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##=============================================================================##
##      context.S
##
##      CalmRISC32 context switch code
##
##=============================================================================
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##=============================================================================
#######DESCRIPTIONBEGIN####
##
## Author(s):   msalter
## Contributors: msalter
## Date:        2001-02-12
## Purpose:     CalmRISC32 context switch code
## Description: This file contains implementations of the thread context 
##              switch routines. It also contains the longjmp() and setjmp()
##              routines.
##
######DESCRIPTIONEND####
##
##=============================================================================

#include <pkgconf/hal.h>
#include <cyg/hal/arch.inc>

#------------------------------------------------------------------------------
# hal_thread_switch_context
# Switch thread contexts
# A0 = address of sp of next thread to execute
# A1 = address of sp save location of current thread

        .global hal_thread_switch_context
hal_thread_switch_context:              
        // FIXME        
        # Now load the destination thread by dropping through
        # to hal_thread_load_context
        
#------------------------------------------------------------------------------
# hal_thread_load_context
# Load thread context
# A0 = 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:
        // FIXME

#------------------------------------------------------------------------------
# HAL longjmp, setjmp implementations
# hal_setjmp saves only callee save registers into given buffer
# Note: These definitions are repeated in hal_arch.h. If changes are required
# remember to update both sets.

#define CYGARC_JMP_BUF_R0        0
#define CYGARC_JMP_BUF_R1        1
#define CYGARC_JMP_BUF_R2        2
#define CYGARC_JMP_BUF_R3        3
#define CYGARC_JMP_BUF_R4        4
#define CYGARC_JMP_BUF_R5        5
#define CYGARC_JMP_BUF_R6        6
#define CYGARC_JMP_BUF_R7        7
#define CYGARC_JMP_BUF_R12       8
#define CYGARC_JMP_BUF_R13       9
#define CYGARC_JMP_BUF_R14      10
#define CYGARC_JMP_BUF_R15      11

#define CYGARC_JMP_BUF_SIZE     48

// FIXME: The follwing restricts us to using only 32 bit registers
// in jump buffers. If/when we move to a full 64 bit architecture,
// this will need to change, as will the instructions that we use to
// save and restore them.

#define jmpbuf_regsize 4
        
        .globl  hal_setjmp
hal_setjmp:
        ld      r8, r0
        ldw     @[r8+0], r0
        ldw     @[r8+4], r1
        ldw     @[r8+8], r2
        ldw     @[r8+12], r3
        ldw     @[r8+16], r4
        ldw     @[r8+20], r5
        ldw     @[r8+24], r6
        ldw     @[r8+28], r7
        ldw     @[r8+32], r12
        ldw     @[r8+36], r13
        ldw     @[r8+40], r14
        ldw     @[r8+44], sp

        jmpd    r14
         ldw    r0, #0

        .globl  hal_longjmp
hal_longjmp:    
        ld      r9, r0
        ld      r8, r1
        ldw     sp, @[r9+44]
        ldw     r14, @[r9+40]
        ldw     r13, @[r9+36]
        ldw     r12, @[r9+32]
        ldw     r7, @[r9+28]
        ldw     r6, @[r9+24]
        ldw     r5, @[r9+20]
        ldw     r4, @[r9+16]
        ldw     r3, @[r9+12]
        ldw     r2, @[r9+8]
        ldw     r1, @[r9+4]
        # Value to return is in r8.  If zero, return 1
        ld      r0, r8
        cmp eq  r0, #0
        brf     0f
        ldw     r0, #1
    0:
        jmpd    r14
         nop
        
        
#------------------------------------------------------------------------------
# end of context.S