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/*  cpu_asm.S

 *

 *  This file contains the basic algorithms for all assembly code used

 *  in an specific CPU port of RTEMS.  These algorithms must be implemented

 *  in assembly language

 *

 *  Author:     Craig Lebakken 

 *

 *  COPYRIGHT (c) 1996 by Transition Networks Inc.

 *

 *  To anyone who acknowledges that this file is provided "AS IS"

 *  without any express or implied warranty:

 *      permission to use, copy, modify, and distribute this file

 *      for any purpose is hereby granted without fee, provided that

 *      the above copyright notice and this notice appears in all

 *      copies, and that the name of Transition Networks not be used in

 *      advertising or publicity pertaining to distribution of the

 *      software without specific, written prior permission.

 *      Transition Networks makes no representations about the suitability

 *      of this software for any purpose.

 *

 *  Derived from c/src/exec/score/cpu/no_cpu/cpu_asm.s:

 *

 *  COPYRIGHT (c) 1989-1999.

 *  On-Line Applications Research Corporation (OAR).

 *

 *  The license and distribution terms for this file may be

 *  found in the file LICENSE in this distribution or at

 *  http://www.OARcorp.com/rtems/license.html.

 *

 *  $Id: cpu_asm.S,v 1.2 2001-09-27 11:59:28 chris Exp $

 */

/* @(#)cpu_asm.S       08/20/96     1.15 */

#include "cpu_asm.h"

#include "iregdef.h"

#include "idtcpu.h"

#define FRAME(name,frm_reg,offset,ret_reg)      \

        .globl  name;                           \

        .ent    name;                           \

name:;                                          \

        .frame  frm_reg,offset,ret_reg

#define ENDFRAME(name)                          \

        .end name

#define EXCP_STACK_SIZE (NREGS*R_SZ)

#if __ghs__

#define sd sw

#define ld lw

#define dmtc0 mtc0

#define dsll sll

#define dmfc0 mfc0

#endif

#if 1  /* 32 bit unsigned32 types */

#define sint sw

#define lint lw

#define stackadd addiu

#define intadd addu

#define SZ_INT 4

#define SZ_INT_POW2 2

#else /* 64 bit unsigned32 types */

#define sint dw

#define lint dw

#define stackadd daddiu

#define intadd daddu

#define SZ_INT 8

#define SZ_INT_POW2 3

#endif

#ifdef __GNUC__

#define EXTERN(x,size) .extern x,size

#else

#define EXTERN(x,size)

#endif

/* NOTE: these constants must match the Context_Control structure in cpu.h */

#define S0_OFFSET 0

#define S1_OFFSET 1

#define S2_OFFSET 2

#define S3_OFFSET 3

#define S4_OFFSET 4

#define S5_OFFSET 5

#define S6_OFFSET 6

#define S7_OFFSET 7

#define SP_OFFSET 8

#define FP_OFFSET 9

#define RA_OFFSET 10

#define C0_SR_OFFSET 11

#define C0_EPC_OFFSET 12

/* NOTE: these constants must match the Context_Control_fp structure in cpu.h */

#define FP0_OFFSET  0

#define FP1_OFFSET  1

#define FP2_OFFSET  2

#define FP3_OFFSET  3

#define FP4_OFFSET  4

#define FP5_OFFSET  5

#define FP6_OFFSET  6

#define FP7_OFFSET  7

#define FP8_OFFSET  8

#define FP9_OFFSET  9

#define FP10_OFFSET 10

#define FP11_OFFSET 11

#define FP12_OFFSET 12

#define FP13_OFFSET 13

#define FP14_OFFSET 14

#define FP15_OFFSET 15

#define FP16_OFFSET 16

#define FP17_OFFSET 17

#define FP18_OFFSET 18

#define FP19_OFFSET 19

#define FP20_OFFSET 20

#define FP21_OFFSET 21

#define FP22_OFFSET 22

#define FP23_OFFSET 23

#define FP24_OFFSET 24

#define FP25_OFFSET 25

#define FP26_OFFSET 26

#define FP27_OFFSET 27

#define FP28_OFFSET 28

#define FP29_OFFSET 29

#define FP30_OFFSET 30

#define FP31_OFFSET 31

/*PAGE

 *

 *  _CPU_ISR_Get_level

 */

#if 0

unsigned32 _CPU_ISR_Get_level( void )

{

  /*

   *  This routine returns the current interrupt level.

