usr/src/ucb/lisp/franz/tahoe/dmlad.s


        .globl  _dmlad
/*
        routine for destructive multiplication and addition to a bignum by
        two fixnums.

        from C, the invocation is dmlad(sdot,mul,add);
        where sdot is the address of the first special cell of the bignum
        mul is the multiplier, add is the fixnum to be added (The latter
        being passed by value, as is the usual case.


        Register assignments:

        r11 = current sdot
        r10 = carry
        r9  = previous sdot, for relinking.
        r8  = temporary kluge variable
*/

_dmlad: .word   0x0f00
        movl    4(fp),r11               #initialize cell pointer
        movl    12(fp),r10              #initialize carry
loop:   emul    8(fp),(r11),r10,r0      #r0 gets cell->car times mul + carry

        ediv    $0x40000000,r0,r10,r8   #cell->car gets prod % 2**30
        movl    r8,(r11)
                                        #carry gets quotient
/*      extzv   $0,$30,r0,(r11)
        extv    $30,$32,r0,r10
*/
        movl    r11,r9                  #save last cell for fixup at end.
        movl    4(r11),r11              #move to next cell
        bneq    loop                    #done indicated by 0 for next sdot
        tstl    r10                     #if carry zero no need to allocate
        beql    done                    #new bigit
        mcoml   r10,r3                  #test to see if neg 1.
        bneq    alloc                   #if not must allocate new cell.
        tstl    (r9)                    #make sure product isn't -2**30
        beql    alloc
        movl    r0,(r9)                 #save old lower half of product.
        brb     done
alloc:  callf   $4,_newdot              #otherwise allocate new bigit
        movl    r10,(r0)                #store carry
        movl    r0,4(r9)                #save new link cell
done:   movl    4(fp),r0
        ret