current progress

himbaechel/uarch/gatemate/pack_mult.cc

@@ -36,14 +36,10 @@ struct APassThroughCell
 {
     APassThroughCell(CellInfo *lower, CellInfo *upper, IdString name) : lower{lower}, upper{upper}
     {
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_D0, 4);   // IN1
         lower->params[id_INIT_L01] = Property(LUT_ZERO, 4); // (unused)
         lower->params[id_INIT_L10] = Property(LUT_D0, 4);   // L00 -> COMB2OUT
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_D0, 4);   // IN5
         upper->params[id_INIT_L03] = Property(LUT_ZERO, 4); // (unused)
         upper->params[id_INIT_L11] = Property(LUT_D0, 4);   // L02
@@ -62,8 +58,8 @@ struct APassThroughCell
     PortRef a0() const { return PortRef{upper, id_IN1}; }
     PortRef a1() const { return PortRef{lower, id_IN1}; }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // Propagate B0 through POUTY1 and B1 through COUTY1
@@ -72,6 +68,8 @@ struct APassThroughCell
 // TODO: is it worth trying to unify this with APassThroughCell?
 struct BPassThroughCell
 {
+    BPassThroughCell() : lower{nullptr}, upper{nullptr} {}
+
     BPassThroughCell(CellInfo *lower, CellInfo *upper, IdString name) : lower{lower}, upper{upper}
     {
         lower->cluster = name;
@@ -80,8 +78,6 @@ struct BPassThroughCell
         lower->params[id_INIT_L01] = Property(LUT_ZERO, 4); // (unused)
         lower->params[id_INIT_L10] = Property(LUT_D0, 4);   // L00 -> COMB2OUT
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_D0, 4);   // IN5
         upper->params[id_INIT_L03] = Property(LUT_ZERO, 4); // (unused)
         upper->params[id_INIT_L11] = Property(LUT_D0, 4);   // L02
@@ -97,25 +93,23 @@ struct BPassThroughCell
     PortRef b0() const { return PortRef{upper, id_IN1}; }
     PortRef b1() const { return PortRef{lower, id_IN1}; }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // TODO: Micko points out this is an L2T4 CPE_HALF
 struct CarryGenCell
 {
+    CarryGenCell() : lower{nullptr}, upper{nullptr} {}
+
     CarryGenCell(CellInfo *lower, CellInfo *upper, IdString name, bool is_even_x) : lower{lower}, upper{upper}
     {
         // TODO: simplify AND with zero/OR with zero into something more sensical.
 
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_ZERO, 4); // (unused)
         lower->params[id_INIT_L01] = Property(LUT_D1, 4);   // CINX
         lower->params[id_INIT_L10] = Property(is_even_x ? LUT_AND : LUT_OR, 4);
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_D1, 4);   // PINY1
         upper->params[id_INIT_L03] = Property(LUT_ZERO, 4); // (unused)
         upper->params[id_INIT_L11] = Property(is_even_x ? LUT_AND : LUT_OR, 4);
@@ -134,25 +128,23 @@ struct CarryGenCell
         upper->params[id_C_O1] = Property(0b11, 2); // COMB1OUT -> OUT1
     }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // This prepares B bits for multiplication.
 struct MultfabCell
 {
+    MultfabCell() : lower{nullptr}, upper{nullptr} {}
+
     MultfabCell(CellInfo *lower, CellInfo *upper, IdString name, bool is_even_x) : lower{lower}, upper{upper}
     {
         // TODO: perhaps C_I[1234] could be pips?
 
