pfpsp.s

linux内核源码

	mov.l		%usp,%a0		# fetch user stack pointer
	mov.l		%a0,EXC_A7(%a6)		# save on stack
	bra.b		fu_cont
# if the exception is an opclass zero or two unimplemented data type
# exception, then the a7' calculated here is wrong since it doesn't
# stack an ea. however, we don't need an a7' for this case anyways.
fu_s:
	lea		0x4+EXC_EA(%a6),%a0	# load old a7'
	mov.l		%a0,EXC_A7(%a6)		# save on stack

fu_cont:

# the FPIAR holds the "current PC" of the faulting instruction
# the FPIAR should be set correctly for ALL exceptions passing through
# this point.
	mov.l		USER_FPIAR(%a6),EXC_EXTWPTR(%a6)
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x4,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_long		# fetch the instruction words
	mov.l		%d0,EXC_OPWORD(%a6)	# store OPWORD and EXTWORD

############################

	clr.b		SPCOND_FLG(%a6)		# clear special condition flag

# Separate opclass three (fpn-to-mem) ops since they have a different
# stack frame and protocol.
	btst		&0x5,EXC_CMDREG(%a6)	# is it an fmove out?
	bne.w		fu_out			# yes

# Separate packed opclass two instructions.
	bfextu		EXC_CMDREG(%a6){&0:&6},%d0
	cmpi.b		%d0,&0x13
	beq.w		fu_in_pack


# I'm not sure at this point what FPSR bits are valid for this instruction.
# so, since the emulation routines re-create them anyways, zero exception field
	andi.l		&0x00ff00ff,USER_FPSR(%a6) # zero exception field

	fmov.l		&0x0,%fpcr		# zero current control regs
	fmov.l		&0x0,%fpsr

# Opclass two w/ memory-to-fpn operation will have an incorrect extended
# precision format if the src format was single or double and the
# source data type was an INF, NAN, DENORM, or UNNORM
	lea		FP_SRC(%a6),%a0		# pass ptr to input
	bsr.l		fix_skewed_ops

# we don't know whether the src operand or the dst operand (or both) is the
# UNNORM or DENORM. call the function that tags the operand type. if the
# input is an UNNORM, then convert it to a NORM, DENORM, or ZERO.
	lea		FP_SRC(%a6),%a0		# pass: ptr to src op
	bsr.l		set_tag_x		# tag the operand type
	cmpi.b		%d0,&UNNORM		# is operand an UNNORM?
	bne.b		fu_op2			# no
	bsr.l		unnorm_fix		# yes; convert to NORM,DENORM,or ZERO

fu_op2:
	mov.b		%d0,STAG(%a6)		# save src optype tag

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg

# bit five of the fp extension word separates the monadic and dyadic operations
# at this point
	btst		&0x5,1+EXC_CMDREG(%a6)	# is operation monadic or dyadic?
	beq.b		fu_extract		# monadic
	cmpi.b		1+EXC_CMDREG(%a6),&0x3a	# is operation an ftst?
	beq.b		fu_extract		# yes, so it's monadic, too

	bsr.l		load_fpn2		# load dst into FP_DST

	lea		FP_DST(%a6),%a0		# pass: ptr to dst op
	bsr.l		set_tag_x		# tag the operand type
	cmpi.b		%d0,&UNNORM		# is operand an UNNORM?
	bne.b		fu_op2_done		# no
	bsr.l		unnorm_fix		# yes; convert to NORM,DENORM,or ZERO
fu_op2_done:
	mov.b		%d0,DTAG(%a6)		# save dst optype tag

fu_extract:
	clr.l		%d0
	mov.b		FPCR_MODE(%a6),%d0	# fetch rnd mode/prec

	bfextu		1+EXC_CMDREG(%a6){&1:&7},%d1 # extract extension

	lea		FP_SRC(%a6),%a0
	lea		FP_DST(%a6),%a1

	mov.l		(tbl_unsupp.l,%pc,%d1.l*4),%d1 # fetch routine addr
	jsr		(tbl_unsupp.l,%pc,%d1.l*1)

