arch/m68k/ifpsp060/src/pfpsp.S

Source file repositories/reference/linux-study-clean/arch/m68k/ifpsp060/src/pfpsp.S

File Facts

System
Linux kernel
Corpus path
arch/m68k/ifpsp060/src/pfpsp.S
Extension
.S
Size
462530 bytes
Lines
14746
Domain
Architecture Layer
Bucket
arch/m68k
Inferred role
Architecture Layer: arch/m68k
Status
atlas-only

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

bfextu		EXC_CMDREG(%a6){&6:&3},%d0 # dyadic; load dst reg
	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		fovfl_op2_done		# no
	bsr.l		unnorm_fix		# yes; convert to NORM,DENORM,or ZERO
fovfl_op2_done:
	mov.b		%d0,DTAG(%a6)		# save dst optype tag

fovfl_extract:

#$#	mov.l		FP_SRC_EX(%a6),TRAP_SRCOP_EX(%a6)
#$#	mov.l		FP_SRC_HI(%a6),TRAP_SRCOP_HI(%a6)
#$#	mov.l		FP_SRC_LO(%a6),TRAP_SRCOP_LO(%a6)
#$#	mov.l		FP_DST_EX(%a6),TRAP_DSTOP_EX(%a6)
#$#	mov.l		FP_DST_HI(%a6),TRAP_DSTOP_HI(%a6)
#$#	mov.l		FP_DST_LO(%a6),TRAP_DSTOP_LO(%a6)

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

	mov.b		1+EXC_CMDREG(%a6),%d1
	andi.w		&0x007f,%d1		# extract extension

	andi.l		&0x00ff01ff,USER_FPSR(%a6) # zero all but accured field

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

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

# maybe we can make these entry points ONLY the OVFL entry points of each routine.
	mov.l		(tbl_unsupp.l,%pc,%d1.w*4),%d1 # fetch routine addr
	jsr		(tbl_unsupp.l,%pc,%d1.l*1)

# the operation has been emulated. the result is in fp0.
# the EXOP, if an exception occurred, is in fp1.
# we must save the default result regardless of whether
# traps are enabled or disabled.
	bfextu		EXC_CMDREG(%a6){&6:&3},%d0
	bsr.l		store_fpreg

# the exceptional possibilities we have left ourselves with are ONLY overflow
# and inexact. and, the inexact is such that overflow occurred and was disabled
# but inexact was enabled.
	btst		&ovfl_bit,FPCR_ENABLE(%a6)
	bne.b		fovfl_ovfl_on

	btst		&inex2_bit,FPCR_ENABLE(%a6)
	bne.b		fovfl_inex_on

	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
#$#	add.l		&24,%sp
	bra.l		_fpsp_done

# overflow is enabled AND overflow, of course, occurred. so, we have the EXOP
# in fp1. now, simply jump to _real_ovfl()!
fovfl_ovfl_on:
	fmovm.x		&0x40,FP_SRC(%a6)	# save EXOP (fp1) to stack

	mov.w		&0xe005,2+FP_SRC(%a6)	# save exc status

	fmovm.x		EXC_FPREGS(%a6),&0xc0	# restore fp0-fp1

Annotation

Implementation Notes