   */

}

#endif

/* return the current exception level for the 4650 */

FRAME(_CPU_ISR_Get_level,sp,0,ra)

        mfc0 v0,C0_SR

        nop

        andi v0,SR_EXL

        srl v0,1

        j ra

ENDFRAME(_CPU_ISR_Get_level)

FRAME(_CPU_ISR_Set_level,sp,0,ra)

        nop

        mfc0 v0,C0_SR

        nop

        andi v0,SR_EXL

        beqz v0,_CPU_ISR_Set_1          /* normalize v0 */

        nop

        li v0,1

_CPU_ISR_Set_1:

        beq v0,a0,_CPU_ISR_Set_exit     /* if (current_level != new_level ) */

        nop

        bnez a0,_CPU_ISR_Set_2

        nop

        nop

        mfc0 t0,C0_SR

        nop

        li t1,~SR_EXL

        and t0,t1

        nop

        mtc0 t0,C0_SR                   /* disable exception level */

        nop

        j ra

        nop

_CPU_ISR_Set_2:

        nop

        mfc0 t0,C0_SR

        nop

        li t1,~SR_IE

        and t0,t1

        nop

        mtc0 t0,C0_SR                   /* first disable ie bit (recommended) */

        nop

        ori t0,SR_EXL|SR_IE             /* enable exception level  */

        nop

        mtc0 t0,C0_SR

        nop

_CPU_ISR_Set_exit:

        j ra

        nop

ENDFRAME(_CPU_ISR_Set_level)

/*

 *  _CPU_Context_save_fp_context

 *

 *  This routine is responsible for saving the FP context

 *  at *fp_context_ptr.  If the point to load the FP context

 *  from is changed then the pointer is modified by this routine.

 *

 *  Sometimes a macro implementation of this is in cpu.h which dereferences

 *  the ** and a similarly named routine in this file is passed something

 *  like a (Context_Control_fp *).  The general rule on making this decision

 *  is to avoid writing assembly language.

 */

/* void _CPU_Context_save_fp(

 * void **fp_context_ptr

 * )

 * {

 * }

 */

FRAME(_CPU_Context_save_fp,sp,0,ra)

        .set noat

        ld a1,(a0)

        swc1 $f0,FP0_OFFSET*4(a1)

        swc1 $f1,FP1_OFFSET*4(a1)

        swc1 $f2,FP2_OFFSET*4(a1)

        swc1 $f3,FP3_OFFSET*4(a1)

        swc1 $f4,FP4_OFFSET*4(a1)

        swc1 $f5,FP5_OFFSET*4(a1)

        swc1 $f6,FP6_OFFSET*4(a1)

        swc1 $f7,FP7_OFFSET*4(a1)

        swc1 $f8,FP8_OFFSET*4(a1)

        swc1 $f9,FP9_OFFSET*4(a1)

        swc1 $f10,FP10_OFFSET*4(a1)

        swc1 $f11,FP11_OFFSET*4(a1)

        swc1 $f12,FP12_OFFSET*4(a1)

        swc1 $f13,FP13_OFFSET*4(a1)

        swc1 $f14,FP14_OFFSET*4(a1)

        swc1 $f15,FP15_OFFSET*4(a1)

        swc1 $f16,FP16_OFFSET*4(a1)

        swc1 $f17,FP17_OFFSET*4(a1)

        swc1 $f18,FP18_OFFSET*4(a1)

        swc1 $f19,FP19_OFFSET*4(a1)

        swc1 $f20,FP20_OFFSET*4(a1)

        swc1 $f21,FP21_OFFSET*4(a1)

        swc1 $f22,FP22_OFFSET*4(a1)

