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Annotation of cci/usr/src/lib/libc/tahoe/gen/cvtud.x, revision 1.1.1.1

1.1       root        1: #include       <machine/fp.h>
                      2: 
                      3:        .text
                      4:        .globl  Xcvtud
                      5: _cvtud:
                      6: Xcvtud:        .word   0x003c          # we use r2,r3,r4,r5
                      7: 
                      8:  #
                      9:  #     Some initializations:
                     10:  #
                     11:        clrl    r2              # r2 - exponent.
                     12:        movl    4(fp),r0        # fetch operand.
                     13:        jeql    retzero         # return zero.
                     14:  # 
                     15:  #     Compute exponent:
                     16:  #
                     17: positive:
                     18:        ffs     r0,r1
                     19:        incl    r1
                     20:        addl2   r1,r2
                     21:        shrl    r1,r0,r0
                     22:        jneq    positive        # look for more set bits.
                     23:  #
                     24:  # we have the exponent in r2.
                     25:  #
                     26:        movl    4(fp),r0        # r0,r1 will hold the resulting f.p. number.
                     27:        clrl    r1
                     28:  #
                     29:  #     Shift the fraction part to its proper place:
                     30:  #
                     31:        subl3   r2,$HID_POS,r3
                     32:        jlss    shiftr          # if less then zero we have to shift right.
                     33:        shll    r3,r0,r0        # else we shift left.
                     34:        jmp     shifted
                     35: shiftr:
                     36:        mnegl   r3,r3
                     37:        shrq    r3,r0,r0
                     38: shifted:
                     39:        andl2   $CLEARHID,r0    # clear the hidden bit.
                     40:        shal    $EXPSHIFT,r2,r2 # shift the exponent to its proper place.
                     41:        orl2    $EXPSIGN,r2     # set the exponent sign bit(to bias it).
                     42:        orl2    r2,r0           # combine exponent & fraction.
                     43: sign_ok:
                     44:        ret
                     45: 
                     46: retzero:
                     47:        clrl    r0
                     48:        clrl    r1
                     49:        ret
                     50: 
                     51:        

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