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FPGA/Cx4: introduce wait states (fix MMX2 attract mode)

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Maximilian Rehkopf 2012-05-02 10:30:22 +02:00
parent 812a796568
commit 1b272a7a7d
1 changed files with 30 additions and 8 deletions
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38
verilog/sd2snes_cx4/cx4.v
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@ -431,7 +431,7 @@ end
/***************************
=========== CPU ===========
***************************/
reg [4:0] CPU_STATE;
reg [5:0] CPU_STATE;
reg [2:0] cpu_sp;
initial cpu_sp = 3'b000;
wire [15:0] cpu_op_w;
@ -451,16 +451,19 @@ reg [23:0] cpu_dummy;
reg [23:0] cpu_tmp;
reg [23:0] cpu_sa; // tmp register for shifted accumulator
reg [7:0] cpu_wait;
initial cpu_wait = 8'h00;
wire [9:0] cx4_datrom_addr = cpu_a[9:0];
wire [23:0] cx4_datrom_do;
wire [7:0] cx4_datram_do;
parameter ST_CPU_IDLE = 5'b00001;
parameter ST_CPU_0 = 5'b00010;
parameter ST_CPU_1 = 5'b00100;
parameter ST_CPU_2 = 5'b01000;
parameter ST_CPU_3 = 5'b10000;
parameter ST_CPU_IDLE = 6'b000001;
parameter ST_CPU_0 = 6'b000010;
parameter ST_CPU_1 = 6'b000100;
parameter ST_CPU_2 = 6'b001000;
parameter ST_CPU_3 = 6'b010000;
parameter ST_CPU_4 = 6'b100000;
initial CPU_STATE = ST_CPU_IDLE;
@ -636,7 +639,7 @@ always @(posedge CLK) begin
cpu_sp <= cpu_sp - 1;
end
OP_WAI: if(BUS_RDY) cpu_pc <= cpu_pc + 1;
OP_BUS: begin
OP_BUS: begin
cpu_bus_rq <= 1'b0;
cpu_pc <= cpu_pc + 1;
end
@ -710,7 +713,6 @@ always @(posedge CLK) begin
endcase
end
ST_CPU_3: begin
CPU_STATE <= ST_CPU_0;
case(op)
OP_BUS: cpu_busaddr <= cpu_busaddr + 1;
OP_WRRAM: cx4_cpu_datram_we <= 1'b0;
@ -747,6 +749,21 @@ always @(posedge CLK) begin
end
endcase
cpu_op <= cpu_op_w;
casex(cpu_op_w[15:11])
5'b00x01, 5'b00x10, 5'b00100, 5'b00111: begin
cpu_wait <= 8'h08;
CPU_STATE <= ST_CPU_4;
end
5'b01000: begin
cpu_wait <= 8'h04;
CPU_STATE <= ST_CPU_4;
end
default: begin
cpu_wait <= 8'h00;
CPU_STATE <= ST_CPU_0;
end
endcase
casex(cpu_op_w[15:11])
5'b00000: op <= OP_NOP;
@ -790,6 +807,11 @@ always @(posedge CLK) begin
op_param <= cpu_op_w[7:0];
op_sa <= cpu_op_w[9:8];
end
ST_CPU_4: begin
cpu_wait <= cpu_wait - 1;
if(cpu_wait) CPU_STATE <= ST_CPU_4;
else CPU_STATE <= ST_CPU_0;
end
endcase
end