|
| x_operr.sa 3.5 7/1/91
|
| fpsp_operr --- FPSP handler for operand error exception
|
| See 68040 User's Manual pp. 9-44f
|
| Note 1: For trap disabled 040 does the following:
| If the dest is a fp reg, then an extended precision non_signaling
| NAN is stored in the dest reg. If the dest format is b, w, or l and
| the source op is a NAN, then garbage is stored as the result (actually
| the upper 32 bits of the mantissa are sent to the integer unit). If
| the dest format is integer (b, w, l) and the operr is caused by
| integer overflow, or the source op is inf, then the result stored is
| garbage.
| There are three cases in which operr is incorrectly signaled on the
| 040. This occurs for move_out of format b, w, or l for the largest
| negative integer (-2^7 for b, -2^15 for w, -2^31 for l).
|
| On opclass = 011 fmove.(b,w,l) that causes a conversion
| overflow -> OPERR, the exponent in wbte (and fpte) is:
| byte 56 - (62 - exp)
| word 48 - (62 - exp)
| long 32 - (62 - exp)
|
| where exp = (true exp) - 1
|
| So, wbtemp and fptemp will contain the following on erroneously
| signalled operr:
| fpts = 1
| fpte = $4000 (15 bit externally)
| byte fptm = $ffffffff ffffff80
| word fptm = $ffffffff ffff8000
| long fptm = $ffffffff 80000000
|
| Note 2: For trap enabled 040 does the following:
| If the inst is move_out, then same as Note 1.
| If the inst is not move_out, the dest is not modified.
| The exceptional operand is not defined for integer overflow
| during a move_out.
|
| Copyright (C) Motorola, Inc. 1990
| All Rights Reserved
|
| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA
| The copyright notice above does not evidence any
| actual or intended publication of such source code.
X_OPERR: |idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.h"
|xref mem_write
|xref real_operr
|xref real_inex
|xref get_fline
|xref fpsp_done
|xref reg_dest
.global fpsp_operr
fpsp_operr:
|
link %a6,#-LOCAL_SIZE
fsave -(%a7)
moveml %d0-%d1/%a0-%a1,USER_DA(%a6)
fmovemx %fp0-%fp3,USER_FP0(%a6)
fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
|
| Check if this is an opclass 3 instruction.
| If so, fall through, else branch to operr_end
|
btstb #TFLAG,T_BYTE(%a6)
beqs operr_end
|
| If the destination size is B,W,or L, the operr must be
| handled here.
|
movel CMDREG1B(%a6),%d0
bfextu %d0{#3:#3},%d0 |0=long, 4=word, 6=byte
cmpib #0,%d0 |determine size; check long
beq operr_long
cmpib #4,%d0 |check word
beq operr_word
cmpib #6,%d0 |check byte
beq operr_byte
|
| The size is not B,W,or L, so the operr is handled by the
| kernel handler. Set the operr bits and clean up, leaving
| only the integer exception frame on the stack, and the
| fpu in the original exceptional state.
|
operr_end:
bsetb #operr_bit,FPSR_EXCEPT(%a6)
bsetb #aiop_bit,FPSR_AEXCEPT(%a6)
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
frestore (%a7)+
unlk %a6
bral real_operr
operr_long:
moveql #4,%d1 |write size to d1
moveb STAG(%a6),%d0 |test stag for nan
andib #0xe0,%d0 |clr all but tag
cmpib #0x60,%d0 |check for nan
beq operr_nan
cmpil #0x80000000,FPTEMP_LO(%a6) |test if ls lword is special
bnes chklerr |if not equal, check for incorrect operr
bsr check_upper |check if exp and ms mant are special
tstl %d0
bnes chklerr |if d0 is true, check for incorrect operr
movel #0x80000000,%d0 |store special case result
bsr operr_store
bra not_enabled |clean and exit
|
| CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
|
chklerr:
movew FPTEMP_EX(%a6),%d0
andw #0x7FFF,%d0 |ignore sign bit
cmpw #0x3FFE,%d0 |this is the only possible exponent value
bnes chklerr2
fixlong:
movel FPTEMP_LO(%a6),%d0
bsr operr_store
bra not_enabled
chklerr2:
movew FPTEMP_EX(%a6),%d0
andw #0x7FFF,%d0 |ignore sign bit
cmpw #0x4000,%d0
bcc store_max |exponent out of range
movel FPTEMP_LO(%a6),%d0
andl #0x7FFF0000,%d0 |look for all 1's on bits 30-16
cmpl #0x7FFF0000,%d0
beqs fixlong
tstl FPTEMP_LO(%a6)
bpls chklepos
cmpl #0xFFFFFFFF,FPTEMP_HI(%a6)
beqs fixlong
bra store_max
chklepos:
tstl FPTEMP_HI(%a6)
beqs fixlong
bra store_max
operr_word:
moveql #2,%d1 |write size to d1
moveb STAG(%a6),%d0 |test stag for nan
andib #0xe0,%d0 |clr all but tag
cmpib #0x60,%d0 |check for nan
beq operr_nan
cmpil #0xffff8000,FPTEMP_LO(%a6) |test if ls lword is special
bnes chkwerr |if not equal, check for incorrect operr
bsr check_upper |check if exp and ms mant are special
tstl %d0
bnes chkwerr |if d0 is true, check for incorrect operr
movel #0x80000000,%d0 |store special case result
bsr operr_store
bra not_enabled |clean and exit
|
| CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
|
chkwerr:
movew FPTEMP_EX(%a6),%d0
andw #0x7FFF,%d0 |ignore sign bit
cmpw #0x3FFE,%d0 |this is the only possible exponent value
bnes store_max
movel FPTEMP_LO(%a6),%d0
swap %d0
bsr operr_store
bra not_enabled
operr_byte:
moveql #1,%d1 |write size to d1
moveb STAG(%a6),%d0 |test stag for nan
andib #0xe0,%d0 |clr all but tag
cmpib #0x60,%d0 |check for nan
beqs operr_nan
cmpil #0xffffff80,FPTEMP_LO(%a6) |test if ls lword is special
bnes chkberr |if not equal, check for incorrect operr
bsr check_upper |check if exp and ms mant are special
tstl %d0
bnes chkberr |if d0 is true, check for incorrect operr
movel #0x80000000,%d0 |store special case result
bsr operr_store
bra not_enabled |clean and exit
|
| CHECK FOR INCORRECTLY GENERATED OPERR EXCEPTION HERE
|
chkberr:
movew FPTEMP_EX(%a6),%d0
andw #0x7FFF,%d0 |ignore sign bit
cmpw #0x3FFE,%d0 |this is the only possible exponent value
bnes store_max
movel FPTEMP_LO(%a6),%d0
asll #8,%d0
swap %d0
bsr operr_store
bra not_enabled
|
| This operr condition is not of the special case. Set operr
| and aiop and write the portion of the nan to memory for the
| given size.
