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Annotation of 3BSD/cmd/lisp/dmlad.s, revision 1.1

1.1     ! root        1:        .globl  _dmlad
        !             2: #
        !             3: #      routine for destructive multiplication and additon to a bignum by
        !             4: #      two fixnums.
        !             5: #
        !             6: #      from C, the invocation is dmlad(sdot,mul,add);
        !             7: #      where sdot is the address of the first special cell of the bignum
        !             8: #      mul is the multiplier, add is the fixnum to be added (The latter
        !             9: #      being passed by value, as is the usual case.
        !            10: #
        !            11: #
        !            12: #      Register assignments:
        !            13: #
        !            14: #      r11 = current sdot
        !            15: #      r10 = carry
        !            16: #      r9  = previous sdot, for relinking.
        !            17: #
        !            18: _dmlad:        .word   0x0e00
        !            19:        movl    4(ap),r11               #initialize cell pointer
        !            20:        movl    12(ap),r10              #initialize carry
        !            21: loop:  emul    8(ap),(r11),r10,r0      #r0 gets cell->car times mul + carry
        !            22: #      ediv    $0x40000000,r0,r10,(r11)#cell->car gets prod % 2**30
        !            23: #                                      #carry gets quotient
        !            24:        extzv   $0,$30,r0,(r11)
        !            25:        extv    $30,$32,r0,r10
        !            26:        movl    r11,r9                  #save last cell for fixup at end.
        !            27:        movl    4(r11),r11              #move to next cell
        !            28:        bneq    loop                    #done indicated by 0 for next sdot
        !            29:        tstl    r10                     #if carry zero no need to allocate
        !            30:        beql    done                    #new bigit
        !            31:        mcoml   r10,r3                  #test to see if neg 1.
        !            32:        bneq    alloc                   #if not must allocate new cell.
        !            33:        tstl    (r9)                    #make sure product isn't -2**30
        !            34:        beql    alloc
        !            35:        movl    r0,(r9)                 #save old lower half of product.
        !            36:        brb     done
        !            37: alloc: calls   $0,_newsdot             #otherwise allocate new bigit
        !            38:        movl    r10,(r0)                #store carry
        !            39:        movl    r0,4(r9)                #save new link cell
        !            40: done:  movl    4(ap),r0
        !            41:        ret

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