Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

|

|       get_op.sa 3.6 5/19/92

|

|       get_op.sa 3.5 4/26/91

|

|  Description: This routine is called by the unsupported format/data

| type exception handler ('unsupp' - vector 55) and the unimplemented

| instruction exception handler ('unimp' - vector 11).  'get_op'

| determines the opclass (0, 2, or 3) and branches to the

| opclass handler routine.  See 68881/2 User's Manual table 4-11

| for a description of the opclasses.

|

| For UNSUPPORTED data/format (exception vector 55) and for

| UNIMPLEMENTED instructions (exception vector 11) the following

| applies:

|

| - For unnormalized numbers (opclass 0, 2, or 3) the

| number(s) is normalized and the operand type tag is updated.

|

| - For a packed number (opclass 2) the number is unpacked and the

| operand type tag is updated.

|

| - For denormalized numbers (opclass 0 or 2) the number(s) is not

| changed but passed to the next module.  The next module for

| unimp is do_func, the next module for unsupp is res_func.

|

| For UNSUPPORTED data/format (exception vector 55) only the

| following applies:

|

| - If there is a move out with a packed number (opclass 3) the

| number is packed and written to user memory.  For the other

| opclasses the number(s) are written back to the fsave stack

| and the instruction is then restored back into the '040.  The

| '040 is then able to complete the instruction.

|

| For example:

| fadd.x fpm,fpn where the fpm contains an unnormalized number.

| The '040 takes an unsupported data trap and gets to this

| routine.  The number is normalized, put back on the stack and

| then an frestore is done to restore the instruction back into

| the '040.  The '040 then re-executes the fadd.x fpm,fpn with

| a normalized number in the source and the instruction is

| successful.

|

| Next consider if in the process of normalizing the un-

| normalized number it becomes a denormalized number.  The

| routine which converts the unnorm to a norm (called mk_norm)

| detects this and tags the number as a denorm.  The routine

| res_func sees the denorm tag and converts the denorm to a

| norm.  The instruction is then restored back into the '040

| which re_executes the instruction.

|

|

|               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.

GET_OP:    |idnt    2,1 | Motorola 040 Floating Point Software Package

        |section        8

#include "fpsp.h"

        .global PIRN,PIRZRM,PIRP

        .global SMALRN,SMALRZRM,SMALRP

        .global BIGRN,BIGRZRM,BIGRP

PIRN:

        .long 0x40000000,0xc90fdaa2,0x2168c235    |pi

PIRZRM:

        .long 0x40000000,0xc90fdaa2,0x2168c234    |pi

PIRP:

        .long 0x40000000,0xc90fdaa2,0x2168c235    |pi

|round to nearest

SMALRN:

        .long 0x3ffd0000,0x9a209a84,0xfbcff798    |log10(2)

        .long 0x40000000,0xadf85458,0xa2bb4a9a    |e

        .long 0x3fff0000,0xb8aa3b29,0x5c17f0bc    |log2(e)

        .long 0x3ffd0000,0xde5bd8a9,0x37287195    |log10(e)

        .long 0x00000000,0x00000000,0x00000000    |0.0

| round to zero;round to negative infinity

SMALRZRM:

        .long 0x3ffd0000,0x9a209a84,0xfbcff798    |log10(2)

        .long 0x40000000,0xadf85458,0xa2bb4a9a    |e

        .long 0x3fff0000,0xb8aa3b29,0x5c17f0bb    |log2(e)

        .long 0x3ffd0000,0xde5bd8a9,0x37287195    |log10(e)

        .long 0x00000000,0x00000000,0x00000000    |0.0

| round to positive infinity

SMALRP:

        .long 0x3ffd0000,0x9a209a84,0xfbcff799    |log10(2)

        .long 0x40000000,0xadf85458,0xa2bb4a9b    |e

        .long 0x3fff0000,0xb8aa3b29,0x5c17f0bc    |log2(e)

        .long 0x3ffd0000,0xde5bd8a9,0x37287195    |log10(e)

        .long 0x00000000,0x00000000,0x00000000    |0.0

|round to nearest

BIGRN:

        .long 0x3ffe0000,0xb17217f7,0xd1cf79ac    |ln(2)

        .long 0x40000000,0x935d8ddd,0xaaa8ac17    |ln(10)

