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Annotation of 43BSDReno/pgrm/lisp/franz/tahoe/dmlad.s, revision 1.1.1.1

1.1       root        1: 
                      2:        .globl  _dmlad
                      3: /*
                      4:        routine for destructive multiplication and addition to a bignum by
                      5:        two fixnums.
                      6: 
                      7:        from C, the invocation is dmlad(sdot,mul,add);
                      8:        where sdot is the address of the first special cell of the bignum
                      9:        mul is the multiplier, add is the fixnum to be added (The latter
                     10:        being passed by value, as is the usual case.
                     11: 
                     12: 
                     13:        Register assignments:
                     14: 
                     15:        r11 = current sdot
                     16:        r10 = carry
                     17:        r9  = previous sdot, for relinking.
                     18:        r8  = temporary kluge variable
                     19: */
                     20: 
                     21: _dmlad:        .word   0x0f00
                     22:        movl    4(fp),r11               #initialize cell pointer
                     23:        movl    12(fp),r10              #initialize carry
                     24: loop:  emul    8(fp),(r11),r10,r0      #r0 gets cell->car times mul + carry
                     25: 
                     26:        ediv    $0x40000000,r0,r10,r8   #cell->car gets prod % 2**30
                     27:        movl    r8,(r11)
                     28:                                        #carry gets quotient
                     29: /*     extzv   $0,$30,r0,(r11)
                     30:        extv    $30,$32,r0,r10
                     31: */
                     32:        movl    r11,r9                  #save last cell for fixup at end.
                     33:        movl    4(r11),r11              #move to next cell
                     34:        bneq    loop                    #done indicated by 0 for next sdot
                     35:        tstl    r10                     #if carry zero no need to allocate
                     36:        beql    done                    #new bigit
                     37:        mcoml   r10,r3                  #test to see if neg 1.
                     38:        bneq    alloc                   #if not must allocate new cell.
                     39:        tstl    (r9)                    #make sure product isn't -2**30
                     40:        beql    alloc
                     41:        movl    r0,(r9)                 #save old lower half of product.
                     42:        brb     done
                     43: alloc: callf   $4,_newdot              #otherwise allocate new bigit
                     44:        movl    r10,(r0)                #store carry
                     45:        movl    r0,4(r9)                #save new link cell
                     46: done:  movl    4(fp),r0
                     47:        ret

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