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_D1, 4);                        // PINY1
         lower->params[id_INIT_L01] = Property(is_even_x ? LUT_ZERO : LUT_D1, 4); // CINX
         lower->params[id_INIT_L10] = Property(LUT_XOR, 4);                       // XOR
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_D1, 4);                              // PINY1
         upper->params[id_INIT_L03] = Property(LUT_ZERO, 4);                            // (unused)
         upper->params[id_INIT_L11] = Property(LUT_D0, 4);                              // L02
@@ -175,26 +167,24 @@ struct MultfabCell
         upper->params[id_C_O1] = Property(0b11, 2); // COMB1OUT -> OUT1
     }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // CITE: CPE_ges_f-routing-1.pdf
 // TODO:
 struct FRoutingCell
 {
+    FRoutingCell() : lower{nullptr}, upper{nullptr} {}
+
     FRoutingCell(CellInfo *lower, CellInfo *upper, IdString name, bool is_even_x) : lower{lower}, upper{upper}
     {
         // TODO: simplify AND with zero/OR with zero into something more sensical.
 
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_D1, 4);  // PINY1
         lower->params[id_INIT_L01] = Property(LUT_ONE, 4); // (unused)
         lower->params[id_INIT_L10] = Property(LUT_AND, 4);
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_ZERO, 4); // (unused)
         upper->params[id_INIT_L03] = Property(LUT_ONE, 4);  // (unused)
         upper->params[id_INIT_L11] = Property(LUT_AND, 4);
@@ -216,8 +206,8 @@ struct FRoutingCell
         upper->params[id_C_O2] = Property(0b11, 2); // COMB2OUT -> OUT2
     }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // Multiply two bits of A with two bits of B.
@@ -225,16 +215,14 @@ struct FRoutingCell
 // CITE: CPE_MULT.pdf
 struct MultCell
 {
+    MultCell() : lower{nullptr}, upper{nullptr} {}
+
     MultCell(CellInfo *lower, CellInfo *upper, IdString name) : lower{lower}, upper{upper}
     {
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_AND, 4);
         lower->params[id_INIT_L01] = Property(LUT_D1, 4); // CINX
         lower->params[id_INIT_L10] = Property(LUT_XOR, 4);
 
-        upper->cluster = name;
-        upper->constr_abs_z = false;
         upper->params[id_INIT_L02] = Property(LUT_AND, 4);
         upper->params[id_INIT_L03] = Property(LUT_D1, 4); // PINX
         upper->params[id_INIT_L11] = Property(LUT_XOR, 4);
@@ -254,16 +242,16 @@ struct MultCell
     PortRef a1() const { return PortRef{upper, id_IN1}; }
     PortRef a2() const { return PortRef{lower, id_IN1}; }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 struct MultMsbCell
 {
+    MultMsbCell() : lower{nullptr}, upper{nullptr} {}
+
     MultMsbCell(CellInfo *lower, CellInfo *upper, IdString name) : lower{lower}, upper{upper}
     {
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_AND, 4);
         lower->params[id_INIT_L01] = Property(LUT_D1, 4); // CINX
         lower->params[id_INIT_L10] = Property(LUT_XOR, 4);
@@ -286,17 +274,17 @@ struct MultMsbCell
         upper->params[id_C_O1] = Property(0b10, 2); // CP_OUT1 -> OUT1
     }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 // CITE: CPE_ges_MSB-routing.pdf
 struct MsbRoutingCell
 {
+    MsbRoutingCell() : lower{nullptr}, upper{nullptr} {}
+
     MsbRoutingCell(CellInfo *lower, CellInfo *upper, IdString name) : lower{lower}, upper{upper}
     {
-        lower->cluster = name;
-        lower->constr_abs_z = false;
         lower->params[id_INIT_L00] = Property(LUT_D1, 4);   // PINY1
         lower->params[id_INIT_L01] = Property(LUT_ZERO, 4); // (unused)
         lower->params[id_INIT_L10] = Property(LUT_OR, 4);
@@ -321,20 +309,18 @@ struct MsbRoutingCell
         upper->params[id_C_O2] = Property(0b10, 2); // CP_OUT2 -> OUT2
     }
 
-    CellInfo *upper;
     CellInfo *lower;
+    CellInfo *upper;
 };
 
 struct MultiplierColumn
 {
-    // the variables are in bottom-up physical order as a mnemonic.
-
     BPassThroughCell b_passthru;
     CarryGenCell carry;
     MultfabCell multfab;
     FRoutingCell f_route;
     std::vector<MultCell> mults;
-    MultMsbCell multmsb;
+    MultMsbCell mult_msb;
     MsbRoutingCell msb_route;
 };
 
