Issue: AUTORESET.

[firearm.git] / Issue.v

diff --git a/Issue.v b/Issue.v
index a6b7109fa7ce65c3e741fdaaaa9a789e0b30d214..a8274ec55821b6970b6accf226e0bdfc9033f490 100644 (file)
--- a/Issue.v
+++ b/Issue.v
@@ -4,24 +4,24 @@ module Issue(
        input clk,
        input Nrst,     /* XXX not used yet */
        
        input clk,
        input Nrst,     /* XXX not used yet */
        

-       input stall,    /* pipeline control */
+       input stall_1a, /* pipeline control */

        input flush,    /* XXX not used yet */
        
        input flush,    /* XXX not used yet */
        

-       input inbubble, /* stage inputs */
-       input [31:0] insn,
-       input [31:0] inpc,
-       input [31:0] cpsr,
+       input bubble_1a,        /* stage inputs */
+       input [31:0] insn_1a,
+       input [31:0] pc_1a,
+       input [31:0] cpsr_1a,

        
        

-       output reg outstall = 0,        /* stage outputs */
-       output reg outbubble = 1,
-       output reg [31:0] outpc = 0,
-       output reg [31:0] outinsn = 0
+       output wire stall_0a,   /* stage outputs */
+       output reg bubble_2a = 1,
+       output reg [31:0] pc_2a = 0,
+       output reg [31:0] insn_2a = 0

        /* XXX other? */
        );
        
 `ifdef COPY_PASTA_FODDER
        /* from page 2 of ARM7TDMIvE2.pdf */
        /* XXX other? */
        );
        
 `ifdef COPY_PASTA_FODDER
        /* from page 2 of ARM7TDMIvE2.pdf */

-       casex (insn)
+       casex (insn_1a)

        `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
 //     `DECODE_ALU_MUL_LONG:   /* Multiply long */
        `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */
        `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
 //     `DECODE_ALU_MUL_LONG:   /* Multiply long */
        `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */


@@ -58,17 +58,17 @@ module Issue(
                        idxbit = (16'b1) << r;
        endfunction
        
                        idxbit = (16'b1) << r;
        endfunction
        

-       wire [3:0] rn = insn[19:16];
-       wire [3:0] rd = insn[15:12];
-       wire [3:0] rs = insn[11:8];
-       wire [3:0] rm = insn[3:0];
-       wire [3:0] cond = insn[31:28];
+       wire [3:0] rn = insn_1a[19:16];
+       wire [3:0] rd = insn_1a[15:12];
+       wire [3:0] rs = insn_1a[11:8];
+       wire [3:0] rm = insn_1a[3:0];
+       wire [3:0] cond = insn_1a[31:28];

        
        

-       wire [3:0] rd_mul = insn[19:16];
-       wire [3:0] rn_mul = insn[15:12];
-       wire [3:0] rs_mul = insn[11:8];
+       wire [3:0] rd_mul = insn_1a[19:16];
+       wire [3:0] rn_mul = insn_1a[15:12];
+       wire [3:0] rs_mul = insn_1a[11:8];

        
        

-       wire [3:0] alu_opc = insn[24:21];
+       wire [3:0] alu_opc = insn_1a[24:21];

        
        function alu_is_logical;
                input [3:0] op;
        
        function alu_is_logical;
                input [3:0] op;


@@ -100,18 +100,18 @@ module Issue(
        endfunction
        
        always @(*)
        endfunction
        
        always @(*)

-               casez (insn)
+               casez (insn_1a)

                `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                `DECODE_ALU_MULT:       /* Multiply -- must come before ALU, because it pattern matches a specific case of ALU */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = (insn[21] /* accum */ ? idxbit(rn_mul) : 0) | idxbit(rs_mul) | idxbit(rm);
-                       def_cpsr = insn[20] /* setcc */;
+                       use_regs = (insn_1a[21] /* accum */ ? idxbit(rn_mul) : 0) | idxbit(rs_mul) | idxbit(rm);
+                       def_cpsr = insn_1a[20] /* setcc */;

