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Annotation of 43BSDReno/lib/libc/tahoe/fpe/cvtfl.s, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1986 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * This code is derived from software contributed to Berkeley by
        !             6:  * Computer Consoles Inc.
        !             7:  *
        !             8:  * Redistribution and use in source and binary forms are permitted
        !             9:  * provided that: (1) source distributions retain this entire copyright
        !            10:  * notice and comment, and (2) distributions including binaries display
        !            11:  * the following acknowledgement:  ``This product includes software
        !            12:  * developed by the University of California, Berkeley and its contributors''
        !            13:  * in the documentation or other materials provided with the distribution
        !            14:  * and in all advertising materials mentioning features or use of this
        !            15:  * software. Neither the name of the University nor the names of its
        !            16:  * contributors may be used to endorse or promote products derived
        !            17:  * from this software without specific prior written permission.
        !            18:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
        !            19:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
        !            20:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            21:  */
        !            22: 
        !            23: #if defined(SYSLIBC_SCCS) && !defined(lint)
        !            24:        .asciz "@(#)cvtfl.s     1.3 (Berkeley) 6/1/90"
        !            25: #endif /* SYSLIBC_SCCS and not lint */
        !            26: 
        !            27: #include <tahoemath/fp.h>
        !            28: #include "DEFS.h"
        !            29:  
        !            30: XENTRY(cvtfu, R2|R3|R4|R5)
        !            31:        jbr     1f
        !            32: 
        !            33: XENTRY(cvtfl, R2|R3|R4|R5)
        !            34:  #
        !            35:  #Some initializations:
        !            36:  #
        !            37: 1:
        !            38:        movl    4(fp),r0        # fetch operand.
        !            39:        clrl    r3              # r3 - negative flag.
        !            40:  #
        !            41:  #get exponent
        !            42:  #
        !            43:        andl3   $EXPMASK,r0,r2  # r2 will hold the exponent.
        !            44:        jeql    is_reserved     # check for reserved operand. 
        !            45:        cmpl    $ONE_EXP,r2     # if exponent is less then 1,return zero.
        !            46:        jgtr    retzero
        !            47:        andl2   $0!EXPSIGN,r2   # turn off biased exponent sign
        !            48:        shrl    $EXPSHIFT,r2,r2
        !            49:  #
        !            50:  #get fraction
        !            51:  #
        !            52:        bbc     $31,r0,positive # if negative remember it.
        !            53:        incl    r3
        !            54: positive:
        !            55:                                # clear the non fraction parts.
        !            56:        andl2   $(0!(EXPMASK | SIGNBIT)),r0
        !            57:                                # add the hidden bit.
        !            58:        orl2    $(0!CLEARHID),r0
        !            59:        subl2   $24,r2          # compute the shift.
        !            60:        jgtr    shift_left
        !            61:        mnegl   r2,r2
        !            62:        shrl    r2,r0,r0        # shift right.
        !            63:        jmp     shifted
        !            64: shift_left:
        !            65:        cmpl    r2,$7
        !            66:        jgtr    overflow
        !            67: go_on: shll    r2,r0,r0        # shift right.
        !            68: shifted:
        !            69:        bbc     $0,r3,done      # check for negative
        !            70:        mnegl   r0,r0
        !            71: done:  
        !            72:        ret
        !            73: 
        !            74: retzero:
        !            75:        clrl    r0
        !            76:        ret
        !            77: overflow:
        !            78:        callf   $4,sfpover
        !            79:        jmp     go_on
        !            80: 
        !            81: is_reserved:
        !            82:        bbc     $31,r0,retzero
        !            83: 
        !            84:        callf   $4,sfpresop
        !            85:        ret

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