|
operr_nan:
orl #opaop_mask,USER_FPSR(%a6) |set operr & aiop
movel ETEMP_HI(%a6),%d0 |output will be from upper 32 bits
bsr operr_store
bra end_operr
|
| Store_max loads the max pos or negative for the size, sets
| the operr and aiop bits, and clears inex and ainex, incorrectly
| set by the 040.
|
store_max:
orl #opaop_mask,USER_FPSR(%a6) |set operr & aiop
bclrb #inex2_bit,FPSR_EXCEPT(%a6)
bclrb #ainex_bit,FPSR_AEXCEPT(%a6)
fmovel #0,%FPSR
tstw FPTEMP_EX(%a6) |check sign
blts load_neg
movel #0x7fffffff,%d0
bsr operr_store
bra end_operr
load_neg:
movel #0x80000000,%d0
bsr operr_store
bra end_operr
|
| This routine stores the data in d0, for the given size in d1,
| to memory or data register as required. A read of the fline
| is required to determine the destination.
|
operr_store:
movel %d0,L_SCR1(%a6) |move write data to L_SCR1
movel %d1,-(%a7) |save register size
bsrl get_fline |fline returned in d0
movel (%a7)+,%d1
bftst %d0{#26:#3} |if mode is zero, dest is Dn
bnes dest_mem
|
| Destination is Dn. Get register number from d0. Data is on
| the stack at (a7). D1 has size: 1=byte,2=word,4=long/single
|
andil #7,%d0 |isolate register number
cmpil #4,%d1
beqs op_long |the most frequent case
cmpil #2,%d1
bnes op_con
orl #8,%d0
bras op_con
op_long:
orl #0x10,%d0
op_con:
movel %d0,%d1 |format size:reg for reg_dest
bral reg_dest |call to reg_dest returns to caller
| ;of operr_store
|
| Destination is memory. Get <ea> from integer exception frame
| and call mem_write.
|
dest_mem:
leal L_SCR1(%a6),%a0 |put ptr to write data in a0
movel EXC_EA(%a6),%a1 |put user destination address in a1
movel %d1,%d0 |put size in d0
bsrl mem_write
rts
|
| Check the exponent for $c000 and the upper 32 bits of the
| mantissa for $ffffffff. If both are true, return d0 clr
| and store the lower n bits of the least lword of FPTEMP
| to d0 for write out. If not, it is a real operr, and set d0.
|
check_upper:
cmpil #0xffffffff,FPTEMP_HI(%a6) |check if first byte is all 1's
bnes true_operr |if not all 1's then was true operr
cmpiw #0xc000,FPTEMP_EX(%a6) |check if incorrectly signalled
beqs not_true_operr |branch if not true operr
cmpiw #0xbfff,FPTEMP_EX(%a6) |check if incorrectly signalled
beqs not_true_operr |branch if not true operr
true_operr:
movel #1,%d0 |signal real operr
rts
not_true_operr:
clrl %d0 |signal no real operr
rts
|
| End_operr tests for operr enabled. If not, it cleans up the stack
| and does an rte. If enabled, it cleans up the stack and branches
| to the kernel operr handler with only the integer exception
| frame on the stack and the fpu in the original exceptional state
| with correct data written to the destination.
|
end_operr:
btstb #operr_bit,FPCR_ENABLE(%a6)
beqs not_enabled
enabled:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
frestore (%a7)+
unlk %a6
bral real_operr
not_enabled:
|
| It is possible to have either inex2 or inex1 exceptions with the
| operr. If the inex enable bit is set in the FPCR, and either
| inex2 or inex1 occurred, we must clean up and branch to the
| real inex handler.
|
ck_inex:
moveb FPCR_ENABLE(%a6),%d0
andb FPSR_EXCEPT(%a6),%d0
andib #0x3,%d0
beq operr_exit
|
| Inexact enabled and reported, and we must take an inexact exception.
|
take_inex:
moveb #INEX_VEC,EXC_VEC+1(%a6)
movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
orl #sx_mask,E_BYTE(%a6)
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
frestore (%a7)+
unlk %a6
bral real_inex
|
| Since operr is only an E1 exception, there is no need to frestore
| any state back to the fpu.
|
operr_exit:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
unlk %a6
bral fpsp_done
|end