                        def_regs = idxbit(rd_mul);
                end
 //             `DECODE_ALU_MUL_LONG:   /* Multiply long */
                `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */
                begin
                        def_regs = idxbit(rd_mul);
                end
 //             `DECODE_ALU_MUL_LONG:   /* Multiply long */
                `DECODE_ALU_MRS:        /* MRS (Transfer PSR to register) */
                begin

-                       use_cpsr = `COND_MATTERS(cond) || (insn[22] == 0) /* Source = CPSR */;
+                       use_cpsr = `COND_MATTERS(cond) || (insn_1a[22] == 0) /* Source = CPSR */;

                        use_regs = 0;
                        def_cpsr = 0;
                        def_regs = idxbit(rd);
                        use_regs = 0;
                        def_cpsr = 0;
                        def_regs = idxbit(rd);


@@ -126,7 +126,7 @@ module Issue(
                `DECODE_ALU_MSR_FLAGS:  /* MSR (Transfer register or immediate to PSR, flag bits only) */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                `DECODE_ALU_MSR_FLAGS:  /* MSR (Transfer register or immediate to PSR, flag bits only) */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = insn[25] ? 0 : idxbit(rm);
+                       use_regs = insn_1a[25] ? 0 : idxbit(rm);

                        def_cpsr = 1;
                        def_regs = 0;
                end
                        def_cpsr = 1;
                        def_regs = 0;
                end


@@ -147,27 +147,27 @@ module Issue(
                `DECODE_ALU_HDATA_REG:  /* Halfword transfer - register offset */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                `DECODE_ALU_HDATA_REG:  /* Halfword transfer - register offset */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = idxbit(rn) | idxbit(rm) | (insn[20] /* L */ ? 0 : idxbit(rd));
+                       use_regs = idxbit(rn) | idxbit(rm) | (insn_1a[20] /* L */ ? 0 : idxbit(rd));

                        def_cpsr = 0;
                        def_cpsr = 0;

-                       def_regs = insn[20] /* L */ ? idxbit(rd) : 0;
+                       def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0;

                end
                `DECODE_ALU_HDATA_IMM:  /* Halfword transfer - immediate offset */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                end
                `DECODE_ALU_HDATA_IMM:  /* Halfword transfer - immediate offset */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : idxbit(rd));
+                       use_regs = idxbit(rn) | (insn_1a[20] /* L */ ? 0 : idxbit(rd));

                        def_cpsr = 0;
                        def_cpsr = 0;

-                       def_regs = insn[20] /* L */ ? idxbit(rd) : 0;
+                       def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0;

                end
                `DECODE_ALU:    /* ALU */
                begin
                end
                `DECODE_ALU:    /* ALU */
                begin

-                       use_cpsr = `COND_MATTERS(cond) | (!insn[25] /* I */ && shift_requires_carry(insn[11:4]));
+                       use_cpsr = `COND_MATTERS(cond) | (!insn_1a[25] /* I */ && shift_requires_carry(insn_1a[11:4]));

                        use_regs =
                        use_regs =

-                               (insn[25] /* I */ ? 0 :
-                                       (insn[4] /* shift by reg */ ?
+                               (insn_1a[25] /* I */ ? 0 :
+                                       (insn_1a[4] /* shift by reg */ ?

                                                (idxbit(rs) | idxbit(rm)) :
                                                (idxbit(rm)))) |
                                (((alu_opc != `ALU_MOV) && (alu_opc != `ALU_MVN)) ? idxbit(rn) : 0);
                                                (idxbit(rs) | idxbit(rm)) :
                                                (idxbit(rm)))) |
                                (((alu_opc != `ALU_MOV) && (alu_opc != `ALU_MVN)) ? idxbit(rn) : 0);

-                       def_cpsr = insn[20] /* S */;
+                       def_cpsr = insn_1a[20] /* S */;

