


LL_RIVER(5ICD)		    05/27/86		   LL_RIVER(5ICD)



NNNNAAAAMMMMEEEE
     ll_river - LDMC river routing facility

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
     ####iiiinnnncccclllluuuuddddeeee <<<<llllllll____rrrriiiivvvveeeerrrr....hhhh>>>>

     llllllll____rrrriiiivvvveeeerrrr ((((ttttvvvv1111,,,, ttttvvvv2222,,,, ooooppppttttssss))))
     TTTTEEEERRRRMMMMVVVVEEEECCCC ****ttttvvvv1111,,,, ****ttttvvvv2222;;;;
     ssssttttrrrruuuucccctttt llllllll____rrrriiiivvvveeeerrrr____ooooppppttttssss ****ooooppppttttssss;;;;


PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
     ttttvvvv1111     specifies a vector of pointers to TERM nodes.  The
	     terminals must be sorted on coordinate value.

     ttttvvvv2222     specifies another vector of pointers to TERM nodes.
	     The terminals denoted by this vector will be con-
	     nected to the terminals denoted by tv1.

     ooooppppttttssss    is a pointer to an ll_river_opts options structure.
	     If the default options are suitable, this parameter
	     may be NULL.  Otherwise, you must define a private
	     options structure and initialize it to
	     _D_E_F_A_U_L_T__R_I_V_E_R__O_P_T_S to guarantee forward software
	     compatibility.  Currently the supported options are:

	     ooooppppttttssss....sssshhhhiiiifffftttt
		     (default 0) If 1, the ll_river function will
		     compute a lateral translation (perpendicular
		     to the direction of the wires that are
		     created) of the terminals in _t_v_2, so as to
		     mimimize the total routing area.  The wires
		     are then layed down in accordance with the
		     modified position of the terminals.  This is
		     useful in case _t_v_2 corresponds to terminals
		     of a not yet placed cell, i.e. when _t_v_2 was
		     obtained from _m_g_e_t_t_e_r_m, but it is the
		     responsibility of the user to assure that
		     the cell is in fact placed in the computed
		     position afterwards.  This position is
		     stored in _o_p_t_s._t_x and _o_p_t_s._t_y respectively.

	     ooooppppttttssss....ppppllllaaaacccceeee
		     (default 0) The same as _o_p_t_s._s_h_i_f_t for the
		     direction paralel to the direction of the
		     wires.

	     ooooppppttttssss....ttttxxxx,,,, ooooppppttttssss....ttttyyyy
		     Output parameter, see _o_p_t_s._s_h_i_f_t and
		     _o_p_t_s._p_l_a_c_e .





		   The Nelsis IC Design System			1






LL_RIVER(5ICD)		    05/27/86		   LL_RIVER(5ICD)



DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     River routing can be used to connect cells of which the ter-
     minals do not align, but which can be connected in such a
     way that the wires do not cross each other.

     _L_l__r_i_v_e_r is the LDMC river routing primitive.  It connects
     subsequent terminals of tv1 to corresponding terminals of
     tv2 with the same layer.  The wires that are created are
     straight if the terminals align or consist of 3 pieces if
     they don't.

     _L_l__r_i_v_e_r operates for each layer separately.  Thus, wires in
     different layers can overlap or cross each other.

EEEEXXXXAAAAMMMMPPPPLLLLEEEE
     This example outlines how to abut 2 cells with a river rout-
     ing channel between them.	The actual position of the new
     cell is computed by the river router and the wiring is
     created, after which the cell is actually layed down:

     #include <stdldmc.h>
     #include <ll_river.h>
     ...
     {
	  static struct ll_river_opts opts = DEFAULT_RIVER_OPTS;
	  ...
	  opts.shift = 1;
	  opts.place = 1;
	  ...
	  ll_river (itv, mtv, &opts);
	  ...
	  tx = opts.tx + mp -> xl; /* compensate for origin */
	  ty = opts.ty + mp -> yb;
	  mc (inst_name, mp -> name, 0, 0, tx, ty, 0, 0, 0, 0, "");
	  ...
     }

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     ldmcintro(5ICD)
















2		   The Nelsis IC Design System