        swc1 $f23,FP23_OFFSET*4(a1)

        swc1 $f24,FP24_OFFSET*4(a1)

        swc1 $f25,FP25_OFFSET*4(a1)

        swc1 $f26,FP26_OFFSET*4(a1)

        swc1 $f27,FP27_OFFSET*4(a1)

        swc1 $f28,FP28_OFFSET*4(a1)

        swc1 $f29,FP29_OFFSET*4(a1)

        swc1 $f30,FP30_OFFSET*4(a1)

        swc1 $f31,FP31_OFFSET*4(a1)

        j ra

        nop

        .set at

ENDFRAME(_CPU_Context_save_fp)

/*

 *  _CPU_Context_restore_fp_context

 *

 *  This routine is responsible for restoring the FP context

 *  at *fp_context_ptr.  If the point to load the FP context

 *  from is changed then the pointer is modified by this routine.

 *

 *  Sometimes a macro implementation of this is in cpu.h which dereferences

 *  the ** and a similarly named routine in this file is passed something

 *  like a (Context_Control_fp *).  The general rule on making this decision

 *  is to avoid writing assembly language.

 */

/* void _CPU_Context_restore_fp(

 * void **fp_context_ptr

 * )

 * {

 * }

 */

FRAME(_CPU_Context_restore_fp,sp,0,ra)

        .set noat

        ld a1,(a0)

        lwc1 $f0,FP0_OFFSET*4(a1)

        lwc1 $f1,FP1_OFFSET*4(a1)

        lwc1 $f2,FP2_OFFSET*4(a1)

        lwc1 $f3,FP3_OFFSET*4(a1)

        lwc1 $f4,FP4_OFFSET*4(a1)

        lwc1 $f5,FP5_OFFSET*4(a1)

        lwc1 $f6,FP6_OFFSET*4(a1)

        lwc1 $f7,FP7_OFFSET*4(a1)

        lwc1 $f8,FP8_OFFSET*4(a1)

        lwc1 $f9,FP9_OFFSET*4(a1)

        lwc1 $f10,FP10_OFFSET*4(a1)

        lwc1 $f11,FP11_OFFSET*4(a1)

        lwc1 $f12,FP12_OFFSET*4(a1)

        lwc1 $f13,FP13_OFFSET*4(a1)

        lwc1 $f14,FP14_OFFSET*4(a1)

        lwc1 $f15,FP15_OFFSET*4(a1)

        lwc1 $f16,FP16_OFFSET*4(a1)

        lwc1 $f17,FP17_OFFSET*4(a1)

        lwc1 $f18,FP18_OFFSET*4(a1)

        lwc1 $f19,FP19_OFFSET*4(a1)

        lwc1 $f20,FP20_OFFSET*4(a1)

        lwc1 $f21,FP21_OFFSET*4(a1)

        lwc1 $f22,FP22_OFFSET*4(a1)

        lwc1 $f23,FP23_OFFSET*4(a1)

        lwc1 $f24,FP24_OFFSET*4(a1)

        lwc1 $f25,FP25_OFFSET*4(a1)

        lwc1 $f26,FP26_OFFSET*4(a1)

        lwc1 $f27,FP27_OFFSET*4(a1)

        lwc1 $f28,FP28_OFFSET*4(a1)

        lwc1 $f29,FP29_OFFSET*4(a1)

        lwc1 $f30,FP30_OFFSET*4(a1)

        lwc1 $f31,FP31_OFFSET*4(a1)

        j ra

        nop

        .set at

ENDFRAME(_CPU_Context_restore_fp)

/*  _CPU_Context_switch

 *

 *  This routine performs a normal non-FP context switch.