        .long 0x3fff0000,0x80000000,0x00000000    |10 ^ 0

        .global PTENRN

PTENRN:

        .long 0x40020000,0xA0000000,0x00000000    |10 ^ 1

        .long 0x40050000,0xC8000000,0x00000000    |10 ^ 2

        .long 0x400C0000,0x9C400000,0x00000000    |10 ^ 4

        .long 0x40190000,0xBEBC2000,0x00000000    |10 ^ 8

        .long 0x40340000,0x8E1BC9BF,0x04000000    |10 ^ 16

        .long 0x40690000,0x9DC5ADA8,0x2B70B59E    |10 ^ 32

        .long 0x40D30000,0xC2781F49,0xFFCFA6D5    |10 ^ 64

        .long 0x41A80000,0x93BA47C9,0x80E98CE0    |10 ^ 128

        .long 0x43510000,0xAA7EEBFB,0x9DF9DE8E    |10 ^ 256

        .long 0x46A30000,0xE319A0AE,0xA60E91C7    |10 ^ 512

        .long 0x4D480000,0xC9767586,0x81750C17    |10 ^ 1024

        .long 0x5A920000,0x9E8B3B5D,0xC53D5DE5    |10 ^ 2048

        .long 0x75250000,0xC4605202,0x8A20979B    |10 ^ 4096

|round to minus infinity

BIGRZRM:

        .long 0x3ffe0000,0xb17217f7,0xd1cf79ab    |ln(2)

        .long 0x40000000,0x935d8ddd,0xaaa8ac16    |ln(10)

        .long 0x3fff0000,0x80000000,0x00000000    |10 ^ 0

        .global PTENRM

PTENRM:

        .long 0x40020000,0xA0000000,0x00000000    |10 ^ 1

        .long 0x40050000,0xC8000000,0x00000000    |10 ^ 2

        .long 0x400C0000,0x9C400000,0x00000000    |10 ^ 4

        .long 0x40190000,0xBEBC2000,0x00000000    |10 ^ 8

        .long 0x40340000,0x8E1BC9BF,0x04000000    |10 ^ 16

        .long 0x40690000,0x9DC5ADA8,0x2B70B59D    |10 ^ 32

        .long 0x40D30000,0xC2781F49,0xFFCFA6D5    |10 ^ 64

        .long 0x41A80000,0x93BA47C9,0x80E98CDF    |10 ^ 128

        .long 0x43510000,0xAA7EEBFB,0x9DF9DE8D    |10 ^ 256

        .long 0x46A30000,0xE319A0AE,0xA60E91C6    |10 ^ 512

        .long 0x4D480000,0xC9767586,0x81750C17    |10 ^ 1024

        .long 0x5A920000,0x9E8B3B5D,0xC53D5DE5    |10 ^ 2048

        .long 0x75250000,0xC4605202,0x8A20979A    |10 ^ 4096

|round to positive infinity

BIGRP:

        .long 0x3ffe0000,0xb17217f7,0xd1cf79ac    |ln(2)

        .long 0x40000000,0x935d8ddd,0xaaa8ac17    |ln(10)

        .long 0x3fff0000,0x80000000,0x00000000    |10 ^ 0

        .global PTENRP

PTENRP:

        .long 0x40020000,0xA0000000,0x00000000    |10 ^ 1

        .long 0x40050000,0xC8000000,0x00000000    |10 ^ 2

        .long 0x400C0000,0x9C400000,0x00000000    |10 ^ 4

        .long 0x40190000,0xBEBC2000,0x00000000    |10 ^ 8

        .long 0x40340000,0x8E1BC9BF,0x04000000    |10 ^ 16

        .long 0x40690000,0x9DC5ADA8,0x2B70B59E    |10 ^ 32

        .long 0x40D30000,0xC2781F49,0xFFCFA6D6    |10 ^ 64

        .long 0x41A80000,0x93BA47C9,0x80E98CE0    |10 ^ 128

        .long 0x43510000,0xAA7EEBFB,0x9DF9DE8E    |10 ^ 256

        .long 0x46A30000,0xE319A0AE,0xA60E91C7    |10 ^ 512

        .long 0x4D480000,0xC9767586,0x81750C18    |10 ^ 1024

        .long 0x5A920000,0x9E8B3B5D,0xC53D5DE6    |10 ^ 2048

        .long 0x75250000,0xC4605202,0x8A20979B    |10 ^ 4096

        |xref   nrm_zero

        |xref   decbin

        |xref   round

        .global    get_op

        .global    uns_getop

        .global    uni_getop

get_op:

