//
// $Id$
//
// 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
//
// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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_SNAN: //idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.defs"
|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
