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@ -1,7 +1,31 @@
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// From Eddie Hung
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// extracted from: https://github.com/eddiehung/vtr-with-yosys/blob/vtr7-with-yosys/vtr_flow/misc/yosys_models.v#L220
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// revised by Andre DeHon
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// further revised by David Shah
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/*
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* yosys -- Yosys Open SYnthesis Suite
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*
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* Copyright (C) 2012 Clifford Wolf <clifford@clifford.at>
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* 2019 Eddie Hung <eddie@fpgeh.com>
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* 2019 David Shah <dave@ds0.me>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* ---
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*
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* Tech-mapping rules for decomposing arbitrarily-sized $mul cells
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* into an equivalent collection of smaller `DSP_NAME cells (with the
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* same interface as $mul) no larger than `DSP_[AB]_MAXWIDTH, attached
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* to $shl and $add cells.
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*
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*/
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`ifndef DSP_A_MAXWIDTH
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$error("Macro DSP_A_MAXWIDTH must be defined");
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`endif
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@ -125,6 +149,9 @@ module \$__mul (A, B, Y);
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.B(B),
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.Y(partial[i])
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);
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// TODO: Currently a 'cascade' approach to summing the partial
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// products is taken here, but a more efficient 'binary
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// reduction' approach also exists...
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assign partial_sum[i] = (partial[i] << i*(`DSP_A_MAXWIDTH-sign_headroom)) + partial_sum[i-1];
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end
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@ -182,6 +209,9 @@ module \$__mul (A, B, Y);
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.B({{sign_headroom{1'b0}}, B[i*(`DSP_B_MAXWIDTH-sign_headroom) +: `DSP_B_MAXWIDTH-sign_headroom]}),
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.Y(partial[i])
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);
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// TODO: Currently a 'cascade' approach to summing the partial
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// products is taken here, but a more efficient 'binary
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// reduction' approach also exists...
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assign partial_sum[i] = (partial[i] << i*(`DSP_B_MAXWIDTH-sign_headroom)) + partial_sum[i-1];
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end
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