        clrb    DY_MO_FLG(%a6)

        tstb    UFLG_TMP(%a6)   |test flag for unsupp/unimp state

        beq     uni_getop

uns_getop:

        btstb   #direction_bit,CMDREG1B(%a6)

        bne     opclass3        |branch if a fmove out (any kind)

        btstb   #6,CMDREG1B(%a6)

        beqs    uns_notpacked

        bfextu  CMDREG1B(%a6){#3:#3},%d0

        cmpb    #3,%d0

        beq     pack_source     |check for a packed src op, branch if so

uns_notpacked:

        bsr     chk_dy_mo       |set the dyadic/monadic flag

        tstb    DY_MO_FLG(%a6)

        beqs    src_op_ck       |if monadic, go check src op

|                               ;else, check dst op (fall through)

        btstb   #7,DTAG(%a6)

        beqs    src_op_ck       |if dst op is norm, check src op

        bras    dst_ex_dnrm     |else, handle destination unnorm/dnrm

uni_getop:

        bfextu  CMDREG1B(%a6){#0:#6},%d0 |get opclass and src fields

        cmpil   #0x17,%d0               |if op class and size fields are $17,

|                               ;it is FMOVECR; if not, continue

|

| If the instruction is fmovecr, exit get_op.  It is handled

| in do_func and smovecr.sa.

|

        bne     not_fmovecr     |handle fmovecr as an unimplemented inst

        rts

not_fmovecr:

        btstb   #E1,E_BYTE(%a6) |if set, there is a packed operand

        bne     pack_source     |check for packed src op, branch if so

| The following lines of are coded to optimize on normalized operands

        moveb   STAG(%a6),%d0

        orb     DTAG(%a6),%d0   |check if either of STAG/DTAG msb set

        bmis    dest_op_ck      |if so, some op needs to be fixed

        rts

dest_op_ck:

        btstb   #7,DTAG(%a6)    |check for unsupported data types in

        beqs    src_op_ck       |the destination, if not, check src op

        bsr     chk_dy_mo       |set dyadic/monadic flag

        tstb    DY_MO_FLG(%a6)  |

        beqs    src_op_ck       |if monadic, check src op

|

| At this point, destination has an extended denorm or unnorm.

|

dst_ex_dnrm:

        movew   FPTEMP_EX(%a6),%d0 |get destination exponent

        andiw   #0x7fff,%d0     |mask sign, check if exp = 0000

        beqs    src_op_ck       |if denorm then check source op.

|                               ;denorms are taken care of in res_func

|                               ;(unsupp) or do_func (unimp)

|                               ;else unnorm fall through

        leal    FPTEMP(%a6),%a0 |point a0 to dop - used in mk_norm

        bsr     mk_norm         |go normalize - mk_norm returns:

|                               ;L_SCR1{7:5} = operand tag

|                               ;       (000 = norm, 100 = denorm)

|                               ;L_SCR1{4} = fpte15 or ete15

|                               ;       0 = exp >  $3fff

|                               ;       1 = exp <= $3fff

|                               ;and puts the normalized num back

|                               ;on the fsave stack

|

        moveb L_SCR1(%a6),DTAG(%a6) |write the new tag & fpte15

|                               ;to the fsave stack and fall

|                               ;through to check source operand

|

src_op_ck:

        btstb   #7,STAG(%a6)

        beq     end_getop       |check for unsupported data types on the

|                               ;source operand

        btstb   #5,STAG(%a6)

        bnes    src_sd_dnrm     |if bit 5 set, handle sgl/dbl denorms

|

| At this point only unnorms or extended denorms are possible.

