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/*  rdbg_cpu_asm.s
 *
 *  This file contains all assembly code for the Motorola m68k implementation
 *  of RDBG.
 *
 * rdbg_cpu_asm.S,v 1.3 2002/05/14 15:13:52 joel Exp
 *
 */

#include <asm.h>
#include <rtems/score/cpu.h>    

        BEGIN_CODE

/*
 *  void copyback_data_cache_and_invalidate_instr_cache(addr, size)
 *
 *  This routine performs a copy of the data cache 
 *  and invalidate the instruction cache
 */

        .align  2
        PUBLIC (copyback_data_cache_and_invalidate_instr_cache)

SYM (copyback_data_cache_and_invalidate_instr_cache):
        nop     | how?
        rts


        
/*
 * void enterRdbg(void)
 *      
 * This function performs trap #4
 * It is used :
 *   1 - in the user code, to simulate a Breakpoint.
 *       (with justSaveContext = 0)
 *   2 - in the RDBG code, to push a ctx in the list.
 *       (with justSaveContext = 1)
 *
 * In most of case, it will be use as described in 1.
 * The 2nd possibility will be used by RDBG to obtain
 * its own ctx
 */

        PUBLIC (enterRdbg)

SYM (enterRdbg):
        trap    #4
        rts


/*
 * void excHandler(void)
 *      
 * lotsa copypaste from cpu_asm.S
 *
 */

/* 
 * The RTEMS jump table pushes vector
 *
 * The two types of exception frames on m68000 are
 *
 * unsigned16 sr <- sp
 * unsigned32 pc
 *
 * unsigned16 fc <- sp
 * unsigned32 addr
 * unsigned16 instr
 * unsigned16 sr
 * unsigned32 pc
 *
 * after real frame we push d0-d1/a0-a1
 *
 * after that we push CPU_Exception_frame
 *
 * exframe      <- sp
 * d0-d1/a0-a1
 * frame
 */
#if ( M68K_COLDFIRE_ARCH == 1 )
.set SR_OFFSET,    2                     | Status register offset
.set PC_OFFSET,    4                     | Program Counter offset
.set FVO_OFFSET,   0                     | Format/vector offset
#elif ( M68K_HAS_VBR == 1 )
.set SR_OFFSET,    0                     | Status register offset
.set PC_OFFSET,    2                     | Program Counter offset
.set FVO_OFFSET,   6                     | Format/vector offset
#else
.set SR_OFFSET,    2                     | Status register offset
.set PC_OFFSET,    4                     | Program Counter offset
.set FVO_OFFSET,   0                     | Format/vector offset placed in the stack
#endif /* M68K_HAS_VBR */
 
        .align 4
        
        PUBLIC (excHandler)
        PUBLIC (BreakPointExcHdl)

SYM (excFormatLength):  
        /*
         * size of exception stack frame depending on format type
         * This is valid for m68k with VBR (68020/030/040/CPU32/CPU32+)
         *      size | format/name
         */
        dc.w     4*2 |  $0 standard                           
        dc.w     4*2 |  $1 throwaway stackframe               
        dc.w     6*2 |  $2 CHK/CHK2/TRAPcc/TRAPV/DIV0/TRACE   
        dc.w     6*2 |  $3 Coprocessor Post-Instruction (040) 
        dc.w     4*2 |  $4 reserved
        dc.w     4*2 |  $5 reserved
        dc.w     4*2 |  $6 reserved
        dc.w    30*2 |  $7 Access Error (040)                 
        dc.w    29*2 |  $8 Bus Error    (020)                 
        dc.w    10*2 |  $9 Coprocessor Mid-Instruction (020)  
        dc.w    16*2 |  $A Short Bus-Error (020)              
        dc.w    46*2 |  $B Long  Bus-Error (020)              
        dc.w    12*2 |  $C Bus Error/Address Error (CPU32)    
        dc.w     4*2 |  $D reserved
        dc.w     4*2 |  $E reserved
        dc.w     4*2 |  $F reserved
        
