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xianfeng |
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| x_store.sa 3.2 1/24/91
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| store --- store operand to memory or register
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| Used by underflow and overflow handlers.
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| a6 = points to fp value to be stored.
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| Copyright (C) Motorola, Inc. 1990
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| All Rights Reserved
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| For details on the license for this file, please see the
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| file, README, in this same directory.
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X_STORE: |idnt 2,1 | Motorola 040 Floating Point Software Package
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|section 8
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fpreg_mask:
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.byte 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
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#include "fpsp.h"
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|xref mem_write
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|xref get_fline
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|xref g_opcls
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|xref g_dfmtou
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|xref reg_dest
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.global dest_ext
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.global dest_dbl
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.global dest_sgl
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.global store
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store:
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btstb #E3,E_BYTE(%a6)
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beqs E1_sto
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E3_sto:
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movel CMDREG3B(%a6),%d0
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bfextu %d0{#6:#3},%d0 |isolate dest. reg from cmdreg3b
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sto_fp:
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lea fpreg_mask,%a1
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moveb (%a1,%d0.w),%d0 |convert reg# to dynamic register mask
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tstb LOCAL_SGN(%a0)
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beqs is_pos
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bsetb #sign_bit,LOCAL_EX(%a0)
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is_pos:
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fmovemx (%a0),%d0 |move to correct register
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| if fp0-fp3 is being modified, we must put a copy
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| in the USER_FPn variable on the stack because all exception
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| handlers restore fp0-fp3 from there.
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cmpb #0x80,%d0
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bnes not_fp0
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fmovemx %fp0-%fp0,USER_FP0(%a6)
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rts
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not_fp0:
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cmpb #0x40,%d0
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bnes not_fp1
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fmovemx %fp1-%fp1,USER_FP1(%a6)
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rts
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not_fp1:
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cmpb #0x20,%d0
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bnes not_fp2
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fmovemx %fp2-%fp2,USER_FP2(%a6)
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rts
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not_fp2:
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cmpb #0x10,%d0
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bnes not_fp3
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fmovemx %fp3-%fp3,USER_FP3(%a6)
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rts
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not_fp3:
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rts
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E1_sto:
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bsrl g_opcls |returns opclass in d0
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cmpib #3,%d0
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beq opc011 |branch if opclass 3
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movel CMDREG1B(%a6),%d0
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bfextu %d0{#6:#3},%d0 |extract destination register
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bras sto_fp
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opc011:
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bsrl g_dfmtou |returns dest format in d0
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| ;ext=00, sgl=01, dbl=10
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movel %a0,%a1 |save source addr in a1
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movel EXC_EA(%a6),%a0 |get the address
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cmpil #0,%d0 |if dest format is extended
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beq dest_ext |then branch
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cmpil #1,%d0 |if dest format is single
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beq dest_sgl |then branch
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| fall through to dest_dbl
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| dest_dbl --- write double precision value to user space
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|Input
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| a0 -> destination address
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| a1 -> source in extended precision
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|Output
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| a0 -> destroyed
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| a1 -> destroyed
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| d0 -> 0
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|Changes extended precision to double precision.
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| Note: no attempt is made to round the extended value to double.
