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| kernel_ex.sa 3.3 12/19/90
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|
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| This file contains routines to force exception status in the
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| fpu for exceptional cases detected or reported within the
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| transcendental functions. Typically, the t_xx routine will
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| set the appropriate bits in the USER_FPSR word on the stack.
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| The bits are tested in gen_except.sa to determine if an exceptional
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| situation needs to be created on return from the FPSP.
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|
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| Copyright (C) Motorola, Inc. 1990
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| All Rights Reserved
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|
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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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|
KERNEL_EX: |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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|
mns_inf: .long 0xffff0000,0x00000000,0x00000000
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pls_inf: .long 0x7fff0000,0x00000000,0x00000000
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nan: .long 0x7fff0000,0xffffffff,0xffffffff
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huge: .long 0x7ffe0000,0xffffffff,0xffffffff
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|
|xref ovf_r_k
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|xref unf_sub
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|xref nrm_set
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.global t_dz
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.global t_dz2
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.global t_operr
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.global t_unfl
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.global t_ovfl
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.global t_ovfl2
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.global t_inx2
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.global t_frcinx
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.global t_extdnrm
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.global t_resdnrm
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.global dst_nan
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.global src_nan
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| DZ exception
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| if dz trap disabled
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| store properly signed inf (use sign of etemp) into fp0
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| set FPSR exception status dz bit, condition code
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| inf bit, and accrued dz bit
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| return
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| frestore the frame into the machine (done by unimp_hd)
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|
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| else dz trap enabled
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| set exception status bit & accrued bits in FPSR
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| set flag to disable sto_res from corrupting fp register
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| return
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| frestore the frame into the machine (done by unimp_hd)
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|
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| t_dz2 is used by monadic functions such as flogn (from do_func).
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| t_dz is used by monadic functions such as satanh (from the
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| transcendental function).
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t_dz2:
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bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
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fmovel #0,%FPSR |clr status bits (Z set)
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btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
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bnes dz_ena_end
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bras m_inf |flogx always returns -inf
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t_dz:
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fmovel #0,%FPSR |clr status bits (Z set)
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btstb #dz_bit,FPCR_ENABLE(%a6) |test FPCR for dz exc enabled
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bnes dz_ena
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| dz disabled
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btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
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beqs p_inf |branch if pos sign
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m_inf:
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fmovemx mns_inf,%fp0-%fp0 |load -inf
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bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
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bras set_fpsr
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p_inf:
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fmovemx pls_inf,%fp0-%fp0 |load +inf
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set_fpsr:
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orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
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rts
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| dz enabled
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dz_ena:
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btstb #sign_bit,ETEMP_EX(%a6) |check sign for neg or pos
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beqs dz_ena_end
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bsetb #neg_bit,FPSR_CC(%a6) |set neg bit in FPSR
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dz_ena_end:
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orl #dzinf_mask,USER_FPSR(%a6) |set I,DZ,ADZ
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st STORE_FLG(%a6)
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rts
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| OPERR exception
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| if (operr trap disabled)
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| set FPSR exception status operr bit, condition code
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| nan bit; Store default NAN into fp0
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| frestore the frame into the machine (done by unimp_hd)
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| else (operr trap enabled)
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| set FPSR exception status operr bit, accrued operr bit
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| set flag to disable sto_res from corrupting fp register
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| frestore the frame into the machine (done by unimp_hd)
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t_operr:
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orl #opnan_mask,USER_FPSR(%a6) |set NaN, OPERR, AIOP
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btstb #operr_bit,FPCR_ENABLE(%a6) |test FPCR for operr enabled
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bnes op_ena
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fmovemx nan,%fp0-%fp0 |load default nan
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rts
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op_ena:
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st STORE_FLG(%a6) |do not corrupt destination
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rts
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| t_unfl --- UNFL exception
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| This entry point is used by all routines requiring unfl, inex2,
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| aunfl, and ainex to be set on exit.
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| On entry, a0 points to the exceptional operand. The final exceptional
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| operand is built in FP_SCR1 and only the sign from the original operand
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| is used.
