/**
 * FILE: stack.s
 *
 * DESCRIPTION:
 * RP2350 Stack Initialization.
 * 
 * BRIEF:
 * Provides stack pointer initialization for Main and Process Stack
 * Pointers (MSP/PSP) and their limits.
 *
 * AUTHOR: Kevin Thomas
 * CREATION DATE: November 27, 2025
 * UPDATE DATE: November 27, 2025
 */

.syntax unified                                  // use unified assembly syntax
.cpu cortex-m33                                  // target Cortex-M33 core
.thumb                                           // use Thumb instruction set

.include "constants.s"

/**
 * Initialize the .text section. 
 * The .text section contains executable code.
 */
.section .text                                   // code section
.align 2                                         // align to 4-byte boundary

/**
 * @brief   Initialize stack pointers.
 *
 * @details Sets Main and Process Stack Pointers (MSP/PSP) and their limits.
 *
 * @param   None
 * @retval  None
 */
.global Init_Stack
.type Init_Stack, %function
Init_Stack:
  ldr   r0, =STACK_TOP                           // load stack top
  msr   PSP, r0                                  // set PSP
  ldr   r0, =STACK_LIMIT                         // load stack limit
  msr   MSPLIM, r0                               // set MSP limit
  msr   PSPLIM, r0                               // set PSP limit
  ldr   r0, =STACK_TOP                           // reload stack top
  msr   MSP, r0                                  // set MSP
  bx    lr                                       // return