1 files changed, 168 insertions, 17 deletions

diff --git a/kernel/mem.h b/kernel/mem.h
index 6d727e71d..ae87b1285 100644
--- a/kernel/mem.h
+++ b/kernel/mem.h
@@ -21,38 +21,76 @@
 #define MEM_H
 
 #include "kernel/yosys.h"
+#include "kernel/ffinit.h"
 
 YOSYS_NAMESPACE_BEGIN
 
-struct MemRd {
-	dict<IdString, Const> attributes;
+struct MemRd : RTLIL::AttrObject {
+	bool removed;
 	Cell *cell;
-	bool clk_enable, clk_polarity;
-	bool transparent;
-	SigSpec clk, en, addr, data;
-	MemRd() : cell(nullptr) {}
+	int wide_log2;
+	bool clk_enable, clk_polarity, ce_over_srst;
+	Const arst_value, srst_value, init_value;
+	// One bit for every write port, true iff simultanous read on this
+	// port and write on the other port will bypass the written data
+	// to this port's output (default behavior is to read old value).
+	// Can only be set for write ports that have the same clock domain.
+	std::vector<bool> transparency_mask;
+	// One bit for every write port, true iff simultanous read on this
+	// port and write on the other port will return an all-X (don't care)
+	// value.  Mutually exclusive with transparency_mask.
+	// Can only be set for write ports that have the same clock domain.
+	// For optimization purposes, this will also be set if we can
+	// determine that the two ports can never be active simultanously
+	// (making the above vacuously true).
+	std::vector<bool> collision_x_mask;
+	SigSpec clk, en, arst, srst, addr, data;
+
+	MemRd() : removed(false), cell(nullptr) {}
+
+	// Returns the address of given subword index accessed by this port.
+	SigSpec sub_addr(int sub) {
+		SigSpec res = addr;
+		for (int i = 0; i < wide_log2; i++)
+			res[i] = State(sub >> i & 1);
+		return res;
+	}
 };
 
-struct MemWr {
-	dict<IdString, Const> attributes;
+struct MemWr : RTLIL::AttrObject {
+	bool removed;
 	Cell *cell;
+	int wide_log2;
 	bool clk_enable, clk_polarity;
+	std::vector<bool> priority_mask;
 	SigSpec clk, en, addr, data;
-	MemWr() : cell(nullptr) {}
+
+	MemWr() : removed(false), cell(nullptr) {}
+
+	// Returns the address of given subword index accessed by this port.
+	SigSpec sub_addr(int sub) {
+		SigSpec res = addr;
+		for (int i = 0; i < wide_log2; i++)
+			res[i] = State(sub >> i & 1);
+		return res;
+	}
+
+	std::pair<SigSpec, std::vector<int>> compress_en();
+	SigSpec decompress_en(const std::vector<int> &swizzle, SigSpec sig);
 };
 
-struct MemInit {
-	dict<IdString, Const> attributes;
+struct MemInit : RTLIL::AttrObject {
+	bool removed;
 	Cell *cell;
 	Const addr;
 	Const data;
-	MemInit() : cell(nullptr) {}
+	Const en;
+	MemInit() : removed(false), cell(nullptr) {}
 };
 
-struct Mem {
+struct Mem : RTLIL::AttrObject {
 	Module *module;
 	IdString memid;
-	dict<IdString, Const> attributes;
 	bool packed;
 	RTLIL::Memory *mem;
 	Cell *cell;
@@ -61,15 +99,128 @@ struct Mem {
 	std::vector<MemRd> rd_ports;
 	std::vector<MemWr> wr_ports;
 
