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Annotation of 43BSDTahoe/lib/libc/tahoe/fpe/cvtud.s, revision 1.1.1.1

1.1       root        1: #ifdef LIBC_SCCS
                      2:        .asciz  "@(#)cvtud.s    1.1 (Berkeley/CCI) 7/2/86"
                      3: #endif LIBC_SCCS
                      4: 
                      5: #include <tahoemath/fp.h>
                      6: #include "DEFS.h"
                      7: 
                      8: XENTRY(cvtud, R2|R3|R4|R5)
                      9:  #
                     10:  #     Some initializations:
                     11:  #
                     12:        clrl    r2              # r2 - exponent.
                     13:        movl    4(fp),r0        # fetch operand.
                     14:        jeql    retzero         # return zero.
                     15:  # 
                     16:  #     Compute exponent:
                     17:  #
                     18: positive:
                     19:        ffs     r0,r1
                     20:        incl    r1
                     21:        addl2   r1,r2
                     22:        shrl    r1,r0,r0
                     23:        jneq    positive        # look for more set bits.
                     24:  #
                     25:  # we have the exponent in r2.
                     26:  #
                     27:        movl    4(fp),r0        # r0,r1 will hold the resulting f.p. number.
                     28:        clrl    r1
                     29:  #
                     30:  #     Shift the fraction part to its proper place:
                     31:  #
                     32:        subl3   r2,$HID_POS,r3
                     33:        jlss    shiftr          # if less then zero we have to shift right.
                     34:        shll    r3,r0,r0        # else we shift left.
                     35:        jmp     shifted
                     36: shiftr:
                     37:        mnegl   r3,r3
                     38:        shrq    r3,r0,r0
                     39: shifted:
                     40:        andl2   $CLEARHID,r0    # clear the hidden bit.
                     41:        shal    $EXPSHIFT,r2,r2 # shift the exponent to its proper place.
                     42:        orl2    $EXPSIGN,r2     # set the exponent sign bit(to bias it).
                     43:        orl2    r2,r0           # combine exponent & fraction.
                     44: sign_ok:
                     45:        ret
                     46: 
                     47: retzero:
                     48:        clrl    r0
                     49:        clrl    r1
                     50:        ret
                     51: 
                     52:        

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