Abstract:
A programmable logic structure is disclosed that has a set of dedicated lines which extend internally throughout different dedicated logic cells within a logic and routing block (LRB), extend from a previous logic routing block to the present logic and routing block, or extend from the present logic and routing block to the next logic and routing block. One set of dedicated lines from a first logic and routing block can be stitched to another set of dedicated lines of a second logic and routing block for extending the reach as well as bypassing a logic and routing block, or bypassing a dedicated logic cell in the same logic and routing block. The dedicated lines between logic and routing blocks allow a logic and routing block to receive more inputs from its own switch box or to drive more outputs than provided by the logic and routing block as specified by a given function.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates generally to integrated circuits (ICs) such as field programmable gate arrays (FPGAs), and more particularly to enhancing connections between functional blocks in programmable logic devices. 
     2. Description of Related Art 
     Field programmable gate arrays are often selected by design engineers to provide a flexible approach in programming and re-programming integrated circuits in order to accommodate a system specification, correct errors in the system, or make improvements to the system by reprogramming the FPGA. One conventional field programmable gate array architecture is implemented using groups of look-up tables and programmable interconnect circuits. While the look-up tables and sequential elements are connected to each other, the connections to the groups of look-up tables typically originate from a switch box located in each group of the look-up table. A hierarchical interconnect structure connects to elements in a look-up table through a switch box, thereby serving as the primary source of connecting look-up tables from one logic block to another logic block. The inputs to the look-up tables are therefore generated primarily from the switch box. The look-up table outputs are directly fed to other look-up tables as well as the elements within the look-up tables, but the connections inputs in other look-up tables are made through the switch box. 
     In another conventional structure, a majority of the inputs required for performing all functionality of configurable logic blocks are typically restricted to inputs associated with a particular configurable logic block, other than through the use of the switch box. The same is true for outputs of a particular configurable logic block which are restricted to within the configurable logic block other than through the use of the switch box. 
     Accordingly, it is desirable to design a programmable logic structure that enhances the connectivity of inputs and outputs in a programmable logic and routing module without boundary limitations. 
     SUMMARY OF THE INVENTION 
     The present invention describes a programmable logic structure that has a set of dedicated lines which extend internally throughout different dedicated logic cells within a logic and routing block (LRB), extend from a previous logic routing block to the present logic and routing block, or extend from the present logic and routing block to the next logic and routing block. One set of dedicated lines from a first logic and routing block can be stitched to another set of dedicated lines of a second logic and routing block for extending the reach as well as bypassing a logic and routing block, or bypassing a dedicated logic cell in the same logic and routing block. The dedicated lines between logic and routing blocks allow a logic and routing block to receive more inputs from its own switch box or to drive more outputs than provided by the logic and routing block as specified by a given function. 
     Broadly stated, claim  1  recites a programmable logic structure comprising a first logic and routing block; a second logic and routing block; and first one or more dedicated lines extending through the first logic and routing block and the second logic and routing block. 
     Advantageously, the present invention provides a design for signals to cross a logic and routing block boundary. In addition, the present invention advantageously allows signals to skip a particular logic and routing block so that inputs and outputs need not be in contiguous locations. Furthermore, the present invention advantageously allows the creation of large wide logic structures in which functional blocks (e.g. function generators, multiplexers, wide gates, and wide multiplexers) with different inputs but common control signals in producing the benefits of not having to use a switch box in order to distribute control signals to all of the functional blocks in a given structure, thereby significantly reducing the burden on the switch box to distribute high fanout control and data lines in a programmable logic device. 
     Other structures and methods are disclosed in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims. These and other embodiments, features, aspects, and advantages of the invention will become better understood with regard to the following description, appended claims and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a logic diagram illustrating a partial dedicated logic cell employing one or more dedicated lines in a logic and routing block in accordance with the present invention. 
