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Pipeline external SRAM reads

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FallenSigh
2026-07-02 00:23:57 +08:00
parent baf3f6f696
commit ed2876b3a8
1 changed files with 37 additions and 34 deletions
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71
rtl/ip/Bus_interconnects/axi2sram_sp_external.v
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@@ -104,6 +104,10 @@ module axi2sram_sp_external #(
reg [AXI_ADDR_WIDTH-1:0] req_addr_d, req_addr_q;
reg [7:0] cnt_d, cnt_q;
reg [AXI_DATA_WIDTH-1:0] rdata_q;
reg rlast_q;
reg read_capture;
reg read_capture_last;
function automatic [AXI_ADDR_WIDTH-1:0] get_wrap_boundary;
input [AXI_ADDR_WIDTH-1:0] unaligned_address;
@@ -146,6 +150,8 @@ module axi2sram_sp_external #(
ax_req_d_burst = ax_req_q_burst;
req_addr_d = req_addr_q;
cnt_d = cnt_q;
read_capture = 1'b0;
read_capture_last = 1'b0;
// Memory default assignments
data_o = s_wdata;
be_o = s_wstrb;
@@ -158,6 +164,7 @@ module axi2sram_sp_external #(
s_arready = 1'b0;
// read response channel
s_rvalid = 1'b0;
s_rdata = 'h0;
s_rresp = 'h0;
s_rlast = 'h0;
s_rid = ax_req_q_id;
@@ -183,7 +190,7 @@ module axi2sram_sp_external #(
ax_req_d_len = s_arlen;
ax_req_d_size = s_arsize;
ax_req_d_burst = s_arburst;
state_d = READ;
state_d = READ_ADDR;
// we can request the first address, this saves us time
req_o = 1'b1;
addr_o = s_araddr;
@@ -230,14 +237,11 @@ module axi2sram_sp_external #(
end
READ: begin
// keep request to memory high
req_o = 1'b1;
addr_o = req_addr_q;
// send the response
s_rvalid = 1'b1;
s_rdata = data_i;
s_rdata = rdata_q;
s_rid = ax_req_q_id;
s_rlast = (cnt_q == ax_req_q_len + 1);
s_rlast = rlast_q;
// check that the master is ready, the slave must not wait on this
if (s_rready) begin
// we sent the last byte -> go back to idle
@@ -246,7 +250,24 @@ module axi2sram_sp_external #(
// we already got everything
end
else begin
state_d = READ_ADDR;
req_o = 1'b1;
case (ax_req_q_burst)
FIXED, INCR: addr_o = cons_addr;
WRAP: begin
if (cons_addr == upper_wrap_boundary) begin
addr_o = wrap_boundary;
end else if (cons_addr > upper_wrap_boundary) begin
addr_o = ax_req_q_addr + ((cnt_q - ax_req_q_len) << LOG_NR_BYTES);
end else begin
addr_o = cons_addr;
end
end
endcase
cnt_d = cnt_q + 1;
req_addr_d = addr_o;
read_capture = 1'b1;
read_capture_last = (cnt_d == ax_req_q_len + 1);
state_d = READ;
end
end
end
@@ -254,32 +275,9 @@ module axi2sram_sp_external #(
READ_ADDR: begin
// keep request to memory high
req_o = 1'b1;
// send the response
s_rvalid = 1'b0;
// ----------------------------
// Next address generation
// ----------------------------
// handle the correct burst type
case (ax_req_q_burst)
FIXED, INCR: addr_o = cons_addr;
WRAP: begin
// check if the address reached warp boundary
if (cons_addr == upper_wrap_boundary) begin
addr_o = wrap_boundary;
// address warped beyond boundary
end else if (cons_addr > upper_wrap_boundary) begin
addr_o = ax_req_q_addr + ((cnt_q - ax_req_q_len) << LOG_NR_BYTES);
// we are still in the incremental regime
end else begin
addr_o = cons_addr;
end
end
endcase
// we need to change the address here for the upcoming request
// we can decrease the counter as the master has consumed the read data
cnt_d = cnt_q + 1;
// save the request address for the next cycle
req_addr_d = addr_o;
addr_o = req_addr_q;
read_capture = 1'b1;
read_capture_last = (cnt_q == ax_req_q_len + 1);
state_d = READ;
end
@@ -352,6 +350,8 @@ module axi2sram_sp_external #(
ax_req_q_size <= 3'h0;
req_addr_q <= 'h0;
cnt_q <= 8'h0;
rdata_q <= 'h0;
rlast_q <= 1'b0;
end else begin
state_q <= state_d;
ax_req_q_addr <= ax_req_d_addr;
@@ -361,6 +361,10 @@ module axi2sram_sp_external #(
ax_req_q_size <= ax_req_d_size;
req_addr_q <= req_addr_d;
cnt_q <= cnt_d;
if (read_capture) begin
rdata_q <= data_i;
rlast_q <= read_capture_last;
end
end
end
@@ -377,4 +381,3 @@ module axi2sram_sp_external #(
// end
endmodule