 */

/* void _CPU_Context_switch(

 * Context_Control  *run,

 * Context_Control  *heir

 * )

 * {

 * }

 */

FRAME(_CPU_Context_switch,sp,0,ra)

        mfc0 t0,C0_SR

        li t1,~SR_IE

        sd t0,C0_SR_OFFSET*8(a0)        /* save status register */

        and t0,t1

        mtc0 t0,C0_SR                   /* first disable ie bit (recommended) */

        ori t0,SR_EXL|SR_IE             /* enable exception level to disable interrupts */

        mtc0 t0,C0_SR

        sd ra,RA_OFFSET*8(a0)           /* save current context */

        sd sp,SP_OFFSET*8(a0)

        sd fp,FP_OFFSET*8(a0)

        sd s0,S0_OFFSET*8(a0)

        sd s1,S1_OFFSET*8(a0)

        sd s2,S2_OFFSET*8(a0)

        sd s3,S3_OFFSET*8(a0)

        sd s4,S4_OFFSET*8(a0)

        sd s5,S5_OFFSET*8(a0)

        sd s6,S6_OFFSET*8(a0)

        sd s7,S7_OFFSET*8(a0)

        dmfc0 t0,C0_EPC

        sd t0,C0_EPC_OFFSET*8(a0)

_CPU_Context_switch_restore:

        ld s0,S0_OFFSET*8(a1)           /* restore context */

        ld s1,S1_OFFSET*8(a1)

        ld s2,S2_OFFSET*8(a1)

        ld s3,S3_OFFSET*8(a1)

        ld s4,S4_OFFSET*8(a1)

        ld s5,S5_OFFSET*8(a1)

        ld s6,S6_OFFSET*8(a1)

        ld s7,S7_OFFSET*8(a1)

        ld fp,FP_OFFSET*8(a1)

        ld sp,SP_OFFSET*8(a1)

        ld ra,RA_OFFSET*8(a1)

        ld t0,C0_EPC_OFFSET*8(a1)

        dmtc0 t0,C0_EPC

        ld t0,C0_SR_OFFSET*8(a1)

        andi t0,SR_EXL

        bnez t0,_CPU_Context_1          /* set exception level from restore context */

        li t0,~SR_EXL

        mfc0 t1,C0_SR

        nop

        and t1,t0

        mtc0 t1,C0_SR

_CPU_Context_1:

        j ra

        nop

ENDFRAME(_CPU_Context_switch)

/*

 *  _CPU_Context_restore

 *

 *  This routine is generally used only to restart self in an

 *  efficient manner.  It may simply be a label in _CPU_Context_switch.

 *

 *  NOTE: May be unnecessary to reload some registers.

 */

#if 0

void _CPU_Context_restore(

  Context_Control *new_context

)

{

}

#endif

FRAME(_CPU_Context_restore,sp,0,ra)

        dadd a1,a0,zero

        j _CPU_Context_switch_restore

        nop

ENDFRAME(_CPU_Context_restore)

EXTERN(_ISR_Nest_level, SZ_INT)

EXTERN(_Thread_Dispatch_disable_level,SZ_INT)

EXTERN(_Context_Switch_necessary,SZ_INT)

EXTERN(_ISR_Signals_to_thread_executing,SZ_INT)

.extern _Thread_Dispatch

.extern _ISR_Vector_table

/*  void __ISR_Handler()

 *

 *  This routine provides the RTEMS interrupt management.

 *

 */

#if 0

void _ISR_Handler()

{

   /*

    *  This discussion ignores a lot of the ugly details in a real

    *  implementation such as saving enough registers/state to be

    *  able to do something real.  Keep in mind that the goal is

    *  to invoke a user's ISR handler which is written in C and

    *  uses a certain set of registers.

    *

    *  Also note that the exact order is to a large extent flexible.

    *  Hardware will dictate a sequence for a certain subset of

    *  _ISR_Handler while requirements for setting

    */

  /*

   *  At entry to "common" _ISR_Handler, the vector number must be

   *  available.  On some CPUs the hardware puts either the vector

   *  number or the offset into the vector table for this ISR in a

   *  known place.  If the hardware does not give us this information,

   *  then the assembly portion of RTEMS for this port will contain

   *  a set of distinct interrupt entry points which somehow place

   *  the vector number in a known place (which is safe if another

   *  interrupt nests this one) and branches to _ISR_Handler.