         FIG. 2  is an architectural diagram illustrating a logic and routing block having multiple dedicated logic cells in a logic and routing block in accordance with the present invention. 
         FIG. 3  is a logic diagram illustrating a dedicated logic cell employing eight dedicated lines in accordance with the present invention. 
         FIG. 4  is a logic diagram illustrating the first implementation of a dedicated logic cell that operates as an 8-input function generator in accordance with the present invention. 
         FIG. 5  is a logic diagram illustrating the second implementation of a dedicated logic cell that serves as a 7-input function generator in accordance with the present invention. 
         FIG. 6  is a logic diagram illustrating the third implementation of a dedicated logic cell employing four 2:1 multiplexers with a common select line in accordance with the present invention. 
         FIG. 7  is a logic diagram illustrating the fourth implementation of using eight dedicated lines in large multiplexers in accordance with the present invention. 
         FIG. 8  is a logic diagram illustrating the fifth implementation of using dedicated lines as control lines in a configurable sequential circuit in accordance with the present invention. 
         FIG. 9  is a logic diagram illustrating the sixth implementation of a programmable logic circuit with shared dedicated lines as control lines among multiple macro blocks in accordance with the present invention. 
         FIG. 10  is a flow diagram illustrating the process of operating one or more dedicated lines in a logic and routing block in accordance with the present invention. 
     
    
    
     Reference symbols or names are used in the Figures to indicate certain components, aspects or features therein, with reference symbols common to more than one Figure indicating like components, aspects or features shown therein. 
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , there is shown a logic diagram illustrating a partial dedicated logic cell  100  employing the use of one or more dedicated lines  110  for connections between logic and routing blocks (LRBs), or connections from one dedicated logic cell (DLC) to another dedicated logic cell. The one or more dedicated lines  110  enter the partial dedicated logic cell  100  in a present logic and routing block through a control input line  111 . The first multiplexer  120  has a first input connected to the control input  111  for receiving the one or more dedicated lines  110 , a second input connected to line inputs  115  from a look-up table, a third input connected to a Vdd  121 , and a fourth input connected a ground  122 , and an output  127  connected to an adjacent dedicated logic cell in the same logic and routing block. Configurable select lines  125  allow selection from one of the four inputs  110 ,  115 ,  121 , or  122  in the first multiplexer  120  for generating the output  127  to the adjacent dedicated logic cell in the same logic and routing block. The second multiplexer  130  has a first input connected to a control input  111  for receiving the one or more dedicated lines  110 , a second input connected to line inputs  115  from the look-up table, a third input connected to a Vdd  131 , and a fourth input connected to a ground  132 , and an output  137  connected to the next logic and routing block (or the next dedicated logic cell.) Configurable select lines  135  allow selection from one of the four inputs,  111 ,  115 ,  131 , or  132  in the second multiplexer  130  to the next logic and routing block. 
     The logic and routing blocks that provide the additional inputs need not be adjacent to the current logic and routing block where the function is implemented. The one or more dedicated lines can be used either as data or control signals. By deploying the one or more dedicated lines, the connectivity of a logic and routing block for enabling input and output connections can be made seamlessly irrespective of a logic and routing block boundary  140 . The one or more dedicated lines  110  connect between logic and routing blocks that allow a logic and routing block to receive inputs from other logic and routing blocks when a given function implemented in the logic and routing block requires more inputs than provided by the switchbox  250  in the logic and routing block. The one or more dedicated lines  110  also allow the logic and routing block to drive more outputs than provided by the present logic and routing block. 
     In this embodiment, the partial dedicated logic cell  100  employs eight dedicated lines  110  for each pair of dedicated logic cells. The eight dedicated lines  110  can be used as either data or control signal lines for various modes of operation. The eight dedicated lines are fed by eight outputs of a dedicated logic cell (not shown) or from a previous set of dedicated lines (not shown). Each dedicated line in the eight dedicated lines  110  can be tied to a high or low voltage. The eight dedicated lines  110  are fed to functional blocks to enable creation of larger functional blocks than permissible from a switch box, as shown in  FIG. 2 . For example, 6 and 7-input general purpose function generators (i.e., look-up tables or “LUTs”) and 8-input limited function generators are possible by using the dedicated input lines to provide inputs from other logic and routing blocks. 
