isp.s

linux内核源码

	mov.l		(EXC_AREGS,%a6,%d1.w*4),%a0 # put base in a0

	btst		&0x8,%d0
	beq.b		addr_ind_index_8bit	# for ext word or not?

	movm.l		&0x3c00,-(%sp)		# save d2-d5

	mov.l		%d0,%d5			# put extword in d5
	mov.l		%a0,%d3			# put base in d3

	bra.l		calc_mem_ind		# calc memory indirect

addr_ind_index_8bit:
	mov.l		%d2,-(%sp)		# save old d2

	mov.l		%d0,%d1
	rol.w		&0x4,%d1
	andi.w		&0xf,%d1		# extract index regno

	mov.l		(EXC_DREGS,%a6,%d1.w*4),%d1 # fetch index reg value

	btst		&0xb,%d0		# is it word or long?
	bne.b		aii8_long
	ext.l		%d1			# sign extend word index
aii8_long:
	mov.l		%d0,%d2
	rol.w		&0x7,%d2
	andi.l		&0x3,%d2		# extract scale value

	lsl.l		%d2,%d1			# shift index by scale

	extb.l		%d0			# sign extend displacement
	add.l		%d1,%d0			# index + disp
	add.l		%d0,%a0			# An + (index + disp)

	mov.l		(%sp)+,%d2		# restore old d2
	rts

######################
# Immediate: #<data> #
#########################################################################
# word, long: <ea> of the data is the current extension word		#
#	pointer value. new extension word pointer is simply the old	#
#	plus the number of bytes in the data type(2 or 4).		#
#########################################################################
immediate:
	mov.b		&immed_flg,SPCOND_FLG(%a6) # set immediate flag

	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch extension word ptr
	rts

###########################
# Absolute short: (XXX).W #
###########################
abs_short:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x2,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_word		# fetch short address

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	mov.w		%d0,%a0			# return <ea> in a0
	rts

##########################
# Absolute long: (XXX).L #
##########################
abs_long:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x4,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_long		# fetch long address

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	mov.l		%d0,%a0			# return <ea> in a0
	rts

#######################################################
# Program counter indirect w/ displacement: (d16, PC) #
#######################################################
pc_ind:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x2,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_word		# fetch word displacement

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	mov.w		%d0,%a0			# sign extend displacement

	add.l		EXC_EXTWPTR(%a6),%a0	# pc + d16

# _imem_read_word() increased the extwptr by 2. need to adjust here.
	subq.l		&0x2,%a0		# adjust <ea>

	rts

##########################################################
# PC indirect w/ index(8-bit displacement): (d8, PC, An) #
# "     "     w/   "  (base displacement): (bd, PC, An)  #
# PC memory indirect postindexed: ([bd, PC], Xn, od)     #
# PC memory indirect preindexed: ([bd, PC, Xn], od)      #
##########################################################
pc_ind_ext:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x2,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_word		# fetch ext word

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	mov.l		EXC_EXTWPTR(%a6),%a0	# put base in a0
	subq.l		&0x2,%a0		# adjust base

	btst		&0x8,%d0		# is disp only 8 bits?
	beq.b		pc_ind_index_8bit	# yes

# the indexed addressing mode uses a base displacement of size
# word or long
	movm.l		&0x3c00,-(%sp)		# save d2-d5

	mov.l		%d0,%d5			# put extword in d5
	mov.l		%a0,%d3			# put base in d3

	bra.l		calc_mem_ind		# calc memory indirect

pc_ind_index_8bit:
	mov.l		%d2,-(%sp)		# create a temp register

	mov.l		%d0,%d1			# make extword copy
	rol.w		&0x4,%d1		# rotate reg num into place
	andi.w		&0xf,%d1		# extract register number

	mov.l		(EXC_DREGS,%a6,%d1.w*4),%d1 # fetch index reg value

	btst		&0xb,%d0		# is index word or long?
	bne.b		pii8_long		# long
	ext.l		%d1			# sign extend word index
pii8_long:
	mov.l		%d0,%d2			# make extword copy
	rol.w		&0x7,%d2		# rotate scale value into place
	andi.l		&0x3,%d2		# extract scale value

