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Diffstat (limited to 'opencores/8b10b/encode_8b10b.v')
| -rw-r--r-- | opencores/8b10b/encode_8b10b.v | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/opencores/8b10b/encode_8b10b.v b/opencores/8b10b/encode_8b10b.v new file mode 100644 index 000000000..c1f09b9ce --- /dev/null +++ b/opencores/8b10b/encode_8b10b.v @@ -0,0 +1,120 @@ +// Chuck Benz, Hollis, NH Copyright (c)2002 +// +// The information and description contained herein is the +// property of Chuck Benz. +// +// Permission is granted for any reuse of this information +// and description as long as this copyright notice is +// preserved. Modifications may be made as long as this +// notice is preserved. + +// per Widmer and Franaszek + +module encode_8b10b (datain, dispin, dataout, dispout) ; + input [8:0] datain ; + input dispin ; // 0 = neg disp; 1 = pos disp + output [9:0] dataout ; + output dispout ; + + + wire ai = datain[0] ; + wire bi = datain[1] ; + wire ci = datain[2] ; + wire di = datain[3] ; + wire ei = datain[4] ; + wire fi = datain[5] ; + wire gi = datain[6] ; + wire hi = datain[7] ; + wire ki = datain[8] ; + + wire aeqb = (ai & bi) | (!ai & !bi) ; + wire ceqd = (ci & di) | (!ci & !di) ; + wire l22 = (ai & bi & !ci & !di) | + (ci & di & !ai & !bi) | + ( !aeqb & !ceqd) ; + wire l40 = ai & bi & ci & di ; + wire l04 = !ai & !bi & !ci & !di ; + wire l13 = ( !aeqb & !ci & !di) | + ( !ceqd & !ai & !bi) ; + wire l31 = ( !aeqb & ci & di) | + ( !ceqd & ai & bi) ; + + // The 5B/6B encoding + + wire ao = ai ; + wire bo = (bi & !l40) | l04 ; + wire co = l04 | ci | (ei & di & !ci & !bi & !ai) ; + wire do = di & ! (ai & bi & ci) ; + wire eo = (ei | l13) & ! (ei & di & !ci & !bi & !ai) ; + wire io = (l22 & !ei) | + (ei & !di & !ci & !(ai&bi)) | // D16, D17, D18 + (ei & l40) | + (ki & ei & di & ci & !bi & !ai) | // K.28 + (ei & !di & ci & !bi & !ai) ; + + // pds16 indicates cases where d-1 is assumed + to get our encoded value + wire pd1s6 = (ei & di & !ci & !bi & !ai) | (!ei & !l22 & !l31) ; + // nds16 indicates cases where d-1 is assumed - to get our encoded value + wire nd1s6 = ki | (ei & !l22 & !l13) | (!ei & !di & ci & bi & ai) ; + + // ndos6 is pds16 cases where d-1 is + yields - disp out - all of them + wire ndos6 = pd1s6 ; + // pdos6 is nds16 cases where d-1 is - yields + disp out - all but one + wire pdos6 = ki | (ei & !l22 & !l13) ; + + + // some Dx.7 and all Kx.7 cases result in run length of 5 case unless + // an alternate coding is used (referred to as Dx.A7, normal is Dx.P7) + // specifically, D11, D13, D14, D17, D18, D19. + wire alt7 = fi & gi & hi & (ki | + (dispin ? (!ei & di & l31) : (ei & !di & l13))) ; + + + wire fo = fi & ! alt7 ; + wire go = gi | (!fi & !gi & !hi) ; + wire ho = hi ; + wire jo = (!hi & (gi ^ fi)) | alt7 ; + + // nd1s4 is cases where d-1 is assumed - to get our encoded value + wire nd1s4 = fi & gi ; + // pd1s4 is cases where d-1 is assumed + to get our encoded value + wire pd1s4 = (!fi & !gi) | (ki & ((fi & !gi) | (!fi & gi))) ; + + // ndos4 is pd1s4 cases where d-1 is + yields - disp out - just some + wire ndos4 = (!fi & !gi) ; + // pdos4 is nd1s4 cases where d-1 is - yields + disp out + wire pdos4 = fi & gi & hi ; + + // only legal K codes are K28.0->.7, K23/27/29/30.7 + // K28.0->7 is ei=di=ci=1,bi=ai=0 + // K23 is 10111 + // K27 is 11011 + // K29 is 11101 + // K30 is 11110 - so K23/27/29/30 are ei & l31 + wire illegalk = ki & + (ai | bi | !ci | !di | !ei) & // not K28.0->7 + (!fi | !gi | !hi | !ei | !l31) ; // not K23/27/29/30.7 + + // now determine whether to do the complementing + // complement if prev disp is - and pd1s6 is set, or + and nd1s6 is set + wire compls6 = (pd1s6 & !dispin) | (nd1s6 & dispin) ; + + // disparity out of 5b6b is disp in with pdso6 and ndso6 + // pds16 indicates cases where d-1 is assumed + to get our encoded value + // ndos6 is cases where d-1 is + yields - disp out + // nds16 indicates cases where d-1 is assumed - to get our encoded value + // pdos6 is cases where d-1 is - yields + disp out + // disp toggles in all ndis16 cases, and all but that 1 nds16 case + + wire disp6 = dispin ^ (ndos6 | pdos6) ; + + wire compls4 = (pd1s4 & !disp6) | (nd1s4 & disp6) ; + assign dispout = disp6 ^ (ndos4 | pdos4) ; + + assign dataout = {(jo ^ compls4), (ho ^ compls4), + (go ^ compls4), (fo ^ compls4), + (io ^ compls6), (eo ^ compls6), + (do ^ compls6), (co ^ compls6), + (bo ^ compls6), (ao ^ compls6)} ; + +endmodule |