   *

   */

#endif

FRAME(_ISR_Handler,sp,0,ra)

.set noreorder

#if USE_IDTKIT

/* IDT/Kit incorrectly adds 4 to EPC before returning.  This compensates */

        lreg    k0, R_EPC*R_SZ(sp)

        daddiu    k0,k0,-4

        sreg    k0, R_EPC*R_SZ(sp)

        lreg    k0, R_CAUSE*R_SZ(sp)

        li      k1, ~CAUSE_BD

        and     k0, k1

        sreg    k0, R_CAUSE*R_SZ(sp)

#endif

/* save registers not already saved by IDT/sim */

        stackadd sp,sp,-EXCP_STACK_SIZE /* store ra on the stack */

        sreg    ra, R_RA*R_SZ(sp)

        sreg    v0, R_V0*R_SZ(sp)

        sreg    v1, R_V1*R_SZ(sp)

        sreg    a0, R_A0*R_SZ(sp)

        sreg    a1, R_A1*R_SZ(sp)

        sreg    a2, R_A2*R_SZ(sp)

        sreg    a3, R_A3*R_SZ(sp)

        sreg    t0, R_T0*R_SZ(sp)

        sreg    t1, R_T1*R_SZ(sp)

        sreg    t2, R_T2*R_SZ(sp)

        sreg    t3, R_T3*R_SZ(sp)

        sreg    t4, R_T4*R_SZ(sp)

        sreg    t5, R_T5*R_SZ(sp)

        sreg    t6, R_T6*R_SZ(sp)

        sreg    t7, R_T7*R_SZ(sp)

        mflo    k0

        sreg    t8, R_T8*R_SZ(sp)

        sreg    k0, R_MDLO*R_SZ(sp)

        sreg    t9, R_T9*R_SZ(sp)

        mfhi    k0

        sreg    gp, R_GP*R_SZ(sp)

        sreg    fp, R_FP*R_SZ(sp)

        sreg    k0, R_MDHI*R_SZ(sp)

        .set noat

        sreg    AT, R_AT*R_SZ(sp)

        .set at

        stackadd sp,sp,-40              /* store ra on the stack */

        sd ra,32(sp)

/* determine if an interrupt generated this exception */

        mfc0 k0,C0_CAUSE

        and k1,k0,CAUSE_EXCMASK

        bnez k1,_ISR_Handler_prom_exit /* not an external interrupt, pass exception to Monitor */

        mfc0 k1,C0_SR

        and k0,k1

        and k0,CAUSE_IPMASK

        beq k0,zero,_ISR_Handler_quick_exit /* external interrupt not enabled, ignore */

        nop

  /*

   *  save some or all context on stack

   *  may need to save some special interrupt information for exit

   *

   *  #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )

   *    if ( _ISR_Nest_level == 0 )

   *      switch to software interrupt stack

   *  #endif

   */

#if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )

        lint t0,_ISR_Nest_level

        beq t0, zero,  _ISR_Handler_1

        nop

        /* switch stacks */

_ISR_Handler_1:

#else

        lint t0,_ISR_Nest_level

#endif

  /*

   *  _ISR_Nest_level++;

   */

        addi t0,t0,1

        sint t0,_ISR_Nest_level

  /*

   *  _Thread_Dispatch_disable_level++;

   */

        lint t1,_Thread_Dispatch_disable_level

        addi t1,t1,1

        sint t1,_Thread_Dispatch_disable_level

#if 0

        nop

        j _ISR_Handler_4

        nop

  /*

   *  while ( interrupts_pending(cause_reg) ) {

   *     vector = BITFIELD_TO_INDEX(cause_reg);

   *     (*_ISR_Vector_table[ vector ])( vector );

   *  }

   */

_ISR_Handler_2:

