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[/] [eco32/] [trunk/] [fp/] [implementation/] [mmix/] [permu-heap.mms] - Blame information for rev 203

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Line No. Rev Author Line
1 15 hellwig
* Permutation generator a la Heap
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N  IS   5               $n$ (3, 4, 5, or 6)
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t  IS   $255
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j  IS   $0              $8j$
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k  IS   $1              $8k$
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ak IS   $2
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aj IS   $3
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   LOC  Data_Segment
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a  GREG @               Base address for $a_0\ldots a_{n-1}$
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A0 IS   @
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A1 IS   @+8
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A2 IS   @+16
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*  LOC  @+8*N           Space for $a_0\ldots a_{n-1}$
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   BYTE "11111111","22222222","33333333"
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   BYTE "44444444","55555555","66666666"
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   BYTE #a,0
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   LOC  (@+7)&-8        (align to octabyte)
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c  GREG @-8*3           Location of $c_0$
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   LOC  @-8*3+8*N       $8c_3\ldots 8c_{n-1}$, initially zero
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   OCTA -1              $c_n=-1$, a convenient sentinel
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u  GREG 0               Contents of $a_0$, except in inner loop
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v  GREG 0               Contents of $a_1$, except in inner loop
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w  GREG 0               Contents of $a_2$, except in inner loop
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   LOC  #100
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1H STCO 0,c,k           $c_k\gets 0$.
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   INCL k,8             $k\gets k+1$.
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0H LDO  j,c,k           $j\gets c_k$.
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   CMP  t,j,k
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   BZ   t,1B            Loop if $c_k=k$.
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   BN   j,Done          Terminate if $c_k<0$ ($k=n$).
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   LDO  ak,a,k          Fetch $a_k$.
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   ADD  t,j,8
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   STO  t,c,k           $c_k\gets j+1$.
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   AND  t,k,#8
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   CSZ  j,t,0           Set $j\gets 0$ if $k$ is even.
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   LDO  aj,a,j          Fetch $a_j$.
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   STO  ak,a,j          Replace it by $a_k$.
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   CSZ  u,j,ak          Set $u\gets a_k$ if $j=0$.
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   SUB  j,j,8           $j\gets j-1$.
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   CSZ  v,j,ak          Set $v\gets a_k$ if $j=0$.
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   SUB  j,j,8           $j\gets j-1$.
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   CSZ  w,j,ak          Set $w\gets a_k$ if $j=0$.
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   STO  aj,a,k          Replace $a_k$ by what was $a_j$.
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In PUSHJ 0,Visit
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   STO   v,A0           $a_0\gets v$.
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   STO   u,A1           $a_1\gets u$.
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   PUSHJ 0,Visit
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   STO   w,A0           $a_0\gets w$.
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   STO   v,A2           $a_2\gets v$.
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   PUSHJ 0,Visit
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   STO   u,A0           $a_0\gets u$.
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   STO   w,A1           $a_1\gets w$.
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   PUSHJ 0,Visit
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   STO   v,A0           $a_0\gets v$.
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   STO   u,A2           $a_2\gets u$.
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   PUSHJ 0,Visit
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   STO   w,A0           $a_0\gets w$.
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   STO   v,A1           $a_1\gets v$.
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   PUSHJ 0,Visit
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   SET   t,u            Swap $u\leftrightarrow w$.
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   SET   u,w
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   SET   w,t
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   SET   k,8*3          $k\gets3$.
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   JMP   0B
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Visit LDA  t,A0
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      TRAP 0,Fputs,StdOut
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      POP
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Main  LDO  u,A0
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      LDO  v,A1
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      LDO  w,A2
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      JMP  In
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Done  TRAP 0,Halt,0

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