Memory: Move all state machine code out to its own always block.
authorJoshua Wise <joshua@rebirth.joshuawise.com>
Sat, 31 Jan 2009 07:49:29 +0000 (02:49 -0500)
committerJoshua Wise <joshua@rebirth.joshuawise.com>
Sat, 31 Jan 2009 07:49:29 +0000 (02:49 -0500)
Memory.v

index 40e60d7..cb1f74f 100644 (file)
--- a/Memory.v
+++ b/Memory.v
@@ -1,5 +1,23 @@
 `include "ARM_Constants.v"
 
+`define SWP_READING    2'b01
+`define SWP_WRITING    2'b10
+
+`define LSRH_MEMIO     3'b001
+`define LSRH_BASEWB    3'b010
+`define LSRH_WBFLUSH   3'b100
+
+`define LSR_MEMIO      4'b0001
+`define LSR_STRB_WR    4'b0010
+`define LSR_BASEWB     4'b0100
+`define LSR_WBFLUSH    4'b1000
+
+`define LSM_SETUP      4'b0001
+`define LSM_MEMIO      4'b0010
+`define LSM_BASEWB     4'b0100
+`define LSM_WBFLUSH    4'b1000
+
+
 module Memory(
        input clk,
        input Nrst,
@@ -114,6 +132,169 @@ module Memory(
                        delayedflush <= 1;
                else if (!outstall /* anything has been handled this time around */)
                        delayedflush <= 0;
+       
+       /* Drive the state machines and stall. */
+       always @(*)
+       begin
+               outstall = 1'b0;
+               next_lsm_state = lsm_state;
+               next_lsr_state = lsr_state;
+               next_lsrh_state = lsrh_state;
+               next_swp_state = swp_state;
+               casez(insn)
+               `DECODE_ALU_SWP: if(!inbubble) begin
+                       case(swp_state)
+                       `SWP_READING: begin
+                               outstall = 1'b1;
+                               if (!rw_wait)
+                                       next_swp_state = `SWP_WRITING;
+                               $display("SWP: read stage");
+                       end
+                       `SWP_WRITING: begin
+                               outstall = rw_wait;
+                               if(!rw_wait)
+                                       next_swp_state = `SWP_READING;
+                               $display("SWP: write stage");
+                       end
+                       default: begin
+                               outstall = 1'bx;
+                               next_swp_state = 2'bxx;
+                       end
+                       endcase
+               end
+               `DECODE_ALU_MULT: begin end
+               `DECODE_ALU_HDATA_REG,
+               `DECODE_ALU_HDATA_IMM: if(!inbubble) begin
+                       case(lsrh_state)
+                       `LSRH_MEMIO: begin
+                               outstall = rw_wait;
+                               if(insn[21] | !insn[24]) begin
+                                       outstall = 1'b1;
+                                       if(!rw_wait)
+                                               next_lsrh_state = `LSRH_BASEWB;
+                               end
+                               
+                               if (flush) /* special case! */ begin
+                                       outstall = 1'b0;
+                                       next_lsrh_state = `LSRH_MEMIO;
+                               end
+                               
+                               $display("ALU_LDRSTRH: rd_req %d, wr_req %d", rd_req, wr_req);
+                       end
+                       `LSRH_BASEWB: begin
+                               outstall = 1'b1;
+                               next_lsrh_state = `LSRH_WBFLUSH;
+                       end
+                       `LSRH_WBFLUSH: begin
+                               outstall = 1'b0;
+                               next_lsrh_state = `LSRH_MEMIO;
+                       end
+                       default: begin
+                               outstall = 1'bx;
+                               next_lsrh_state = 3'bxxx;
+                       end
+                       endcase
+               end
+               `DECODE_LDRSTR_UNDEFINED: begin end
+               `DECODE_LDRSTR: if(!inbubble) begin
+                       outstall = rw_wait;
+                       case(lsr_state)
+                       `LSR_MEMIO: begin
+                               outstall = rw_wait;
+                               next_lsr_state = `LSR_MEMIO;
+                               if (insn[22] /* B */ && !insn[20] /* L */) begin        /* i.e., strb */
+                                       outstall = 1'b1;
+                                       if (!rw_wait)
+                                               next_lsr_state = `LSR_STRB_WR;
+                               end else if (insn[21] /* W */ || !insn[24] /* P */) begin       /* writeback needed */
+                                       outstall = 1'b1;
+                                       if (!rw_wait)
+                                               next_lsr_state = `LSR_BASEWB;
+                               end
+                               
+                               if (flush) begin
+                                       outstall = 1'b0;
+                                       next_lsr_state = `LSR_MEMIO;
+                               end
