//
//
// gen_except.sa 3.7 1/16/92
//
// gen_except --- FPSP routine to detect reportable exceptions
//
// This routine compares the exception enable byte of the
// user_fpcr on the stack with the exception status byte
// of the user_fpsr.
//
// Any routine which may report an exceptions must load
// the stack frame in memory with the exceptional operand(s).
//
// Priority for exceptions is:
//
// Highest: bsun
// snan
// operr
// ovfl
// unfl
// dz
// inex2
// Lowest: inex1
//
// Note: The IEEE standard specifies that inex2 is to be
// reported if ovfl occurs and the ovfl enable bit is not
// set but the inex2 enable bit is.
//
//
// 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// THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.
GEN_EXCEPT: //idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.defs"
|xref real_trace
|xref fpsp_done
|xref fpsp_fmt_error
exc_tbl:
.long bsun_exc
.long commonE1
.long commonE1
.long ovfl_unfl
.long ovfl_unfl
.long commonE1
.long commonE3
.long commonE3
.long no_match
.global gen_except
gen_except:
cmpib #IDLE_SIZE-4,1(%a7) //test for idle frame
beq do_check //go handle idle frame
cmpib #UNIMP_40_SIZE-4,1(%a7) //test for orig unimp frame
beqs unimp_x //go handle unimp frame
cmpib #UNIMP_41_SIZE-4,1(%a7) //test for rev unimp frame
beqs unimp_x //go handle unimp frame
cmpib #BUSY_SIZE-4,1(%a7) //if size <> $60, fmt error
bnel fpsp_fmt_error
leal BUSY_SIZE+LOCAL_SIZE(%a7),%a1 //init a1 so fpsp.h
// ;equates will work
// Fix up the new busy frame with entries from the unimp frame
//
movel ETEMP_EX(%a6),ETEMP_EX(%a1) //copy etemp from unimp
movel ETEMP_HI(%a6),ETEMP_HI(%a1) //frame to busy frame
movel ETEMP_LO(%a6),ETEMP_LO(%a1)
movel CMDREG1B(%a6),CMDREG1B(%a1) //set inst in frame to unimp
movel CMDREG1B(%a6),%d0 //fix cmd1b to make it
andl #0x03c30000,%d0 //work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 //extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 //put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 //extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 //put them in the right place
movel %d0,CMDREG3B(%a1) //in the busy frame
//
// Or in the FPSR from the emulation with the USER_FPSR on the stack.
//
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
movel USER_FPSR(%a6),FPSR_SHADOW(%a1) //set exc bits
orl #sx_mask,E_BYTE(%a1)
bra do_clean
//
// Frame is an unimp frame possible resulting from an fmove <ea>,fp0
// that caused an exception
//
// a1 is modified to point into the new frame allowing fpsp equates
// to be valid.
//
unimp_x:
cmpib #UNIMP_40_SIZE-4,1(%a7) //test for orig unimp frame
bnes test_rev
leal UNIMP_40_SIZE+LOCAL_SIZE(%a7),%a1
bras unimp_con
test_rev:
cmpib #UNIMP_41_SIZE-4,1(%a7) //test for rev unimp frame
bnel fpsp_fmt_error //if not $28 or $30
leal UNIMP_41_SIZE+LOCAL_SIZE(%a7),%a1
unimp_con:
//
// Fix up the new unimp frame with entries from the old unimp frame
//
movel CMDREG1B(%a6),CMDREG1B(%a1) //set inst in frame to unimp
//
// Or in the FPSR from the emulation with the USER_FPSR on the stack.
//
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
bra do_clean
//
// Frame is idle, so check for exceptions reported through
// USER_FPSR and set the unimp frame accordingly.
// A7 must be incremented to the point before the
// idle fsave vector to the unimp vector.
//
do_check:
addl #4,%a7 //point A7 back to unimp frame
//
// Or in the FPSR from the emulation with the USER_FPSR on the stack.
//
fmovel %FPSR,%d0
orl %d0,USER_FPSR(%a6)
//
// On a busy frame, we must clear the nmnexc bits.
