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Annotation of 43BSDReno/lib/libc/tahoe/fpe/cvtfl.s, revision 1.1.1.1

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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