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##=============================================================================

##

##      context.S

##

##      MN10300 context switch code

##

##=============================================================================

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##=============================================================================

#######DESCRIPTIONBEGIN####

##

## Author(s):   nickg

## Contributors:        nickg

## Date:        1998-04-27

## Purpose:     MN10300 context switch code

## Description: This file contains implementations of the thread context

##              switch routines. It also contains the longjmp() and setjmp()

##              routines.

##

######DESCRIPTIONEND####

##

##=============================================================================

#include 

#include 

#------------------------------------------------------------------------------

# hal_thread_switch_context

# Switch thread contexts

# D0 = address of sp of next thread to execute

# D1 = address of sp save location of current thread

        .global _hal_thread_switch_context

_hal_thread_switch_context:

        add     -8,sp           # space for SP and PSW

        mov     d2,a0           # move d2->a0 since PSW can only be

                                # saved to a data register

        hal_cpu_get_psw d2      # save PSW to d2

        mov     d2,(4,sp)       # store in stack loc

        mov     a0,d2           # retrieve old d2 value

        hal_cpu_save_all        # save entire register set

        mov     d1,a2           # move save loc addr to A2

        mov     sp,(0,a2)       # store SP in save location

        # Now load the destination thread by dropping through

        # to hal_thread_load_context

#------------------------------------------------------------------------------

# hal_thread_load_context

# Load thread context

# D0 = address of sp of next thread to execute

# Note that this function is also the second half of hal_thread_switch_context

# and is simply dropped into from it.

        .global _hal_thread_load_context

_hal_thread_load_context:

        mov     d0,a2           # move next sp loc to a2

        mov     (0,a2),sp       # load SP with new value

        hal_cpu_load_all        # load whole register set

        mov     (4,sp),d1       # retrieve saved PSW

        hal_cpu_set_psw d1      # and restore it

        add     8,sp            # skip saved SP and PSW

        ret     [],0            # and return

##-----------------------------------------------------------------------------

## HAL longjmp(), setjmp() implementations

## These implementations omit the usual movm [d2,d3,a2,a3],(sp)

## Which is the first instruction of all C compiled functions.

## Note: These definitions are repeated in hal_arch.h. If changes are required

## remember to update both sets.

#define CYGARC_JMP_BUF_SP        0

#define CYGARC_JMP_BUF_D2        1

#define CYGARC_JMP_BUF_D3        2

#define CYGARC_JMP_BUF_A2        3

#define CYGARC_JMP_BUF_A3        4

#define CYGARC_JMP_BUF_LR        5

#define CYGARC_JMP_BUF_SIZE      6

        # This just preserves the callee save registers

        # namely a2,a3,d2,d3

        # setjmp cannot use movm to do this as we need to keep

        # the sp underneath all live data at all times.

        .globl _hal_setjmp

_hal_setjmp:                    # d0=env

        mov     d0,a0           # env

        mov     d2,(CYGARC_JMP_BUF_D2*4,a0)

        mov     d3,(CYGARC_JMP_BUF_D3*4,a0)

        mov     a2,(CYGARC_JMP_BUF_A2*4,a0)

        mov     a3,(CYGARC_JMP_BUF_A3*4,a0)

        mov     mdr,d1          # link saved by call (also in (0,sp))

        mov     d1,(CYGARC_JMP_BUF_LR*4,a0)

        mov     sp,a1

        mov     a1,(CYGARC_JMP_BUF_SP*4,a0) # a1==(caller''s sp)

        clr     d0              # return 0

        ret     [],0

        # longjmp returns to caller of setjmp

        # after restoring callee save registers

        .globl _hal_longjmp

_hal_longjmp:

        mov     d0,a0

        mov     (CYGARC_JMP_BUF_D2*4,a0),d2

        mov     (CYGARC_JMP_BUF_D3*4,a0),d3

        mov     (CYGARC_JMP_BUF_A2*4,a0),a2

        mov     (CYGARC_JMP_BUF_A3*4,a0),a3

        mov     (CYGARC_JMP_BUF_LR*4,a0),d0

##      mov     d0,mdr

        mov     (CYGARC_JMP_BUF_SP*4,a0),a1 # stashed (caller''s sp)

        mov     a1,sp

        mov     d0,(0,sp)       # put link on stack

        mov     d1,d0           # return arg1

        ret     [],0            # this ignores (0,sp) and does pc=mdr

#------------------------------------------------------------------------------

# end of context.S