LXR linux/arch/m68k/fpsp040/x

   1|
   2|       x_fline.sa 3.3 1/10/91
   3|
   4|       fpsp_fline --- FPSP handler for fline exception
   5|
   6|       First determine if the exception is one of the unimplemented
   7|       floating point instructions.  If so, let fpsp_unimp handle it.
   8|       Next, determine if the instruction is an fmovecr with a non-zero
   9|       <ea> field.  If so, handle here and return.  Otherwise, it
  10|       must be a real F-line exception.
  11|
  12
  13|               Copyright (C) Motorola, Inc. 1990
  14|                       All Rights Reserved
  15|
  16|       For details on the license for this file, please see the
  17|       file, README, in this same directory.
  18
  19X_FLINE:        |idnt    2,1 | Motorola 040 Floating Point Software Package
  20
  21        |section        8
  22
  23#include "fpsp.h"
  24
  25        |xref   real_fline
  26        |xref   fpsp_unimp
  27        |xref   uni_2
  28        |xref   mem_read
  29        |xref   fpsp_fmt_error
  30
  31        .global fpsp_fline
  32fpsp_fline:
  33|
  34|       check for unimplemented vector first.  Use EXC_VEC-4 because
  35|       the equate is valid only after a 'link a6' has pushed one more
  36|       long onto the stack.
  37|
  38        cmpw    #UNIMP_VEC,EXC_VEC-4(%a7)
  39        beql    fpsp_unimp
  40
  41|
  42|       fmovecr with non-zero <ea> handling here
  43|
  44        subl    #4,%a7          |4 accounts for 2-word difference
  45|                               ;between six word frame (unimp) and
  46|                               ;four word frame
  47        link    %a6,#-LOCAL_SIZE
  48        fsave   -(%a7)
  49        moveml  %d0-%d1/%a0-%a1,USER_DA(%a6)
  50        moveal  EXC_PC+4(%a6),%a0       |get address of fline instruction
  51        leal    L_SCR1(%a6),%a1 |use L_SCR1 as scratch
  52        movel   #4,%d0
  53        addl    #4,%a6          |to offset the sub.l #4,a7 above so that
  54|                               ;a6 can point correctly to the stack frame
  55|                               ;before branching to mem_read
  56        bsrl    mem_read
  57        subl    #4,%a6
  58        movel   L_SCR1(%a6),%d0 |d0 contains the fline and command word
  59        bfextu  %d0{#4:#3},%d1  |extract coprocessor id
  60        cmpib   #1,%d1          |check if cpid=1
  61        bne     not_mvcr        |exit if not
  62        bfextu  %d0{#16:#6},%d1
  63        cmpib   #0x17,%d1               |check if it is an FMOVECR encoding
  64        bne     not_mvcr
  65|                               ;if an FMOVECR instruction, fix stack
  66|                               ;and go to FPSP_UNIMP
  67fix_stack:
  68        cmpib   #VER_40,(%a7)   |test for orig unimp frame
  69        bnes    ck_rev
  70        subl    #UNIMP_40_SIZE-4,%a7 |emulate an orig fsave
  71        moveb   #VER_40,(%a7)
  72        moveb   #UNIMP_40_SIZE-4,1(%a7)
  73        clrw    2(%a7)
  74        bras    fix_con
  75ck_rev:
  76        cmpib   #VER_41,(%a7)   |test for rev unimp frame
  77        bnel    fpsp_fmt_error  |if not $40 or $41, exit with error
  78        subl    #UNIMP_41_SIZE-4,%a7 |emulate a rev fsave
  79        moveb   #VER_41,(%a7)
  80        moveb   #UNIMP_41_SIZE-4,1(%a7)
  81        clrw    2(%a7)
  82fix_con:
  83        movew   EXC_SR+4(%a6),EXC_SR(%a6) |move stacked sr to new position
  84        movel   EXC_PC+4(%a6),EXC_PC(%a6) |move stacked pc to new position
  85        fmovel  EXC_PC(%a6),%FPIAR |point FPIAR to fline inst
  86        movel   #4,%d1
  87        addl    %d1,EXC_PC(%a6) |increment stacked pc value to next inst
  88        movew   #0x202c,EXC_VEC(%a6) |reformat vector to unimp
  89        clrl    EXC_EA(%a6)     |clear the EXC_EA field
  90        movew   %d0,CMDREG1B(%a6) |move the lower word into CMDREG1B
  91        clrl    E_BYTE(%a6)
  92        bsetb   #UFLAG,T_BYTE(%a6)
  93        moveml  USER_DA(%a6),%d0-%d1/%a0-%a1 |restore data registers
  94        bral    uni_2
  95
  96not_mvcr:
  97        moveml  USER_DA(%a6),%d0-%d1/%a0-%a1 |restore data registers
  98        frestore (%a7)+
  99        unlk    %a6
 100        addl    #4,%a7
 101        bral    real_fline
 102
 103        |end
 104