                        def_regs = alu_flags_only(alu_opc) ? 0 : idxbit(rd);
                end
                `DECODE_LDRSTR_UNDEFINED:       /* Undefined. I hate ARM */
                        def_regs = alu_flags_only(alu_opc) ? 0 : idxbit(rd);
                end
                `DECODE_LDRSTR_UNDEFINED:       /* Undefined. I hate ARM */


@@ -180,30 +180,30 @@ module Issue(
                `DECODE_LDRSTR:
                begin
                        use_cpsr = `COND_MATTERS(cond);
                `DECODE_LDRSTR:
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : idxbit(rd));
+                       use_regs = idxbit(rn) | (insn_1a[25] /* I */ ? idxbit(rm) : 0) | (insn_1a[20] /* L */ ? 0 : idxbit(rd));

                        def_cpsr = 0;
                        def_cpsr = 0;

-                       def_regs = insn[20] /* L */ ? idxbit(rd) : 0;
+                       def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0;

                end
                `DECODE_LDMSTM:         /* Block data transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                end
                `DECODE_LDMSTM:         /* Block data transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = idxbit(rn) | (insn[20] /* L */ ? 0 : insn[15:0]);
-                       def_cpsr = insn[22];    /* This is a superset of all cases, anyway. */
-                       def_regs = (insn[21] /* W */ ? idxbit(rn) : 0) | (insn[20] /* L */ ? insn[15:0] : 0);
+                       use_regs = idxbit(rn) | (insn_1a[20] /* L */ ? 0 : insn_1a[15:0]);
+                       def_cpsr = insn_1a[22]; /* This is a superset of all cases, anyway. */
+                       def_regs = (insn_1a[21] /* W */ ? idxbit(rn) : 0) | (insn_1a[20] /* L */ ? insn_1a[15:0] : 0);

                end
                `DECODE_BRANCH: /* Branch */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                        use_regs = 0;
                        def_cpsr = 0;
                end
                `DECODE_BRANCH: /* Branch */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                        use_regs = 0;
                        def_cpsr = 0;

-                       def_regs = 0;
+                       def_regs = insn_1a[24] /* L */ ? (16'b1 << 14) : 0;

                end
                `DECODE_LDCSTC: /* Coprocessor data transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                        use_regs = idxbit(rn);
                        def_cpsr = 0;
                end
                `DECODE_LDCSTC: /* Coprocessor data transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                        use_regs = idxbit(rn);
                        def_cpsr = 0;

-                       def_regs = insn[21] /* W */ ? idxbit(rn) : 0;
+                       def_regs = insn_1a[21] /* W */ ? idxbit(rn) : 0;

                end
                `DECODE_CDP:    /* Coprocessor data op */
                begin
                end
                `DECODE_CDP:    /* Coprocessor data op */
                begin


@@ -215,9 +215,9 @@ module Issue(
                `DECODE_MRCMCR:         /* Coprocessor register transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);
                `DECODE_MRCMCR:         /* Coprocessor register transfer */
                begin
                        use_cpsr = `COND_MATTERS(cond);

-                       use_regs = insn[20] /* L */ ? 0 : idxbit(rd);
+                       use_regs = insn_1a[20] /* L */ ? 0 : idxbit(rd);

                        def_cpsr = 0;
                        def_cpsr = 0;

-                       def_regs = insn[20] /* L */ ? idxbit(rd) : 0;
+                       def_regs = insn_1a[20] /* L */ ? idxbit(rd) : 0;

                end
                `DECODE_SWI:    /* SWI */
                begin
                end
                `DECODE_SWI:    /* SWI */
                begin


@@ -236,79 +236,74 @@ module Issue(
                endcase
        
        /* Condition checking logic */
                endcase
        
        /* Condition checking logic */

-       reg condition_met;
+       reg condition_met_1a;

        always @(*)
        always @(*)