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| dbl_sign = ext_sign
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| dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)
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| get rid of ext integer bit
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| dbl_mant = ext_mant{62:12}
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| --------------- --------------- ---------------
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| extended -> |s| exp | |1| ms mant | | ls mant |
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| --------------- --------------- ---------------
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| 95 64 63 62 32 31 11 0
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| v v
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| --------------- ---------------
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| double -> |s|exp| mant | | mant |
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| --------------- ---------------
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| 63 51 32 31 0
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dest_dbl:
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clrl %d0 |clear d0
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movew LOCAL_EX(%a1),%d0 |get exponent
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subw #0x3fff,%d0 |subtract extended precision bias
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cmpw #0x4000,%d0 |check if inf
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beqs inf |if so, special case
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addw #0x3ff,%d0 |add double precision bias
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swap %d0 |d0 now in upper word
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lsll #4,%d0 |d0 now in proper place for dbl prec exp
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tstb LOCAL_SGN(%a1)
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beqs get_mant |if positive, go process mantissa
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bsetl #31,%d0 |if negative, put in sign information
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| ; before continuing
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bras get_mant |go process mantissa
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inf:
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movel #0x7ff00000,%d0 |load dbl inf exponent
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clrl LOCAL_HI(%a1) |clear msb
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tstb LOCAL_SGN(%a1)
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beqs dbl_inf |if positive, go ahead and write it
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bsetl #31,%d0 |if negative put in sign information
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dbl_inf:
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movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
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bras dbl_wrt
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get_mant:
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movel LOCAL_HI(%a1),%d1 |get ms mantissa
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bfextu %d1{#1:#20},%d1 |get upper 20 bits of ms
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orl %d1,%d0 |put these bits in ms word of double
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movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
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movel LOCAL_HI(%a1),%d1 |get ms mantissa
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movel #21,%d0 |load shift count
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lsll %d0,%d1 |put lower 11 bits in upper bits
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movel %d1,LOCAL_HI(%a1) |build lower lword in memory
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movel LOCAL_LO(%a1),%d1 |get ls mantissa
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bfextu %d1{#0:#21},%d0 |get ls 21 bits of double
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orl %d0,LOCAL_HI(%a1) |put them in double result
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dbl_wrt:
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movel #0x8,%d0 |byte count for double precision number
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exg %a0,%a1 |a0=supervisor source, a1=user dest
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bsrl mem_write |move the number to the user's memory
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rts
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| dest_sgl --- write single precision value to user space
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|Input
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| a0 -> destination address
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| a1 -> source in extended precision
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|Output
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| a0 -> destroyed
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| a1 -> destroyed
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| d0 -> 0
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|Changes extended precision to single precision.
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| sgl_sign = ext_sign
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| sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)
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| get rid of ext integer bit
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| sgl_mant = ext_mant{62:12}
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| --------------- --------------- ---------------
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| extended -> |s| exp | |1| ms mant | | ls mant |
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| --------------- --------------- ---------------
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| 95 64 63 62 40 32 31 12 0
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| v v
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| ---------------
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| single -> |s|exp| mant |
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| ---------------
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| 31 22 0
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dest_sgl:
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clrl %d0
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movew LOCAL_EX(%a1),%d0 |get exponent
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subw #0x3fff,%d0 |subtract extended precision bias
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cmpw #0x4000,%d0 |check if inf
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beqs sinf |if so, special case
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addw #0x7f,%d0 |add single precision bias
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swap %d0 |put exp in upper word of d0
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lsll #7,%d0 |shift it into single exp bits
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tstb LOCAL_SGN(%a1)
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beqs get_sman |if positive, continue
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bsetl #31,%d0 |if negative, put in sign first
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bras get_sman |get mantissa
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sinf:
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movel #0x7f800000,%d0 |load single inf exp to d0
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tstb LOCAL_SGN(%a1)
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beqs sgl_wrt |if positive, continue
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bsetl #31,%d0 |if negative, put in sign info
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bras sgl_wrt
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get_sman:
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movel LOCAL_HI(%a1),%d1 |get ms mantissa
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bfextu %d1{#1:#23},%d1 |get upper 23 bits of ms
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orl %d1,%d0 |put these bits in ms word of single
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sgl_wrt:
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movel %d0,L_SCR1(%a6) |put the new exp back on the stack
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movel #0x4,%d0 |byte count for single precision number
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tstl %a0 |users destination address
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beqs sgl_Dn |destination is a data register
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exg %a0,%a1 |a0=supervisor source, a1=user dest
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leal L_SCR1(%a6),%a0 |point a0 to data
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bsrl mem_write |move the number to the user's memory
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rts
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sgl_Dn:
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bsrl get_fline |returns fline word in d0
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andw #0x7,%d0 |isolate register number
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movel %d0,%d1 |d1 has size:reg formatted for reg_dest
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orl #0x10,%d1 |reg_dest wants size added to reg#
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bral reg_dest |size is X, rts in reg_dest will
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| ;return to caller of dest_sgl
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dest_ext:
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tstb LOCAL_SGN(%a1) |put back sign into exponent word
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beqs dstx_cont
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bsetb #sign_bit,LOCAL_EX(%a1)
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dstx_cont:
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clrb LOCAL_SGN(%a1) |clear out the sign byte
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movel #0x0c,%d0 |byte count for extended number
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exg %a0,%a1 |a0=supervisor source, a1=user dest
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bsrl mem_write |move the number to the user's memory
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rts
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|end
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