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|
| x_snan.sa 3.3 7/1/91
|
| fpsp_snan --- FPSP handler for signalling NAN exception
|
| SNAN for float -> integer conversions (integer conversion of
| an SNAN) is a non-maskable run-time exception.
|
| For trap disabled the 040 does the following:
| If the dest data format is s, d, or x, then the SNAN bit in the NAN
| is set to one and the resulting non-signaling NAN (truncated if
| necessary) is transferred to the dest. If the dest format is b, w,
| or l, then garbage is written to the dest (actually the upper 32 bits
| of the mantissa are sent to the integer unit).
|
| For trap enabled the 040 does the following:
| If the inst is move_out, then the results are the same as for trap
| disabled with the exception posted. If the instruction is not move_
| out, the dest. is not modified, and the exception is posted.
|

| Copyright (C) Motorola, Inc. 1990
| All Rights Reserved
|
| For details on the license for this file, please see the
| file, README, in this same directory.

X_SNAN: |idnt 2,1 | Motorola 040 Floating Point Software Package

|section 8

#include "fpsp.h"

|xref get_fline
|xref mem_write
|xref real_snan
|xref real_inex
|xref fpsp_done
|xref reg_dest

.global fpsp_snan
fpsp_snan:
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 trap enabled
|
btstb #snan_bit,FPCR_ENABLE(%a6)
bnes ena |If enabled, then branch

bsrl move_out |else SNAN disabled
|
| It is possible to have an inex1 exception with the
| snan. 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 end_snan
|
| Inexact enabled and reported, and we must take an inexact exception.
|
take_inex:
moveb #INEX_VEC,EXC_VEC+1(%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
|
| SNAN is enabled. Check if inst is move_out.
| Make any corrections to the 040 output as necessary.
|
ena:
btstb #5,CMDREG1B(%a6) |if set, inst is move out
beq not_out

bsrl move_out

report_snan:
moveb (%a7),VER_TMP(%a6)
cmpib #VER_40,(%a7) |test for orig unimp frame
bnes ck_rev
moveql #13,%d0 |need to zero 14 lwords
bras rep_con
ck_rev:
moveql #11,%d0 |need to zero 12 lwords
rep_con:
clrl (%a7)
loop1:
clrl -(%a7) |clear and dec a7
dbra %d0,loop1
moveb VER_TMP(%a6),(%a7) |format a busy frame
moveb #BUSY_SIZE-4,1(%a7)
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_snan
|
| Exit snan handler by expanding the unimp frame into a busy frame
|
end_snan:
bclrb #E1,E_BYTE(%a6)

moveb (%a7),VER_TMP(%a6)
cmpib #VER_40,(%a7) |test for orig unimp frame
bnes ck_rev2
moveql #13,%d0 |need to zero 14 lwords
bras rep_con2
ck_rev2:
moveql #11,%d0 |need to zero 12 lwords
rep_con2:
clrl (%a7)
loop2:
clrl -(%a7) |clear and dec a7
dbra %d0,loop2
moveb VER_TMP(%a6),(%a7) |format a busy frame
moveb #BUSY_SIZE-4,1(%a7) |write busy size
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 fpsp_done

|
| Move_out
|
move_out:
movel EXC_EA(%a6),%a0 |get <ea> from exc frame

bfextu CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
cmpil #0,%d0 |check for long
beqs sto_long |branch if move_out long

cmpil #4,%d0 |check for word
beqs sto_word |branch if move_out word

cmpil #6,%d0 |check for byte
beqs sto_byte |branch if move_out byte

|
| Not byte, word or long
|
rts
|
| Get the 32 most significant bits of etemp mantissa
|
sto_long:
movel ETEMP_HI(%a6),%d1
movel #4,%d0 |load byte count
|
| Set signalling nan bit
|
bsetl #30,%d1
|
| Store to the users destination address
|
tstl %a0 |check if <ea> is 0
beqs wrt_dn |destination is a data register

movel %d1,-(%a7) |move the snan onto the stack
movel %a0,%a1 |load dest addr into a1
movel %a7,%a0 |load src addr of snan into a0
bsrl mem_write |write snan to user memory
movel (%a7)+,%d1 |clear off stack
rts
|
| Get the 16 most significant bits of etemp mantissa
|
sto_word:
movel ETEMP_HI(%a6),%d1
movel #2,%d0 |load byte count
|
| Set signalling nan bit
|
bsetl #30,%d1
|
| Store to the users destination address
|
tstl %a0 |check if <ea> is 0
beqs wrt_dn |destination is a data register

movel %d1,-(%a7) |move the snan onto the stack
movel %a0,%a1 |load dest addr into a1
movel %a7,%a0 |point to low word
bsrl mem_write |write snan to user memory
movel (%a7)+,%d1 |clear off stack
rts
|
| Get the 8 most significant bits of etemp mantissa
|
sto_byte:
movel ETEMP_HI(%a6),%d1
movel #1,%d0 |load byte count
|
| Set signalling nan bit
|
bsetl #30,%d1
|
| Store to the users destination address
|
tstl %a0 |check if <ea> is 0
beqs wrt_dn |destination is a data register
movel %d1,-(%a7) |move the snan onto the stack
movel %a0,%a1 |load dest addr into a1
movel %a7,%a0 |point to source byte
bsrl mem_write |write snan to user memory
movel (%a7)+,%d1 |clear off stack
rts

|
| wrt_dn --- write to a data register
|
| We get here with D1 containing the data to write and D0 the
| number of bytes to write: 1=byte,2=word,4=long.
|
wrt_dn:
movel %d1,L_SCR1(%a6) |data
movel %d0,-(%a7) |size
bsrl get_fline |returns fline word in d0
movel %d0,%d1
andil #0x7,%d1 |d1 now holds register number
movel (%sp)+,%d0 |get original size
cmpil #4,%d0
beqs wrt_long
cmpil #2,%d0
bnes wrt_byte
wrt_word:
orl #0x8,%d1
bral reg_dest
wrt_long:
orl #0x10,%d1
bral reg_dest
wrt_byte:
bral reg_dest
|
| Check if it is a src nan or dst nan
|
not_out:
movel DTAG(%a6),%d0
bfextu %d0{#0:#3},%d0 |isolate dtag in lsbs

cmpib #3,%d0 |check for nan in destination
bnes issrc |destination nan has priority
dst_nan:
btstb #6,FPTEMP_HI(%a6) |check if dest nan is an snan
bnes issrc |no, so check source for snan
movew FPTEMP_EX(%a6),%d0
bras cont
issrc:
movew ETEMP_EX(%a6),%d0
cont:
btstl #15,%d0 |test for sign of snan
beqs clr_neg
bsetb #neg_bit,FPSR_CC(%a6)
bra report_snan
clr_neg:
bclrb #neg_bit,FPSR_CC(%a6)
bra report_snan

|end
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