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Annotation of 43BSDReno/lib/libc/tahoe/fpe/sfnorm.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 "@(#)sfnorm.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(sfnorm, R2|R3|R4|R5|R6)
                     31:        clrl    r1
                     32:        movl    r0,r4           /* copy to temporary. */
                     33:        jeql    retzero
                     34:        clrl    r3              /* r3 - pos of m.s.b */
                     35: inr00: ffs     r4,r6
                     36:        incl    r6
                     37:        addl2   r6,r3
                     38:        shrl    r6,r4,r4
                     39:        jneq    inr00
                     40: 
                     41: cmpshift:
                     42:                                /* compute the shift (r4). */
                     43:        subl3   r3,$HID_POS,r4
                     44:        jlss    shiftr          /* if less then zero we shift right. */
                     45:        shll    r4,r0,r0        /* else we shift left. */
                     46:        subl2   r4,r2           /* uodate exponent. */
                     47:        jleq    underflow       /* if less then 0 (biased) it is underflow. */
                     48:        jmp     combine         /* go to combine exponent and fraction. */
                     49: shiftr:
                     50:        mnegl   r4,r4
                     51:        shrl    r4,r0,r0        /* shift right. */
                     52:        addl2   r4,r2           /* update exponent */
                     53:        cmpl    r2,$256
                     54:        jgeq    overflow        /* check for overflow. */
                     55: combine:
                     56:        andl2   $CLEARHID,r0    /* clear the hidden bit. */
                     57:        shal    $EXPSHIFT,r2,r2 /* shift the exponent to its proper place. */
                     58:        orl2    r2,r0
                     59:        ret
                     60: 
                     61: underflow:
                     62:        callf   $4,sfpunder
                     63:        ret
                     64: 
                     65: overflow:
                     66:        callf   $4,sfpover
                     67:        ret
                     68: retzero:
                     69:        clrl    r0
                     70:        ret

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