|

src_ex_dnrm:

        movew   ETEMP_EX(%a6),%d0 |get source exponent

        andiw   #0x7fff,%d0     |mask sign, check if exp = 0000

        beq     end_getop       |if denorm then exit, denorms are

|                               ;handled in do_func

        leal    ETEMP(%a6),%a0  |point a0 to sop - used in mk_norm

        bsr     mk_norm         |go normalize - mk_norm returns:

|                               ;L_SCR1{7:5} = operand tag

|                               ;       (000 = norm, 100 = denorm)

|                               ;L_SCR1{4} = fpte15 or ete15

|                               ;       0 = exp >  $3fff

|                               ;       1 = exp <= $3fff

|                               ;and puts the normalized num back

|                               ;on the fsave stack

|

        moveb   L_SCR1(%a6),STAG(%a6) |write the new tag & ete15

        rts                     |end_getop

|

| At this point, only single or double denorms are possible.

| If the inst is not fmove, normalize the source.  If it is,

| do nothing to the input.

|

src_sd_dnrm:

        btstb   #4,CMDREG1B(%a6)        |differentiate between sgl/dbl denorm

        bnes    is_double

is_single:

        movew   #0x3f81,%d1     |write bias for sgl denorm

        bras    common          |goto the common code

is_double:

        movew   #0x3c01,%d1     |write the bias for a dbl denorm

common:

        btstb   #sign_bit,ETEMP_EX(%a6) |grab sign bit of mantissa

        beqs    pos

        bset    #15,%d1         |set sign bit because it is negative

pos:

        movew   %d1,ETEMP_EX(%a6)

|                               ;put exponent on stack

        movew   CMDREG1B(%a6),%d1

        andw    #0xe3ff,%d1     |clear out source specifier

        orw     #0x0800,%d1     |set source specifier to extended prec

        movew   %d1,CMDREG1B(%a6)       |write back to the command word in stack

|                               ;this is needed to fix unsupp data stack

        leal    ETEMP(%a6),%a0  |point a0 to sop

        bsr     mk_norm         |convert sgl/dbl denorm to norm

        moveb   L_SCR1(%a6),STAG(%a6) |put tag into source tag reg - d0

        rts                     |end_getop

|

| At this point, the source is definitely packed, whether

| instruction is dyadic or monadic is still unknown

|

pack_source:

        movel   FPTEMP_LO(%a6),ETEMP(%a6)       |write ms part of packed

|                               ;number to etemp slot

        bsr     chk_dy_mo       |set dyadic/monadic flag

        bsr     unpack

        tstb    DY_MO_FLG(%a6)

        beqs    end_getop       |if monadic, exit

|                               ;else, fix FPTEMP

pack_dya:

        bfextu  CMDREG1B(%a6){#6:#3},%d0 |extract dest fp reg

        movel   #7,%d1

        subl    %d0,%d1

        clrl    %d0

        bsetl   %d1,%d0         |set up d0 as a dynamic register mask

        fmovemx %d0,FPTEMP(%a6) |write to FPTEMP

        btstb   #7,DTAG(%a6)    |check dest tag for unnorm or denorm

        bne     dst_ex_dnrm     |else, handle the unnorm or ext denorm

|

| Dest is not denormalized.  Check for norm, and set fpte15

| accordingly.

|

        moveb   DTAG(%a6),%d0

        andib   #0xf0,%d0               |strip to only dtag:fpte15

        tstb    %d0             |check for normalized value

        bnes    end_getop       |if inf/nan/zero leave get_op

        movew   FPTEMP_EX(%a6),%d0

        andiw   #0x7fff,%d0

        cmpiw   #0x3fff,%d0     |check if fpte15 needs setting

        bges    end_getop       |if >= $3fff, leave fpte15=0

        orb     #0x10,DTAG(%a6)

        bras    end_getop

|

| At this point, it is either an fmoveout packed, unnorm or denorm

|

opclass3:

        clrb    DY_MO_FLG(%a6)  |set dyadic/monadic flag to monadic

        bfextu  CMDREG1B(%a6){#4:#2},%d0

        cmpib   #3,%d0

        bne     src_ex_dnrm     |if not equal, must be unnorm or denorm

|                               ;else it is a packed move out

|                               ;exit

end_getop:

        rts

|

| Sets the DY_MO_FLG correctly. This is used only on if it is an

| unsupported data type exception.  Set if dyadic.