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t_unfl:
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clrl FP_SCR1(%a6) |set exceptional operand to zero
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clrl FP_SCR1+4(%a6)
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clrl FP_SCR1+8(%a6)
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tstb (%a0) |extract sign from caller's exop
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bpls unfl_signok
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bset #sign_bit,FP_SCR1(%a6)
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unfl_signok:
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leal FP_SCR1(%a6),%a0
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orl #unfinx_mask,USER_FPSR(%a6)
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| ;set UNFL, INEX2, AUNFL, AINEX
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unfl_con:
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btstb #unfl_bit,FPCR_ENABLE(%a6)
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beqs unfl_dis
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unfl_ena:
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bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
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bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
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bsetb #sticky_bit,STICKY(%a6) |set sticky bit
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bclrb #E1,E_BYTE(%a6)
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unfl_dis:
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bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
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bclrb #sign_bit,LOCAL_EX(%a0)
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sne LOCAL_SGN(%a0) |convert to internal ext format
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bsr unf_sub |returns IEEE result at a0
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| ;and sets FPSR_CC accordingly
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bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
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beqs unfl_fin
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bsetb #sign_bit,LOCAL_EX(%a0)
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bsetb #sign_bit,FP_SCR1(%a6) |set sign bit of exc operand
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unfl_fin:
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fmovemx (%a0),%fp0-%fp0 |store result in fp0
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rts
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| t_ovfl2 --- OVFL exception (without inex2 returned)
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| This entry is used by scale to force catastrophic overflow. The
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| ovfl, aovfl, and ainex bits are set, but not the inex2 bit.
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t_ovfl2:
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orl #ovfl_inx_mask,USER_FPSR(%a6)
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movel ETEMP(%a6),FP_SCR1(%a6)
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movel ETEMP_HI(%a6),FP_SCR1+4(%a6)
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movel ETEMP_LO(%a6),FP_SCR1+8(%a6)
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| Check for single or double round precision. If single, check if
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| the lower 40 bits of ETEMP are zero; if not, set inex2. If double,
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| check if the lower 21 bits are zero; if not, set inex2.
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moveb FPCR_MODE(%a6),%d0
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andib #0xc0,%d0
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beq t_work |if extended, finish ovfl processing
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cmpib #0x40,%d0 |test for single
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bnes t_dbl
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t_sgl:
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tstb ETEMP_LO(%a6)
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bnes t_setinx2
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movel ETEMP_HI(%a6),%d0
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andil #0xff,%d0 |look at only lower 8 bits
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bnes t_setinx2
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bra t_work
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t_dbl:
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movel ETEMP_LO(%a6),%d0
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andil #0x7ff,%d0 |look at only lower 11 bits
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beq t_work
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t_setinx2:
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orl #inex2_mask,USER_FPSR(%a6)
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bras t_work
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| t_ovfl --- OVFL exception
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|** Note: the exc operand is returned in ETEMP.
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t_ovfl:
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orl #ovfinx_mask,USER_FPSR(%a6)
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t_work:
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btstb #ovfl_bit,FPCR_ENABLE(%a6) |test FPCR for ovfl enabled
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beqs ovf_dis
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ovf_ena:
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clrl FP_SCR1(%a6) |set exceptional operand
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clrl FP_SCR1+4(%a6)
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clrl FP_SCR1+8(%a6)
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bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
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bclrb #wbtemp15_bit,WB_BYTE(%a6) |clear wbtemp15
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bsetb #sticky_bit,STICKY(%a6) |set sticky bit
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bclrb #E1,E_BYTE(%a6)
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| ;fall through to disabled case
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| For disabled overflow call 'ovf_r_k'. This routine loads the
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| correct result based on the rounding precision, destination
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| format, rounding mode and sign.
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ovf_dis:
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bsr ovf_r_k |returns unsigned ETEMP_EX
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| ;and sets FPSR_CC accordingly.
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bfclr ETEMP_SGN(%a6){#0:#8} |fix sign
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beqs ovf_pos
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bsetb #sign_bit,ETEMP_EX(%a6)
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bsetb #sign_bit,FP_SCR1(%a6) |set exceptional operand sign
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ovf_pos:
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fmovemx ETEMP(%a6),%fp0-%fp0 |move the result to fp0
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rts
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| INEX2 exception
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| The inex2 and ainex bits are set.
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t_inx2:
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orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
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rts
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| Force Inex2
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| This routine is called by the transcendental routines to force
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| the inex2 exception bits set in the FPSR. If the underflow bit
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| is set, but the underflow trap was not taken, the aunfl bit in
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| the FPSR must be set.