	lsl.l		%d2,%d1			# shift index by scale

	extb.l		%d0			# sign extend displacement
	add.l		%d1,%d0			# index + disp
	add.l		%d0,%a0			# An + (index + disp)

	mov.l		(%sp)+,%d2		# restore temp register

	rts

# a5 = exc_extwptr	(global to uaeh)
# a4 = exc_opword	(global to uaeh)
# a3 = exc_dregs	(global to uaeh)

# d2 = index		(internal "     "    )
# d3 = base		(internal "     "    )
# d4 = od		(internal "     "    )
# d5 = extword		(internal "     "    )
calc_mem_ind:
	btst		&0x6,%d5		# is the index suppressed?
	beq.b		calc_index
	clr.l		%d2			# yes, so index = 0
	bra.b		base_supp_ck
calc_index:
	bfextu		%d5{&16:&4},%d2
	mov.l		(EXC_DREGS,%a6,%d2.w*4),%d2
	btst		&0xb,%d5		# is index word or long?
	bne.b		no_ext
	ext.l		%d2
no_ext:
	bfextu		%d5{&21:&2},%d0
	lsl.l		%d0,%d2
base_supp_ck:
	btst		&0x7,%d5		# is the bd suppressed?
	beq.b		no_base_sup
	clr.l		%d3
no_base_sup:
	bfextu		%d5{&26:&2},%d0	# get bd size
#	beq.l		_error			# if (size == 0) it's reserved
	cmpi.b		%d0,&2
	blt.b		no_bd
	beq.b		get_word_bd

	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x4,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_long

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	bra.b		chk_ind
get_word_bd:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x2,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_word

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	ext.l		%d0			# sign extend bd

chk_ind:
	add.l		%d0,%d3			# base += bd
no_bd:
	bfextu		%d5{&30:&2},%d0		# is od suppressed?
	beq.w		aii_bd
	cmpi.b		%d0,&0x2
	blt.b		null_od
	beq.b		word_od

	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x4,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_long

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	bra.b		add_them

word_od:
	mov.l		EXC_EXTWPTR(%a6),%a0	# fetch instruction addr
	addq.l		&0x2,EXC_EXTWPTR(%a6)	# incr instruction ptr
	bsr.l		_imem_read_word

	tst.l		%d1			# ifetch error?
	bne.l		isp_iacc		# yes

	ext.l		%d0			# sign extend od
	bra.b		add_them

null_od:
	clr.l		%d0
add_them:
	mov.l		%d0,%d4
	btst		&0x2,%d5		# pre or post indexing?
	beq.b		pre_indexed

	mov.l		%d3,%a0
	bsr.l		_dmem_read_long

	tst.l		%d1			# dfetch error?
	bne.b		calc_ea_err		# yes

	add.l		%d2,%d0			# <ea> += index
	add.l		%d4,%d0			# <ea> += od
	bra.b		done_ea

pre_indexed:
	add.l		%d2,%d3			# preindexing
	mov.l		%d3,%a0
	bsr.l		_dmem_read_long

	tst.l		%d1			# ifetch error?
	bne.b		calc_ea_err		# yes

	add.l		%d4,%d0			# ea += od
	bra.b		done_ea

aii_bd:
	add.l		%d2,%d3			# ea = (base + bd) + index
	mov.l		%d3,%d0
done_ea:
	mov.l		%d0,%a0

	movm.l		(%sp)+,&0x003c		# restore d2-d5
	rts

# if dmem_read_long() returns a fail message in d1, the package
# must create an access error frame. here, we pass a skeleton fslw
# and the failing address to the routine that creates the new frame.
# FSLW:
#	read = true
#	size = longword
#	TM = data
#	software emulation error = true
calc_ea_err:
	mov.l		%d3,%a0			# pass failing address
	mov.l		&0x01010001,%d0		# pass fslw
	bra.l		isp_dacc