SYM (excHandler):       
#if ( M68K_COLDFIRE_ARCH == 1 )
        lea     a7@(-16),a7
        movm.l  d0-d1/a0-a1,a7@          | save d0-d1,a0-a1
        movew   a7@(16+FVO_OFFSET),d0    | d0 = F/VO
        andl    #0x0ffc,d0               | d0 = vector offset in vbr
        lsrl    #2,d0                    | d0 = vector number
        lea     a7@(16),a1               | address of orig frame
        lea     a7@(16),a0               | address of orig frame
        lea     a0@(8),a0                | skip exception frame
#else
        moveml  d0-d1/a0-a1,a7@-         | save d0-d1,a0-a1
        movew   a7@(16+FVO_OFFSET),d0    | d0 = F/VO
#if ( M68K_HAS_VBR == 1 )
        movew   d0,d1                    | d1 is copy of F/VO
        andl    #0x0ffc,d0               | d0 = vector offset in vbr
        lsrl    #2,d0                    | d0 = vector number
        lsrl    #8,d1
        lsrl    #3,d1
        andl    #0x001f,d1               | d1 is format number
        lea     SYM (excFormatLength),a1
        movew   a1@(d1),d1               | d1 = size of exc frame
        lea     a7@(16,d1),a0
        lea     a7@(16),a1               | address of orig frame

#else /* (M68k_HAS_VBR == 0) */
        lea     a7@(16),a1               | address of orig frame
        lea     a1@(6),a0                | skip stack frame
/*
 * skip bus error stack frame...
 */     
        cmpi.l  #3,d0
        bgt     1f                       | if >3 then normal exc
        lea     a1@(8),a0                | skip extra stuff
        lea     a0@(6),a0                | a0 = orig sp
1:
#endif /* M68K_HAS_VBR */
#endif /* ( M68K_COLDFIRE_ARCH == 0 ) */

        /*
        * at this point:
        * a0 points to stack above exception stack frame
        * a1 points to start of exception stack frame
        */
        
        movew   a1@(SR_OFFSET),d1        | d1 = sr
        andl    #0xffff,d1
        lea     a7@(-76),a7              | reserve room for exception frame
|                                          build CPU_Exception_frame
        movel   d0,a7@                   | vecnum
        movel   d1,a7@(4)                | sr
        movel   a1@(PC_OFFSET),d1        | d1 = pc
#if ( M68K_COLDFIRE_ARCH == 0 )
        cmpiw   #47,d0                   | trap #15, breakpoint?
#else
        cmpil   #47,d0                   | trap #15, breakpoint?
#endif
        bne     2f
        subql   #2,d1                    | real PC is at trap insn
2:      movel   d1,a7@(8)                | store pc to exframe struct
        movel   a7@(76),a7@(12)          | the orig d0 pushed at beginning
        movel   a7@(76+4),a7@(16)        | the orig d1 pushed at beginning
        movel   d2,a7@(20)
        movel   d3,a7@(24)
        movel   d4,a7@(28)
        movel   d5,a7@(32)
        movel   d6,a7@(36)
        movel   d7,a7@(40)
        movel   a7@(76+8),a7@(44)        | the orig a0 pushed at beginning
        movel   a7@(76+12),a7@(48)       | the orig a1 pushed at beginning
        movel   a2,a7@(52)
        movel   a3,a7@(56)
        movel   a4,a7@(60)
        movel   a5,a7@(64)
        movel   a6,a7@(68)
        movel   a0,a7@(72)               | stack pointer before exception
        lea     a7@,a0                   | exframe address
        movel   a1,a7@-                  | save top of orig frame
        movel   a0,a7@-                  | push exframe address
        jsr     SYM(BreakPointExcHdl)
        addql   #4,a7                    | pop exframe address
        movel   a7@+,a1                  | restore orig frame address
| XXX what should be restored from exframe??
        movel   a7@(4),d1                | sr
        movew   d1,a1@(SR_OFFSET)        | store sr to frame XXX ???
        movel   a7@(8),a1@(PC_OFFSET)    | store pc to frame XXX ???
        movel   a7@(12),a7@(76)          | d0 to be restored from stack
        movel   a7@(16),a7@(76+4)        | d1 to be restored from stack
        movel   a7@(20),d2
        movel   a7@(24),d3
        movel   a7@(28),d4
        movel   a7@(32),d5
        movel   a7@(36),d6
        movel   a7@(40),d7
        movel   a7@(44),a7@(76+8)        | a0 to be restored from stack
        movel   a7@(48),a7@(76+12)       | a1 to be restored from stack
        movel   a7@(52),a2
        movel   a7@(56),a3
        movel   a7@(60),a4
        movel   a7@(64),a5
        movel   a7@(68),a6
        addl    #76,a7                   | pop exframe
        
#if ( M68K_COLDFIRE_ARCH == 0 )
        moveml  a7@+,d0-d1/a0-a1         | restore d0-d1,a0-a1
#else
        moveml  a7@,d0-d1/a0-a1          | restore d0-d1,a0-a1
        lea     a7@(16),a7
#endif

#if ( M68K_HAS_VBR == 0 )
        addql   #2,a7                    | pop format/id
#endif /* M68K_HAS_VBR */

| XXX bus err cleanup

        rte

END_CODE

END