+	// Removes this memory from the module.  The data in helper structures
+	// is unaffected except for the cell/mem fields.
 	void remove();
+
+	// Commits all changes in helper structures into the module — ports and
+	// inits marked as removed are actually removed, new ports/inits create
+	// new cells, modified port/inits are commited into their existing
+	// cells.  Note that this reindexes the ports and inits array (actually
+	// removing the ports/inits marked as removed).
 	void emit();
-	void remove_wr_port(int idx);
-	void remove_rd_port(int idx);
+
+	// Marks all inits as removed.
 	void clear_inits();
+
+	// Coalesces inits: whenever two inits have overlapping or touching
+	// address ranges, they are combined into one, with the higher-priority
+	// one's data overwriting the other.  Running this results in
+	// an inits list equivalent to the original, in which all entries
+	// cover disjoint (and non-touching) address ranges, and all enable
+	// masks are all-1.
+	void coalesce_inits();
+
+	// Checks consistency of this memory and all its ports/inits, using
+	// log_assert.
+	void check();
+
+	// Gathers all initialization data into a single big const covering
+	// the whole memory.  For all non-initialized bits, Sx will be returned.
 	Const get_init_data() const;
+
+	// Constructs and returns the helper structures for all memories
+	// in a module.
 	static std::vector<Mem> get_all_memories(Module *module);
+
+	// Constructs and returns the helper structures for all selected
+	// memories in a module.
 	static std::vector<Mem> get_selected_memories(Module *module);
-	Cell *extract_rdff(int idx);
+
+	// Converts a synchronous read port into an asynchronous one by
+	// extracting the data (or, in some rare cases, address) register
+	// into a separate cell, together with any soft-transparency
+	// logic necessary to preserve its semantics.  Returns the created
+	// register cell, if any.  Note that in some rare cases this function
+	// may succeed and perform a conversion without creating a new
+	// register — a nullptr result doesn't imply nothing was done.
+	Cell *extract_rdff(int idx, FfInitVals *initvals);
+
+	// Splits all wide ports in this memory into equivalent narrow ones.
+	// This function performs no modifications at all to the actual
+	// netlist unless and until emit() is called.
+	void narrow();
+
+	// If write port idx2 currently has priority over write port idx1,
+	// inserts extra logic on idx1's enable signal to disable writes
+	// when idx2 is writing to the same address, then removes the priority
+	// from the priority mask.  If there is a memory port that is
+	// transparent with idx1, but not with idx2, that port is converted
+	// to use soft transparency logic.
+	void emulate_priority(int idx1, int idx2, FfInitVals *initvals);
+
+	// Creates soft-transparency logic on read port ridx, bypassing the
+	// data from write port widx.  Should only be called when ridx is
+	// transparent wrt widx in the first place.  Once we're done, the
+	// transparency_mask bit will be cleared, and the collision_x_mask
+	// bit will be set instead (since whatever value is read will be
+	// replaced by the soft transparency logic).
+	void emulate_transparency(int widx, int ridx, FfInitVals *initvals);
+
+	// Prepares for merging write port idx2 into idx1 (where idx1 < idx2).
+	// Specifically, takes care of priority masks: any priority relations
+	// that idx2 had are replicated onto idx1, unless they conflict with
+	// priorities already present on idx1, in which case emulate_priority
+	// is called.  Likewise, ensures transparency and undefined collision
+	// masks of all read ports have the same values for both ports,
+	// calling emulate_transparency if necessary.
+	void prepare_wr_merge(int idx1, int idx2, FfInitVals *initvals);
+
+	// Prepares for merging read port idx2 into idx1.
+	// Specifically, makes sure the transparency and undefined collision
+	// masks of both ports are equal, by changing undefined behavior
+	// of one port to the other's defined behavior, or by calling
+	// emulate_transparency if necessary.
+	void prepare_rd_merge(int idx1, int idx2, FfInitVals *initvals);
+
+	// Prepares the memory for widening a port to a given width.  This
+	// involves ensuring that start_offset and size are aligned to the
+	// target width.
+	void widen_prep(int wide_log2);
+
+	// Widens a write port up to a given width.  The newly port is
+	// equivalent to the original, made by replicating enable/data bits
+	// and masking enable bits with decoders on the low part of the
+	// original address.
+	void widen_wr_port(int idx, int wide_log2);
+
+	// Emulates a sync read port's enable functionality in soft logic,
+	// changing the actual read port's enable to be always-on.
+	void emulate_rden(int idx, FfInitVals *initvals);
+
+	// Emulates a sync read port's initial/reset value functionality in
+	// soft logic, removing it from the actual read port.
+	void emulate_reset(int idx, bool emu_init, bool emu_arst, bool emu_srst, FfInitVals *initvals);
+
+	// Given a read port with ce_over_srst set, converts it to a port
+	// with ce_over_srst unset without changing its behavior by adding
+	// emulation logic.
+	void emulate_rd_ce_over_srst(int idx);
+
+	// Given a read port with ce_over_srst unset, converts it to a port
+	// with ce_over_srst set without changing its behavior by adding
+	// emulation logic.
+	void emulate_rd_srst_over_ce(int idx);
+
+	// Returns true iff emulate_read_first makes sense to call.
+	bool emulate_read_first_ok();
+
+	// Emulates all read-first read-write port relationships in terms of
+	// all-transparent ports, by delaying all write ports by one cycle.
+	// This can only be used when all read ports and all write ports are
+	// in the same clock domain.
+	void emulate_read_first(FfInitVals *initvals);
+
 	Mem(Module *module, IdString memid, int width, int start_offset, int size) : module(module), memid(memid), packed(false), mem(nullptr), cell(nullptr), width(width), start_offset(start_offset), size(size) {}
 };