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t_frcinx:
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orl #inx2a_mask,USER_FPSR(%a6) |set INEX2, AINEX
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btstb #unfl_bit,FPSR_EXCEPT(%a6) |test for unfl bit set
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beqs no_uacc1 |if clear, do not set aunfl
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bsetb #aunfl_bit,FPSR_AEXCEPT(%a6)
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no_uacc1:
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rts
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| DST_NAN
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| Determine if the destination nan is signalling or non-signalling,
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| and set the FPSR bits accordingly. See the MC68040 User's Manual
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| section 3.2.2.5 NOT-A-NUMBERS.
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dst_nan:
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btstb #sign_bit,FPTEMP_EX(%a6) |test sign of nan
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beqs dst_pos |if clr, it was positive
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bsetb #neg_bit,FPSR_CC(%a6) |set N bit
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dst_pos:
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btstb #signan_bit,FPTEMP_HI(%a6) |check if signalling
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beqs dst_snan |branch if signalling
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fmovel %d1,%fpcr |restore user's rmode/prec
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fmovex FPTEMP(%a6),%fp0 |return the non-signalling nan
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| Check the source nan. If it is signalling, snan will be reported.
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moveb STAG(%a6),%d0
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andib #0xe0,%d0
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cmpib #0x60,%d0
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bnes no_snan
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btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
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bnes no_snan
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orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
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no_snan:
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rts
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dst_snan:
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btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
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beqs dst_dis |branch if disabled
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orb #nan_tag,DTAG(%a6) |set up dtag for nan
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st STORE_FLG(%a6) |do not store a result
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orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
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rts
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dst_dis:
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bsetb #signan_bit,FPTEMP_HI(%a6) |set SNAN bit in sop
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fmovel %d1,%fpcr |restore user's rmode/prec
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fmovex FPTEMP(%a6),%fp0 |load non-sign. nan
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orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
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rts
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| SRC_NAN
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| Determine if the source nan is signalling or non-signalling,
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| and set the FPSR bits accordingly. See the MC68040 User's Manual
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| section 3.2.2.5 NOT-A-NUMBERS.
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src_nan:
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btstb #sign_bit,ETEMP_EX(%a6) |test sign of nan
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beqs src_pos |if clr, it was positive
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bsetb #neg_bit,FPSR_CC(%a6) |set N bit
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src_pos:
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btstb #signan_bit,ETEMP_HI(%a6) |check if signalling
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beqs src_snan |branch if signalling
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fmovel %d1,%fpcr |restore user's rmode/prec
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fmovex ETEMP(%a6),%fp0 |return the non-signalling nan
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rts
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src_snan:
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btstb #snan_bit,FPCR_ENABLE(%a6) |check if trap enabled
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beqs src_dis |branch if disabled
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bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
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orb #norm_tag,DTAG(%a6) |set up dtag for norm
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orb #nan_tag,STAG(%a6) |set up stag for nan
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st STORE_FLG(%a6) |do not store a result
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orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
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rts
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src_dis:
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bsetb #signan_bit,ETEMP_HI(%a6) |set SNAN bit in sop
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fmovel %d1,%fpcr |restore user's rmode/prec
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fmovex ETEMP(%a6),%fp0 |load non-sign. nan
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orl #snaniop_mask,USER_FPSR(%a6) |set NAN, SNAN, AIOP
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rts
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| For all functions that have a denormalized input and that f(x)=x,
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| this is the entry point
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t_extdnrm:
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orl #unfinx_mask,USER_FPSR(%a6)
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| ;set UNFL, INEX2, AUNFL, AINEX
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bras xdnrm_con
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| Entry point for scale with extended denorm. The function does
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| not set inex2, aunfl, or ainex.
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t_resdnrm:
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orl #unfl_mask,USER_FPSR(%a6)
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xdnrm_con:
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btstb #unfl_bit,FPCR_ENABLE(%a6)
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beqs xdnrm_dis
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| If exceptions are enabled, the additional task of setting up WBTEMP
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| is needed so that when the underflow exception handler is entered,
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| the user perceives no difference between what the 040 provides vs.
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| what the FPSP provides.