     In  FIG. 2 , there is shown an architectural diagram illustrating a logic and routing block  200  comprising a first dedicated logic cell (DLC  0 )  210 , a second dedicated logic cell (DLC  1 )  220 , a third dedicated logic cell (DLC  2 )  230 , a fourth dedicated logic cell (DLC  3 )  240  and a switch box  250  for providing programmable switch matrices. A set of dedicated lines is used to interconnect between adjacent dedicated logic cells, either for connecting to adjacent dedicated logic cells within the logic and routing block, adjacent dedicated logic cells between the logic and routing block  200  and a previous logic and routing block, or adjacent dedicated logic cells between the logic routing block  200  and a next logic and routing block. A first set of eight dedicated lines  211  is connected from a previous dedicated logic cell  260  (not shown) to the first dedicated logic cell  210 . A second set of eight dedicated lines  212  is connected from the first dedicated logic cell DLC 0   210  to the second dedicated cell DLC 1   220 . A third set of dedicated lines  213  is connected from the second dedicated cell  220  to the next dedicated local cell  270  (not shown). A fourth set of eight dedicated lines  221  is connected from the previous dedicated logic cell  260  (not shown) to the third dedicated logic cell  230 . A fifth set of eight dedicated lines  222  is connected from the third dedicated logic cell  230  to the fourth dedicated logic cell  240 . A sixth set of eight dedicated lines  223  is connected from the fourth dedicated logic cell  240  to the next dedicated logic cell  270  (not shown). The switch box  250  functions as a source for feeding control of data signals to any one of the dedicated lines  211 ,  212 ,  213 ,  221 ,  222 , or  223 . While the first set of eight dedicated lines  211  and the fourth set of eight dedicated lines  221  are connected from the previous logic and cell block  260 , (not shown) the third set of eight dedicated lines  213  and the sixth set of eight dedicated lines  223  are connected to the next logic and cell block  270  (not shown). 
     The one ore more dedicated lines can be driven by the previous corresponding one or more dedicated lines as well as driving the next corresponding one or more dedicated lines, which would extend the distance of the dedicated lines. In effect, one set of dedicated lines can be connected (“stitched”) to another set of dedicated lines, as may be called for by a particular programmable logic device, for concatenating different sets of dedicated lines together that extend across different logic and routing blocks. 
     In  FIG. 3 , there is shown a logic diagram illustrating the first implementation of a dedicated logic cell  300  with eight dedicated lines  310 – 317 . The dedicated logic cell  300  comprises a first set of function generators, a first function generator (FG)  320 , a second function generator  322 , a third function generator  324 , and a fourth function generator  326  where each function generator has four inputs for receiving A[0]  301 , A[1]  302 , A[2]  303 , and A[3]  304  from the switch box  250 . The dedicated logic cell  300  comprises a second set of function generators, a fifth function generator  330 , a sixth function generator  332 , a seventh function generator  334 , and an eighth function generator  336  where each function generator has four inputs for receiving B[0]  305 , B[1]  306 , B[2]  307 , and B[3]  308  from the switch box  250 . A first multiplexer  340  has a first input connected to an output of the first function generator  320 , a second input connected to the eighth dedicated line C 7   317 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. A second multiplexer  341  has a first input connected to an output of the second function generator  322 , a second input connected to the seventh dedicated line C 6   316 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. A third multiplexer  342  has a first input connected to an output of the third function generator  324 , a second input connected to the fifth dedicated line C 5   315 , a third input connected to a ground, a fourth input connected to a Vdd, and an output connected to the next DLC. A fourth multiplexer  343  has a first input connected to an output of the fourth function generator  326 , a second input connected to the fifth dedicated line C 4   314 , a third input connected to a Vdd, a fourth input connected to a ground, and an output to the next DLC. A fifth multiplexer  344  has a first input connected to an output of the fifth function generator  330 , a second input connected to the fourth dedicated line C 3   313 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. A sixth multiplexer  345  has a first input connected to an output of the sixth function generator  332 , a second input connected to the third dedicated line C 2   312 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. A seventh multiplexer  346  has a first input connected to an output of the seventh function generator  334 , a second input connected to the second dedicated line C 1   311 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. An eighth multiplexer  347  has a first input connected to an output of the eighth function generator  336 , a second input connected to the first dedicated line C 0   310 , a third input connected to a Vdd, a fourth input connected to a ground, and an output connected to the next DLC. 
