|
| kernel_ex.sa 3.3 12/19/90
|
| This file contains routines to force exception status in the
| fpu for exceptional cases detected or reported within the
| transcendental functions. Typically, the t_xx routine will
| set the appropriate bits in the USER_FPSR word on the stack.
| The bits are tested in gen_except.sa to determine if an exceptional
| situation needs to be created on return from the FPSP.
|
| 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| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.
KERNEL_EX: |idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.h"
mns_inf: .long 0xffff0000,0x00000000,0x00000000
pls_inf: .long 0x7fff0000,0x00000000,0x00000000
nan: .long 0x7fff0000,0xffffffff,0xffffffff
huge: .long 0x7ffe0000,0xffffffff,0xffffffff
|xref ovf_r_k
|xref unf_sub
|xref nrm_set
.global t_dz
.global t_dz2
.global t_operr
.global t_unfl
.global t_ovfl
.global t_ovfl2
.global t_inx2
.global t_frcinx
.global t_extdnrm
.global t_resdnrm
.global dst_nan
.global src_nan
|
| DZ exception
|
|
| if dz trap disabled
| store properly signed inf (use sign of etemp) into fp0
| set FPSR exception status dz bit, condition code
| inf bit, and accrued dz bit
| return
| frestore the frame into the machine (done by unimp_hd)
|
| else dz trap enabled
| set exception status bit & accrued bits in FPSR
| set flag to disable sto_res from corrupting fp register
| return
| frestore the frame into the machine (done by unimp_hd)
|
| t_dz2 is used by monadic functions such as flogn (from do_func).
| t_dz is used by monadic functions such as satanh (from the
| transcendental function).
|
t_dz2:
bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
fmovel #0,%FPSR |clr status bits (Z set)
btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
bnes dz_ena_end
bras m_inf |flogx always returns -inf
t_dz:
fmovel #0,%FPSR |clr status bits (Z set)
btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
bnes dz_ena
|
| dz disabled
|
btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
beqs p_inf |branch if pos sign
m_inf:
fmovemx mns_inf,%fp0-%fp0 |load -inf
bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
bras set_fpsr
p_inf:
fmovemx pls_inf,%fp0-%fp0 |load +inf
set_fpsr:
orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
rts
|
| dz enabled
|
dz_ena:
btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
beqs dz_ena_end
bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
dz_ena_end:
orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
st STORE_FLG(%a6)
rts
|
| OPERR exception
|
| if (operr trap disabled)
| set FPSR exception status operr bit, condition code
| nan bit; Store default NAN into fp0
| frestore the frame into the machine (done by unimp_hd)
|
| else (operr trap enabled)
| set FPSR exception status operr bit, accrued operr bit
| set flag to disable sto_res from corrupting fp register
| frestore the frame into the machine (done by unimp_hd)
|
t_operr:
orl #opnan_mask,USER_FPSR(%a6) |set NaN, OPERR, AIOP
btstb #operr_bit,FPCR_ENABLE(%a6) |test FPCR for operr enabled
bnes op_ena
fmovemx nan,%fp0-%fp0 |load default nan
rts
op_ena:
st STORE_FLG(%a6) |do not corrupt destination
rts
|
| t_unfl --- UNFL exception
|
| This entry point is used by all routines requiring unfl, inex2,
| aunfl, and ainex to be set on exit.
|
| On entry, a0 points to the exceptional operand. The final exceptional
| operand is built in FP_SCR1 and only the sign from the original operand
| is used.
|
t_unfl:
clrl FP_SCR1(%a6) |set exceptional operand to zero
clrl FP_SCR1+4(%a6)
clrl FP_SCR1+8(%a6)
tstb (%a0) |extract sign from caller's exop
bpls unfl_signok
bset #sign_bit,FP_SCR1(%a6)
unfl_signok:
leal FP_SCR1(%a6),%a0
orl #unfinx_mask,USER_FPSR(%a6)
| ;set UNFL, INEX2, AUNFL, AINEX
unfl_con:
btstb #unfl_bit,FPCR_ENABLE(%a6)
beqs unfl_dis
unfl_ena:
bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
bsetb #sticky_bit,STICKY(%a6) |set sticky bit
bclrb #E1,E_BYTE(%a6)
unfl_dis:
bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
bclrb #sign_bit,LOCAL_EX(%a0)
sne LOCAL_SGN(%a0) |convert to internal ext format
bsr unf_sub |returns IEEE result at a0
| ;and sets FPSR_CC accordingly
bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
beqs unfl_fin
bsetb #sign_bit,LOCAL_EX(%a0)
bsetb #sign_bit,FP_SCR1(%a6) |set sign bit of exc operand
unfl_fin:
fmovemx (%a0),%fp0-%fp0 |store result in fp0
rts
|
| t_ovfl2 --- OVFL exception (without inex2 returned)
|
| This entry is used by scale to force catastrophic overflow. The
| ovfl, aovfl, and ainex bits are set, but not the inex2 bit.