@@ -343,6 +329,15 @@ struct Multiplier
 {
     std::vector<APassThroughCell> a_passthrus;
     std::vector<MultiplierColumn> cols;
+
+    size_t cpe_count() const
+    {
+        auto count = a_passthrus.size();
+        for (const auto &col : cols) {
+            count += 6 + col.mults.size();
+        }
+        return count;
+    }
 };
 
 void GateMatePacker::pack_mult()
@@ -350,18 +345,59 @@ void GateMatePacker::pack_mult()
     // note to self: use constr_children for recursive constraints
     // fpga_generic.pas in p_r might have useful info
 
-    auto create_mult_cell = [&](IdString name) {
+    auto create_a_passthru = [&](IdString name) {
-        // instantiate a full CPE by creating two halves.
+        auto *a_passthru_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$a_passthru_lower", name.c_str(ctx)));
-        auto *lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$lower", name.c_str(ctx)));
+        auto *a_passthru_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$a_passthru_upper", name.c_str(ctx)));
-        auto *upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$upper", name.c_str(ctx)));
+        return APassThroughCell{a_passthru_lower, a_passthru_upper, name};
-        return MultCell{lower, upper, name};
     };
 
-    auto create_multfab_cell = [&](IdString name, bool is_multfa) {
+    auto create_mult_col = [&](IdString name, int a_width, bool is_even_x) {
-        // instantiate a full CPE by creating two halves.
+        // Ideally this would be the MultiplierColumn constructor, but we need create_cell_ptr here.
-        auto *lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$lower", name.c_str(ctx)));
+        auto col = MultiplierColumn{};
-        auto *upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$upper", name.c_str(ctx)));
+
-        return MultfabCell{lower, upper, name, is_multfa};
+        {
+            auto *b_passthru_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$b_passthru_lower", name.c_str(ctx)));
+            auto *b_passthru_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$b_passthru_upper", name.c_str(ctx)));
+            col.b_passthru = BPassThroughCell{b_passthru_lower, b_passthru_upper, name};
+        }
+
+        {
+            auto *carry_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$carry_lower", name.c_str(ctx)));
+            auto *carry_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$carry_upper", name.c_str(ctx)));
+            col.carry = CarryGenCell{carry_lower, carry_upper, name, is_even_x};
+        }
+
+        {
+            auto *multfab_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$multfab_lower", name.c_str(ctx)));
+            auto *multfab_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$multfab_upper", name.c_str(ctx)));
+            col.multfab = MultfabCell{multfab_lower, multfab_upper, name, is_even_x};
+        }
+
+        {
+            auto *f_route_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$f_route_lower", name.c_str(ctx)));
+            auto *f_route_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$f_route_upper", name.c_str(ctx)));
+            col.f_route = FRoutingCell{f_route_lower, f_route_upper, name, is_even_x};
+        }
+
+        for (int i = 0; i < a_width / 2; i++) {
+            auto *mult_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$row%d$mult_lower", name.c_str(ctx), i));
+            auto *mult_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$row%d$mult_upper", name.c_str(ctx), i));
+            col.mults.push_back(MultCell{mult_lower, mult_upper, name});
+        }
+
+        {
+            auto *mult_msb_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$mult_msb_lower", name.c_str(ctx)));
+            auto *mult_msb_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$mult_msb_upper", name.c_str(ctx)));
+            col.mult_msb = MultMsbCell{mult_msb_lower, mult_msb_upper, name};
+        }
+
+        {
+            auto *msb_route_lower = create_cell_ptr(id_CPE_HALF_L, ctx->idf("%s$msb_route_lower", name.c_str(ctx)));
+            auto *msb_route_upper = create_cell_ptr(id_CPE_HALF_U, ctx->idf("%s$msb_route_upper", name.c_str(ctx)));
+            col.msb_route = MsbRoutingCell{msb_route_lower, msb_route_upper, name};
+        }
+
+        return col;
     };
 
