An Automatic Approach to Generate Haste Code from Simulink ...

& VECTOR_16& VECTOR_17& VECTOR_32= type [0..2ˆ16-1]= type [0..2ˆ17-1]= type [0..2ˆ32-1]Table 4. Synthesis result comparisons of the same Simulinkmodel in different implementations. The designs have beenimplemented using a 180nm technology library.& datapath = main proc (& O ! chan VECTOR_32& A ? chan VECTOR_16& B ? chan VECTOR_16).begin// Internal channel declaration& Y1_6 : chan VECTOR_16 broad// ...// External function declaration& Sum = func (& A1 ? var VECTOR_16& A2 ? var VECTOR_16): VECTOR_16. import// ...// Haste shell description of each block& Sum_sh = proc (& Y1 ! chan VECTOR_17& A1 ? chan VECTOR_16& A2 ? chan VECTOR_16).begin& v_A1 : var VECTOR_16 := 0& v_A2 : var VECTOR_16 := 0|forever do( A1 ? v_A1 || A2 ? v_A2 ); Y1 ! Sum( .A1(v_A1), .A2(v_A2))odend// ...|// Block instance and connection// ...|| Sum_sh ( .Y1( Y1_6 ),.A1( Y1_8 ), .A2( Y1_3 ))// ...endFigure 12. Example of the Haste code generated for the mainprocedure.This model is quite complex, since it is composed of about150 blocks, including: about 30 16-bit wide multiplicationby constant values, 15 8-bit wide multipliers, and 30 16-bit wide adders. It has been used to develop a hand-writtenimplementation in Haste. Thanks to the collaboration withan industrial partner we had access to synthesis resultsof this asynchronous hand-written version and we couldcompare this with the Haste version generated by our tool.Comparisons for both versions are based on optimized prelayoutnetlists mapped onto the same technology library.The results of this analysis are reported in Tab. 4. Inthis table we compare the hand written Haste code withtwo versions of the automatically generated one: the first isDesign Hand written Automatic GeneratedTool TiDE 5.2 TiDE 5.2 TiDE 6.0Sequentialµm 2 32018 89792 11632Logic 138244 357368 152468Totalµm 2 173694 468746 164100Overhead — +170% -5.5%Coding time about 1 week 20 minutespassed through version 5.2 of TiDE flow, while the secondhas been processed with the new pre-release version (6.0).Unfortunately it was not possible to compile hand-writtenversion with the TiDE 6.0 flow, since it does not supportanymore some low level constructs available in the oldrelease. We can notice a number of differences between thethree versions proposed. The designs are not architecturallythe same, since the number of registers is not the same inall of them. This is due to the code generated (or written):• for the hand-written code, most of the blocks in theSimulink model have been implemented using Hastefunctions [15]. The number of blocks for which thedesigner decided to insert registers is small comparedto the total number of blocks.• for the TiDE 5.2 version, each block has registers onits inputs, which results in a high overhead, since manyof them are not required.• for the TiDE 6.0 version, the compiler automaticallydecides the minimum number of registers required forthe described circuit.For the reasons above, we can conclude that at the momentthe code generated automatically and compiled with theTiDE 6.0 version represents the lower bound with respect tothe number of registers. On the other hand the same designcompiled with the 5.2 version is the upper bound, since thegranularity at the Simulink level is very fine-grained.Since our work was targeted for the TiDE 6.0 version,the results shown in Tab. 4 are promising. The achievedimplementation based on this new flow 2 requires less areathan the hand-written counterpart.In order to guarantee the circuit equivalence, we simulatethe netlist generated from TiDE 5.2 of the hand-writtencode and the automatically generated one with the sametest bench. Since we had not access to the testbenchesused to develop the original version, we had to create anew tesbench based on the data streams derived from theSimulink simulation. Because we are still working on afeature which generates input patterns directly from the2. At the moment TiDE 6.0 is not complete; indeed some operationshave to be performed by hand, but the optimizations performed by the toolare stable and will not change significantly with the official tool release.9