/* software interrupt priorities can be applied here */

        li t1,-1

/* convert bit field into interrupt index */

_ISR_Handler_3:

        andi t2,t0,1

        addi t1,1

        beql t2,zero,_ISR_Handler_3

        dsrl t0,1

        li t1,7

        dsll t1,3                       /* convert index to byte offset (*8) */

        la t3,_ISR_Vector_table

        intadd t1,t3

        lint t1,(t1)

        jalr t1

        nop

        j _ISR_Handler_5

        nop

_ISR_Handler_4:

        mfc0 t0,C0_CAUSE

        andi t0,CAUSE_IPMASK

        bne t0,zero,_ISR_Handler_2

        dsrl t0,t0,8

_ISR_Handler_5:

#else

        nop

        li t1,7

        dsll t1,t1,SZ_INT_POW2

        la t3,_ISR_Vector_table

        intadd t1,t3

        lint t1,(t1)

        jalr t1

        nop

#endif

  /*

   *  --_ISR_Nest_level;

   */

        lint t2,_ISR_Nest_level

        addi t2,t2,-1

        sint t2,_ISR_Nest_level

  /*

   *  --_Thread_Dispatch_disable_level;

   */

        lint t1,_Thread_Dispatch_disable_level

        addi t1,t1,-1

        sint t1,_Thread_Dispatch_disable_level

  /*

   *  if ( _Thread_Dispatch_disable_level || _ISR_Nest_level )

   *    goto the label "exit interrupt (simple case)"

   */

        or t0,t2,t1

        bne t0,zero,_ISR_Handler_exit

        nop

  /*

   *  #if ( CPU_HAS_SOFTWARE_INTERRUPT_STACK == TRUE )

   *    restore stack

   *  #endif

   *

   *  if ( !_Context_Switch_necessary && !_ISR_Signals_to_thread_executing )

   *    goto the label "exit interrupt (simple case)"

   */

        lint t0,_Context_Switch_necessary

        lint t1,_ISR_Signals_to_thread_executing

        or t0,t0,t1

        beq t0,zero,_ISR_Handler_exit

        nop

  /*

   *  call _Thread_Dispatch() or prepare to return to _ISR_Dispatch

   */

        jal _Thread_Dispatch

        nop

  /*

   *  prepare to get out of interrupt

   *  return from interrupt  (maybe to _ISR_Dispatch)

   *

   *  LABEL "exit interrupt (simple case):

   *  prepare to get out of interrupt

   *  return from interrupt

   */

_ISR_Handler_exit:

        ld ra,32(sp)

        stackadd sp,sp,40

/* restore interrupt context from stack */

        lreg    k0, R_MDLO*R_SZ(sp)

        mtlo    k0

        lreg    k0, R_MDHI*R_SZ(sp)

        lreg    a2, R_A2*R_SZ(sp)

        mthi    k0

        lreg    a3, R_A3*R_SZ(sp)

        lreg    t0, R_T0*R_SZ(sp)

        lreg    t1, R_T1*R_SZ(sp)

        lreg    t2, R_T2*R_SZ(sp)

        lreg    t3, R_T3*R_SZ(sp)

        lreg    t4, R_T4*R_SZ(sp)

        lreg    t5, R_T5*R_SZ(sp)

        lreg    t6, R_T6*R_SZ(sp)

        lreg    t7, R_T7*R_SZ(sp)

        lreg    t8, R_T8*R_SZ(sp)

        lreg    t9, R_T9*R_SZ(sp)

        lreg    gp, R_GP*R_SZ(sp)

        lreg    fp, R_FP*R_SZ(sp)

        lreg    ra, R_RA*R_SZ(sp)

        lreg    a0, R_A0*R_SZ(sp)

        lreg    a1, R_A1*R_SZ(sp)

        lreg    v1, R_V1*R_SZ(sp)

        lreg    v0, R_V0*R_SZ(sp)

        .set noat

        lreg    AT, R_AT*R_SZ(sp)

        .set at

        stackadd sp,sp,EXCP_STACK_SIZE /* store ra on the stack */

#if USE_IDTKIT

/* we handled exception, so return non-zero value */

        li v0,1

#endif

_ISR_Handler_quick_exit:

#ifdef USE_IDTKIT

        j ra

#else

        eret

#endif

        nop

_ISR_Handler_prom_exit:

