/**
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 *
 * \brief ARM context switch
 *
 * \version $Id: proc.c 18271 2007-10-11 14:51:31Z batt $
 *
 * \author Stefano Fedrigo <aleph@develer.com>
 * \author Francesco Sacchi <batt@develer.com>
 */

/* void asm_switch_context(void **new_sp [r0], void **save_sp [r1]) */
.globl asm_switch_context
asm_switch_context:
	mrs	r2, cpsr               /* Save status. */

	/*
	 * To work correctly the lr should point to proc_exit, so when process finish
	 * could be return
	 */
	push {lr}                  /* Add one element on stack, for next switching */

	stmfd	sp!, {r2, r4-r11, lr}  /* Save registers. */

	str     sp, [r1]               /* Save old stack pointer. */
	ldr	sp, [r0]               /* Load new stack pointer */

	ldmfd	sp!, {r2, r4-r11, lr}  /* Load new registers. */
	msr	cpsr, r2               /* restore flags reg. */

	pop {r0}                  /* pop on stack address of the process that we want to jump */
	mov	pc, r0