add wbadaddr routine for Harris write-only memory

[unix-history] / usr / src / sys / tahoe / stand / machdep.c

/*      machdep.c       1.3     87/10/27        */

#include "../tahoe/mem.h"
#include "../tahoe/mtpr.h"
#include "../tahoe/SYS.h"

       .set    _scb, 0x0
       .set    HIGH, 0x1f      # mask for total disable
       .set    BERVEC, 0x80    # offset into scb of the bus error vector 
       .set    RESTVEC, 0x8    # offset into scb of the restart vector 

ENTRY(mtpr, 0)
       mtpr    8(fp),4(fp)
       ret

ENTRY(mfpr, 0)
       mfpr    4(fp),r0
       ret

ENTRY(bcopy, R2|R1|R0)
       movl    4(fp),r0
       movl    8(fp),r1
       movl    12(fp),r2
       movblk
       ret

/*
* badaddr(addr, len)
*      see if access addr with a len type instruction causes a machine check
*      len is length of access (1=byte, 2=short, 4=long)
*      r0 = 0 means good(exists); r0 =1 means does not exist.
*/
ENTRY(badaddr, R5|R4|R3|R2|R1)
       mfpr    $IPL,r1
       mtpr    $HIGH,$IPL
       mfpr    $SCBB,r5
       mtpr    $0,$SCBB
       movl    *$BERVEC,r2
       movl    4(fp),r3
       movl    8(fp),r4
       movab   9f,*$BERVEC
       bbc     $0,r4,1f; tstb  (r3)
1:      bbc     $1,r4,1f; tstw  (r3)
1:      bbc     $2,r4,1f; tstl  (r3)
1:      clrl    r0                      # made it w/o machine checks
2:      movl    r2,*$BERVEC
       mtpr    r1,$IPL
       mtpr    r5,$SCBB
       ret

/*
* wbadaddr(addr, len, value)
*      see if write of value to addr with a len type instruction causes
*      a machine check
*      len is length of access (1=byte, 2=short, 4=long)
*      r0 = 0 means good(exists); r0 =1 means does not exist.
*/
ENTRY(wbadaddr, R5|R4|R3|R2|R1)
       mfpr    $IPL,r1
       mtpr    $HIGH,$IPL
       mfpr    $SCBB,r5
       mtpr    $0,$SCBB
       movl    *$BERVEC,r2
       movl    4(fp),r3
       movl    8(fp),r4
       movab   9f,*$BERVEC
       bbc     $0,r4,1f; movb  15(fp), (r3)
1:      bbc     $1,r4,1f; movw  14(fp), (r3)
1:      bbc     $2,r4,1f; movl  12(fp), (r3)
1:      clrl    r0                      # made it w/o machine checks
2:      movl    r2,*$BERVEC
       mtpr    r1,$IPL
       mtpr    r5,$SCBB
       ret

       .align  2
9:                      # Here we catch buss error (if it comes)
       andl3   4(sp),$ERRCD,r0
       cmpl    r0,$APE
       jneq    1f
       halt                    # Address parity error !!!
1:      cmpl    r0,$VBE
       jneq    1f
       halt                    # Versabus error
1:
       movl    $1,r0           # Anything else = bad address
       movab   8(sp),sp        # discard buss error trash
       movab   2b,(sp)         # new program counter on stack.
       rei

ENTRY(movow, 0)
       movow   10(fp),*4(fp)
       ret

ENTRY(movob, 0)
       movob   11(fp),*4(fp)
       ret