|
t_ovfl2:
orl #ovfl_inx_mask,USER_FPSR(%a6)
movel ETEMP(%a6),FP_SCR1(%a6)
movel ETEMP_HI(%a6),FP_SCR1+4(%a6)
movel ETEMP_LO(%a6),FP_SCR1+8(%a6)
|
| Check for single or double round precision. If single, check if
| the lower 40 bits of ETEMP are zero; if not, set inex2. If double,
| check if the lower 21 bits are zero; if not, set inex2.
|
moveb FPCR_MODE(%a6),%d0
andib #0xc0,%d0
beq t_work |if extended, finish ovfl processing
cmpib #0x40,%d0 |test for single
bnes t_dbl
t_sgl:
tstb ETEMP_LO(%a6)
bnes t_setinx2
movel ETEMP_HI(%a6),%d0
andil #0xff,%d0 |look at only lower 8 bits
bnes t_setinx2
bra t_work
t_dbl:
movel ETEMP_LO(%a6),%d0
andil #0x7ff,%d0 |look at only lower 11 bits
beq t_work
t_setinx2:
orl #inex2_mask,USER_FPSR(%a6)
bras t_work
|
| t_ovfl --- OVFL exception
|
|** Note: the exc operand is returned in ETEMP.
|
t_ovfl:
orl #ovfinx_mask,USER_FPSR(%a6)
t_work:
btstb #ovfl_bit,FPCR_ENABLE(%a6) |test FPCR for ovfl enabled
beqs ovf_dis
ovf_ena:
clrl FP_SCR1(%a6) |set exceptional operand
clrl FP_SCR1+4(%a6)
clrl FP_SCR1+8(%a6)
bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
bclrb #wbtemp15_bit,WB_BYTE(%a6) |clear wbtemp15
bsetb #sticky_bit,STICKY(%a6) |set sticky bit
bclrb #E1,E_BYTE(%a6)
| ;fall through to disabled case
| For disabled overflow call 'ovf_r_k'. This routine loads the
| correct result based on the rounding precision, destination
| format, rounding mode and sign.
|
ovf_dis:
bsr ovf_r_k |returns unsigned ETEMP_EX
| ;and sets FPSR_CC accordingly.
bfclr ETEMP_SGN(%a6){#0:#8} |fix sign
beqs ovf_pos
bsetb #sign_bit,ETEMP_EX(%a6)
bsetb #sign_bit,FP_SCR1(%a6) |set exceptional operand sign
ovf_pos:
fmovemx ETEMP(%a6),%fp0-%fp0 |move the result to fp0
rts
|
| INEX2 exception
|
| The inex2 and ainex bits are set.
|
t_inx2:
orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
rts
|
| Force Inex2
|
| This routine is called by the transcendental routines to force
| the inex2 exception bits set in the FPSR. If the underflow bit
| is set, but the underflow trap was not taken, the aunfl bit in
| the FPSR must be set.
|
t_frcinx:
orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
btstb #unfl_bit,FPSR_EXCEPT(%a6) |test for unfl bit set
beqs no_uacc1 |if clear, do not set aunfl
bsetb #aunfl_bit,FPSR_AEXCEPT(%a6)
no_uacc1:
rts
|
| DST_NAN
|
| Determine if the destination nan is signalling or non-signalling,
| and set the FPSR bits accordingly. See the MC68040 User's Manual
| section 3.2.2.5 NOT-A-NUMBERS.
|
dst_nan:
btstb #sign_bit,FPTEMP_EX(%a6) |test sign of nan
beqs dst_pos |if clr, it was positive
bsetb #neg_bit,FPSR_CC(%a6) |set N bit
dst_pos:
btstb #signan_bit,FPTEMP_HI(%a6) |check if signalling
beqs dst_snan |branch if signalling
fmovel %d1,%fpcr |restore user's rmode/prec
fmovex FPTEMP(%a6),%fp0 |return the non-signalling nan
|
| Check the source nan. If it is signalling, snan will be reported.
|
moveb STAG(%a6),%d0
andib #0xe0,%d0
cmpib #0x60,%d0
bnes no_snan
btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
bnes no_snan
orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
no_snan:
rts
dst_snan:
btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
beqs dst_dis |branch if disabled
orb #nan_tag,DTAG(%a6) |set up dtag for nan
st STORE_FLG(%a6) |do not store a result
orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
rts
dst_dis:
bsetb #signan_bit,FPTEMP_HI(%a6) |set SNAN bit in sop
fmovel %d1,%fpcr |restore user's rmode/prec
fmovex FPTEMP(%a6),%fp0 |load non-sign. nan
orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
rts
|
| SRC_NAN
|
| Determine if the source nan is signalling or non-signalling,
| and set the FPSR bits accordingly. See the MC68040 User's Manual
| section 3.2.2.5 NOT-A-NUMBERS.