//
cmpib #BUSY_SIZE-4,1(%a7) //check frame type
bnes check_fr //if busy, clr nmnexc
clrw NMNEXC(%a6) //clr nmnexc & nmcexc
btstb #5,CMDREG1B(%a6) //test for fmove out
bnes frame_com
movel USER_FPSR(%a6),FPSR_SHADOW(%a6) //set exc bits
orl #sx_mask,E_BYTE(%a6)
bras frame_com
check_fr:
cmpb #UNIMP_40_SIZE-4,1(%a7)
beqs frame_com
clrw NMNEXC(%a6)
frame_com:
moveb FPCR_ENABLE(%a6),%d0 //get fpcr enable byte
andb FPSR_EXCEPT(%a6),%d0 //and in the fpsr exc byte
bfffo %d0{#24:#8},%d1 //test for first set bit
leal exc_tbl,%a0 //load jmp table address
subib #24,%d1 //normalize bit offset to 0-8
movel (%a0,%d1.w*4),%a0 //load routine address based
// ;based on first enabled exc
jmp (%a0) //jump to routine
//
// Bsun is not possible in unimp or unsupp
//
bsun_exc:
bra do_clean
//
// The typical work to be done to the unimp frame to report an
// exception is to set the E1/E3 byte and clr the U flag.
// commonE1 does this for E1 exceptions, which are snan,
// operr, and dz. commonE3 does this for E3 exceptions, which
// are inex2 and inex1, and also clears the E1 exception bit
// left over from the unimp exception.
//
commonE1:
bsetb #E1,E_BYTE(%a6) //set E1 flag
bra commonE //go clean and exit
commonE3:
tstb UFLG_TMP(%a6) //test flag for unsup/unimp state
bnes unsE3
uniE3:
bsetb #E3,E_BYTE(%a6) //set E3 flag
bclrb #E1,E_BYTE(%a6) //clr E1 from unimp
bra commonE
unsE3:
tstb RES_FLG(%a6)
bnes unsE3_0
unsE3_1:
bsetb #E3,E_BYTE(%a6) //set E3 flag
unsE3_0:
bclrb #E1,E_BYTE(%a6) //clr E1 flag
movel CMDREG1B(%a6),%d0
andl #0x03c30000,%d0 //work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 //extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 //put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 //extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 //put them in the right place
movel %d0,CMDREG3B(%a6) //in the busy frame
commonE:
bclrb #UFLAG,T_BYTE(%a6) //clr U flag from unimp
bra do_clean //go clean and exit
//
// No bits in the enable byte match existing exceptions. Check for
// the case of the ovfl exc without the ovfl enabled, but with
// inex2 enabled.
//
no_match:
btstb #inex2_bit,FPCR_ENABLE(%a6) //check for ovfl/inex2 case
beqs no_exc //if clear, exit
btstb #ovfl_bit,FPSR_EXCEPT(%a6) //now check ovfl
beqs no_exc //if clear, exit
bras ovfl_unfl //go to unfl_ovfl to determine if
// ;it is an unsupp or unimp exc
// No exceptions are to be reported. If the instruction was
// unimplemented, no FPU restore is necessary. If it was
// unsupported, we must perform the restore.
no_exc:
tstb UFLG_TMP(%a6) //test flag for unsupp/unimp state
beqs uni_no_exc
uns_no_exc:
tstb RES_FLG(%a6) //check if frestore is needed
bne do_clean //if clear, no frestore needed
uni_no_exc:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
unlk %a6
bra finish_up
//
// Unsupported Data Type Handler:
// Ovfl:
// An fmoveout that results in an overflow is reported this way.
// Unfl:
// An fmoveout that results in an underflow is reported this way.
//
// Unimplemented Instruction Handler:
// Ovfl:
// Only scosh, setox, ssinh, stwotox, and scale can set overflow in
// this manner.
// Unfl:
// Stwotox, setox, and scale can set underflow in this manner.
// Any of the other Library Routines such that f(x)=x in which
// x is an extended denorm can report an underflow exception.
// It is the responsibility of the exception-causing exception
// to make sure that WBTEMP is correct.
//
// The exceptional operand is in FP_SCR1.