#ifdef CPU_R3000

        la      k0, (R_VEC+((48)*8))

#endif

#ifdef CPU_R4000

        la      k0, (R_VEC+((112)*8)) /* R4000 Sim's location is different */

#endif

        j       k0

        nop

       .set    reorder

ENDFRAME(_ISR_Handler)

FRAME(mips_enable_interrupts,sp,0,ra)

        mfc0 t0,C0_SR           /* get status reg */

        nop

        or t0,t0,a0

        mtc0 t0,C0_SR           /* save updated status reg */

        j ra

        nop

ENDFRAME(mips_enable_interrupts)

FRAME(mips_disable_interrupts,sp,0,ra)

        mfc0 v0,C0_SR           /* get status reg */

        li t1,SR_IMASK          /* t1 = load interrupt mask word */

        not t0,t1               /* t0 = ~t1 */

        and t0,v0               /* clear imask bits */

        mtc0 t0,C0_SR           /* save status reg */

        and v0,t1               /* mask return value (only return imask bits) */

        jr ra

        nop

ENDFRAME(mips_disable_interrupts)

FRAME(mips_enable_global_interrupts,sp,0,ra)

        mfc0 t0,C0_SR           /* get status reg */

        nop

        ori t0,SR_IE

        mtc0 t0,C0_SR           /* save updated status reg */

        j ra

        nop

ENDFRAME(mips_enable_global_interrupts)

FRAME(mips_disable_global_interrupts,sp,0,ra)

        li t1,SR_IE

        mfc0 t0,C0_SR           /* get status reg */

        not t1

        and t0,t1

        mtc0 t0,C0_SR           /* save updated status reg */

        j ra

        nop

ENDFRAME(mips_disable_global_interrupts)

/* return the value of the status register in v0.  Used for debugging */

FRAME(mips_get_sr,sp,0,ra)

        mfc0 v0,C0_SR

        j ra

        nop

ENDFRAME(mips_get_sr)

FRAME(mips_break,sp,0,ra)

#if 1

        break 0x0

        j mips_break

#else

        j ra

#endif

        nop

ENDFRAME(mips_break)

/*PAGE

 *

 *  _CPU_Internal_threads_Idle_thread_body

 *

 *  NOTES:

 *

 *  1. This is the same as the regular CPU independent algorithm.

 *

 *  2. If you implement this using a "halt", "idle", or "shutdown"

 *     instruction, then don't forget to put it in an infinite loop.

 *

 *  3. Be warned. Some processors with onboard DMA have been known

 *     to stop the DMA if the CPU were put in IDLE mode.  This might

 *     also be a problem with other on-chip peripherals.  So use this

 *     hook with caution.

 */

FRAME(_CPU_Thread_Idle_body,sp,0,ra)

        wait                    /* enter low power mode */

        j _CPU_Thread_Idle_body

        nop

ENDFRAME(_CPU_Thread_Idle_body)

#define VEC_CODE_LENGTH 10*4

/**************************************************************************

**

**      init_exc_vecs() - moves the exception code into the addresses

**                        reserved for exception vectors

**

**      UTLB Miss exception vector at address 0x80000000

**

**      General exception vector at address 0x80000080

**

**      RESET exception vector is at address 0xbfc00000

**

***************************************************************************/

#define INITEXCFRM ((2*4)+4)            /* ra + 2 arguments */

FRAME(init_exc_vecs,sp,0,ra)

/* This code yanked from SIM */

#if defined(CPU_R3000)

        .set    noreorder

        la      t1,exc_utlb_code

        la      t2,exc_norm_code

        li      t3,UT_VEC

        li      t4,E_VEC

        li      t5,VEC_CODE_LENGTH

1:

        lw      t6,0(t1)

        lw      t7,0(t2)

        sw      t6,0(t3)

        sw      t7,0(t4)

        addiu   t1,4

        addiu   t3,4

        addiu   t4,4

        subu    t5,4

        bne     t5,zero,1b

        addiu   t2,4

        move    t5,ra           # assumes clear_cache doesnt use t5

        li      a0,UT_VEC

        jal     clear_cache

        li      a1,VEC_CODE_LENGTH

        nop

        li      a0,E_VEC

        jal     clear_cache

        li      a1,VEC_CODE_LENGTH

        move    ra,t5           # restore ra

        j       ra

        nop

        .set    reorder

#endif

#if defined(CPU_R4000)

