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|
|
| sint.sa 3.1 12/10/90
|
| The entry point sINT computes the rounded integer
| equivalent of the input argument, sINTRZ computes
| the integer rounded to zero of the input argument.
|
| Entry points sint and sintrz are called from do_func
| to emulate the fint and fintrz unimplemented instructions,
| respectively. Entry point sintdo is used by bindec.
|
| Input: (Entry points sint and sintrz) Double-extended
| number X in the ETEMP space in the floating-point
| save stack.
| (Entry point sintdo) Double-extended number X in
| location pointed to by the address register a0.
| (Entry point sintd) Double-extended denormalized
| number X in the ETEMP space in the floating-point
| save stack.
|
| Output: The function returns int(X) or intrz(X) in fp0.
|
| Modifies: fp0.
|
| Algorithm: (sint and sintrz)
|
| 1. If exp(X) >= 63, return X.
| If exp(X) < 0, return +/- 0 or +/- 1, according to
| the rounding mode.
|
| 2. (X is in range) set rsc = 63 - exp(X). Unnormalize the
| result to the exponent $403e.
|
| 3. Round the result in the mode given in USER_FPCR. For
| sintrz, force round-to-zero mode.
|
| 4. Normalize the rounded result; store in fp0.
|
| For the denormalized cases, force the correct result
| for the given sign and rounding mode.
|
| Sign(X)
| RMODE + -
| ----- --------
| RN +0 -0
| RZ +0 -0
| RM +0 -1
| RP +1 -0
|
|
| 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.
|SINT idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
#include "fpsp.h"
|xref dnrm_lp
|xref nrm_set
|xref round
|xref t_inx2
|xref ld_pone
|xref ld_mone
|xref ld_pzero
|xref ld_mzero
|xref snzrinx
|
| FINT
|
.global sint
sint:
bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
| ;implicitly has extend precision
| ;in upper word.
movel %d1,L_SCR1(%a6) |save mode bits
bras sintexc
|
| FINT with extended denorm inputs.
|
.global sintd
sintd:
btstb #5,FPCR_MODE(%a6)
beq snzrinx |if round nearest or round zero, +/- 0
btstb #4,FPCR_MODE(%a6)
beqs rnd_mns
rnd_pls:
btstb #sign_bit,LOCAL_EX(%a0)
bnes sintmz
bsr ld_pone |if round plus inf and pos, answer is +1
bra t_inx2
rnd_mns:
btstb #sign_bit,LOCAL_EX(%a0)
beqs sintpz
bsr ld_mone |if round mns inf and neg, answer is -1
bra t_inx2
sintpz:
bsr ld_pzero
bra t_inx2
sintmz:
bsr ld_mzero
bra t_inx2
|
| FINTRZ
|
.global sintrz
sintrz:
movel #1,L_SCR1(%a6) |use rz mode for rounding
| ;implicitly has extend precision
| ;in upper word.
bras sintexc
|
| SINTDO
|
| Input: a0 points to an IEEE extended format operand
| Output: fp0 has the result
|
| Exceptions:
|
| If the subroutine results in an inexact operation, the inx2 and
| ainx bits in the USER_FPSR are set.
|
|
.global sintdo
sintdo:
bfextu FPCR_MODE(%a6){#2:#2},%d1 |use user's mode for rounding
| ;implicitly has ext precision
| ;in upper word.
movel %d1,L_SCR1(%a6) |save mode bits
|
| Real work of sint is in sintexc
|
sintexc:
bclrb #sign_bit,LOCAL_EX(%a0) |convert to internal extended
| ;format
sne LOCAL_SGN(%a0)
cmpw #0x403e,LOCAL_EX(%a0) |check if (unbiased) exp > 63
bgts out_rnge |branch if exp < 63
cmpw #0x3ffd,LOCAL_EX(%a0) |check if (unbiased) exp < 0
bgt in_rnge |if 63 >= exp > 0, do calc
|
| Input is less than zero. Restore sign, and check for directed
| rounding modes. L_SCR1 contains the rmode in the lower byte.
|
un_rnge:
btstb #1,L_SCR1+3(%a6) |check for rn and rz
beqs un_rnrz
tstb LOCAL_SGN(%a0) |check for sign
bnes un_rmrp_neg
|
| Sign is +. If rp, load +1.0, if rm, load +0.0
|
cmpib #3,L_SCR1+3(%a6) |check for rp
beqs un_ldpone |if rp, load +1.0
bsr ld_pzero |if rm, load +0.0
bra t_inx2
un_ldpone:
bsr ld_pone
bra t_inx2
|
| Sign is -. If rm, load -1.0, if rp, load -0.0
|
un_rmrp_neg:
cmpib #2,L_SCR1+3(%a6) |check for rm
beqs un_ldmone |if rm, load -1.0
bsr ld_mzero |if rp, load -0.0
bra t_inx2
un_ldmone:
bsr ld_mone
bra t_inx2
|
| Rmode is rn or rz; return signed zero
|
un_rnrz:
tstb LOCAL_SGN(%a0) |check for sign
bnes un_rnrz_neg
bsr ld_pzero
bra t_inx2
un_rnrz_neg:
bsr ld_mzero
bra t_inx2
|
| Input is greater than 2^63. All bits are significant. Return
| the input.
|
out_rnge:
bfclr LOCAL_SGN(%a0){#0:#8} |change back to IEEE ext format
beqs intps
bsetb #sign_bit,LOCAL_EX(%a0)
intps:
fmovel %fpcr,-(%sp)
fmovel #0,%fpcr
fmovex LOCAL_EX(%a0),%fp0 |if exp > 63
| ;then return X to the user
| ;there are no fraction bits
fmovel (%sp)+,%fpcr
rts
in_rnge:
| ;shift off fraction bits
clrl %d0 |clear d0 - initial g,r,s for
| ;dnrm_lp
movel #0x403e,%d1 |set threshold for dnrm_lp
| ;assumes a0 points to operand
bsr dnrm_lp
| ;returns unnormalized number
| ;pointed by a0
| ;output d0 supplies g,r,s
| ;used by round
movel L_SCR1(%a6),%d1 |use selected rounding mode
|
|
bsr round |round the unnorm based on users
| ;input a0 ptr to ext X
| ; d0 g,r,s bits
| ; d1 PREC/MODE info
| ;output a0 ptr to rounded result
| ;inexact flag set in USER_FPSR
| ;if initial grs set
|
| normalize the rounded result and store value in fp0
|
bsr nrm_set |normalize the unnorm
| ;Input: a0 points to operand to
| ;be normalized
| ;Output: a0 points to normalized
| ;result
bfclr LOCAL_SGN(%a0){#0:#8}
beqs nrmrndp
bsetb #sign_bit,LOCAL_EX(%a0) |return to IEEE extended format
nrmrndp:
fmovel %fpcr,-(%sp)
fmovel #0,%fpcr
fmovex LOCAL_EX(%a0),%fp0 |move result to fp0
fmovel (%sp)+,%fpcr
rts
|end
|