     A corresponding set of multiplexers is connected to the respective one of the multiplexers  340 – 347  for generating outputs to logic and routing blocks. A ninth multiplexer  350  has a first input connected to the output of the first function generator  320 , a second input connected to the eighth dedicated line C 7   317 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to a logic and routing block. A tenth multiplexer  351  has a first input connected to the output of the second function generator  322 , a second input connected to the seventh dedicated line C 6   316 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. An eleventh multiplexer  352  has a first input connected to the output of the third function generator  324 , a second input connected to the sixth dedicated line C 5   315 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. A twelfth multiplexer  353  has a first input connected to the output of the fourth function generator  326 , a second input connected to the fifth dedicated line C 4   314 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. A thirteenth multiplexer  354  has a first input connected to the output of the fifth function generator  330 , a second input connected to the fourth dedicated line C 3   313 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. A fourteenth multiplexer  355  has a first input connected to the output of the sixth function generator  332 , a second input connected to the third dedicated line C 2   312 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. A fifteenth multiplexer  356  has a first input connected to the output of the seventh function generator  334 , a second input connected to the second dedicated line C 1   311 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. A sixteenth multiplexer  357  has a first input connected to the output of the eighth function generator  336 , a second input connected to the first dedicated line C 0   310 , a third input connected to a Vdd, a fourth input connected to a ground, and an output for connecting to the logic and routing block. 
     The following diagrams,  FIGS. 4 through 9 , show the different applications of adopting the use of the one or more dedicated lines. Turning now to  FIG. 4 , there is shown a logic diagram illustrating the first implementation of a dedicated logic cell  400  that operates as a 7-input function generator, which is equivalent to two 6-input look-up tables. The dedicated logic cell  400  employs dedicated lines C 0   410 , C 1   411 , C 2   412 , and C 3   413  that function as select lines to 4:1 multiplexers  430  and  440 . If the eight inputs are referred to as I[0:7], the first four inputs I[0:3] are supplied by either A[0:3]  401 – 404  or B[0:3]  405 – 408 , the fifth and sixth inputs are generated from C 0   412  and C 1   411 , and the sixth and seventh inputs are generated from C 2412  and C 3412 . A first 6-input look-up table in the logic dedicated cell  400  comprises a first function generator  420 , a second function generator  422 , a third function generator  424 , and a fourth function generator  426  that have outputs feeding into inputs of the 4:1 multiplexer  430 . Each of the first, second, third and fourth function generators  420 ,  422 ,  424 , and  426  have four inputs for receiving the incoming signals A[0:3]  401 – 404 . The dedicated lines C 2   412  and C 3   413  function as select lines to the 4:1 multiplexer  430  for selecting one of the inputs from either the first, second, third, or fourth function generator  420 ,  422 ,  424 ,  426 , as well as generating an output signal of OUT 0   435 . A second 6-input look-up table in the logic dedicated cell  400  comprises a fifth function generator  430 , a sixth function generator  432 , a seventh function generator  434 , and an eighth function generator  436  that have outputs feeding into inputs of the 4:1 multiplexer  440 . Each of the first, second, third and fourth function generators  430 ,  432 ,  434 , and  436  have four inputs for receiving the incoming signals B[0:3]  405 – 408 . The dedicated lines C 0   410  and C 1   411  function as select lines to the 4:1 multiplexer  440  for selecting one of the inputs from either the fifth, sixth, seventh, or eighth function generator  430 ,  432 ,  434 ,  436 , and generating an output signal of OUT 1   445 . 
