
    _ebss  = .;   /* legacy alias */
    _ezero = .;   /* legacy alias */
  } > ram

  /* Heap starts here (used by sbrk / malloc) */
  . = ALIGN(4);
  end  = .;
  _end = .;
}