//
ovfl_unfl:
tstb UFLG_TMP(%a6) //test flag for unsupp/unimp state
beqs ofuf_con
//
// The caller was from an unsupported data type trap. Test if the
// caller set CU_ONLY. If so, the exceptional operand is expected in
// FPTEMP, rather than WBTEMP.
//
tstb CU_ONLY(%a6) //test if inst is cu-only
beq unsE3
// move.w #$fe,CU_SAVEPC(%a6)
clrb CU_SAVEPC(%a6)
bsetb #E1,E_BYTE(%a6) //set E1 exception flag
movew ETEMP_EX(%a6),FPTEMP_EX(%a6)
movel ETEMP_HI(%a6),FPTEMP_HI(%a6)
movel ETEMP_LO(%a6),FPTEMP_LO(%a6)
bsetb #fptemp15_bit,DTAG(%a6) //set fpte15
bclrb #UFLAG,T_BYTE(%a6) //clr U flag from unimp
bra do_clean //go clean and exit
ofuf_con:
moveb (%a7),VER_TMP(%a6) //save version number
cmpib #BUSY_SIZE-4,1(%a7) //check for busy frame
beqs busy_fr //if unimp, grow to busy
cmpib #VER_40,(%a7) //test for orig unimp frame
bnes try_41 //if not, test for rev frame
moveql #13,%d0 //need to zero 14 lwords
bras ofuf_fin
try_41:
cmpib #VER_41,(%a7) //test for rev unimp frame
bnel fpsp_fmt_error //if neither, exit with error
moveql #11,%d0 //need to zero 12 lwords
ofuf_fin:
clrl (%a7)
loop1:
clrl -(%a7) //clear and dec a7
dbra %d0,loop1
moveb VER_TMP(%a6),(%a7)
moveb #BUSY_SIZE-4,1(%a7) //write busy fmt word.
busy_fr:
movel FP_SCR1(%a6),WBTEMP_EX(%a6) //write
movel FP_SCR1+4(%a6),WBTEMP_HI(%a6) //exceptional op to
movel FP_SCR1+8(%a6),WBTEMP_LO(%a6) //wbtemp
bsetb #E3,E_BYTE(%a6) //set E3 flag
bclrb #E1,E_BYTE(%a6) //make sure E1 is clear
bclrb #UFLAG,T_BYTE(%a6) //clr U flag
movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
orl #sx_mask,E_BYTE(%a6)
movel CMDREG1B(%a6),%d0 //fix cmd1b to make it
andl #0x03c30000,%d0 //work for cmd3b
bfextu CMDREG1B(%a6){#13:#1},%d1 //extract bit 2
lsll #5,%d1
swap %d1
orl %d1,%d0 //put it in the right place
bfextu CMDREG1B(%a6){#10:#3},%d1 //extract bit 3,4,5
lsll #2,%d1
swap %d1
orl %d1,%d0 //put them in the right place
movel %d0,CMDREG3B(%a6) //in the busy frame
//
// Check if the frame to be restored is busy or unimp.
//** NOTE *** Bug fix for errata (0d43b #3)
// If the frame is unimp, we must create a busy frame to
// fix the bug with the nmnexc bits in cases in which they
// are set by a previous instruction and not cleared by
// the save. The frame will be unimp only if the final
// instruction in an emulation routine caused the exception
// by doing an fmove <ea>,fp0. The exception operand, in
// internal format, is in fptemp.
//
do_clean:
cmpib #UNIMP_40_SIZE-4,1(%a7)
bnes do_con
moveql #13,%d0 //in orig, need to zero 14 lwords
bras do_build
do_con:
cmpib #UNIMP_41_SIZE-4,1(%a7)
bnes do_restore //frame must be busy
moveql #11,%d0 //in rev, need to zero 12 lwords
do_build:
moveb (%a7),VER_TMP(%a6)
clrl (%a7)
loop2:
clrl -(%a7) //clear and dec a7
dbra %d0,loop2
//
// Use a1 as pointer into new frame. a6 is not correct if an unimp or
// busy frame was created as the result of an exception on the final
// instruction of an emulation routine.