|

chk_dy_mo:

        movew   CMDREG1B(%a6),%d0

        btstl   #5,%d0          |testing extension command word

        beqs    set_mon         |if bit 5 = 0 then monadic

        btstl   #4,%d0          |know that bit 5 = 1

        beqs    set_dya         |if bit 4 = 0 then dyadic

        andiw   #0x007f,%d0     |get rid of all but extension bits {6:0}

        cmpiw   #0x0038,%d0     |if extension = $38 then fcmp (dyadic)

        bnes    set_mon

set_dya:

        st      DY_MO_FLG(%a6)  |set the inst flag type to dyadic

        rts

set_mon:

        clrb    DY_MO_FLG(%a6)  |set the inst flag type to monadic

        rts

|

|       MK_NORM

|

| Normalizes unnormalized numbers, sets tag to norm or denorm, sets unfl

| exception if denorm.

|

| CASE opclass 0x0 unsupp

|       mk_norm till msb set

|       set tag = norm

|

| CASE opclass 0x0 unimp

|       mk_norm till msb set or exp = 0

|       if integer bit = 0

|          tag = denorm

|       else

|          tag = norm

|

| CASE opclass 011 unsupp

|       mk_norm till msb set or exp = 0

|       if integer bit = 0

|          tag = denorm

|          set unfl_nmcexe = 1

|       else

|          tag = norm

|

| if exp <= $3fff

|   set ete15 or fpte15 = 1

| else set ete15 or fpte15 = 0

| input:

|       a0 = points to operand to be normalized

| output:

|       L_SCR1{7:5} = operand tag (000 = norm, 100 = denorm)

|       L_SCR1{4}   = fpte15 or ete15 (0 = exp > $3fff, 1 = exp <=$3fff)

|       the normalized operand is placed back on the fsave stack

mk_norm:

        clrl    L_SCR1(%a6)

        bclrb   #sign_bit,LOCAL_EX(%a0)

        sne     LOCAL_SGN(%a0)  |transform into internal extended format

        cmpib   #0x2c,1+EXC_VEC(%a6) |check if unimp

        bnes    uns_data        |branch if unsupp

        bsr     uni_inst        |call if unimp (opclass 0x0)

        bras    reload

uns_data:

        btstb   #direction_bit,CMDREG1B(%a6) |check transfer direction

        bnes    bit_set         |branch if set (opclass 011)

        bsr     uns_opx         |call if opclass 0x0

        bras    reload

bit_set:

        bsr     uns_op3         |opclass 011

reload:

        cmpw    #0x3fff,LOCAL_EX(%a0) |if exp > $3fff

        bgts    end_mk          |   fpte15/ete15 already set to 0

        bsetb   #4,L_SCR1(%a6)  |else set fpte15/ete15 to 1

|                               ;calling routine actually sets the

|                               ;value on the stack (along with the

|                               ;tag), since this routine doesn't

|                               ;know if it should set ete15 or fpte15

|                               ;ie, it doesn't know if this is the

|                               ;src op or dest op.

end_mk:

        bfclr   LOCAL_SGN(%a0){#0:#8}

        beqs    end_mk_pos

        bsetb   #sign_bit,LOCAL_EX(%a0) |convert back to IEEE format

end_mk_pos:

        rts

|

|     CASE opclass 011 unsupp

|

uns_op3:

        bsr     nrm_zero        |normalize till msb = 1 or exp = zero

        btstb   #7,LOCAL_HI(%a0)        |if msb = 1

        bnes    no_unfl         |then branch

set_unfl:

        orw     #dnrm_tag,L_SCR1(%a6) |set denorm tag

        bsetb   #unfl_bit,FPSR_EXCEPT(%a6) |set unfl exception bit

no_unfl:

        rts

|

|     CASE opclass 0x0 unsupp

|

uns_opx:

        bsr     nrm_zero        |normalize the number

        btstb   #7,LOCAL_HI(%a0)        |check if integer bit (j-bit) is set

        beqs    uns_den         |if clear then now have a denorm

uns_nrm:

        orb     #norm_tag,L_SCR1(%a6) |set tag to norm

        rts

uns_den:

        orb     #dnrm_tag,L_SCR1(%a6) |set tag to denorm

        rts

|

|     CASE opclass 0x0 unimp

|

uni_inst:

        bsr     nrm_zero

        btstb   #7,LOCAL_HI(%a0)        |check if integer bit (j-bit) is set

        beqs    uni_den         |if clear then now have a denorm

uni_nrm:

        orb     #norm_tag,L_SCR1(%a6) |set tag to norm

        rts

uni_den:

        orb     #dnrm_tag,L_SCR1(%a6) |set tag to denorm

        rts

|

|       Decimal to binary conversion

|

| Special cases of inf and NaNs are completed outside of decbin.