#
# Exceptions in order of precedence:
#	BSUN	: none
#	SNAN	: all dyadic ops
#	OPERR	: fsqrt(-NORM)
#	OVFL	: all except ftst,fcmp
#	UNFL	: all except ftst,fcmp
#	DZ	: fdiv
#	INEX2	: all except ftst,fcmp
#	INEX1	: none (packed doesn't go through here)
#

# we determine the highest priority exception(if any) set by the
# emulation routine that has also been enabled by the user.
	mov.b		FPCR_ENABLE(%a6),%d0	# fetch exceptions set
	bne.b		fu_in_ena		# some are enabled

fu_in_cont:
# fcmp and ftst do not store any result.
	mov.b		1+EXC_CMDREG(%a6),%d0	# fetch extension
	andi.b		&0x38,%d0		# extract bits 3-5
	cmpi.b		%d0,&0x38		# is instr fcmp or ftst?
	beq.b		fu_in_exit		# yes

	bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg
	bsr.l		store_fpreg		# store the result

fu_in_exit:

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0/fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	unlk		%a6

	bra.l		_fpsp_done

fu_in_ena:
	and.b		FPSR_EXCEPT(%a6),%d0	# keep only ones enabled
	bfffo		%d0{&24:&8},%d0		# find highest priority exception
	bne.b		fu_in_exc		# there is at least one set

#
# No exceptions occurred that were also enabled. Now:
#
#	if (OVFL && ovfl_disabled && inexact_enabled) {
#	    branch to _real_inex() (even if the result was exact!);
#	} else {
#	    save the result in the proper fp reg (unless the op is fcmp or ftst);
#	    return;
#	}
#
	btst		&ovfl_bit,FPSR_EXCEPT(%a6) # was overflow set?
	beq.b		fu_in_cont		# no

fu_in_ovflchk:
	btst		&inex2_bit,FPCR_ENABLE(%a6) # was inexact enabled?
	beq.b		fu_in_cont		# no
	bra.w		fu_in_exc_ovfl		# go insert overflow frame

#
# An exception occurred and that exception was enabled:
#
#	shift enabled exception field into lo byte of d0;
#	if (((INEX2 || INEX1) && inex_enabled && OVFL && ovfl_disabled) ||
#	    ((INEX2 || INEX1) && inex_enabled && UNFL && unfl_disabled)) {
#		/*
#		 * this is the case where we must call _real_inex() now or else
#		 * there will be no other way to pass it the exceptional operand
#		 */
#		call _real_inex();
#	} else {
#		restore exc state (SNAN||OPERR||OVFL||UNFL||DZ||INEX) into the FPU;
#	}
#
fu_in_exc:
	subi.l		&24,%d0			# fix offset to be 0-8
	cmpi.b		%d0,&0x6		# is exception INEX? (6)
	bne.b		fu_in_exc_exit		# no

# the enabled exception was inexact
	btst		&unfl_bit,FPSR_EXCEPT(%a6) # did disabled underflow occur?
	bne.w		fu_in_exc_unfl		# yes
	btst		&ovfl_bit,FPSR_EXCEPT(%a6) # did disabled overflow occur?
	bne.w		fu_in_exc_ovfl		# yes

# here, we insert the correct fsave status value into the fsave frame for the
# corresponding exception. the operand in the fsave frame should be the original
# src operand.
fu_in_exc_exit:
	mov.l		%d0,-(%sp)		# save d0
	bsr.l		funimp_skew		# skew sgl or dbl inputs
	mov.l		(%sp)+,%d0		# restore d0

	mov.w		(tbl_except.b,%pc,%d0.w*2),2+FP_SRC(%a6) # create exc status

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0/fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	frestore	FP_SRC(%a6)		# restore src op

	unlk		%a6

	bra.l		_fpsp_done

tbl_except:
	short		0xe000,0xe006,0xe004,0xe005
	short		0xe003,0xe002,0xe001,0xe001

fu_in_exc_unfl:
	mov.w		&0x4,%d0
	bra.b		fu_in_exc_exit
fu_in_exc_ovfl:
	mov.w		&0x03,%d0
	bra.b		fu_in_exc_exit

