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-rw-r--r--design/interface_wrapper.v125
1 files changed, 125 insertions, 0 deletions
diff --git a/design/interface_wrapper.v b/design/interface_wrapper.v
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+/*
+ * For now, this wrapper ignores SEL_O signals - we'll update it for
+ * byte-granular accesses later.
+ */
+`default_nettype none
+
+module interface_wrapper
+ (
+ input wire CLK_I,
+ input wire RST_I,
+
+ output wire RAW_ACK_I,
+ output wire RAW_ERR_I, /* We'll start using it soon */
+ input wire [20:0] RAW_ADR_O,
+ output wire [31:0] RAW_DAT_I,
+ input wire [31:0] RAW_DAT_O,
+ input wire [3:0] RAW_SEL_O, /* We'll start using it soon */
+ input wire RAW_STB_O,
+ input wire RAW_CYC_O,
+ input wire RAW_WE_O,
+ output wire RAW_STALL_I,
+
+ input wire WRAPPED_ACK_I,
+ output wire [19:0] WRAPPED_ADR_O,
+ input wire [15:0] WRAPPED_DAT_I,
+ output wire [15:0] WRAPPED_DAT_O,
+ output wire WRAPPED_STB_O,
+ output wire WRAPPED_CYC_O,
+ output wire WRAPPED_WE_O,
+ input wire WRAPPED_STALL_I
+ );
+
+ /* RAW -> WRAPPED */
+ wire wrapped_request_happens;
+ assign wrapped_request_happens = WRAPPED_STB_O && !WRAPPED_STALL_I;
+
+ wire raw_request_wanted;
+ assign raw_request_wanted = RAW_STB_O && RAW_CYC_O;
+
+ reg [19:0] ADR_O_waiting;
+ reg [31:0] DAT_O_waiting;
+ reg WE_O_waiting;
+ reg [1:0] request_out_waiting;
+
+ wire can_accept_request;
+ assign can_accept_request = !request_out_waiting[0] ||
+ (!request_out_waiting[1] &&
+ wrapped_request_happens);
+
+ assign WRAPPED_ADR_O = request_out_waiting[0] ?
+ ADR_O_waiting : RAW_ADR_O >> 1;
+ assign WRAPPED_DAT_O = request_out_waiting[0] ?
+ DAT_O_waiting[15:0] : RAW_DAT_O[15:0];
+ assign WRAPPED_WE_O = request_out_waiting[0] ?
+ WE_O_waiting : RAW_WE_O;
+ assign WRAPPED_STB_O = request_out_waiting[0] || raw_request_wanted;
+
+ assign WRAPPED_CYC_O = RAW_CYC_O;
+
+ always @ (posedge CLK_I) begin
+ if (RST_I) begin
+ ADR_O_waiting <= 20'bx;
+ DAT_O_waiting <= 32'bx;
+ WE_O_waiting <= 1'bx;
+ request_out_waiting <= 2'b0;
+ end else begin
+ if (wrapped_request_happens) begin
+ if (request_out_waiting[1]) begin
+ ADR_O_waiting <= ADR_O_waiting + 1;
+ DAT_O_waiting <= {16'bx, DAT_O_waiting[31:16]};
+ request_out_waiting <= {1'b0, request_out_waiting[1]};
+ end else begin
+ ADR_O_waiting <= RAW_ADR_O >> 1;
+ WE_O_waiting <= RAW_WE_O;
+ request_out_waiting[0] <= raw_request_wanted;
+
+ if (request_out_waiting[0]) begin
+ ADR_O_waiting <= RAW_ADR_O >> 1;
+ DAT_O_waiting <= RAW_DAT_O;
+ request_out_waiting[1] <= raw_request_wanted;
+ end else begin
+ ADR_O_waiting <= (RAW_ADR_O >> 1) + 1;
+ DAT_O_waiting <= {16'bx, RAW_DAT_O[31:16]};
+ request_out_waiting[1] <= 0;
+ end
+ end // else: !if(request_out_waiting[1])
+ end else if (!request_out_waiting[0]) begin // if (wr_request_happens)
+ ADR_O_waiting <= RAW_ADR_O >> 1;
+ WE_O_waiting <= RAW_WE_O;
+ DAT_O_waiting <= RAW_DAT_O;
+ request_out_waiting <= {2{raw_request_wanted}};
+ end
+ end // else: !if(RST_I)
+ end // always @ (posedge CLK_I)
+
+ /* WRAPPED -> RAW */
+ wire wrapped_request_completes;
+ assign wrapped_request_completes = WRAPPED_CYC_O && WRAPPED_ACK_I;
+
+ reg [15:0] DAT_I_waiting;
+ reg DAT_I_received;
+
+ assign RAW_ACK_I = WRAPPED_ACK_I && DAT_I_received;
+ assign RAW_ERR_I = 0; /* We'll start using it soon */
+ assign RAW_DAT_I = {WRAPPED_DAT_I, DAT_I_waiting};
+ assign RAW_STALL_I = !can_accept_request;
+
+ always @ (posedge CLK_I) begin
+ if (WRAPPED_ACK_I)
+ DAT_I_waiting <= WRAPPED_DAT_I;
+
+ if (RST_I)
+ DAT_I_received <= 0;
+ else if (wrapped_request_completes)
+ DAT_I_received <= !DAT_I_received;
+ end
+
+`ifdef SIMULATION
+ /* avoid undefined values */
+ initial begin
+ request_out_waiting <= 0;
+ DAT_I_waiting <= 0;
+ end
+`endif
+endmodule // interface_wrapper