Memory: Add STRB support, en manera de A.
authorJoshua Wise <joshua@rebirth.joshuawise.com>
Sat, 24 Jan 2009 05:39:59 +0000 (00:39 -0500)
committerJoshua Wise <joshua@rebirth.joshuawise.com>
Sat, 24 Jan 2009 05:39:59 +0000 (00:39 -0500)
Memory.v

index 7ca786e..eccddb2 100644 (file)
--- a/Memory.v
+++ b/Memory.v
@@ -65,7 +65,7 @@ module Memory(
        reg [3:0] next_write_num;
        reg [31:0] next_write_data;
 
-       reg [2:0] lsr_state = 3'b001, next_lsr_state;
+       reg [3:0] lsr_state = 4'b0001, next_lsr_state;
        reg [31:0] align_s1, align_s2, align_rddata;
 
        reg [2:0] lsrh_state = 3'b001, next_lsrh_state;
@@ -79,6 +79,9 @@ module Memory(
 
        reg [31:0] swp_oldval, next_swp_oldval;
        reg [1:0] swp_state = 2'b01, next_swp_state;
+       
+       reg do_rd_data_latch;
+       reg [31:0] rd_data_latch = 32'hxxxxxxxx;
 
        always @(posedge clk)
        begin
@@ -100,6 +103,8 @@ module Memory(
                lsm_state <= next_lsm_state;
                lsr_state <= next_lsr_state;
                lsrh_state <= next_lsrh_state;
+               if (do_rd_data_latch)
+                       rd_data_latch <= rd_data;
                prevaddr <= addr;
        end
        
@@ -120,6 +125,7 @@ module Memory(
                busaddr = 32'hxxxxxxxx;
                data_size = 3'bxxx;
                outstall = 1'b0;
+               do_rd_data_latch = 0;
                next_write_reg = write_reg;
                next_write_num = write_num;
                next_write_data = write_data;
@@ -248,42 +254,69 @@ module Memory(
                        align_s2 = raddr[0] ? {align_s1[7:0], align_s1[31:8]} : align_s1;
                        /* select byte or word */
                        align_rddata = insn[22] ? {24'b0, align_s2[7:0]} : align_s2;
-                       wr_data = insn[22] ? {4{op2[7:0]}} : op2; /* XXX need to actually store just a byte */
+                       wr_data = insn[22] ? {24'h0, {op2[7:0]}} : op2;
                        data_size = insn[22] ? 3'b001 : 3'b100;
                        case(lsr_state)
-                       3'b001: begin
-                               rd_req = insn[20] /* L */;
-                               wr_req = ~insn[20] /* L */;
+                       4'b0001: begin
+                               rd_req = insn[20] /* L */ || insn[22] /* B */;
+                               wr_req = !insn[20] /* L */ && !insn[22]/* B */;
                                next_write_reg = insn[20] /* L */;
                                next_write_num = insn[15:12];
                                if(insn[20] /* L */) begin
-                                       next_write_data = align_rddata;
+                                       next_write_data = insn[22] /* B */ ? {24'h0, align_rddata[7:0]} : align_rddata;
                                end
-                               if(insn[21] /* W */ | !insn[24] /* P */) begin
+                               if (insn[22] /* B */ && !insn[20] /* L */) begin
+                                       do_rd_data_latch = 1;
+                                       outstall = 1'b1;
+                                       if (!rw_wait)
+                                               next_lsr_state = 4'b0010;       /* XXX: One-hot, my ass. */
+                               end else if(insn[21] /* W */ | !insn[24] /* P */) begin
                                        outstall = 1'b1;
                                        if(!rw_wait)
-                                               next_lsr_state = 3'b010;
+                                               next_lsr_state = 4'b0100;
                                end
                                $display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
                        end
-                       3'b010: begin
+                       4'b0010: begin
+                               $display("LDRSTR: Handling STRB");
                                outstall = 1;
+                               rd_req = 0;
+                               wr_req = 1;
+                               next_write_reg = 0;
+                               case (busaddr[1:0])
+                               2'b00: wr_data = {rd_data_latch[31:8], op2[7:0]};
+                               2'b01: wr_data = {rd_data_latch[31:16], op2[7:0], rd_data_latch[7:0]};
+                               2'b10: wr_data = {rd_data_latch[31:24], op2[7:0], rd_data_latch[15:0]};
+                               2'b11: wr_data = {op2[7:0], rd_data_latch[23:0]};
+                               endcase
+                               if(insn[21] /* W */ | !insn[24] /* P */) begin
+                                       if(!rw_wait)
+                                               next_lsr_state = 4'b0100;
+                               end else if (!rw_wait)
+                                       next_lsr_state = 4'b1000;
+                       end
+                       4'b0100: begin
+                               outstall = 1;
+                               rd_req = 0;
+                               wr_req= 0;
                                next_outbubble = 0;
                                next_write_reg = 1'b1;
                                next_write_num = insn[19:16];
                                next_write_data = addr;
-                               next_lsr_state = 3'b100;
+                               next_lsr_state = 4'b1000;
                        end
-                       3'b100: begin
+                       4'b1000: begin
+                               rd_req = 0;
+                               wr_req= 0;
                                outstall = 0;
-                               next_lsr_state = 3'b001;
+                               next_lsr_state = 4'b0001;
                        end
                        default: begin end
                        endcase
                        
-                       if ((lsr_state == 3'b001) && flush) begin       /* Reject it. */
+                       if ((lsr_state == 4'b0001) && flush) begin      /* Reject it. */
                                outstall = 1'b0;
-                               next_lsr_state = 3'b001;
+                               next_lsr_state = 4'b0001;
                        end
                end
                /* XXX ldm/stm incorrect in that stupid case where one of the listed regs is the base reg */
This page took 0.024324 seconds and 4 git commands to generate.