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xdnrm_ena:
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movel %a0,-(%a7)
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movel LOCAL_EX(%a0),FP_SCR1(%a6)
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movel LOCAL_HI(%a0),FP_SCR1+4(%a6)
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movel LOCAL_LO(%a0),FP_SCR1+8(%a6)
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lea FP_SCR1(%a6),%a0
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bclrb #sign_bit,LOCAL_EX(%a0)
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sne LOCAL_SGN(%a0) |convert to internal ext format
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tstw LOCAL_EX(%a0) |check if input is denorm
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beqs xdnrm_dn |if so, skip nrm_set
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bsr nrm_set |normalize the result (exponent
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| ;will be negative
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xdnrm_dn:
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bclrb #sign_bit,LOCAL_EX(%a0) |take off false sign
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bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
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beqs xdep
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bsetb #sign_bit,LOCAL_EX(%a0)
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xdep:
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bfclr STAG(%a6){#5:#3} |clear wbtm66,wbtm1,wbtm0
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bsetb #wbtemp15_bit,WB_BYTE(%a6) |set wbtemp15
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bclrb #sticky_bit,STICKY(%a6) |clear sticky bit
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bclrb #E1,E_BYTE(%a6)
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movel (%a7)+,%a0
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xdnrm_dis:
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bfextu FPCR_MODE(%a6){#0:#2},%d0 |get round precision
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bnes not_ext |if not round extended, store
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| ;IEEE defaults
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is_ext:
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btstb #sign_bit,LOCAL_EX(%a0)
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beqs xdnrm_store
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bsetb #neg_bit,FPSR_CC(%a6) |set N bit in FPSR_CC
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bras xdnrm_store
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not_ext:
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bclrb #sign_bit,LOCAL_EX(%a0)
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sne LOCAL_SGN(%a0) |convert to internal ext format
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bsr unf_sub |returns IEEE result pointed by
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| ;a0; sets FPSR_CC accordingly
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bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
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beqs xdnrm_store
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bsetb #sign_bit,LOCAL_EX(%a0)
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xdnrm_store:
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fmovemx (%a0),%fp0-%fp0 |store result in fp0
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rts
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| This subroutine is used for dyadic operations that use an extended
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| denorm within the kernel. The approach used is to capture the frame,
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| fix/restore.
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.global t_avoid_unsupp
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t_avoid_unsupp:
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link %a2,#-LOCAL_SIZE |so that a2 fpsp.h negative
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| ;offsets may be used
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fsave -(%a7)
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tstb 1(%a7) |check if idle, exit if so
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beq idle_end
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btstb #E1,E_BYTE(%a2) |check for an E1 exception if
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| ;enabled, there is an unsupp
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beq end_avun |else, exit
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btstb #7,DTAG(%a2) |check for denorm destination
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beqs src_den |else, must be a source denorm
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|
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| handle destination denorm
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lea FPTEMP(%a2),%a0
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btstb #sign_bit,LOCAL_EX(%a0)
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sne LOCAL_SGN(%a0) |convert to internal ext format
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bclrb #7,DTAG(%a2) |set DTAG to norm
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bsr nrm_set |normalize result, exponent
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| ;will become negative
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bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
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bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
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beqs ck_src_den |check if source is also denorm
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bsetb #sign_bit,LOCAL_EX(%a0)
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ck_src_den:
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btstb #7,STAG(%a2)
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beqs end_avun
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src_den:
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lea ETEMP(%a2),%a0
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btstb #sign_bit,LOCAL_EX(%a0)
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sne LOCAL_SGN(%a0) |convert to internal ext format
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bclrb #7,STAG(%a2) |set STAG to norm
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bsr nrm_set |normalize result, exponent
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| ;will become negative
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bclrb #sign_bit,LOCAL_EX(%a0) |get rid of fake sign
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bfclr LOCAL_SGN(%a0){#0:#8} |convert back to IEEE ext format
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beqs den_com
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bsetb #sign_bit,LOCAL_EX(%a0)
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den_com:
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moveb #0xfe,CU_SAVEPC(%a2) |set continue frame
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clrw NMNEXC(%a2) |clear NMNEXC
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bclrb #E1,E_BYTE(%a2)
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| fmove.l %FPSR,FPSR_SHADOW(%a2)
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| bset.b #SFLAG,E_BYTE(%a2)
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| bset.b #XFLAG,T_BYTE(%a2)
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end_avun:
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frestore (%a7)+
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unlk %a2
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rts
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idle_end:
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addl #4,%a7
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unlk %a2
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rts
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|end
|