#########################################################################
# XDEF **************************************************************** #
#	_moveperipheral(): routine to emulate movep instruction		#
#									#
# XREF **************************************************************** #
#	_dmem_read_byte() - read byte from memory			#
#	_dmem_write_byte() - write byte to memory			#
#	isp_dacc() - handle data access error exception			#
#									#
# INPUT *************************************************************** #
#	none								#
#									#
# OUTPUT ************************************************************** #
#	If exiting through isp_dacc...					#
#		a0 = failing address					#
#		d0 = FSLW						#
#	else								#
#		none							#
#									#
# ALGORITHM ***********************************************************	#
#	Decode the movep instruction words stored at EXC_OPWORD and	#
# either read or write the required bytes from/to memory. Use the	#
# _dmem_{read,write}_byte() routines. If one of the memory routines	#
# returns a failing value, we must pass the failing address and	a FSLW	#
# to the _isp_dacc() routine.						#
#	Since this instruction is used to access peripherals, make sure	#
# to only access the required bytes.					#
#									#
#########################################################################

###########################
# movep.(w,l)	Dx,(d,Ay) #
# movep.(w,l)	(d,Ay),Dx #
###########################
	global		_moveperipheral
_moveperipheral:
	mov.w		EXC_OPWORD(%a6),%d1	# fetch the opcode word

	mov.b		%d1,%d0
	and.w		&0x7,%d0		# extract Ay from opcode word

	mov.l		(EXC_AREGS,%a6,%d0.w*4),%a0 # fetch ay

	add.w		EXC_EXTWORD(%a6),%a0	# add: an + sgn_ext(disp)

	btst		&0x7,%d1		# (reg 2 mem) or (mem 2 reg)
	beq.w		mem2reg

# reg2mem: fetch dx, then write it to memory
reg2mem:
	mov.w		%d1,%d0
	rol.w		&0x7,%d0
	and.w		&0x7,%d0		# extract Dx from opcode word

	mov.l		(EXC_DREGS,%a6,%d0.w*4), %d0 # fetch dx

	btst		&0x6,%d1		# word or long operation?
	beq.b		r2mwtrans

# a0 = dst addr
# d0 = Dx
r2mltrans:
	mov.l		%d0,%d2			# store data
	mov.l		%a0,%a2			# store addr
	rol.l		&0x8,%d2
	mov.l		%d2,%d0

	bsr.l		_dmem_write_byte	# os  : write hi

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	add.w		&0x2,%a2		# incr addr
	mov.l		%a2,%a0
	rol.l		&0x8,%d2
	mov.l		%d2,%d0

	bsr.l		_dmem_write_byte	# os  : write lo

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	add.w		&0x2,%a2		# incr addr
	mov.l		%a2,%a0
	rol.l		&0x8,%d2
	mov.l		%d2,%d0

	bsr.l		_dmem_write_byte	# os  : write lo

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	add.w		&0x2,%a2		# incr addr
	mov.l		%a2,%a0
	rol.l		&0x8,%d2
	mov.l		%d2,%d0

	bsr.l		_dmem_write_byte	# os  : write lo

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	rts

# a0 = dst addr
# d0 = Dx
r2mwtrans:
	mov.l		%d0,%d2			# store data
	mov.l		%a0,%a2			# store addr
	lsr.w		&0x8,%d0

	bsr.l		_dmem_write_byte	# os  : write hi

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	add.w		&0x2,%a2
	mov.l		%a2,%a0
	mov.l		%d2,%d0

	bsr.l		_dmem_write_byte	# os  : write lo

	tst.l		%d1			# dfetch error?
	bne.w		movp_write_err		# yes

	rts

# mem2reg: read bytes from memory.
# determines the dest register, and then writes the bytes into it.
mem2reg:
	btst		&0x6,%d1		# word or long operation?
	beq.b		m2rwtrans

# a0 = dst addr
m2rltrans:
	mov.l		%a0,%a2			# store addr

	bsr.l		_dmem_read_byte		# read first byte

	tst.l		%d1			# dfetch error?
	bne.w		movp_read_err		# yes

	mov.l		%d0,%d2

	add.w		&0x2,%a2		# incr addr by 2 bytes
	mov.l		%a2,%a0

	bsr.l		_dmem_read_byte		# read second byte

	tst.l		%d1			# dfetch error?
	bne.w		movp_read_err		# yes

	lsl.w		&0x8,%d2
	mov.b		%d0,%d2			# append bytes

	add.w		&0x2,%a2		# incr addr by 2 bytes
	mov.l		%a2,%a0