memory: bubble
authorChristopher Lu <lu@stop.hsd1.pa.comcast.net>
Wed, 7 Jan 2009 09:54:31 +0000 (04:54 -0500)
committerChristopher Lu <lu@stop.hsd1.pa.comcast.net>
Wed, 7 Jan 2009 09:54:31 +0000 (04:54 -0500)
Memory.v

index bf25447..c735ed9 100644 (file)
--- a/Memory.v
+++ b/Memory.v
@@ -111,79 +111,75 @@ module Memory(
                next_swp_state = swp_state;
                cur_reg = prev_reg;
 
+               /* XXX shit not given about endianness */
+               /* TODO ldrh/strh */
                casez(insn)
-               `DECODE_ALU_SWP: begin
-                       if(!inbubble) begin
-                               outstall = rw_wait;
-                               next_outbubble = rw_wait;
-                               busaddr = {op0[31:2], 2'b0};
-                               case(swp_state)
-                               2'b01: begin
-                                       rd_req = 1'b1;
-                                       outstall = 1'b1;
-                                       if(!rw_wait) begin
-                                               next_swp_state = 2'b10;
-                                               next_swp_oldval = rd_data;
-                                       end
-                               end
-                               2'b10: begin
-                                       wr_req = 1'b1;
-                                       wr_data = op1;
-                                       next_write_reg = 1'b1;
-                                       next_write_num = insn[15:12];
-                                       next_write_data = swp_oldval;
-                                       if(!rw_wait)
-                                               next_swp_state = 2'b01;
+               `DECODE_ALU_SWP: if(!inbubble) begin
+                       outstall = rw_wait;
+                       next_outbubble = rw_wait;
+                       busaddr = {op0[31:2], 2'b0};
+                       case(swp_state)
+                       2'b01: begin
+                               rd_req = 1'b1;
+                               outstall = 1'b1;
+                               if(!rw_wait) begin
+                                       next_swp_state = 2'b10;
+                                       next_swp_oldval = rd_data;
                                end
-                               default: begin end
-                               endcase
                        end
+                       2'b10: begin
+                               wr_req = 1'b1;
+                               wr_data = op1;
+                               next_write_reg = 1'b1;
+                               next_write_num = insn[15:12];
+                               next_write_data = swp_oldval;
+                               if(!rw_wait)
+                                       next_swp_state = 2'b01;
+                       end
+                       default: begin end
+                       endcase
                end
                `DECODE_LDRSTR_UNDEFINED: begin end
-               `DECODE_LDRSTR: begin
-                       if (!inbubble) begin
-                               next_outbubble = rw_wait;
-                               outstall = rw_wait;
-                               addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
-                               raddr = insn[24] ? op0 : addr; /* pre/post increment */
-                               busaddr = {raddr[31:2], 2'b0};
-
+               `DECODE_LDRSTR: if(!inbubble) begin
+                       next_outbubble = rw_wait;
+                       outstall = rw_wait;
+                       addr = insn[23] ? op0 + op1 : op0 - op1; /* up/down select */
+                       raddr = insn[24] ? op0 : addr; /* pre/post increment */
+                       busaddr = {raddr[31:2], 2'b0};
                                /* rotate to correct position */
-                               align_s1 = raddr[1] ? {rd_data[15:0], rd_data[31:16]} : rd_data;
-                               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;
-                               if(!insn[20]) begin
-                                       wr_data = insn[22] ? {4{op2[7:0]}} : op2; /* XXX need to actually store just a byte */
+                       align_s1 = raddr[1] ? {rd_data[15:0], rd_data[31:16]} : rd_data;
+                       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;
+                       if(!insn[20]) begin
+                               wr_data = insn[22] ? {4{op2[7:0]}} : op2; /* XXX need to actually store just a byte */
+                       end
+                       case(lsr_state)
+                       2'b01: begin
+                               rd_req = insn[20];
+                               wr_req = ~insn[20];
+                               if(insn[20]) begin
+                                       next_write_reg = 1'b1;
+                                       next_write_num = insn[15:12];
+                                       next_write_data = align_rddata;
                                end
-                               case(lsr_state)
-                               2'b01: begin
-                                       rd_req = insn[20];
-                                       wr_req = ~insn[20];
-
-                                       if(insn[20]) begin
-                                               next_write_reg = 1'b1;
-                                               next_write_num = insn[15:12];
-                                               next_write_data = align_rddata;
-                                       end
-
                                        if(insn[21]) begin
-                                               outstall = 1'b1;
-                                               if(!rw_wait)
-                                                       next_lsr_state = 2'b10;
-                                       end
-                               end
-                               2'b10: begin
-                                       next_write_reg = 1'b1;
-                                       next_write_num = insn[19:16];
-                                       next_write_data = addr;
-                                       next_lsr_state = 2'b10;
+                                       outstall = 1'b1;
+                                       if(!rw_wait)
+                                               next_lsr_state = 2'b10;
                                end
-                               default: begin end
-                               endcase
                        end
+                       2'b10: begin
+                               next_write_reg = 1'b1;
+                               next_write_num = insn[19:16];
+                               next_write_data = addr;
+                               next_lsr_state = 2'b10;
+                       end
+                       default: begin end
+                       endcase
                end
-               `DECODE_LDMSTM: begin
+               /* XXX ldm/stm incorrect in that stupid case where one of the listed regs is the base reg */
+               `DECODE_LDMSTM: if(!inbubble) begin
                        outstall = rw_wait;
                        next_outbubble = rw_wait;
                        case(lsm_state)
@@ -309,10 +305,10 @@ module Memory(
                        default: begin end
                        endcase
                end
-               `DECODE_LDCSTC: begin
+               `DECODE_LDCSTC: if(!inbubble) begin
                        $display("WARNING: Unimplemented LDCSTC");
                end
-               `DECODE_CDP: begin
+               `DECODE_CDP: if(!inbubble) begin
                        cp_req = 1;
                        if (cp_busy) begin
                                outstall = 1;
@@ -323,7 +319,7 @@ module Memory(
                                $display("WARNING: Possible CDP undefined instruction");
                        end
                end
-               `DECODE_MRCMCR: begin
+               `DECODE_MRCMCR: if(!inbubble) begin
                        cp_req = 1;
                        cp_rnw = insn[20] /* L */;
                        if (insn[20] == 0 /* store to coprocessor */)
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