diff options
Diffstat (limited to 'kernel/ff.h')
-rw-r--r-- | kernel/ff.h | 325 |
1 files changed, 211 insertions, 114 deletions
diff --git a/kernel/ff.h b/kernel/ff.h index e555e15f1..a06eb0a1c 100644 --- a/kernel/ff.h +++ b/kernel/ff.h @@ -25,55 +25,141 @@ YOSYS_NAMESPACE_BEGIN +// Describes a flip-flop or a latch. +// +// If has_gclk, this is a formal verification FF with implicit global clock: +// Q is simply previous cycle's D. +// +// Otherwise, the FF/latch can have any number of features selected by has_* +// attributes that determine Q's value (in order of decreasing priority): +// +// - on start, register is initialized to val_init +// - if has_sr is present: +// - sig_clr is per-bit async clear, and sets the corresponding bit to 0 +// if active +// - sig_set is per-bit async set, and sets the corresponding bit to 1 +// if active +// - if has_arst is present: +// - sig_arst is whole-reg async reset, and sets the whole register to val_arst +// - if has_aload is present: +// - sig_aload is whole-reg async load (aka latch gate enable), and sets the whole +// register to sig_ad +// - if has_clk is present, and we're currently on a clock edge: +// - if has_ce is present and ce_over_srst is true: +// - ignore clock edge (don't change value) unless sig_ce is active +// - if has_srst is present: +// - sig_srst is whole-reg sync reset and sets the register to val_srst +// - if has_ce is present and ce_over_srst is false: +// - ignore clock edge (don't change value) unless sig_ce is active +// - set whole reg to sig_d +// - if nothing of the above applies, the reg value remains unchanged +// +// Since the yosys FF cell library isn't fully generic, not all combinations +// of the features above can be supported: +// +// - only one of has_srst, has_arst, has_sr can be used +// - if has_clk is used together with has_aload, then has_srst, has_arst, +// has_sr cannot be used +// +// The valid feature combinations are thus: +// +// - has_clk + optional has_ce [dff/dffe] +// - has_clk + optional has_ce + has_arst [adff/adffe] +// - has_clk + optional has_ce + has_aload [aldff/aldffe] +// - has_clk + optional has_ce + has_sr [dffsr/dffsre] +// - has_clk + optional has_ce + has_srst [sdff/sdffe/sdffce] +// - has_aload [dlatch] +// - has_aload + has_arst [adlatch] +// - has_aload + has_sr [dlatchsr] +// - has_sr [sr] +// - has_arst [does not correspond to a native cell, represented as dlatch with const D input] +// - empty set [not a cell — will be emitted as a simple direct connection] + struct FfData { FfInitVals *initvals; + // The FF output. SigSpec sig_q; + // The sync data input, present if has_clk or has_gclk. SigSpec sig_d; + // The async data input, present if has_aload. + SigSpec sig_ad; + // The sync clock, present if has_clk. SigSpec sig_clk; - SigSpec sig_en; + // The clock enable, present if has_ce. + SigSpec sig_ce; + // The async load enable, present if has_aload. + SigSpec sig_aload; + // The async reset, preset if has_arst. SigSpec sig_arst; + // The sync reset, preset if has_srst. SigSpec sig_srst; + // The async clear (per-lane), present if has_sr. SigSpec sig_clr; + // The async set (per-lane), present if has_sr. SigSpec sig_set; - bool has_d; + // True if this is a clocked (edge-sensitive) flip-flop. bool has_clk; - bool has_en; + // True if this is a $ff, exclusive with every other has_*. + bool has_gclk; + // True if this FF has a clock enable. Depends on has_clk. + bool has_ce; + // True if this FF has async load function — this includes D latches. + // If this and has_clk are both set, has_arst and has_sr cannot be set. + bool has_aload; + // True if this FF has sync set/reset. Depends on has_clk, exclusive + // with has_arst, has_sr, has_aload. bool has_srst; + // True if this FF has async set/reset. Exclusive with has_srst, + // has_sr. If this and has_clk are both set, has_aload cannot be set. bool has_arst; + // True if this FF has per-bit async set + clear. Exclusive with + // has_srst, has_arst. If this and has_clk are both set, has_aload + // cannot be set. bool has_sr; + // If has_ce and has_srst are both set, determines their relative + // priorities: if true, inactive ce disables srst; if false, srst + // operates independent of ce. bool ce_over_srst; + // True if this FF is a fine cell, false if it is a coarse cell. + // If true, width must be 1. bool is_fine; + // Polarities, corresponding to sig_*. True means active-high, false + // means active-low. bool pol_clk; - bool pol_en; + bool pol_ce; + bool pol_aload; bool pol_arst; bool pol_srst; bool pol_clr; bool pol_set; + // The value loaded by sig_arst. Const val_arst; + // The value loaded by sig_srst. Const val_srst; + // The initial value at power-up. Const val_init; - Const val_d; - bool d_is_const; + // The FF data width in bits. int width; dict<IdString, Const> attributes; FfData(FfInitVals *initvals = nullptr, Cell *cell = nullptr) : initvals(initvals) { width = 0; - has_d = true; has_clk = false; - has_en = false; + has_gclk = false; + has_ce = false; + has_aload = false; has_srst = false; has_arst = false; has_sr = false; ce_over_srst = false; is_fine = false; pol_clk = false; - pol_en = false; + pol_aload = false; + pol_ce = false; pol_arst = false; pol_srst = false; pol_clr = false; pol_set = false; - d_is_const = false; if (!cell) return; @@ -88,20 +174,26 @@ struct FfData { std::string type_str = cell->type.str(); if (cell->type.in(ID($ff), ID($dff), ID($dffe), ID($dffsr), ID($dffsre), ID($adff), ID($adffe), ID($sdff), ID($sdffe), ID($sdffce), ID($dlatch), ID($adlatch), ID($dlatchsr), ID($sr))) { - if (cell->type == ID($sr)) { - has_d = false; - } else { + if (cell->type == ID($ff)) { + has_gclk = true; sig_d = cell->getPort(ID::D); - } - if (!cell->type.in(ID($ff), ID($dlatch), ID($adlatch), ID($dlatchsr), ID($sr))) { + } else if (cell->type == ID($sr)) { + // No data input at all. + } else if (cell->type.in(ID($dlatch), ID($adlatch), ID($dlatchsr))) { + has_aload = true; + sig_aload = cell->getPort(ID::EN); + pol_aload = cell->getParam(ID::EN_POLARITY).as_bool(); + sig_ad = cell->getPort(ID::D); + } else { has_clk = true; sig_clk = cell->getPort(ID::CLK); pol_clk = cell->getParam(ID::CLK_POLARITY).as_bool(); + sig_d = cell->getPort(ID::D); } - if (cell->type.in(ID($dffe), ID($dffsre), ID($adffe), ID($sdffe), ID($sdffce), ID($dlatch), ID($adlatch), ID($dlatchsr))) { - has_en = true; - sig_en = cell->getPort(ID::EN); - pol_en = cell->getParam(ID::EN_POLARITY).as_bool(); + if (cell->type.in(ID($dffe), ID($dffsre), ID($adffe), ID($sdffe), ID($sdffce))) { + has_ce = true; + sig_ce = cell->getPort(ID::EN); + pol_ce = cell->getParam(ID::EN_POLARITY).as_bool(); } if (cell->type.in(ID($dffsr), ID($dffsre), ID($dlatchsr), ID($sr))) { has_sr = true; @@ -125,10 +217,10 @@ struct FfData { } } else if (cell->type == ID($_FF_)) { is_fine = true; + has_gclk = true; sig_d = cell->getPort(ID::D); } else if (type_str.substr(0, 5) == "$_SR_") { is_fine = true; - has_d = false; has_sr = true; pol_set = type_str[5] == 'P'; pol_clr = type_str[6] == 'P'; @@ -146,9 +238,9 @@ struct FfData { has_clk = true; pol_clk = type_str[7] == 'P'; sig_clk = cell->getPort(ID::C); - has_en = true; - pol_en = type_str[8] == 'P'; - sig_en = cell->getPort(ID::E); + has_ce = true; + pol_ce = type_str[8] == 'P'; + sig_ce = cell->getPort(ID::E); } else if (type_str.substr(0, 6) == "$_DFF_" && type_str.size() == 10) { is_fine = true; sig_d = cell->getPort(ID::D); @@ -169,9 +261,9 @@ struct FfData { pol_arst = type_str[8] == 'P'; sig_arst = cell->getPort(ID::R); val_arst = type_str[9] == '1' ? State::S1 : State::S0; - has_en = true; - pol_en = type_str[10] == 'P'; - sig_en = cell->getPort(ID::E); + has_ce = true; + pol_ce = type_str[10] == 'P'; + sig_ce = cell->getPort(ID::E); } else if (type_str.substr(0, 8) == "$_DFFSR_" && type_str.size() == 12) { is_fine = true; sig_d = cell->getPort(ID::D); @@ -194,9 +286,9 @@ struct FfData { pol_clr = type_str[11] == 'P'; sig_set = cell->getPort(ID::S); sig_clr = cell->getPort(ID::R); - has_en = true; - pol_en = type_str[12] == 'P'; - sig_en = cell->getPort(ID::E); + has_ce = true; + pol_ce = type_str[12] == 'P'; + sig_ce = cell->getPort(ID::E); } else if (type_str.substr(0, 7) == "$_SDFF_" && type_str.size() == 11) { is_fine = true; sig_d = cell->getPort(ID::D); @@ -217,9 +309,9 @@ struct FfData { pol_srst = type_str[9] == 'P'; sig_srst = cell->getPort(ID::R); val_srst = type_str[10] == '1' ? State::S1 : State::S0; - has_en = true; - pol_en = type_str[11] == 'P'; - sig_en = cell->getPort(ID::E); + has_ce = true; + pol_ce = type_str[11] == 'P'; + sig_ce = cell->getPort(ID::E); } else if (type_str.substr(0, 9) == "$_SDFFCE_" && type_str.size() == 14) { is_fine = true; sig_d = cell->getPort(ID::D); @@ -230,32 +322,35 @@ struct FfData { pol_srst = type_str[10] == 'P'; sig_srst = cell->getPort(ID::R); val_srst = type_str[11] == '1' ? State::S1 : State::S0; - has_en = true; - pol_en = type_str[12] == 'P'; - sig_en = cell->getPort(ID::E); + has_ce = true; + pol_ce = type_str[12] == 'P'; + sig_ce = cell->getPort(ID::E); ce_over_srst = true; } else if (type_str.substr(0, 9) == "$_DLATCH_" && type_str.size() == 11) { is_fine = true; - sig_d = cell->getPort(ID::D); - has_en = true; - pol_en = type_str[9] == 'P'; - sig_en = cell->getPort(ID::E); + has_aload = true; + sig_ad = cell->getPort(ID::D); + has_aload = true; + pol_aload = type_str[9] == 'P'; + sig_aload = cell->getPort(ID::E); } else if (type_str.substr(0, 9) == "$_DLATCH_" && type_str.size() == 13) { is_fine = true; - sig_d = cell->getPort(ID::D); - has_en = true; - pol_en = type_str[9] == 'P'; - sig_en = cell->getPort(ID::E); + has_aload = true; + sig_ad = cell->getPort(ID::D); + has_aload = true; + pol_aload = type_str[9] == 