# If the input operand to this operation was opclass two and a single
# or double precision denorm, inf, or nan, the operand needs to be
# "corrected" in order to have the proper equivalent extended precision
# number.
	global		fix_skewed_ops
fix_skewed_ops:
	bfextu		EXC_CMDREG(%a6){&0:&6},%d0 # extract opclass,src fmt
	cmpi.b		%d0,&0x11		# is class = 2 & fmt = sgl?
	beq.b		fso_sgl			# yes
	cmpi.b		%d0,&0x15		# is class = 2 & fmt = dbl?
	beq.b		fso_dbl			# yes
	rts					# no

fso_sgl:
	mov.w		LOCAL_EX(%a0),%d0	# fetch src exponent
	andi.w		&0x7fff,%d0		# strip sign
	cmpi.w		%d0,&0x3f80		# is |exp| == $3f80?
	beq.b		fso_sgl_dnrm_zero	# yes
	cmpi.w		%d0,&0x407f		# no; is |exp| == $407f?
	beq.b		fso_infnan		# yes
	rts					# no

fso_sgl_dnrm_zero:
	andi.l		&0x7fffffff,LOCAL_HI(%a0) # clear j-bit
	beq.b		fso_zero		# it's a skewed zero
fso_sgl_dnrm:
# here, we count on norm not to alter a0...
	bsr.l		norm			# normalize mantissa
	neg.w		%d0			# -shft amt
	addi.w		&0x3f81,%d0		# adjust new exponent
	andi.w		&0x8000,LOCAL_EX(%a0)	# clear old exponent
	or.w		%d0,LOCAL_EX(%a0)	# insert new exponent
	rts

fso_zero:
	andi.w		&0x8000,LOCAL_EX(%a0)	# clear bogus exponent
	rts

fso_infnan:
	andi.b		&0x7f,LOCAL_HI(%a0)	# clear j-bit
	ori.w		&0x7fff,LOCAL_EX(%a0)	# make exponent = $7fff
	rts

fso_dbl:
	mov.w		LOCAL_EX(%a0),%d0	# fetch src exponent
	andi.w		&0x7fff,%d0		# strip sign
	cmpi.w		%d0,&0x3c00		# is |exp| == $3c00?
	beq.b		fso_dbl_dnrm_zero	# yes
	cmpi.w		%d0,&0x43ff		# no; is |exp| == $43ff?
	beq.b		fso_infnan		# yes
	rts					# no

fso_dbl_dnrm_zero:
	andi.l		&0x7fffffff,LOCAL_HI(%a0) # clear j-bit
	bne.b		fso_dbl_dnrm		# it's a skewed denorm
	tst.l		LOCAL_LO(%a0)		# is it a zero?
	beq.b		fso_zero		# yes
fso_dbl_dnrm:
# here, we count on norm not to alter a0...
	bsr.l		norm			# normalize mantissa
	neg.w		%d0			# -shft amt
	addi.w		&0x3c01,%d0		# adjust new exponent
	andi.w		&0x8000,LOCAL_EX(%a0)	# clear old exponent
	or.w		%d0,LOCAL_EX(%a0)	# insert new exponent
	rts

#################################################################

# fmove out took an unimplemented data type exception.
# the src operand is in FP_SRC. Call _fout() to write out the result and
# to determine which exceptions, if any, to take.
fu_out:

# Separate packed move outs from the UNNORM and DENORM move outs.
	bfextu		EXC_CMDREG(%a6){&3:&3},%d0
	cmpi.b		%d0,&0x3
	beq.w		fu_out_pack
	cmpi.b		%d0,&0x7
	beq.w		fu_out_pack


# I'm not sure at this point what FPSR bits are valid for this instruction.
# so, since the emulation routines re-create them anyways, zero exception field.
# fmove out doesn't affect ccodes.
	and.l		&0xffff00ff,USER_FPSR(%a6) # zero exception field

	fmov.l		&0x0,%fpcr		# zero current control regs
	fmov.l		&0x0,%fpsr

# the src can ONLY be a DENORM or an UNNORM! so, don't make any big subroutine
# call here. just figure out what it is...
	mov.w		FP_SRC_EX(%a6),%d0	# get exponent
	andi.w		&0x7fff,%d0		# strip sign
	beq.b		fu_out_denorm		# it's a DENORM