     log_info("Packing multipliers...\n");
@@ -378,13 +414,70 @@ void GateMatePacker::pack_mult()
         auto a_width = int_or_default(mult->params, id_A_WIDTH);
         auto b_width = int_or_default(mult->params, id_B_WIDTH);
         auto p_width = int_or_default(mult->params, id_P_WIDTH);
-        log_info("    Configuring '%s' as a %d * %d = %d multiplier\n", mult->name.c_str(ctx), a_width, b_width,
+        log_info("    Configuring '%s' as a %d-bit * %d-bit = %d-bit multiplier.\n", mult->name.c_str(ctx), a_width,
-                 p_width);
+                 b_width, p_width);
 
-        NPNR_ASSERT(a_width <= 2);
+        auto m = Multiplier{};
-        NPNR_ASSERT(b_width <= 2);
 
-        auto [mult_l, mult_u] = create_mult_cell(mult->name);
+        // Step 1: instantiate all the CPEs.
+        for (int a = 0; a <= a_width / 2; a++)
+            m.a_passthrus.push_back(create_a_passthru(ctx->idf("%s$col0$row%d", mult->name.c_str(ctx), a)));
+        for (int b = 0; b <= b_width / 2; b++)
+            m.cols.push_back(create_mult_col(ctx->idf("%s$col%d", mult->name.c_str(ctx), b + 1), a_width, b % 2 == 0));
+
+        // Step 2: constrain them together.
+        // We define (0,0) to be the B passthrough cell of column 1.
+        auto *root = m.cols[0].b_passthru.upper;
+
+        auto constrain_cell = [&](CellInfo *cell, int x_offset, int y_offset) {
+            if (cell == root)
+                return;
+            root->constr_children.push_back(cell);
+            cell->cluster = root->name;
+            cell->constr_abs_z = false;
+            cell->constr_x = x_offset;
+            cell->constr_y = y_offset;
+        };
+
+        // Constrain A passthrough cells.
+        for (int a = 0; a <= a_width / 2; a++) {
+            auto &a_passthru = m.a_passthrus[a];
+            constrain_cell(a_passthru.lower, -1, 4 + a);
+            constrain_cell(a_passthru.upper, -1, 4 + a);
+        }
+
+        // Constrain multiplier columns.
+        for (int b = 0; b <= b_width / 2; b++) {
+            auto &col = m.cols[b];
+            constrain_cell(col.b_passthru.lower, b, b);
+            constrain_cell(col.b_passthru.upper, b, b);
+
+            constrain_cell(col.carry.lower, b + 1, b);
+            constrain_cell(col.carry.upper, b + 1, b);
+
+            constrain_cell(col.multfab.lower, b + 2, b);
+            constrain_cell(col.multfab.upper, b + 2, b);
+
+            constrain_cell(col.f_route.lower, b + 3, b);
+            constrain_cell(col.f_route.upper, b + 3, b);
+
+            for (size_t mult_idx = 0; mult_idx < col.mults.size(); mult_idx++) {
+                constrain_cell(col.mults[mult_idx].lower, b + 4 + mult_idx, b);
+                constrain_cell(col.mults[mult_idx].upper, b + 4 + mult_idx, b);
+            }
+
+            constrain_cell(col.mult_msb.lower, b + 4 + col.mults.size() + 1, b);
+            constrain_cell(col.mult_msb.upper, b + 4 + col.mults.size() + 1, b);
+
+            constrain_cell(col.msb_route.lower, b + 4 + col.mults.size() + 2, b);
+            constrain_cell(col.msb_route.upper, b + 4 + col.mults.size() + 2, b);
+        }
+
+        // Step 3: connect them.
+
+        // Connect A passthrough cells.
+
+        log_info("        Created %zu CPEs.\n", m.cpe_count());
     }
 }