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|
|
| x_store.sa 3.2 1/24/91
|
| store --- store operand to memory or register
|
| Used by underflow and overflow handlers.
|
| a6 = points to fp value to be stored.
|
| 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| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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.
X_STORE: |idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
fpreg_mask:
.byte 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
.include "fpsp.h"
|xref mem_write
|xref get_fline
|xref g_opcls
|xref g_dfmtou
|xref reg_dest
.global dest_ext
.global dest_dbl
.global dest_sgl
.global store
store:
btstb #E3,E_BYTE(%a6)
beqs E1_sto
E3_sto:
movel CMDREG3B(%a6),%d0
bfextu %d0{#6:#3},%d0 |isolate dest. reg from cmdreg3b
sto_fp:
lea fpreg_mask,%a1
moveb (%a1,%d0.w),%d0 |convert reg# to dynamic register mask
tstb LOCAL_SGN(%a0)
beqs is_pos
bsetb #sign_bit,LOCAL_EX(%a0)
is_pos:
fmovemx (%a0),%d0 |move to correct register
|
| if fp0-fp3 is being modified, we must put a copy
| in the USER_FPn variable on the stack because all exception
| handlers restore fp0-fp3 from there.
|
cmpb #0x80,%d0
bnes not_fp0
fmovemx %fp0-%fp0,USER_FP0(%a6)
rts
not_fp0:
cmpb #0x40,%d0
bnes not_fp1
fmovemx %fp1-%fp1,USER_FP1(%a6)
rts
not_fp1:
cmpb #0x20,%d0
bnes not_fp2
fmovemx %fp2-%fp2,USER_FP2(%a6)
rts
not_fp2:
cmpb #0x10,%d0
bnes not_fp3
fmovemx %fp3-%fp3,USER_FP3(%a6)
rts
not_fp3:
rts
E1_sto:
bsrl g_opcls |returns opclass in d0
cmpib #3,%d0
beq opc011 |branch if opclass 3
movel CMDREG1B(%a6),%d0
bfextu %d0{#6:#3},%d0 |extract destination register
bras sto_fp
opc011:
bsrl g_dfmtou |returns dest format in d0
| ;ext=00, sgl=01, dbl=10
movel %a0,%a1 |save source addr in a1
movel EXC_EA(%a6),%a0 |get the address
cmpil #0,%d0 |if dest format is extended
beq dest_ext |then branch
cmpil #1,%d0 |if dest format is single
beqs dest_sgl |then branch
|
| fall through to dest_dbl
|
|
| dest_dbl --- write double precision value to user space
|
|Input
| a0 -> destination address
| a1 -> source in extended precision
|Output
| a0 -> destroyed
| a1 -> destroyed
| d0 -> 0
|
|Changes extended precision to double precision.
| Note: no attempt is made to round the extended value to double.
| dbl_sign = ext_sign
| dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)
| get rid of ext integer bit
| dbl_mant = ext_mant{62:12}
|
| --------------- --------------- ---------------
| extended -> |s| exp | |1| ms mant | | ls mant |
| --------------- --------------- ---------------
| 95 64 63 62 32 31 11 0
| | |
| | |
| | |
| v v
| --------------- ---------------
| double -> |s|exp| mant | | mant |
| --------------- ---------------
| 63 51 32 31 0
|
dest_dbl:
clrl %d0 |clear d0
movew LOCAL_EX(%a1),%d0 |get exponent
subw #0x3fff,%d0 |subtract extended precision bias
cmpw #0x4000,%d0 |check if inf
beqs inf |if so, special case
addw #0x3ff,%d0 |add double precision bias
swap %d0 |d0 now in upper word
lsll #4,%d0 |d0 now in proper place for dbl prec exp
tstb LOCAL_SGN(%a1)
beqs get_mant |if positive, go process mantissa
bsetl #31,%d0 |if negative, put in sign information
| ; before continuing
bras get_mant |go process mantissa
inf:
movel #0x7ff00000,%d0 |load dbl inf exponent