+                               $display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
+                       end
+                       `LSR_STRB_WR: begin
+                               outstall = 1;
+                               if(insn[21] /* W */ | !insn[24] /* P */) begin
+                                       if(!rw_wait)
+                                               next_lsr_state = `LSR_BASEWB;
+                               end else if (!rw_wait)
+                                       next_lsr_state = `LSR_WBFLUSH;
+                               $display("LDRSTR: Handling STRB");
+                       end
+                       `LSR_BASEWB: begin
+                               outstall = 1;
+                               next_lsr_state = `LSR_WBFLUSH;
+                       end
+                       `LSR_WBFLUSH: begin
+                               outstall = 0;
+                               next_lsr_state = `LSR_MEMIO;
+                       end
+                       default: begin
+                               outstall = 1'bx;
+                               next_lsr_state = 4'bxxxx;
+                       end
+                       endcase
+                       $display("LDRSTR: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsr_state, next_lsr_state, outstall);
+               end
+               `DECODE_LDMSTM: if(!inbubble) begin
+                       outstall = rw_wait;
+                       case(lsm_state)
+                       `LSM_SETUP: begin
+                               outstall = 1'b1;
+                               next_lsm_state = `LSM_MEMIO;
+                               if (flush) begin
+                                       outstall = 1'b0;
+                                       next_lsm_state = `LSM_SETUP;
+                               end
+                               $display("LDMSTM: Round 1: base register: %08x, reg list %b", op0, op1[15:0]);
+                       end
+                       `LSM_MEMIO: begin
+                               outstall = 1'b1;
+                               if(next_regs == 16'b0) begin
+                                       next_lsm_state = `LSM_BASEWB;
+                               end
+                               
+                               $display("LDMSTM: Stage 2: Writing: regs %b, next_regs %b, reg %d, wr_data %08x, addr %08x", regs, next_regs, cur_reg, wr_data, busaddr);
+                       end
+                       `LSM_BASEWB: begin
+                               outstall = 1;
+                               next_lsm_state = `LSM_WBFLUSH;
+                               $display("LDMSTM: Stage 3: Writing back");
+                       end
+                       `LSM_WBFLUSH: begin
+                               outstall = 0;
+                               next_lsm_state = `LSM_SETUP;
+                       end
+                       default: begin
+                               outstall = 1'bx;
+                               next_lsm_state = 4'bxxxx;
+                       end
+                       endcase
+                       $display("LDMSTM: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsm_state, next_lsm_state, outstall);
+               end
+               `DECODE_LDCSTC: if(!inbubble) begin
+                       $display("WARNING: Unimplemented LDCSTC");
+               end
+               `DECODE_CDP: if (!inbubble) begin
+                       if (cp_busy) begin
+                               outstall = 1;
+                       end
+               end
+               `DECODE_MRCMCR: if (!inbubble) begin
+                       if (cp_busy) begin
+                               outstall = 1;
+                       end
+                       $display("MRCMCR: ack %d, busy %d", cp_ack, cp_busy);
+               end
+               default: begin end
+               endcase
+       end
 
        always @(*)
        begin
@@ -124,7 +305,6 @@ module Memory(
                wr_data = 32'hxxxxxxxx;
                busaddr = 32'hxxxxxxxx;
                data_size = 3'bxxx;
-               outstall = 1'b0;
                st_read = 4'hx;
                do_rd_data_latch = 0;
                next_write_reg = write_reg;
@@ -141,46 +321,21 @@ module Memory(
                lsrh_rddata = 32'hxxxxxxxx;
                lsrh_rddata_s1 = 16'hxxxx;
                lsrh_rddata_s2 = 8'hxx;
-               next_lsm_state = lsm_state;
-               next_lsr_state = lsr_state;
-               next_lsrh_state = lsrh_state;
                next_swp_oldval = swp_oldval;
-               next_swp_state = swp_state;
                cur_reg = prev_reg;
 
-`define SWP_READING 2'b01
-`define SWP_WRITING 2'b10
-
-`define LSRH_MEMIO     3'b001
-`define LSRH_BASEWB    3'b010
-`define LSRH_WBFLUSH   3'b100
-
-`define LSR_MEMIO      4'b0001
-`define LSR_STRB_WR    4'b0010
-`define LSR_BASEWB     4'b0100
-`define LSR_WBFLUSH    4'b1000
-
-`define LSM_SETUP      4'b0001
-`define LSM_MEMIO      4'b0010
-`define LSM_BASEWB     4'b0100
-`define LSM_WBFLUSH    4'b1000
-
                /* XXX shit not given about endianness */
