usr/src/sys/tahoe/math/Kcvtdl.s

/*      Kcvtdl.s        1.4     90/12/04        */

#include "../math/fp.h"
#include "../math/Kfp.h"
#include "../tahoe/SYS.h"


        .text
        .globl  _Kcvtdl
        .globl  _Kcvtdu
_Kcvtdu:
_Kcvtdl:
        .word   R5|R4|R3|R2

 #
 #Some initializations:
 #
        clrl    r3              # r3 - negative flag.
        movl    4(fp),r0        # fetch operand.
        movl    8(fp),r1
 #
 #get exponent
 #
        andl3   $EXPMASK,r0,r2  # r2 will hold the exponent.
        jeql    retzero
        cmpl    $TWO_EXP,r2     # if exponent is less then -2,return zero.
        jgtr    retzero
        andl2   $0!EXPSIGN,r2   # turn off biased exponent sign
        shrl    $EXPSHIFT,r2,r2
 #
 #get fraction
 #
        bbc     $31,r0,positive # if negative remember it.
        incl    r3
positive:
                                # clear the non fraction parts.
        andl2   $(0!(EXPMASK | SIGNBIT)),r0
                                # add the hidden bit.
        orl2    $(0!CLEARHID),r0
        subl2   $24,r2          # compute the shift.
        jgtr    shift_left
        mnegl   r2,r2
        shrl    r2,r0,r0        # shift right.
        jmp     shifted
shift_left:
        cmpl    r2,$7
        jgtr    overflow
go_on:  shlq    r2,r0,r0        # shift right.
shifted:
        bbc     $0,r3,done      # check for negative
        mnegl   r0,r0
done:
        ret

retzero:
        clrl    r0
        ret
overflow:
        ret