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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+| THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF MOTOROLA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
+ beq 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
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