-               casez(insn[31:28])
-               `COND_EQ:       condition_met = cpsr[`CPSR_Z];
-               `COND_NE:       condition_met = !cpsr[`CPSR_Z];
-               `COND_CS:       condition_met = cpsr[`CPSR_C];
-               `COND_CC:       condition_met = !cpsr[`CPSR_C];
-               `COND_MI:       condition_met = cpsr[`CPSR_N];
-               `COND_PL:       condition_met = !cpsr[`CPSR_N];
-               `COND_VS:       condition_met = cpsr[`CPSR_V];
-               `COND_VC:       condition_met = !cpsr[`CPSR_V];
-               `COND_HI:       condition_met = cpsr[`CPSR_C] && !cpsr[`CPSR_Z];
-               `COND_LS:       condition_met = !cpsr[`CPSR_C] || cpsr[`CPSR_Z];
-               `COND_GE:       condition_met = cpsr[`CPSR_N] == cpsr[`CPSR_V];
-               `COND_LT:       condition_met = cpsr[`CPSR_N] != cpsr[`CPSR_V];
-               `COND_GT:       condition_met = !cpsr[`CPSR_Z] && (cpsr[`CPSR_N] == cpsr[`CPSR_V]);
-               `COND_LE:       condition_met = cpsr[`CPSR_Z] || (cpsr[`CPSR_N] != cpsr[`CPSR_V]);
-               `COND_AL:       condition_met = 1;
-               `COND_NV:       condition_met = 0;
-               default:        condition_met = 1'bx;
+               casez(insn_1a[31:28])
+               `COND_EQ:       condition_met_1a = cpsr_1a[`CPSR_Z];
+               `COND_NE:       condition_met_1a = !cpsr_1a[`CPSR_Z];
+               `COND_CS:       condition_met_1a = cpsr_1a[`CPSR_C];
+               `COND_CC:       condition_met_1a = !cpsr_1a[`CPSR_C];
+               `COND_MI:       condition_met_1a = cpsr_1a[`CPSR_N];
+               `COND_PL:       condition_met_1a = !cpsr_1a[`CPSR_N];
+               `COND_VS:       condition_met_1a = cpsr_1a[`CPSR_V];
+               `COND_VC:       condition_met_1a = !cpsr_1a[`CPSR_V];
+               `COND_HI:       condition_met_1a = cpsr_1a[`CPSR_C] && !cpsr_1a[`CPSR_Z];
+               `COND_LS:       condition_met_1a = !cpsr_1a[`CPSR_C] || cpsr_1a[`CPSR_Z];
+               `COND_GE:       condition_met_1a = cpsr_1a[`CPSR_N] == cpsr_1a[`CPSR_V];
+               `COND_LT:       condition_met_1a = cpsr_1a[`CPSR_N] != cpsr_1a[`CPSR_V];
+               `COND_GT:       condition_met_1a = !cpsr_1a[`CPSR_Z] && (cpsr_1a[`CPSR_N] == cpsr_1a[`CPSR_V]);
+               `COND_LE:       condition_met_1a = cpsr_1a[`CPSR_Z] || (cpsr_1a[`CPSR_N] != cpsr_1a[`CPSR_V]);
+               `COND_AL:       condition_met_1a = 1;
+               `COND_NV:       condition_met_1a = 0;
+               default:        condition_met_1a = 1'bx;

                endcase
        
        /* Issue logic */
                endcase
        
        /* Issue logic */

-`define STAGE_EXECUTE   0
-`define STAGE_MEMORY    1
-/* Once it's hit writeback, it's essentially hit the regfile so you're done. */
-       reg cpsr_inflight [1:0];
-       reg [15:0] regs_inflight [1:0];
-       
-       reg waiting_cpsr;
-       reg waiting_regs;
-       wire waiting = waiting_cpsr | waiting_regs;
-       
-       initial
-       begin
-               cpsr_inflight[0] = 0;
-               cpsr_inflight[1] = 0;
-               regs_inflight[0] = 0;
-               regs_inflight[1] = 0;
-       end
-               
-       always @(*)
-       begin
-               waiting_cpsr = use_cpsr & (cpsr_inflight[0] | cpsr_inflight[1]);
-               waiting_regs = |(use_regs & (regs_inflight[0] | regs_inflight[1]));
-               
-               outstall = (waiting && !inbubble) || stall;     /* Happens in an always @*, because it is an exception. */
-       end
+       /* Once it's hit writeback, it's hit the regfile via forwarding so you're done. */
+       reg        cpsr_inflight_2a = 0, cpsr_inflight_3a = 0;
+       reg [15:0] regs_inflight_2a = 0, regs_inflight_3a = 0;