'P'; + sig_aload = cell->getPort(ID::E); has_arst = true; pol_arst = type_str[10] == 'P'; sig_arst = cell->getPort(ID::R); val_arst = type_str[11] == '1' ? State::S1 : State::S0; } else if (type_str.substr(0, 11) == "$_DLATCHSR_" && type_str.size() == 15) { is_fine = true; - sig_d = cell->getPort(ID::D); - has_en = true; - pol_en = type_str[11] == 'P'; - sig_en = cell->getPort(ID::E); + has_aload = true; + sig_ad = cell->getPort(ID::D); + has_aload = true; + pol_aload = type_str[11] == 'P'; + sig_aload = cell->getPort(ID::E); has_sr = true; pol_set = type_str[12] == 'P'; pol_clr = type_str[13] == 'P'; @@ -264,17 +359,13 @@ struct FfData { } else { log_assert(0); } - if (has_d && sig_d.is_fully_const()) { - d_is_const = true; - val_d = sig_d.as_const(); - if (has_en && !has_clk && !has_sr && !has_arst) { - // Plain D latches with const D treated specially. - has_en = has_d = false; - has_arst = true; - sig_arst = sig_en; - pol_arst = pol_en; - val_arst = val_d; - } + if (has_aload && !has_clk && !has_sr && !has_arst && sig_ad.is_fully_const()) { + // Plain D latches with const D treated specially. + has_aload = false; + has_arst = true; + sig_arst = sig_aload; + pol_arst = pol_aload; + val_arst = sig_ad.as_const(); } } @@ -282,19 +373,22 @@ struct FfData { FfData slice(const std::vector<int> &bits) { FfData res(initvals); res.sig_clk = sig_clk; - res.sig_en = sig_en; + res.sig_ce = sig_ce; + res.sig_aload = sig_aload; res.sig_arst = sig_arst; res.sig_srst = sig_srst; - res.has_d = has_d; res.has_clk = has_clk; - res.has_en = has_en; + res.has_gclk = has_gclk; + res.has_ce = has_ce; + res.has_aload = has_aload; res.has_arst = has_arst; res.has_srst = has_srst; res.has_sr = has_sr; res.ce_over_srst = ce_over_srst; res.is_fine = is_fine; res.pol_clk = pol_clk; - res.pol_en = pol_en; + res.pol_ce = pol_ce; + res.pol_aload = pol_aload; res.pol_arst = pol_arst; res.pol_srst = pol_srst; res.pol_clr = pol_clr; @@ -302,8 +396,10 @@ struct FfData { res.attributes = attributes; for (int i : bits) { res.sig_q.append(sig_q[i]); - if (has_d) + if (has_clk || has_gclk) res.sig_d.append(sig_d[i]); + if (has_aload) + res.sig_ad.append(sig_ad[i]); if (has_sr) { res.sig_clr.append(sig_clr[i]); res.sig_set.append(sig_set[i]); @@ -316,39 +412,34 @@ struct FfData { res.val_init.bits.push_back(val_init[i]); } res.width = GetSize(res.sig_q); - // Slicing bits out may cause D to become const. - if (has_d && res.sig_d.is_fully_const()) { - res.d_is_const = true; - res.val_d = res.sig_d.as_const(); - } return res; } void unmap_ce(Module *module) { - if (!has_en) + if (!has_ce) return; log_assert(has_clk); if (has_srst && ce_over_srst) unmap_srst(module); if (!is_fine) { - if (pol_en) - sig_d = module->Mux(NEW_ID, sig_q, sig_d, sig_en); + if (pol_ce) + sig_d = module->Mux(NEW_ID, sig_q, sig_d, sig_ce); else - sig_d = module->Mux(NEW_ID, sig_d, sig_q, sig_en); + sig_d = module->Mux(NEW_ID, sig_d, sig_q, sig_ce); } else { - if (pol_en) - sig_d = module->MuxGate(NEW_ID, sig_q, sig_d, sig_en); + if (pol_ce) + sig_d = module->MuxGate(NEW_ID, sig_q, sig_d, sig_ce); else - sig_d = module->MuxGate(NEW_ID, sig_d, sig_q, sig_en); + sig_d = module->MuxGate(NEW_ID, sig_d, sig_q, sig_ce); } - has_en = false; + has_ce = false; } void