clrl LOCAL_HI(%a1) |clear msb
tstb LOCAL_SGN(%a1)
beqs dbl_inf |if positive, go ahead and write it
bsetl #31,%d0 |if negative put in sign information
dbl_inf:
movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
bras dbl_wrt
get_mant:
movel LOCAL_HI(%a1),%d1 |get ms mantissa
bfextu %d1{#1:#20},%d1 |get upper 20 bits of ms
orl %d1,%d0 |put these bits in ms word of double
movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
movel LOCAL_HI(%a1),%d1 |get ms mantissa
movel #21,%d0 |load shift count
lsll %d0,%d1 |put lower 11 bits in upper bits
movel %d1,LOCAL_HI(%a1) |build lower lword in memory
movel LOCAL_LO(%a1),%d1 |get ls mantissa
bfextu %d1{#0:#21},%d0 |get ls 21 bits of double
orl %d0,LOCAL_HI(%a1) |put them in double result
dbl_wrt:
movel #0x8,%d0 |byte count for double precision number
exg %a0,%a1 |a0=supervisor source, a1=user dest
bsrl mem_write |move the number to the user's memory
rts
|
| dest_sgl --- write single precision value to user space
|
|Input
| a0 -> destination address
| a1 -> source in extended precision
|
|Output
| a0 -> destroyed
| a1 -> destroyed
| d0 -> 0
|
|Changes extended precision to single precision.
| sgl_sign = ext_sign
| sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)
| get rid of ext integer bit
| sgl_mant = ext_mant{62:12}
|
| --------------- --------------- ---------------
| extended -> |s| exp | |1| ms mant | | ls mant |
| --------------- --------------- ---------------
| 95 64 63 62 40 32 31 12 0
| | |
| | |
| | |
| v v
| ---------------
| single -> |s|exp| mant |
| ---------------
| 31 22 0
|
dest_sgl:
clrl %d0
movew LOCAL_EX(%a1),%d0 |get exponent
subw #0x3fff,%d0 |subtract extended precision bias
cmpw #0x4000,%d0 |check if inf
beqs sinf |if so, special case
addw #0x7f,%d0 |add single precision bias
swap %d0 |put exp in upper word of d0
lsll #7,%d0 |shift it into single exp bits
tstb LOCAL_SGN(%a1)
beqs get_sman |if positive, continue
bsetl #31,%d0 |if negative, put in sign first
bras get_sman |get mantissa
sinf:
movel #0x7f800000,%d0 |load single inf exp to d0
tstb LOCAL_SGN(%a1)
beqs sgl_wrt |if positive, continue
bsetl #31,%d0 |if negative, put in sign info
bras sgl_wrt
get_sman:
movel LOCAL_HI(%a1),%d1 |get ms mantissa
bfextu %d1{#1:#23},%d1 |get upper 23 bits of ms
orl %d1,%d0 |put these bits in ms word of single
sgl_wrt:
movel %d0,L_SCR1(%a6) |put the new exp back on the stack
movel #0x4,%d0 |byte count for single precision number
tstl %a0 |users destination address
beqs sgl_Dn |destination is a data register
exg %a0,%a1 |a0=supervisor source, a1=user dest
leal L_SCR1(%a6),%a0 |point a0 to data
bsrl mem_write |move the number to the user's memory
rts
sgl_Dn:
bsrl get_fline |returns fline word in d0
andw #0x7,%d0 |isolate register number
movel %d0,%d1 |d1 has size:reg formatted for reg_dest
orl #0x10,%d1 |reg_dest wants size added to reg#
bral reg_dest |size is X, rts in reg_dest will
| ;return to caller of dest_sgl
dest_ext:
tstb LOCAL_SGN(%a1) |put back sign into exponent word
beqs dstx_cont
bsetb #sign_bit,LOCAL_EX(%a1)
dstx_cont:
clrb LOCAL_SGN(%a1) |clear out the sign byte
movel #0x0c,%d0 |byte count for extended number
exg %a0,%a1 |a0=supervisor source, a1=user dest
bsrl mem_write |move the number to the user's memory
rts
|end
|