        .set reorder

        move    t5,ra           # assumes clear_cache doesnt use t5

        /* TLB exception vector */

        la      t1,exc_tlb_code

        li      t2,T_VEC |K1BASE

        li      t3,VEC_CODE_LENGTH

1:

        lw      t6,0(t1)

        addiu   t1,4

        subu    t3,4

        sw      t6,0(t2)

        addiu   t2,4

        bne     t3,zero,1b

        li      a0,T_VEC

        li      a1,VEC_CODE_LENGTH

        jal     clear_cache

        la      t1,exc_xtlb_code

        li      t2,X_VEC |K1BASE

        li      t3,VEC_CODE_LENGTH

1:

        lw      t6,0(t1)

        addiu   t1,4

        subu    t3,4

        sw      t6,0(t2)

        addiu   t2,4

        bne     t3,zero,1b

        /* extended TLB exception vector */

        li      a0,X_VEC

        li      a1,VEC_CODE_LENGTH

        jal     clear_cache

        /* cache error exception vector */

        la      t1,exc_cache_code

        li      t2,C_VEC |K1BASE

        li      t3,VEC_CODE_LENGTH

1:

        lw      t6,0(t1)

        addiu   t1,4

        subu    t3,4

        sw      t6,0(t2)

        addiu   t2,4

        bne     t3,zero,1b

        li      a0,C_VEC

        li      a1,VEC_CODE_LENGTH

        jal     clear_cache

        /* normal exception vector */

        la      t1,exc_norm_code

        li      t2,E_VEC |K1BASE

        li      t3,VEC_CODE_LENGTH

1:

        lw      t6,0(t1)

        addiu   t1,4

        subu    t3,4

        sw      t6,0(t2)

        addiu   t2,4

        bne     t3,zero,1b

        li      a0,E_VEC

        li      a1,VEC_CODE_LENGTH

        jal     clear_cache

        move    ra,t5           # restore ra

        j       ra

#endif

ENDFRAME(init_exc_vecs)

#if defined(CPU_R4000)

FRAME(exc_tlb_code,sp,0,ra)

#ifdef CPU_R3000

        la      k0, (R_VEC+((48)*8))

#endif

#ifdef CPU_R4000

        la      k0, (R_VEC+((112)*8)) /* R4000 Sim's location is different */

#endif

        j       k0

        nop

ENDFRAME(exc_tlb_code)

FRAME(exc_xtlb_code,sp,0,ra)

#ifdef CPU_R3000

        la      k0, (R_VEC+((48)*8))

#endif

#ifdef CPU_R4000

        la      k0, (R_VEC+((112)*8)) /* R4000 Sim's location is different */

#endif

        j       k0

        nop

ENDFRAME(exc_xtlb_code)

FRAME(exc_cache_code,sp,0,ra)

#ifdef CPU_R3000

        la      k0, (R_VEC+((48)*8))

#endif

#ifdef CPU_R4000

        la      k0, (R_VEC+((112)*8)) /* R4000 Sim's location is different */

#endif

        j       k0

        nop

ENDFRAME(exc_cache_code)

FRAME(exc_norm_code,sp,0,ra)

        la      k0, _ISR_Handler /* generic external int hndlr */

        j       k0

        nop

        subu    sp, EXCP_STACK_SIZE             /* set up local stack frame */

ENDFRAME(exc_norm_code)

#endif

/**************************************************************************

**

** enable_int(mask) - enables interrupts - mask is positioned so it only

**                      needs to be or'ed into the status reg. This

**                      also does some other things !!!! caution should

**                      be used if invoking this while in the middle

**                      of a debugging session where the client may have