//
// We need to set the nmcexc bits if the exception is E1. Otherwise,
// the exc taken will be inex2.
//
leal BUSY_SIZE+LOCAL_SIZE(%a7),%a1 //init a1 for new frame
moveb VER_TMP(%a6),(%a7) //write busy fmt word
moveb #BUSY_SIZE-4,1(%a7)
movel FP_SCR1(%a6),WBTEMP_EX(%a1) //write
movel FP_SCR1+4(%a6),WBTEMP_HI(%a1) //exceptional op to
movel FP_SCR1+8(%a6),WBTEMP_LO(%a1) //wbtemp
// btst.b #E1,E_BYTE(%a1)
// beq.b do_restore
bfextu USER_FPSR(%a6){#17:#4},%d0 //get snan/operr/ovfl/unfl bits
bfins %d0,NMCEXC(%a1){#4:#4} //and insert them in nmcexc
movel USER_FPSR(%a6),FPSR_SHADOW(%a1) //set exc bits
orl #sx_mask,E_BYTE(%a1)
do_restore:
moveml USER_DA(%a6),%d0-%d1/%a0-%a1
fmovemx USER_FP0(%a6),%fp0-%fp3
fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
frestore (%a7)+
tstb RES_FLG(%a6) //RES_FLG indicates a "continuation" frame
beq cont
bsr bug1384
cont:
unlk %a6
//
// If trace mode enabled, then go to trace handler. This handler
// cannot have any fp instructions. If there are fp inst's and an
// exception has been restored into the machine then the exception
// will occur upon execution of the fp inst. This is not desirable
// in the kernel (supervisor mode). See MC68040 manual Section 9.3.8.
//
finish_up:
btstb #7,(%a7) //test T1 in SR
bnes g_trace
btstb #6,(%a7) //test T0 in SR
bnes g_trace
bral fpsp_done
//
// Change integer stack to look like trace stack
// The address of the instruction that caused the
// exception is already in the integer stack (is
// the same as the saved friar)
//
// If the current frame is already a 6-word stack then all
// that needs to be done is to change the vector# to TRACE.
// If the frame is only a 4-word stack (meaning we got here
// on an Unsupported data type exception), then we need to grow
// the stack an extra 2 words and get the FPIAR from the FPU.
//
g_trace:
bftst EXC_VEC-4(%sp){#0:#4}
bne g_easy
subw #4,%sp // make room
movel 4(%sp),(%sp)
movel 8(%sp),4(%sp)
subw #BUSY_SIZE,%sp
fsave (%sp)
fmovel %fpiar,BUSY_SIZE+EXC_EA-4(%sp)
frestore (%sp)
addw #BUSY_SIZE,%sp
g_easy:
movew #TRACE_VEC,EXC_VEC-4(%a7)
bral real_trace
//
// This is a work-around for hardware bug 1384.
//
bug1384:
link %a5,#0
fsave -(%sp)
cmpib #0x41,(%sp) // check for correct frame
beq frame_41
bgt nofix // if more advanced mask, do nada
frame_40:
tstb 1(%sp) // check to see if idle
bne notidle
idle40:
clrl (%sp) // get rid of old fsave frame
movel %d1,USER_D1(%a6) // save d1
movew #8,%d1 // place unimp frame instead
loop40: clrl -(%sp)
dbra %d1,loop40
movel USER_D1(%a6),%d1 // restore d1
movel #0x40280000,-(%sp)
frestore (%sp)+
unlk %a5
rts
frame_41:
tstb 1(%sp) // check to see if idle
bne notidle
idle41:
clrl (%sp) // get rid of old fsave frame
movel %d1,USER_D1(%a6) // save d1
movew #10,%d1 // place unimp frame instead
loop41: clrl -(%sp)
dbra %d1,loop41
movel USER_D1(%a6),%d1 // restore d1
movel #0x41300000,-(%sp)
frestore (%sp)+
unlk %a5
rts
notidle:
bclrb #etemp15_bit,-40(%a5)
frestore (%sp)+
unlk %a5
rts
nofix:
frestore (%sp)+
unlk %a5
rts
|end
