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+|
+| 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
+|
+| For details on the license for this file, please see the
+| file, README, in this same directory.
+
+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