                casez(insn)
                `DECODE_ALU_SWP: if(!inbubble) begin
-                       outstall = rw_wait;
                        next_outbubble = rw_wait;
                        busaddr = {op0[31:2], 2'b0};
                        data_size = insn[22] ? 3'b001 : 3'b100;
                        case(swp_state)
                        `SWP_READING: begin
                                rd_req = 1'b1;
-                               outstall = 1'b1;
                                if(!rw_wait) begin
-                                       next_swp_state = `SWP_WRITING;
                                        next_swp_oldval = rd_data;
                                end
-                               $display("SWP: read stage");
                        end
                        `SWP_WRITING: begin
                                wr_req = 1'b1;
@@ -188,9 +343,6 @@ module Memory(
                                next_write_reg = 1'b1;
                                next_write_num = insn[15:12];
                                next_write_data = insn[22] ? {24'b0, swp_oldval[7:0]} : swp_oldval;
-                               if(!rw_wait)
-                                       next_swp_state = `SWP_READING;
-                               $display("SWP: write stage");
                        end
                        default: begin end
                        endcase
@@ -199,7 +351,6 @@ module Memory(
                `DECODE_ALU_HDATA_REG,
                `DECODE_ALU_HDATA_IMM: 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;
@@ -238,36 +389,21 @@ module Memory(
                                if(insn[20]) begin
                                        next_write_reg = 1'b1;
                                end
-                               if(insn[21] | !insn[24]) begin
-                                       outstall = 1'b1;
-                                       if(!rw_wait)
-                                               next_lsrh_state = `LSRH_BASEWB;
-                               end
-                               $display("ALU_LDRSTRH: rd_req %d, wr_req %d", rd_req, wr_req);
                        end
                        `LSRH_BASEWB: begin
                                next_outbubble = 1'b0;
                                next_write_reg = 1'b1;
                                next_write_num = insn[19:16];
                                next_write_data = addr;
-                               next_lsrh_state = `LSRH_WBFLUSH;
                        end
                        `LSRH_WBFLUSH: begin
-                               outstall = 0;
-                               next_lsrh_state = `LSRH_MEMIO;
                        end
                        default: begin end
                        endcase
-                       
-                       if ((lsrh_state == `LSRH_MEMIO) && flush) begin /* Reject it. */
-                               outstall = 1'b0;
-                               next_lsrh_state = `LSRH_MEMIO;
-                       end
                end
                `DECODE_LDRSTR_UNDEFINED: begin end
                `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] ? addr : op0; /* pre/post increment */
                        busaddr = raddr;
@@ -279,7 +415,6 @@ module Memory(
                        wr_data = insn[22] ? {24'h0, {op2[7:0]}} : op2;
                        data_size = insn[22] ? 3'b001 : 3'b100;
                        case(lsr_state)
-
                        `LSR_MEMIO: begin
                                rd_req = insn[20] /* L */ || insn[22] /* B */;
                                wr_req = !insn[20] /* L */ && !insn[22]/* B */;
@@ -290,19 +425,9 @@ module Memory(
                                end
                                if (insn[22] /* B */ && !insn[20] /* L */) begin
                                        do_rd_data_latch = 1;
-                                       outstall = 1'b1;
-                                       if (!rw_wait)
-                                               next_lsr_state = `LSR_STRB_WR;
-                               end else if(insn[21] /* W */ | !insn[24] /* P */) begin
-                                       outstall = 1'b1;
-                                       if(!rw_wait)
-                                               next_lsr_state = `LSR_BASEWB;
                                end
-                               $display("LDRSTR: rd_req %d, wr_req %d, raddr %08x, wait %d", rd_req, wr_req, raddr, rw_wait);
                        end
                        `LSR_STRB_WR: begin
-                               $display("LDRSTR: Handling STRB");
-                               outstall = 1;
                                rd_req = 0;
                                wr_req = 1;
                                next_write_reg = 0;
@@ -312,53 +437,35 @@ module Memory(
                                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 = `LSR_BASEWB;
-                               end else if (!rw_wait)
-                                       next_lsr_state = `LSR_WBFLUSH;
                        end
