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##=============================================================================
##
##      context.S
##
##      mcf52xx context switch code
##
##=============================================================================
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## This file is part of eCos, the Embedded Configurable Operating System.
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##=============================================================================

#include <pkgconf/hal.h>

#------------------------------------------------------------------------------
# function declaration macro

#define FUNC_START(name)                        \
        .text;                                  \
        .even;                                  \
        .globl name;                            \
name:

#------------------------------------------------------------------------------
# hal_thread_switch_context
# Switch thread contexts
# :     0(%sp)  :     return address
# :     4(%sp)  :     to - address of sp of next thread to execute
# :     8(%sp)  :     from - address of sp save location of current thread
#
# d0, d1, a0, a1 are ours to abuse.
#
# externC void hal_thread_switch_context( CYG_ADDRESS to, CYG_ADDRESS from );

FUNC_START(hal_thread_switch_context)

        move.l  4(%sp),%a0                  /*   Read the to and from  from */
        move.l  8(%sp),%a1                  /* parameters from the stack.   */

        lea     -(6+5)*4(%sp),%sp           /*   Save all of the  registers */
        movem.l %d2-%d7/%a2-%a6,(%sp)       /* that    the    C     calling */
                                            /* convention  expects  us   to */
                                            /* preserve.                    */

        move.l  %sp,(%a1)                   /*   Store this threads current */
                                            /* stack pointer to *from.      */

        move.l  (%a0),%sp                   /*   Load the stack pointer for */
                                            /* the next thread from *to.    */

        movem.l (%sp),%d2-%d7/%a2-%a6       /*   Load all of the  preserved */
        lea     (6+5)*4(%sp),%sp            /* registers from the stack.    */

        rts                                 /*   Restore the PC.            */

#------------------------------------------------------------------------------
# hal_thread_load_context
# Load thread context
# :     4(%sp)  :     to - address of sp of next thread to execute
#
# d0, d1, a0, a1 are ours to abuse.

FUNC_START(hal_thread_load_context)

        move.l  4(%sp),%a0                  /*   Read the to parameter from */
        move.l  (%a0),%sp                   /* the stack and switch to that */
                                            /* stack pointer.               */

        movem.l (%sp),%d2-%d7/%a2-%a6       /*   Load all of the  preserved */
        lea     (6+5)*4(%sp),%sp            /* registers from the stack.    */

        rts                                 /*   Restore the PC.            */

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