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| x_snan.sa 3.3 7/1/91
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| fpsp_snan --- FPSP handler for signalling NAN exception
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| SNAN for float -> integer conversions (integer conversion of
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| an SNAN) is a non-maskable run-time exception.
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| For trap disabled the 040 does the following:
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| If the dest data format is s, d, or x, then the SNAN bit in the NAN
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| is set to one and the resulting non-signaling NAN (truncated if
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| necessary) is transferred to the dest. If the dest format is b, w,
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| or l, then garbage is written to the dest (actually the upper 32 bits
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| of the mantissa are sent to the integer unit).
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| For trap enabled the 040 does the following:
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| If the inst is move_out, then the results are the same as for trap
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| disabled with the exception posted. If the instruction is not move_
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| out, the dest. is not modified, and the exception is posted.
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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_SNAN: |idnt 2,1 | Motorola 040 Floating Point Software Package
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|section 8
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#include "fpsp.h"
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|xref get_fline
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|xref mem_write
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|xref real_snan
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|xref real_inex
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|xref fpsp_done
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|xref reg_dest
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.global fpsp_snan
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fpsp_snan:
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link %a6,#-LOCAL_SIZE
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fsave -(%a7)
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moveml %d0-%d1/%a0-%a1,USER_DA(%a6)
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fmovemx %fp0-%fp3,USER_FP0(%a6)
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fmoveml %fpcr/%fpsr/%fpiar,USER_FPCR(%a6)
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| Check if trap enabled
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btstb #snan_bit,FPCR_ENABLE(%a6)
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bnes ena |If enabled, then branch
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bsrl move_out |else SNAN disabled
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| It is possible to have an inex1 exception with the
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| snan. If the inex enable bit is set in the FPCR, and either
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| inex2 or inex1 occurred, we must clean up and branch to the
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| real inex handler.
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ck_inex:
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moveb FPCR_ENABLE(%a6),%d0
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andb FPSR_EXCEPT(%a6),%d0
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andib #0x3,%d0
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beq end_snan
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| Inexact enabled and reported, and we must take an inexact exception.
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take_inex:
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moveb #INEX_VEC,EXC_VEC+1(%a6)
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moveml USER_DA(%a6),%d0-%d1/%a0-%a1
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fmovemx USER_FP0(%a6),%fp0-%fp3
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fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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frestore (%a7)+
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unlk %a6
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bral real_inex
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| SNAN is enabled. Check if inst is move_out.
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| Make any corrections to the 040 output as necessary.
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ena:
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btstb #5,CMDREG1B(%a6) |if set, inst is move out
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beq not_out
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bsrl move_out
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report_snan:
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moveb (%a7),VER_TMP(%a6)
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cmpib #VER_40,(%a7) |test for orig unimp frame
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bnes ck_rev
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moveql #13,%d0 |need to zero 14 lwords
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bras rep_con
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ck_rev:
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moveql #11,%d0 |need to zero 12 lwords
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rep_con:
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clrl (%a7)
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loop1:
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clrl -(%a7) |clear and dec a7
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dbra %d0,loop1
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moveb VER_TMP(%a6),(%a7) |format a busy frame
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moveb #BUSY_SIZE-4,1(%a7)
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movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
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orl #sx_mask,E_BYTE(%a6)
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moveml USER_DA(%a6),%d0-%d1/%a0-%a1
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fmovemx USER_FP0(%a6),%fp0-%fp3
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fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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frestore (%a7)+
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unlk %a6
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bral real_snan
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| Exit snan handler by expanding the unimp frame into a busy frame
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end_snan:
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bclrb #E1,E_BYTE(%a6)
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moveb (%a7),VER_TMP(%a6)
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cmpib #VER_40,(%a7) |test for orig unimp frame
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bnes ck_rev2
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moveql #13,%d0 |need to zero 14 lwords
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bras rep_con2
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ck_rev2:
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moveql #11,%d0 |need to zero 12 lwords
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rep_con2:
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clrl (%a7)
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loop2:
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clrl -(%a7) |clear and dec a7
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dbra %d0,loop2
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moveb VER_TMP(%a6),(%a7) |format a busy frame
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moveb #BUSY_SIZE-4,1(%a7) |write busy size
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movel USER_FPSR(%a6),FPSR_SHADOW(%a6)
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orl #sx_mask,E_BYTE(%a6)
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moveml USER_DA(%a6),%d0-%d1/%a0-%a1
