Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

|
|       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