	lea		FP_SRC(%a6),%a0
	bsr.l		unnorm_fix		# yes; fix it

	mov.b		%d0,STAG(%a6)

	bra.b		fu_out_cont
fu_out_denorm:
	mov.b		&DENORM,STAG(%a6)
fu_out_cont:

	clr.l		%d0
	mov.b		FPCR_MODE(%a6),%d0	# fetch rnd mode/prec

	lea		FP_SRC(%a6),%a0		# pass ptr to src operand

	mov.l		(%a6),EXC_A6(%a6)	# in case a6 changes
	bsr.l		fout			# call fmove out routine

# Exceptions in order of precedence:
#	BSUN	: none
#	SNAN	: none
#	OPERR	: fmove.{b,w,l} out of large UNNORM
#	OVFL	: fmove.{s,d}
#	UNFL	: fmove.{s,d,x}
#	DZ	: none
#	INEX2	: all
#	INEX1	: none (packed doesn't travel through here)

# determine the highest priority exception(if any) set by the
# emulation routine that has also been enabled by the user.
	mov.b		FPCR_ENABLE(%a6),%d0	# fetch exceptions enabled
	bne.w		fu_out_ena		# some are enabled

fu_out_done:

	mov.l		EXC_A6(%a6),(%a6)	# in case a6 changed

# on extended precision opclass three instructions using pre-decrement or
# post-increment addressing mode, the address register is not updated. is the
# address register was the stack pointer used from user mode, then let's update
# it here. if it was used from supervisor mode, then we have to handle this
# as a special case.
	btst		&0x5,EXC_SR(%a6)
	bne.b		fu_out_done_s

	mov.l		EXC_A7(%a6),%a0		# restore a7
	mov.l		%a0,%usp

fu_out_done_cont:
	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0/fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	unlk		%a6

	btst		&0x7,(%sp)		# is trace on?
	bne.b		fu_out_trace		# yes

	bra.l		_fpsp_done

# is the ea mode pre-decrement of the stack pointer from supervisor mode?
# ("fmov.x fpm,-(a7)") if so,
fu_out_done_s:
	cmpi.b		SPCOND_FLG(%a6),&mda7_flg
	bne.b		fu_out_done_cont

# the extended precision result is still in fp0. but, we need to save it
# somewhere on the stack until we can copy it to its final resting place.
# here, we're counting on the top of the stack to be the old place-holders
# for fp0/fp1 which have already been restored. that way, we can write
# over those destinations with the shifted stack frame.
	fmovm.x		&0x80,FP_SRC(%a6)	# put answer on stack

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0/fp1
	fmovm.l		USER_FPCR(%a6),%fpcr,%fpsr,%fpiar # restore ctrl regs
	movm.l		EXC_DREGS(%a6),&0x0303	# restore d0-d1/a0-a1

	mov.l		(%a6),%a6		# restore frame pointer

	mov.l		LOCAL_SIZE+EXC_SR(%sp),LOCAL_SIZE+EXC_SR-0xc(%sp)
	mov.l		LOCAL_SIZE+2+EXC_PC(%sp),LOCAL_SIZE+2+EXC_PC-0xc(%sp)

# now, copy the result to the proper place on the stack
	mov.l		LOCAL_SIZE+FP_SRC_EX(%sp),LOCAL_SIZE+EXC_SR+0x0(%sp)
	mov.l		LOCAL_SIZE+FP_SRC_HI(%sp),LOCAL_SIZE+EXC_SR+0x4(%sp)
	mov.l		LOCAL_SIZE+FP_SRC_LO(%sp),LOCAL_SIZE+EXC_SR+0x8(%sp)

	add.l		&LOCAL_SIZE-0x8,%sp

	btst		&0x7,(%sp)
	bne.b		fu_out_trace

	bra.l		_fpsp_done

fu_out_ena:
	and.b		FPSR_EXCEPT(%a6),%d0	# keep only ones enabled
	bfffo		%d0{&24:&8},%d0		# find highest priority exception
	bne.b		fu_out_exc		# there is at least one set

# no exceptions were set.
# if a disabled overflow occurred and inexact was enabled but the result