     In  FIG. 5 , there is shown a logic diagram illustrating the second implementation of a dedicated logic cell  500  that serves as a 7-input function generator. If the seven inputs are referred to as I[0:6], the first four inputs I[0:3] are supplied by either A[0:3]  501 – 504  or B[0:3]  505 – 508 , the fifth input I[4] is generated from either a configurable select line C 0   510  or C 2   512 , the sixth input I[5] is generated from either a configurable select line C 1   511  or C 3   513 , and the seventh input I[6] is supplied by a configurable select line C 4   514 . The dedicated logic cell  500  comprises a first set of function generators having a first function generator  520 , a second function generator  522 , a third function generator  524 , and a fourth function generator  526  where each function generator has four inputs for receiving A[ 0 :3]  501 – 504  and an output connected to a 4:1 multiplexer  540 . The dedicated logic cell  500  comprises a second set of function generators having a fifth function generator  530 , a sixth function generator  532 , a seventh function generator  534 , and an eighth function generator  536  where each function generator has four inputs for receiving B[0:3]  505 – 508  and an output connected to the 4:1 multiplexer  550 . A third multiplexer  560  has a first input connected to the output of the first 4:1 multiplexer  540 , a second input connected to the output of the second 4:1 multiplexer  550 , and a third input connected to the dedicated line C 4   514  and an output  570 . 
       FIG. 6  shows a logic diagram illustrating the third implementation of a dedicated logic cell  600  employing four 2:1 multiplexers with a common select line. A dedicated line  610  C 0  functions as a common select line that runs through all four 2:1 multiplexers  640 ,  642 ,  644  and  646 . The dedicated logic cell  600  comprises a first set of function generators having a first function generator  620 , a second function generator  622 , a third function generator  624 , and a fourth function generator  626  where each function generator has four inputs for receiving A[0:3]  601 – 604 . The dedicated logic cell  600  comprises a second set of function generators having a fifth function generator  630 , a sixth function generator  632 , a seventh function generator  634 , and an eighth function generator  636  where each function generator has four inputs for receiving B[0:3]  605 – 608 . A first 2:1 multiplexer  640  has a first input for receiving the A[0]  601  and a second input for receiving the B[0]  605 , and generating an OUT[0]  650 . A second 2:1 multiplexer  642  has a first input for receiving the A[1]  602  and a second input for receiving the B[ 1 ]  606 , and generating an OUT[1]  652 . A third 2:1 multiplexer  644  has a first input for receiving the A[2]  603  and a second input for receiving the B[2]  607 , and generating an out[2]  654 . A fourth 2:1 multiplexer  646  has a first input for receiving the A[3]  604  and a second input for receiving the B[3]  607 , and generating an OUT[3]  656 . 