                        `LSR_BASEWB: begin
-                               outstall = 1;
                                rd_req = 0;
-                               wr_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 = `LSR_WBFLUSH;
                        end
                        `LSR_WBFLUSH: begin
                                rd_req = 0;
-                               wr_req= 0;
-                               outstall = 0;
-                               next_lsr_state = `LSR_MEMIO;
+                               wr_req = 0;
                        end
                        default: begin end
                        endcase
-                       
-                       if ((lsr_state == `LSR_MEMIO) && flush) begin   /* Reject it. */
-                               outstall = 1'b0;
-                               next_lsr_state = `LSR_MEMIO;
-                       end
                end
                /* 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;
                        data_size = 3'b100;
                        case(lsm_state)
                        `LSM_SETUP: begin
 //                             next_regs = insn[23] ? op1[15:0] : op1[0:15];
                                /** verilator can suck my dick */
-                               $display("LDMSTM: Round 1: base register: %08x, reg list %b", op0, op1[15:0]);
                                next_regs = insn[23] /* U */ ? op1[15:0] : {op1[0], op1[1], op1[2], op1[3], op1[4], op1[5], op1[6], op1[7],
                                                                            op1[8], op1[9], op1[10], op1[11], op1[12], op1[13], op1[14], op1[15]};
                                offset = 6'b0;
-                               outstall = 1'b1;
-                               next_lsm_state = `LSM_MEMIO;
                        end
-                       4'b0010: begin
+                       `LSM_MEMIO: begin
                                rd_req = insn[20];
                                wr_req = ~insn[20];
                                casez(regs)
@@ -453,43 +560,21 @@ module Memory(
                                st_read = cur_reg;
                                wr_data = (cur_reg == 4'hF) ? (pc + 12) : st_data;
                                busaddr = raddr;
-                               
-                               $display("LDMSTM: Stage 2: Writing: regs %b, next_regs %b, reg %d, wr_data %08x, addr %08x", regs, next_regs, cur_reg, wr_data, busaddr);
-
-                               outstall = 1'b1;
-
-                               if(next_regs == 16'b0) begin
-                                       next_lsm_state = `LSM_BASEWB;
-                               end
                        end
                        `LSM_BASEWB: begin
-                               outstall = 1;
                                next_outbubble = 0;
                                next_write_reg = insn[21] /* writeback */;
                                next_write_num = insn[19:16];
                                next_write_data = insn[23] ? op0 + {26'b0, prev_offset} : op0 - {26'b0, prev_offset};
-                               next_lsm_state = `LSM_WBFLUSH;
-                               $display("LDMSTM: Stage 3: Writing back");
-                       end
-                       `LSM_WBFLUSH: begin
-                               outstall = 0;
-                               next_lsm_state = `LSM_SETUP;
                        end
+                       `LSM_WBFLUSH: begin end
                        default: $stop;
                        endcase
-                       if ((lsm_state == `LSM_SETUP) && flush) begin   /* Reject it. */
-                               outstall = 1'b0;
-                               next_lsm_state = `LSM_SETUP;
-                       end
-                       $display("LDMSTM: Decoded, bubble %d, insn %08x, lsm state %b -> %b, stall %d", inbubble, insn, lsm_state, next_lsm_state, outstall);
-               end
-               `DECODE_LDCSTC: if(!inbubble) begin
-                       $display("WARNING: Unimplemented LDCSTC");
                end
+               `DECODE_LDCSTC: begin end
                `DECODE_CDP: if(!inbubble) begin
                        cp_req = 1;
                        if (cp_busy) begin
-                               outstall = 1;
                                next_outbubble = 1;
                        end
                        if (!cp_ack) begin
@@ -513,13 +598,11 @@ module Memory(
                                end
                        end
                        if (cp_busy) begin
-                               outstall = 1;
                                next_outbubble = 1;
                        end
                        if (!cp_ack) begin
                                $display("WARNING: Possible MRCMCR undefined instruction: cp_ack %d, cp_busy %d",cp_ack, cp_busy);
                        end
-                       $display("MRCMCR: ack %d, busy %d", cp_ack, cp_busy);
                end
                default: begin end
                endcase
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