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|
|
| fpsp.h 3.3 3.3
|
| 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.
| fpsp.h --- stack frame offsets during FPSP exception handling
|
| These equates are used to access the exception frame, the fsave
| frame and any local variables needed by the FPSP package.
|
| All FPSP handlers begin by executing:
|
| link a6,#-LOCAL_SIZE
| fsave -(a7)
| movem.l d0-d1/a0-a1,USER_DA(a6)
| fmovem.x fp0-fp3,USER_FP0(a6)
| fmove.l fpsr/fpcr/fpiar,USER_FPSR(a6)
|
| After initialization, the stack looks like this:
|
| A7 ---> +-------------------------------+
| | |
| | FPU fsave area |
| | |
| +-------------------------------+
| | |
| | FPSP Local Variables |
| | including |
| | saved registers |
| | |
| +-------------------------------+
| A6 ---> | Saved A6 |
| +-------------------------------+
| | |
| | Exception Frame |
| | |
| | |
|
| Positive offsets from A6 refer to the exception frame. Negative
| offsets refer to the Local Variable area and the fsave area.
| The fsave frame is also accessible from the top via A7.
|
| On exit, the handlers execute:
|
| movem.l USER_DA(a6),d0-d1/a0-a1
| fmovem.x USER_FP0(a6),fp0-fp3
| fmove.l USER_FPSR(a6),fpsr/fpcr/fpiar
| frestore (a7)+
| unlk a6
|
| and then either "bra fpsp_done" if the exception was completely
| handled by the package, or "bra real_xxxx" which is an external
| label to a routine that will process a real exception of the
| type that was generated. Some handlers may omit the "frestore"
| if the FPU state after the exception is idle.
|
| Sometimes the exception handler will transform the fsave area
| because it needs to report an exception back to the user. This
| can happen if the package is entered for an unimplemented float
| instruction that generates (say) an underflow. Alternatively,
| a second fsave frame can be pushed onto the stack and the
| handler exit code will reload the new frame and discard the old.
|
| The registers d0, d1, a0, a1 and fp0-fp3 are always saved and
| restored from the "local variable" area and can be used as
| temporaries. If a routine needs to change any
| of these registers, it should modify the saved copy and let
| the handler exit code restore the value.
|
|----------------------------------------------------------------------
|
| Local Variables on the stack
|
.set LOCAL_SIZE,192 | bytes needed for local variables
.set LV,-LOCAL_SIZE | convenient base value
|
.set USER_DA,LV+0 | save space for D0-D1,A0-A1
.set USER_D0,LV+0 | saved user D0
.set USER_D1,LV+4 | saved user D1
.set USER_A0,LV+8 | saved user A0
.set USER_A1,LV+12 | saved user A1
.set USER_FP0,LV+16 | saved user FP0
.set USER_FP1,LV+28 | saved user FP1
.set USER_FP2,LV+40 | saved user FP2
.set USER_FP3,LV+52 | saved user FP3
.set USER_FPCR,LV+64 | saved user FPCR
.set FPCR_ENABLE,USER_FPCR+2 | FPCR exception enable
.set FPCR_MODE,USER_FPCR+3 | FPCR rounding mode control
.set USER_FPSR,LV+68 | saved user FPSR
.set FPSR_CC,USER_FPSR+0 | FPSR condition code
.set FPSR_QBYTE,USER_FPSR+1 | FPSR quotient
.set FPSR_EXCEPT,USER_FPSR+2 | FPSR exception
.set FPSR_AEXCEPT,USER_FPSR+3 | FPSR accrued exception
.set USER_FPIAR,LV+72 | saved user FPIAR
.set FP_SCR1,LV+76 | room for a temporary float value
.set FP_SCR2,LV+92 | room for a temporary float value
.set L_SCR1,LV+108 | room for a temporary long value
.set L_SCR2,LV+112 | room for a temporary long value
.set STORE_FLG,LV+116
.set BINDEC_FLG,LV+117 | used in bindec
.set DNRM_FLG,LV+118 | used in res_func
.set RES_FLG,LV+119 | used in res_func
.set DY_MO_FLG,LV+120 | dyadic/monadic flag
.set UFLG_TMP,LV+121 | temporary for uflag errata
.set CU_ONLY,LV+122 | cu-only flag
.set VER_TMP,LV+123 | temp holding for version number
.set L_SCR3,LV+124 | room for a temporary long value
.set FP_SCR3,LV+128 | room for a temporary float value
.set FP_SCR4,LV+144 | room for a temporary float value
.set FP_SCR5,LV+160 | room for a temporary float value
.set FP_SCR6,LV+176
|
|NEXT equ LV+192 ;need to increase LOCAL_SIZE
|
|--------------------------------------------------------------------------
|
| fsave offsets and bit definitions
|
| Offsets are defined from the end of an fsave because the last 10
| words of a busy frame are the same as the unimplemented frame.
|
.set CU_SAVEPC,LV-92 | micro-pc for CU (1 byte)
.set FPR_DIRTY_BITS,LV-91 | fpr dirty bits
|
.set WBTEMP,LV-76 | write back temp (12 bytes)
.set WBTEMP_EX,WBTEMP | wbtemp sign and exponent (2 bytes)
.set WBTEMP_HI,WBTEMP+4 | wbtemp mantissa [63:32] (4 bytes)
.set WBTEMP_LO,WBTEMP+
|