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fmovemx USER_FP0(%a6),%fp0-%fp3
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fmoveml USER_FPCR(%a6),%fpcr/%fpsr/%fpiar
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frestore (%a7)+
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unlk %a6
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bral fpsp_done
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| Move_out
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move_out:
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movel EXC_EA(%a6),%a0 |get <ea> from exc frame
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bfextu CMDREG1B(%a6){#3:#3},%d0 |move rx field to d0{2:0}
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cmpil #0,%d0 |check for long
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beqs sto_long |branch if move_out long
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cmpil #4,%d0 |check for word
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beqs sto_word |branch if move_out word
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cmpil #6,%d0 |check for byte
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beqs sto_byte |branch if move_out byte
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| Not byte, word or long
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rts
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| Get the 32 most significant bits of etemp mantissa
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sto_long:
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movel ETEMP_HI(%a6),%d1
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movel #4,%d0 |load byte count
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| Set signalling nan bit
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bsetl #30,%d1
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| Store to the users destination address
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tstl %a0 |check if <ea> is 0
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beqs wrt_dn |destination is a data register
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movel %d1,-(%a7) |move the snan onto the stack
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movel %a0,%a1 |load dest addr into a1
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movel %a7,%a0 |load src addr of snan into a0
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bsrl mem_write |write snan to user memory
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movel (%a7)+,%d1 |clear off stack
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rts
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| Get the 16 most significant bits of etemp mantissa
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sto_word:
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movel ETEMP_HI(%a6),%d1
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movel #2,%d0 |load byte count
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| Set signalling nan bit
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bsetl #30,%d1
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| Store to the users destination address
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tstl %a0 |check if <ea> is 0
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beqs wrt_dn |destination is a data register
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movel %d1,-(%a7) |move the snan onto the stack
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movel %a0,%a1 |load dest addr into a1
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movel %a7,%a0 |point to low word
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bsrl mem_write |write snan to user memory
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movel (%a7)+,%d1 |clear off stack
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rts
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| Get the 8 most significant bits of etemp mantissa
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sto_byte:
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movel ETEMP_HI(%a6),%d1
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movel #1,%d0 |load byte count
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| Set signalling nan bit
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bsetl #30,%d1
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| Store to the users destination address
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tstl %a0 |check if <ea> is 0
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beqs wrt_dn |destination is a data register
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movel %d1,-(%a7) |move the snan onto the stack
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movel %a0,%a1 |load dest addr into a1
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movel %a7,%a0 |point to source byte
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bsrl mem_write |write snan to user memory
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movel (%a7)+,%d1 |clear off stack
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rts
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| wrt_dn --- write to a data register
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| We get here with D1 containing the data to write and D0 the
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| number of bytes to write: 1=byte,2=word,4=long.
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wrt_dn:
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movel %d1,L_SCR1(%a6) |data
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movel %d0,-(%a7) |size
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bsrl get_fline |returns fline word in d0
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movel %d0,%d1
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andil #0x7,%d1 |d1 now holds register number
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movel (%sp)+,%d0 |get original size
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cmpil #4,%d0
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beqs wrt_long
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cmpil #2,%d0
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bnes wrt_byte
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wrt_word:
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orl #0x8,%d1
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bral reg_dest
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wrt_long:
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orl #0x10,%d1
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bral reg_dest
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wrt_byte:
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bral reg_dest
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| Check if it is a src nan or dst nan
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not_out:
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movel DTAG(%a6),%d0
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bfextu %d0{#0:#3},%d0 |isolate dtag in lsbs
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cmpib #3,%d0 |check for nan in destination
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bnes issrc |destination nan has priority
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dst_nan:
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btstb #6,FPTEMP_HI(%a6) |check if dest nan is an snan
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bnes issrc |no, so check source for snan
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movew FPTEMP_EX(%a6),%d0
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bras cont
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issrc:
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movew ETEMP_EX(%a6),%d0
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cont:
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btstl #15,%d0 |test for sign of snan
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beqs clr_neg
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bsetb #neg_bit,FPSR_CC(%a6)
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bra report_snan
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clr_neg:
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bclrb #neg_bit,FPSR_CC(%a6)
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bra report_snan
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|end
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