|
src_nan:
btstb #sign_bit,ETEMP_EX(%a6) |test sign of nan
beqs src_pos |if clr, it was positive
bsetb #neg_bit,FPSR_CC(%a6) |set N bit
src_pos:
btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
beqs src_snan |branch if signalling
fmovel %d1,%fpcr |restore user's rmode/prec
fmovex ETEMP(%a6),%fp0 |return the non-signalling nan
rts
src_snan:
btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
beqs src_dis |branch if disabled
bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
orb #norm_tag,DTAG(%a6) |set up dtag for norm
orb #nan_tag,STAG(%a6) |set up stag for nan
st STORE_FLG(%a6) |do not store a result
orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
rts
src_dis:
bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
fmovel %d1,%fpcr |restore user's rmode/prec
fmovex ETEMP(%a6),%fp0 |load non-sign. nan
orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
rts
|
| For all functions that have a denormalized input and that f(x)=x,
| this is the entry point
|
t_extdnrm:
orl #unfinx_mask,USER_FPSR(%a6)
| ;set UNFL, INEX2, AUNFL, AINEX
bras xdnrm_con
|
| Entry point for scale with extended denorm. The function does
| not set inex2, aunfl, or ainex.
|
t_resdnrm:
orl #unfl_mask,USER_FPSR(%a6)
xdnrm_con:
btstb #unfl_bit,FPCR_ENABLE(%a6)
beqs xdnrm_dis
|
| If exceptions are enabled, the additional task of setting up WBTEMP
| is needed so that when the underflow exception handler is entered,
| the user perceives no difference between what the 040 provides vs.
| what the FPSP provides.
|
xdnrm_ena:
movel %a0,-(%a7)
movel LOCAL_EX(%a0),FP_SCR1(%a6)
movel LOCAL_HI(%a0),FP_SCR1+4(%a6)
movel LOCAL_LO(%a0),FP_SCR1+8(%a6)
lea FP_SCR1(%a6),%a0
bclrb #sign_bit,LOCAL_EX(%a0)
sne LOCAL_SGN(%a0) |convert to internal ext format
tstw LOCAL_EX(%a0) |check if input is denorm
beqs xdnrm_dn |if so, skip nrm_set
bsr nrm_set |normalize the result (exponent
| ;will be negative
xdnrm_dn:
bclrb #sign_bit,LOCAL_EX(%a0) |take off false sign
bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
beqs xdep
bsetb #sign_bit,LOCAL_EX(%a0)
xdep:
bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
bclrb #sticky_bit,STICKY(%a6) |clear sticky bit
bclrb #E1,E_BYTE(%a6)
movel (%a7)+,%a0
xdnrm_dis:
bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
bnes not_ext |if not round extended, store
| ;IEEE defaults
is_ext:
btstb #sign_bit,LOCAL_EX(%a0)
beqs xdnrm_store
bsetb #neg_bit,FPSR_CC(%a6) |set N bit in FPSR_CC
bras xdnrm_store
not_ext:
bclrb #sign_bit,LOCAL_EX(%a0)
sne LOCAL_SGN(%a0) |convert to internal ext format
bsr unf_sub |returns IEEE result pointed by
| ;a0; sets FPSR_CC accordingly
bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
beqs xdnrm_store
bsetb #sign_bit,LOCAL_EX(%a0)
xdnrm_store:
fmovemx (%a0),%fp0-%fp0 |store result in fp0
rts
|
| This subroutine is used for dyadic operations that use an extended
| denorm within the kernel. The approach used is to capture the frame,
| fix/restore.
|
.global t_avoid_unsupp
t_avoid_unsupp:
link %a2,#-LOCAL_SIZE |so that a2 fpsp.h negative
| ;offsets may be used
fsave -(%a7)
tstb 1(%a7) |check if idle, exit if so
beq idle_end
btstb #E1,E_BYTE(%a2) |check for an E1 exception if
| ;enabled, there is an unsupp
beq end_avun |else, exit
btstb #7,DTAG(%a2) |check for denorm destination
beqs src_den |else, must be a source denorm
|
| handle destination denorm
|
lea FPTEMP(%a2),%a0
btstb #sign_bit,LOCAL_EX(%a0)
sne LOCAL_SGN(%a0) |convert to internal ext format
bclrb #7,DTAG(%a2) |set DTAG to norm
bsr nrm_set |normalize result, exponent
| ;will become negative
bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
beqs ck_src_den |check if source is also denorm
bsetb #sign_bit,LOCAL_EX(%a0)
ck_src_den:
btstb #7,STAG(%a2)
beqs end_avun
src_den:
lea ETEMP(%a2),%a0
btstb #sign_bit,LOCAL_EX(%a0)
sne LOCAL_SGN(%a0) |convert to internal ext format
bclrb #7,STAG(%a2) |set STAG to norm
bsr nrm_set |normalize result, exponent
| ;will become negative
bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
beqs den_com
bsetb #sign_bit,LOCAL_EX(%a0)
den_com:
moveb #0xfe,CU_SAVEPC(%a2) |set continue frame
clrw NMNEXC(%a2) |clear NMNEXC
bclrb #E1,E_BYTE(%a2)
| fmove.l %FPSR,FPSR_SHADOW(%a2)
| bset.b #SFLAG,E_BYTE(%a2)
| bset.b #XFLAG,T_BYTE(%a2)
end_avun:
frestore (%a7)+
unlk %a2
rts
idle_end:
addl #4,%a7
unlk %a2
rts
|end
