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| sint.sa 3.1 12/10/90
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|
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| The entry point sINT computes the rounded integer
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| equivalent of the input argument, sINTRZ computes
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| the integer rounded to zero of the input argument.
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| Entry points sint and sintrz are called from do_func
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| to emulate the fint and fintrz unimplemented instructions,
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| respectively. Entry point sintdo is used by bindec.
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|
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| Input: (Entry points sint and sintrz) Double-extended
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| number X in the ETEMP space in the floating-point
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| save stack.
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| (Entry point sintdo) Double-extended number X in
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| location pointed to by the address register a0.
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| (Entry point sintd) Double-extended denormalized
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| number X in the ETEMP space in the floating-point
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| save stack.
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| Output: The function returns int(X) or intrz(X) in fp0.
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| Modifies: fp0.
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| Algorithm: (sint and sintrz)
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|
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| 1. If exp(X) >= 63, return X.
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| If exp(X) < 0, return +/- 0 or +/- 1, according to
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| the rounding mode.
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|
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| 2. (X is in range) set rsc = 63 - exp(X). Unnormalize the
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| result to the exponent $403e.
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|
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| 3. Round the result in the mode given in USER_FPCR. For
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| sintrz, force round-to-zero mode.
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|
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| 4. Normalize the rounded result; store in fp0.
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| For the denormalized cases, force the correct result
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| for the given sign and rounding mode.
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| Sign(X)
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| RMODE + -
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| ----- --------
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| RN +0 -0
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| RZ +0 -0
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| RM +0 -1
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| RP +1 -0
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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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|
|SINT 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 dnrm_lp
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|xref nrm_set
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|xref round
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|xref t_inx2
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|xref ld_pone
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|xref ld_mone
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|xref ld_pzero
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|xref ld_mzero
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|xref snzrinx
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|
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| FINT
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.global sint
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sint:
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bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
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| ;implicitly has extend precision
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| ;in upper word.
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movel %d1,L_SCR1(%a6) |save mode bits
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bras sintexc
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| FINT with extended denorm inputs.
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.global sintd
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sintd:
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btstb #5,FPCR_MODE(%a6)
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beq snzrinx |if round nearest or round zero, +/- 0
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btstb #4,FPCR_MODE(%a6)
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beqs rnd_mns
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rnd_pls:
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btstb #sign_bit,LOCAL_EX(%a0)
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bnes sintmz
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bsr ld_pone |if round plus inf and pos, answer is +1
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bra t_inx2
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rnd_mns:
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btstb #sign_bit,LOCAL_EX(%a0)
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beqs sintpz
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bsr ld_mone |if round mns inf and neg, answer is -1
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bra t_inx2
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sintpz:
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bsr ld_pzero
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bra t_inx2
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sintmz:
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bsr ld_mzero
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bra t_inx2
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| FINTRZ
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.global sintrz
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sintrz:
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movel #1,L_SCR1(%a6) |use rz mode for rounding
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| ;implicitly has extend precision
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| ;in upper word.
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bras sintexc
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|
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| SINTDO
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| Input: a0 points to an IEEE extended format operand
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| Output: fp0 has the result
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|
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| Exceptions:
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| If the subroutine results in an inexact operation, the inx2 and
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| ainx bits in the USER_FPSR are set.
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.global sintdo
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sintdo:
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bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
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| ;implicitly has ext precision
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| ;in upper word.
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movel %d1,L_SCR1(%a6) |save mode bits
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| Real work of sint is in sintexc
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sintexc:
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bclrb #sign_bit,LOCAL_EX(%a0) |convert to internal extended
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| ;format
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sne LOCAL_SGN(%a0)
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cmpw #0x403e,LOCAL_EX(%a0) |check if (unbiased) exp > 63
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bgts out_rnge |branch if exp < 63
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cmpw #0x3ffd,LOCAL_EX(%a0) |check if (unbiased) exp < 0
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bgt in_rnge |if 63 >= exp > 0, do calc
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|
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| Input is less than zero. Restore sign, and check for directed
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| rounding modes. L_SCR1 contains the rmode in the lower byte.
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un_rnge:
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btstb #1,L_SCR1+3(%a6) |check for rn and rz
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beqs un_rnrz
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tstb LOCAL_SGN(%a0) |check for sign
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bnes un_rmrp_neg
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| Sign is +. If rp, load +1.0, if rm, load +0.0
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cmpib #3,L_SCR1+3(%a6) |check for rp
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beqs un_ldpone |if rp, load +1.0
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bsr ld_pzero |if rm, load +0.0
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bra t_inx2
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un_ldpone:
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bsr ld_pone
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bra t_inx2
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| Sign is -. If rm, load -1.0, if rp, load -0.0
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un_rmrp_neg:
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cmpib #2,L_SCR1+3(%a6) |check for rm
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beqs un_ldmone |if rm, load -1.0
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bsr ld_mzero |if rp, load -0.0
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bra t_inx2
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un_ldmone:
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bsr ld_mone
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bra t_inx2
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| Rmode is rn or rz; return signed zero
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un_rnrz:
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tstb LOCAL_SGN(%a0) |check for sign
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bnes un_rnrz_neg
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bsr ld_pzero
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bra t_inx2
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un_rnrz_neg:
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bsr ld_mzero
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bra t_inx2
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| Input is greater than 2^63. All bits are significant. Return
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| the input.
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out_rnge:
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bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
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beqs intps
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bsetb #sign_bit,LOCAL_EX(%a0)
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intps:
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fmovel %fpcr,-(%sp)
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fmovel #0,%fpcr
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fmovex LOCAL_EX(%a0),%fp0 |if exp > 63
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| ;then return X to the user
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| ;there are no fraction bits
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fmovel (%sp)+,%fpcr
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rts
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in_rnge:
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| ;shift off fraction bits
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clrl %d0 |clear d0 - initial g,r,s for
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| ;dnrm_lp
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movel #0x403e,%d1 |set threshold for dnrm_lp
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| ;assumes a0 points to operand
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bsr dnrm_lp
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| ;returns unnormalized number
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| ;pointed by a0
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| ;output d0 supplies g,r,s
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| ;used by round
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movel L_SCR1(%a6),%d1 |use selected rounding mode
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|
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bsr round |round the unnorm based on users
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| ;input a0 ptr to ext X
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| ; d0 g,r,s bits
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| ; d1 PREC/MODE info
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| ;output a0 ptr to rounded result
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| ;inexact flag set in USER_FPSR
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| ;if initial grs set
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|
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| normalize the rounded result and store value in fp0
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bsr nrm_set |normalize the unnorm
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| ;Input: a0 points to operand to
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| ;be normalized
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| ;Output: a0 points to normalized
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| ;result
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bfclr LOCAL_SGN(%a0){#0:#8}
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beqs nrmrndp
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bsetb #sign_bit,LOCAL_EX(%a0) |return to IEEE extended format
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nrmrndp:
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fmovel %fpcr,-(%sp)
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fmovel #0,%fpcr
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fmovex LOCAL_EX(%a0),%fp0 |move result to fp0
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fmovel (%sp)+,%fpcr
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rts
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|
|end
|
