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Annotation of 43BSDTahoe/sys/tahoemath/Ksfnorm.s, revision 1.1.1.1

1.1       root        1: /*     Ksfnorm.s       1.3     86/01/05        */
                      2: 
                      3: #include "../tahoemath/fp.h"
                      4: #include "../tahoemath/Kfp.h"
                      5: #include "../tahoe/SYS.h"
                      6: 
                      7: /*
                      8:  * Ksfnorm(hfs)
                      9:  */
                     10:        .text
                     11: ENTRY(Ksfnorm, R6|R5|R4|R3|R2)
                     12:        clrl    r1
                     13:        movl    r0,r4           /* copy to temporary. */
                     14:        jeql    retzero
                     15:        clrl    r3              /* r3 - pos of m.s.b */
                     16: inr00: ffs     r4,r6
                     17:        incl    r6
                     18:        addl2   r6,r3
                     19:        shrl    r6,r4,r4
                     20:        jneq    inr00
                     21: 
                     22: cmpshift:
                     23:                                /* compute the shift (r4). */
                     24:        subl3   r3,$HID_POS,r4
                     25:        jlss    shiftr          /* if less then zero we shift right. */
                     26:        shll    r4,r0,r0        /* else we shift left. */
                     27:        subl2   r4,r2           /* uodate exponent. */
                     28:        jleq    underflow       /* if less then 0 (biased) it is underflow. */
                     29:        jmp     combine         /* go to combine exponent and fraction. */
                     30: shiftr:
                     31:        mnegl   r4,r4
                     32:        shrl    r4,r0,r0        /* shift right. */
                     33:        addl2   r4,r2           /* update exponent */
                     34:        cmpl    r2,$256
                     35:        jgeq    overflow        /* check for overflow. */
                     36: combine:
                     37:        andl2   $CLEARHID,r0    /* clear the hidden bit. */
                     38:        shal    $EXPSHIFT,r2,r2 /* shift the exponent to its proper place. */
                     39:        orl2    r2,r0
                     40:        ret
                     41: 
                     42: underflow:
                     43:        orl2    $HFS_UNDF,*4(fp)        
                     44:        ret
                     45: 
                     46: overflow:
                     47:        orl2    $HFS_OVF,*4(fp)
                     48:        ret
                     49: retzero:
                     50:        clrl    r0
                     51:        ret

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