       FIG. 7  is a logic diagram illustrating the fourth implementation of using eight dedicated lines in large multiplexer circuits  700 . The eight dedicated lines, C 0   710 , C 1   711 , C 2   712 , C 3   713 , C 4   714 , C 5   715 , C 6   716 , and C 7   717 , serve as select lines or control lines for multiplexers  720 ,  730 ,  740 , and  750 . The first multiplexer  720  has first inputs for receiving A[0:3]  701 – 704  and second inputs for receiving B[0:3]  705 – 708 . The second multiplexer  730  has first inputs for receiving A[0:3]  701 – 704  and second inputs for receiving B[0:3]  705 – 708 . The dedicated lines C 0   710 , C 1   711 , and C 2   712  function as select lines S 0 , S 1 , and S 2 , respectively, for both the first and second multiplexers  720  and  730 . The three select lines S 0 , S 1 , and S 3  provide the capability to the first and second multiplexers  720  and  730  to function as 8:1 multiplexers, where one of the eight inputs will be selected for sending to the output. Two multiplexer decode logics  730  and  740  operate to decode the inputs C 3   713 , C 4   714 , C 5   715 , C 6   716 , and C 7   717 . The dedicated lines C 3   713 , C 4   714 , C 5   715 , C 6   716 , C 7   717  function as select lines S 3 , S 4 , S 5 , S 6 , S 7 , respectively, for both the two multiplexer decode logics  730  and  740 . A first chaining logic  760  has a first input connected to the output of the first 8:1 multiplexer  720 , a second input connected to a previous multiplexer chaining multiplexer (not shown), a third input connected to the output of the first multiplexer decode logic  740 , and an output. A second chaining logic  770  has a first input connected to the output of the second 8:1 multiplexer  730 , a second input connected to the output of the first multiplexer chaining logic  760 , a third input connected to the output of the second multiplexer decode logic  750 , and an output. The combination of the eight dedicated lines, C 0   710 , C 1   711 , C 2   712 , C 3   713 , C 4   714 , C 5   715 , C 6   716 , and C 7   717 , provides 256 inputs into the circuit  700  that function as a 256:1 multiplexer. 
     In  FIG. 8 , there is shown a logic diagram illustrating the fifth implementation of using dedicated lines as control lines in a configurable sequential circuit  800 . A set of dedicated lines C 0   810 , C 1   811 , C 2   812 , and C 3   813 , provides control signals to a set of sequential elements sharing the same set of control signals that includes a reset (RST) signal, a clear (CLR) signal, a load enable (LDEN) signal, and a clock enable (CE) signal. In this embodiment, the configurable sequential circuit  800  comprises a first configurable sequential element  820 , a second configurable sequential element  830 , a third configurable sequential element  840 , a fourth configurable sequential element  850 , a fifth configurable sequential element  860 , a sixth configurable sequential element  870 , a seventh configurable sequential element  880 , and an eighth configurable sequential element  890 . The first dedicated line C 0   810  functions as a reset (RST) line, the second dedicated line C 1   811  functions as a clear (CLR) line, the third dedicated line C 2   812  functions as a load enable (LDEN) line, and the fourth dedicated line C 3   813  functions as a clocking enable (CE) line. A clock signal  815  is also fed into each of the configurable sequential elements,  820 ,  830 ,  840 ,  850 ,  860 ,  870 ,  880  and  890 . 