| If the input is an snan, the snan bit is not set.

|

| input:

|       ETEMP(a6)       - points to packed decimal string in memory

| output:

|       fp0     - contains packed string converted to extended precision

|       ETEMP   - same as fp0

unpack:

        movew   CMDREG1B(%a6),%d0       |examine command word, looking for fmove's

        andw    #0x3b,%d0

        beq     move_unpack     |special handling for fmove: must set FPSR_CC

        movew   ETEMP(%a6),%d0  |get word with inf information

        bfextu  %d0{#20:#12},%d1        |get exponent into d1

        cmpiw   #0x0fff,%d1     |test for inf or NaN

        bnes    try_zero        |if not equal, it is not special

        bfextu  %d0{#17:#3},%d1 |get SE and y bits into d1

        cmpiw   #7,%d1          |SE and y bits must be on for special

        bnes    try_zero        |if not on, it is not special

|input is of the special cases of inf and NaN

        tstl    ETEMP_HI(%a6)   |check ms mantissa

        bnes    fix_nan         |if non-zero, it is a NaN

        tstl    ETEMP_LO(%a6)   |check ls mantissa

        bnes    fix_nan         |if non-zero, it is a NaN

        bra     finish          |special already on stack

fix_nan:

        btstb   #signan_bit,ETEMP_HI(%a6) |test for snan

        bne     finish

        orl     #snaniop_mask,USER_FPSR(%a6) |always set snan if it is so

        bra     finish

try_zero:

        movew   ETEMP_EX+2(%a6),%d0 |get word 4

        andiw   #0x000f,%d0     |clear all but last ni(y)bble

        tstw    %d0             |check for zero.

        bne     not_spec

        tstl    ETEMP_HI(%a6)   |check words 3 and 2

        bne     not_spec

        tstl    ETEMP_LO(%a6)   |check words 1 and 0

        bne     not_spec

        tstl    ETEMP(%a6)      |test sign of the zero

        bges    pos_zero

        movel   #0x80000000,ETEMP(%a6) |write neg zero to etemp

        clrl    ETEMP_HI(%a6)

        clrl    ETEMP_LO(%a6)

        bra     finish

pos_zero:

        clrl    ETEMP(%a6)

        clrl    ETEMP_HI(%a6)

        clrl    ETEMP_LO(%a6)

        bra     finish

not_spec:

        fmovemx %fp0-%fp1,-(%a7)        |save fp0 - decbin returns in it

        bsr     decbin

        fmovex %fp0,ETEMP(%a6)  |put the unpacked sop in the fsave stack

        fmovemx (%a7)+,%fp0-%fp1

        fmovel  #0,%FPSR                |clr fpsr from decbin

        bra     finish

|

| Special handling for packed move in:  Same results as all other

| packed cases, but we must set the FPSR condition codes properly.

|

move_unpack:

        movew   ETEMP(%a6),%d0  |get word with inf information

        bfextu  %d0{#20:#12},%d1        |get exponent into d1

        cmpiw   #0x0fff,%d1     |test for inf or NaN

        bnes    mtry_zero       |if not equal, it is not special

        bfextu  %d0{#17:#3},%d1 |get SE and y bits into d1

        cmpiw   #7,%d1          |SE and y bits must be on for special

        bnes    mtry_zero       |if not on, it is not special

|input is of the special cases of inf and NaN

        tstl    ETEMP_HI(%a6)   |check ms mantissa

        bnes    mfix_nan                |if non-zero, it is a NaN

        tstl    ETEMP_LO(%a6)   |check ls mantissa

        bnes    mfix_nan                |if non-zero, it is a NaN

|input is inf

        orl     #inf_mask,USER_FPSR(%a6) |set I bit

        tstl    ETEMP(%a6)      |check sign

        bge     finish

        orl     #neg_mask,USER_FPSR(%a6) |set N bit

        bra     finish          |special already on stack

mfix_nan:

        orl     #nan_mask,USER_FPSR(%a6) |set NaN bit

        moveb   #nan_tag,STAG(%a6)      |set stag to NaN

        btstb   #signan_bit,ETEMP_HI(%a6) |test for snan

        bnes    mn_snan

        orl     #snaniop_mask,USER_FPSR(%a6) |set snan bit

        btstb   #snan_bit,FPCR_ENABLE(%a6) |test for snan enabled

        bnes    mn_snan

        bsetb   #signan_bit,ETEMP_HI(%a6) |force snans to qnans

mn_snan:

        tstl    ETEMP(%a6)      |check for sign

        bge     finish          |if clr, go on

        orl     #neg_mask,USER_FPSR(%a6) |set N bit

        bra     finish

mtry_zero:

        movew   ETEMP_EX+2(%a6),%d0 |get word 4

        andiw   #0x000f,%d0     |clear all but last ni(y)bble

        tstw    %d0             |check for zero.

        bnes    mnot_spec

        tstl    ETEMP_HI(%a6)   |check words 3 and 2

        bnes    mnot_spec

        tstl    ETEMP_LO(%a6)   |check words 1 and 0

        bnes    mnot_spec

        tstl    ETEMP(%a6)      |test sign of the zero

        bges    mpos_zero

        orl     #neg_mask+z_mask,USER_FPSR(%a6) |set N and Z

        movel   #0x80000000,ETEMP(%a6) |write neg zero to etemp

        clrl    ETEMP_HI(%a6)

        clrl    ETEMP_LO(%a6)

        bras    finish

mpos_zero:

        orl     #z_mask,USER_FPSR(%a6) |set Z

        clrl    ETEMP(%a6)

        clrl    ETEMP_HI(%a6)

        clrl    ETEMP_LO(%a6)

        bras    finish

mnot_spec:

        fmovemx %fp0-%fp1,-(%a7)        |save fp0 ,fp1 - decbin returns in fp0

        bsr     decbin

        fmovex %fp0,ETEMP(%a6)

|                               ;put the unpacked sop in the fsave stack

        fmovemx (%a7)+,%fp0-%fp1

finish:

        movew   CMDREG1B(%a6),%d0       |get the command word

        andw    #0xfbff,%d0     |change the source specifier field to

|                               ;extended (was packed).

        movew   %d0,CMDREG1B(%a6)       |write command word back to fsave stack

|                               ;we need to do this so the 040 will

|                               ;re-execute the inst. without taking

|                               ;another packed trap.

fix_stag:

|Converted result is now in etemp on fsave stack, now set the source

|tag (stag)

|       if (ete =$7fff) then INF or NAN

|               if (etemp = $x.0----0) then

|                       stag = INF

|               else

|                       stag = NAN

|       else

|               if (ete = $0000) then

|                       stag = ZERO

|               else

|                       stag = NORM

|

| Note also that the etemp_15 bit (just right of the stag) must

| be set accordingly.

|

        movew           ETEMP_EX(%a6),%d1

        andiw           #0x7fff,%d1   |strip sign

        cmpw            #0x7fff,%d1

        bnes            z_or_nrm

        movel           ETEMP_HI(%a6),%d1

        bnes            is_nan

        movel           ETEMP_LO(%a6),%d1

        bnes            is_nan

is_inf:

        moveb           #0x40,STAG(%a6)

        movel           #0x40,%d0

        rts

is_nan:

        moveb           #0x60,STAG(%a6)

        movel           #0x60,%d0

        rts

z_or_nrm:

        tstw            %d1

        bnes            is_nrm

is_zro:

| For a zero, set etemp_15

        moveb           #0x30,STAG(%a6)

        movel           #0x20,%d0

        rts

is_nrm:

| For a norm, check if the exp <= $3fff; if so, set etemp_15

        cmpiw           #0x3fff,%d1

        bles            set_bit15

        moveb           #0,STAG(%a6)

        bras            end_is_nrm

set_bit15:

        moveb           #0x10,STAG(%a6)

end_is_nrm:

        movel           #0,%d0

end_fix:

        rts

end_get:

        rts

        |end