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|
|
| skeleton.sa 3.2 4/26/91
|
| This file contains code that is system dependent and will
| need to be modified to install the FPSP.
|
| Each entry point for exception 'xxxx' begins with a 'jmp fpsp_xxxx'.
| Put any target system specific handling that must be done immediately
| before the jump instruction. If there no handling necessary, then
| the 'fpsp_xxxx' handler entry point should be placed in the exception
| table so that the 'jmp' can be eliminated. If the FPSP determines that the
| exception is one that must be reported then there will be a
| return from the package by a 'jmp real_xxxx'. At that point
| the machine state will be identical to the state before
| the FPSP was entered. In particular, whatever condition
| that caused the exception will still be pending when the FPSP
| package returns. Thus, there will be system specific code
| to handle the exception.
|
| If the exception was completely handled by the package, then
| the return will be via a 'jmp fpsp_done'. Unless there is
| OS specific work to be done (such as handling a context switch or
| interrupt) the user program can be resumed via 'rte'.
|
| In the following skeleton code, some typical 'real_xxxx' handling
| code is shown. This code may need to be moved to an appropriate
| place in the target system, or rewritten.
|
| 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.
|
| Modified for Linux-1.3.x by Jes Sorensen (jds@kom.auc.dk)
|
#include <linux/linkage.h>
#include <asm/entry.h>
#include <asm/asm-offsets.h>
|SKELETON idnt 2,1 | Motorola 040 Floating Point Software Package
|section 15
|
| The following counters are used for standalone testing
|
|section 8
#include "fpsp.h"
|xref b1238_fix
|
| Divide by Zero exception
|
| All dz exceptions are 'real', hence no fpsp_dz entry point.
|
.global dz
.global real_dz
dz:
real_dz:
link %a6,#-LOCAL_SIZE
fsave -(%sp)
bclrb #E1,E_BYTE(%a6)
frestore (%sp)+
unlk %a6
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %sp,%sp@- | stack frame pointer argument
bsrl trap_c
addql #4,%sp
bral ret_from_exception
|
| Inexact exception
|
| All inexact exceptions are real, but the 'real' handler
| will probably want to clear the pending exception.
| The provided code will clear the E3 exception (if pending),
| otherwise clear the E1 exception. The frestore is not really
| necessary for E1 exceptions.
|
| Code following the 'inex' label is to handle bug #1232. In this
| bug, if an E1 snan, ovfl, or unfl occurred, and the process was
| swapped out before taking the exception, the exception taken on
| return was inex, rather than the correct exception. The snan, ovfl,
| and unfl exception to be taken must not have been enabled. The
| fix is to check for E1, and the existence of one of snan, ovfl,
| or unfl bits set in the fpsr. If any of these are set, branch
| to the appropriate handler for the exception in the fpsr. Note
| that this fix is only for d43b parts, and is skipped if the
| version number is not $40.
|
|
.global real_inex
.global inex
inex:
link %a6,#-LOCAL_SIZE
fsave -(%sp)
cmpib #VER_40,(%sp) |test version number
bnes not_fmt40
fmovel %fpsr,-(%sp)
btstb #E1,E_BYTE(%a6) |test for E1 set
beqs not_b1232
btstb #snan_bit,2(%sp) |test for snan
beq inex_ckofl
addl #4,%sp
frestore (%sp)+
unlk %a6
bra snan
inex_ckofl:
btstb #ovfl_bit,2(%sp) |test for ovfl
beq inex_ckufl
addl #4,%sp
frestore (%sp)+
unlk %a6
bra ovfl
inex_ckufl:
btstb #unfl_bit,2(%sp) |test for unfl
beq not_b1232
addl #4,%sp
frestore (%sp)+
unlk %a6
bra unfl
|
| We do not have the bug 1232 case. Clean up the stack and call
| real_inex.
|
not_b1232:
addl #4,%sp
frestore (%sp)+
unlk %a6
real_inex:
link %a6,#-LOCAL_SIZE
fsave -(%sp)
not_fmt40:
bclrb #E3,E_BYTE(%a6) |clear and test E3 flag
beqs inex_cke1
|
| Clear dirty bit on dest resister in the frame before branching
| to b1238_fix.
|
moveml %d0/%d1,USER_DA(%a6)
bfextu CMDREG1B(%a6){#6:#3},%d0 |get dest reg no
bclrb %d0,FPR_DIRTY_BITS(%a6) |clr dest dirty bit
bsrl b1238_fix |test for bug1238 case
moveml USER_DA(%a6),%d0/%d1
bras inex_done
inex_cke1:
bclrb #E1,E_BYTE(%a6)
inex_done:
frestore (%sp)+
unlk %a6
SAVE_ALL_INT
GET_CURRENT(%d0)
movel %sp,%sp@- | stack frame pointer argument
bsrl trap_c
addql #4,%sp
bral ret_from_exception
|
| Overflow exception
|