     The first configurable sequential element  820  has a first input for receiving IN[0], a second input for receiving a load data LD[ 0 ], and an output for generating an OUT[0]. When the LDEN signal  812  is asserted, the LD[ 0 ] line is active to load the data IN[0] into the first configurable sequential element  820  and generating the data to the OUT[0]. The second configurable sequential element  830  has a first input for receiving IN[1], a second input for receiving a load data LD[ 1 ], and an output for generating an OUT[1]. When the LDEN signal  812  is asserted, the LD[1] line is active to load the data IN[1] into the second configurable sequential element  830  and to generate the data to the OUT[1]. The third configurable sequential element  840  has a first input for receiving IN[2], a second input for receiving a load data LD[2], and an output for generating an OUT[2]. When the LDEN signal  812  is asserted, the LD[2] line is active to load the data IN[2] into the third configurable sequential element  840  and to generate the data to the OUT[2]. The fourth configurable sequential element  850  has a first input for receiving IN[3], a second input for receiving a load data LD[3], and an output for generating an OUT[3]. When the LDEN signal is asserted, the LD[3] signal  812  is active to load the data IN[3] into the fourth configurable sequential element  850  and to generate the data to the OUT[3]. The fifth configurable sequential element  860  has a first input for receiving IN[4], a second input for receiving a load data LD[4], and an output for generating an OUT[4]. When the LDEN signal  812  is asserted, the LD[4] line is active to load the data IN[4] into the fifth configurable sequential element  860  and to generate the data to the OUT[4]. The sixth configurable sequential element  870  has a first input for receiving IN[5], a second input for receiving a load data LD[5], and an output for generating an OUT[5]. When the LDEN signal  812  is asserted, the LD[5] line is active to load the data IN[5] into the sixth configurable sequential element  870  and to generate the data to the OUT[5]. The seventh configurable sequential element  880  has a first input for receiving IN[6], a second input for receiving a load data LD[6], and an output for generating an OUT[6]. When the LDEN signal  812  is asserted, the LD[6] line is active to load the data IN[6] into the seventh configurable sequential element  880  and to generate the data to the OUT[6]. The eighth configurable sequential element  890  has a first input for receiving IN[7], a second input for receiving a load data LD[7], and an output for generating an OUT[7]. When the LDEN signal  812  is asserted, the LD[7] line is active to load the data IN[7] into the eighth configurable sequential element  890  and to generate the data to the OUT[7]. 
       FIG. 9  is a logic diagram illustrating the sixth implementation of a programmable logic circuit  900  that shares dedicated lines as control lines among multiple macro blocks. Eight dedicated lines C 0   910 , C 1   911 , C 2   912 , C 3   913 , C 4   914 , C 5   915 , C 6   916 , C 7   917 , operate as control lines for larger functional macro blocks such as memory, multiplier and other such macro blocks such that a set of logic and routing blocks provide inputs, outputs and control signals. The eight dedicated lines C 0   910 , C 1   911 , C 2   912 , C 3   913 , C 4   914 , C 5   915 , C 6   916 , C 7   917  serve as common control signals that are shared among a first macro block  920  and a second macro block  930 . The eight dedicated lines C 0 –C 7   910 – 917  are connected to the first macro block  920  through a first dedicated logic cell  940 , and are connected to the second macro block  930  through a third dedicated logic cell  960 . The eight dedicated lines C 0 –C 7   910 – 917  are connected to the first dedicated logic cell  940 , a second dedicated logic cell  950 , the third dedicated logic cell  960 , and a fourth dedicated logic cell  970 . 
       FIG. 10  is a flow diagram illustrating the process of programming a programmable logic circuit having at least one or more dedicated lines in a logic and routing block  200 . At step  1010 , the process  1000  reads a particular programmable logic design selected by a user. The process  1000  identifies logic structures for implementation of the selected design at step  1020 . In a programmable logic circuit, a first dedicated logic cell in a first LRB receives a first set of dedicated lines at step  1030 . Depending on the logic functions to be implemented, there are several options in connecting the first set of dedicated lines in the first dedicated logic cell in the first LRB. With a first option at step  1040 , the first set of dedicated lines in the first dedicated logic cell in the first LRB are connected to a second dedicated logic cell in the same LRB. With a second option at step  1050 , the first set of dedicated lines in the first dedicated logic cell in the first LRB are connected to a second LRB. With a third option at step  1060 , the first set of dedicated logic cell in the first logic cells in the first LRB is stitched to a second set of dedicated lines for connection to an LRB adjacent to the first LRB, or skip over an adjacent LRB to a non-contiguous LRB relative to the first LRB. 
     Those skilled in the art can appreciate from the foregoing description that the broad techniques of the embodiments of the present invention can be implemented in a variety of forms. Therefore, while the embodiments of this invention have been described in connection with particular examples thereof, the true scope of the embodiments of the invention should not be so limited since other modifications, whether explicitly provided for by the specification or implied by the specification, will become apparent to the skilled practitioner upon a study of the drawings, specification, and following claims.