        
        

+       wire waiting_cpsr_1a = use_cpsr & (cpsr_inflight_2a | cpsr_inflight_3a);
+       wire waiting_regs_1a = |(use_regs & (regs_inflight_2a | regs_inflight_3a));
+       wire waiting_1a = waiting_cpsr_1a | waiting_regs_1a;
+       assign stall_0a = (waiting_1a && !bubble_1a && !flush) || stall_1a;
+
+       reg delayedflush = 0;
+       always @(posedge clk/* or negedge Nrst*/)
+               if (!Nrst)
+                       delayedflush <= 0;
+               else if (flush && stall_0a /* halp! I can't do it now, maybe later? */)
+                       delayedflush <= 1;
+               else if (!stall_0a /* anything has been handled this time around */)
+                       delayedflush <= 0;
+

        /* Actually do the issue. */
        /* Actually do the issue. */

-       always @(posedge clk)
+       always @(posedge clk or negedge Nrst)

        begin
        begin

-               if (waiting)
-                       $display("ISSUE: Stalling instruction %08x because %d/%d", insn, waiting_cpsr, waiting_regs);
+               if (waiting_1a)
+                       $display("ISSUE: Stalling instruction %08x because %d/%d", insn_1a, waiting_cpsr_1a, waiting_regs_1a);

 
 

-               if(flush)
-               begin
-                       cpsr_inflight[0] = 1'b0;
-                       cpsr_inflight[1] = 1'b0;
-                       regs_inflight[0] = 16'b0;
-                       regs_inflight[1] = 16'b0;
-                       outbubble <= 1'b1;
-               end
-               else if (!stall)
+               if (!Nrst) begin
+                       bubble_2a <= 1;
+                       /*AUTORESET*/
+                       // Beginning of autoreset for uninitialized flops
+                       cpsr_inflight_2a <= 1'h0;
+                       cpsr_inflight_3a <= 1'h0;
+                       insn_2a <= 32'h0;
+                       pc_2a <= 32'h0;
+                       regs_inflight_2a <= 16'h0;
+                       regs_inflight_3a <= 16'h0;
+                       // End of automatics
+               end else if (!stall_1a)

                begin
                begin

-                       cpsr_inflight[0] <= cpsr_inflight[1];   /* I'm not sure how well selects work with arrays, and that seems like a dumb thing to get anusulated by. */
-                       cpsr_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_cpsr;
-                       regs_inflight[0] <= regs_inflight[1];
-                       regs_inflight[1] <= (waiting || inbubble || !condition_met) ? 0 : def_regs;
+                       cpsr_inflight_3a <= cpsr_inflight_2a;   /* I'm not sure how well selects work with arrays, and that seems like a dumb thing to get anusulated by. */
+                       cpsr_inflight_2a <= (waiting_1a || bubble_1a || !condition_met_1a) ? 0 : def_cpsr;
+                       regs_inflight_3a <= regs_inflight_2a;
+                       regs_inflight_2a <= (waiting_1a || bubble_1a || !condition_met_1a) ? 0 : def_regs;

                        
                        

-                       outbubble <= inbubble | waiting | !condition_met;
-                       outpc <= inpc;
-                       outinsn <= insn;
+                       bubble_2a <= bubble_1a | waiting_1a | !condition_met_1a | flush | delayedflush;
+                       pc_2a <= pc_1a;
+                       insn_2a <= insn_1a;

                end
        end
 endmodule
                end
        end
 endmodule