unmap_srst(Module *module) { if (!has_srst) return; - if (has_en && !ce_over_srst) + if (has_ce && !ce_over_srst) unmap_ce(module); if (!is_fine) { @@ -373,14 +464,14 @@ struct FfData { Cell *emit(Module *module, IdString name) { if (!width) return nullptr; - if (!has_d && !has_sr) { + if (!has_aload && !has_clk && !has_gclk && !has_sr) { if (has_arst) { // Convert this case to a D latch. - has_d = has_en = true; + has_aload = true; has_arst = false; - sig_d = val_arst; - sig_en = sig_arst; - pol_en = pol_arst; + sig_ad = val_arst; + sig_aload = sig_arst; + pol_aload = pol_arst; } else { // No control inputs left. Turn into a const driver. if (initvals) @@ -393,87 +484,93 @@ struct FfData { initvals->set_init(sig_q, val_init); Cell *cell; if (!is_fine) { - if (!has_d) { - log_assert(has_sr); - cell = module->addSr(name, sig_set, sig_clr, sig_q, pol_set, pol_clr); - } else if (!has_clk && !has_en) { + if (has_gclk) { + log_assert(!has_clk); + log_assert(!has_ce); + log_assert(!has_aload); log_assert(!has_arst); log_assert(!has_srst); log_assert(!has_sr); cell = module->addFf(name, sig_d, sig_q); + } else if (!has_aload && !has_clk) { + log_assert(has_sr); + cell = module->addSr(name, sig_set, sig_clr, sig_q, pol_set, pol_clr); } else if (!has_clk) { log_assert(!has_srst); if (has_sr) - cell = module->addDlatchsr(name, sig_en, sig_set, sig_clr, sig_d, sig_q, pol_en, pol_set, pol_clr); + cell = module->addDlatchsr(name, sig_aload, sig_set, sig_clr, sig_ad, sig_q, pol_aload, pol_set, pol_clr); else if (has_arst) - cell = module->addAdlatch(name, sig_en, sig_arst, sig_d, sig_q, val_arst, pol_en, pol_arst); + cell = module->addAdlatch(name, sig_aload, sig_arst, sig_ad, sig_q, val_arst, pol_aload, pol_arst); else - cell = module->addDlatch(name, sig_en, sig_d, sig_q, pol_en); + cell = module->addDlatch(name, sig_aload, sig_ad, sig_q, pol_aload); } else { if (has_sr) { - if (has_en) - cell = module->addDffsre(name, sig_clk, sig_en, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_en, pol_set, pol_clr); + if (has_ce) + cell = module->addDffsre(name, sig_clk, sig_ce, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_ce, pol_set, pol_clr); else cell = module->addDffsr(name, sig_clk, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_set, pol_clr); } else if (has_arst) { - if (has_en) - cell = module->addAdffe(name, sig_clk, sig_en, sig_arst, sig_d, sig_q, val_arst, pol_clk, pol_en, pol_arst); + if (has_ce) + cell = module->addAdffe(name, sig_clk, sig_ce, sig_arst, sig_d, sig_q, val_arst, pol_clk, pol_ce, pol_arst); else cell = module->addAdff(name, sig_clk, sig_arst, sig_d, sig_q, val_arst, pol_clk, pol_arst); } else if (has_srst) { - if (has_en) + if (has_ce) if (ce_over_srst) - cell = module->addSdffce(name, sig_clk, sig_en, sig_srst, sig_d, sig_q, val_srst, pol_clk, pol_en, pol_srst); + cell = module->addSdffce(name, sig_clk, sig_ce, sig_srst, sig_d, sig_q, val_srst, pol_clk, pol_ce, pol_srst); else - cell = module->addSdffe(name, sig_clk, sig_en, sig_srst, sig_d, sig_q, val_srst, pol_clk, pol_en, pol_srst); + cell = module->addSdffe(name, sig_clk, sig_ce, sig_srst, sig_d, sig_q, val_srst, pol_clk, pol_ce, pol_srst); else cell = module->addSdff(name, sig_clk, sig_srst, sig_d, sig_q, val_srst, pol_clk, pol_srst); } else { - if (has_en) - cell = module->addDffe(name, sig_clk, sig_en, sig_d, sig_q, pol_clk, pol_en); + if (has_ce) + cell = module->addDffe(name, sig_clk, sig_ce, sig_d, sig_q, pol_clk, pol_ce); else cell = module->addDff(name, sig_clk, sig_d, sig_q, pol_clk); } } } else { - if (!has_d) { - log_assert(has_sr); - cell = module->addSrGate(name, sig_set, sig_clr, sig_q, pol_set, pol_clr); - } else if (!has_clk && !has_en) { + if (has_gclk) { + log_assert(!has_clk); + log_assert(!has_ce); + log_assert(!has_aload); log_assert(!has_arst); log_assert(!has_srst); log_assert(!has_sr); cell = module->addFfGate(name, sig_d, sig_q); + } else if (!has_aload && !has_clk) { + log_assert(has_sr); + cell = module->addSrGate(name, sig_set, sig_clr, sig_q, pol_set, pol_clr); } else if (!has_clk) { log_assert(!has_srst); if (has_sr) - cell = module->addDlatchsrGate(name, sig_en, sig_set, sig_clr, sig_d, sig_q, pol_en, pol_set, pol_clr); + cell = module->addDlatchsrGate(name, sig_aload, sig_set, sig_clr, sig_ad, sig_q, pol_aload, pol_set, pol_clr); else if (has_arst) - cell = module->addAdlatchGate(name, sig_en, sig_arst, sig_d, sig_q, val_arst.as_bool(), pol_en, pol_arst); + cell = module->addAdlatchGate(name, sig_aload, sig_arst, sig_ad, sig_q, val_arst.as_bool(), pol_aload, pol_arst); else - cell = module->addDlatchGate(name, sig_en, sig_d, sig_q, pol_en); + cell = module->addDlatchGate(name, sig_aload, sig_ad, sig_q, pol_aload); } else { if (has_sr) { - if (has_en) - cell = module->addDffsreGate(name, sig_clk, sig_en, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_en, pol_set, pol_clr); + if (has_ce) + cell = module->addDffsreGate(name, sig_clk, sig_ce, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_ce, pol_set, pol_clr); else cell = module->addDffsrGate(name, sig_clk, sig_set, sig_clr, sig_d, sig_q, pol_clk, pol_set, pol_clr); } else if (has_arst) { - if (has_en) - cell = module->addAdffeGate(name, sig_clk, sig_en, sig_arst, sig_d, sig_q, val_arst.as_bool(), pol_clk, pol_en, pol_arst); + if (has_ce) + cell = module->addAdffeGate(name, sig_clk, sig_ce, sig_arst, sig_d, sig_q, val_arst.as_bool(), pol_clk, pol_ce, pol_arst); else cell = module->addAdffGate(name, sig_clk, sig_arst, sig_d, sig_q, val_arst.as_bool(), pol_clk, pol_arst); } else if (has_srst) { - if (has_en) + if (has_ce) if (ce_over_srst) - cell = module->addSdffceGate(name, sig_clk, sig_en, sig_srst, sig_d, sig_q, val_srst.as_bool(), pol_clk, pol_en, pol_srst); + cell = module->addSdffceGate(name, sig_clk, sig_ce, sig_srst, sig_d, sig_q, val_srst.as_bool(), pol_clk, pol_ce, pol_srst); else - cell = module->addSdffeGate(name, sig_clk, sig_en, sig_srst, sig_d, sig_q, val_srst.as_bool(), pol_clk, pol_en, pol_srst); + cell = module->addSdffeGate(name, sig_clk, sig_ce, sig_srst, sig_d, sig_q, val_srst.as_bool(), pol_clk, pol_ce, pol_srst); else cell = module->addSdffGate(name, sig_clk, sig_srst, sig_d, sig_q, val_srst.as_bool(), pol_clk, pol_srst); } else { - if (has_en) - cell = module->addDffeGate(name, sig_clk, sig_en, sig_d, sig_q, pol_clk, pol_en); + if (has_ce) + cell = module->addDffeGate(name, sig_clk, sig_ce, sig_d, sig_q, pol_clk, pol_ce); else cell = module->addDffGate(name, sig_clk, sig_d, sig_q, pol_clk); } |