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