12 `define DIRECTION_N 3'd0
13 `define DIRECTION_NE 3'd1
14 `define DIRECTION_E 3'd2
15 `define DIRECTION_SE 3'd3
16 `define DIRECTION_S 3'd4
17 `define DIRECTION_SW 3'd5
18 `define DIRECTION_W 3'd6
19 `define DIRECTION_NW 3'd7
21 module chip(input clk, input [2:0] op, input [15:0] I, output reg [15:0] mem_in, input [15:0] mem_out, output reg mem_write, output reg [3:0] led_out = 0);
23 // parity is unimplemented
26 wire [3:0] flagr = I[3:0];
28 wire [0:7] aluc = I[12:5];
31 wire [3:0] cond = I[3:0];
33 wire [0:7] alus = I[12:5];
36 wire [3:0] flagw = I[3:0];
38 wire [3:0] cube = I[11:8];
42 wire [1:0] offset = I[1:0];
43 wire [3:0] leds = I[3:0];
52 reg [7:0] alu_sum = 0;
53 reg [7:0] alu_carry = 0;
56 // these are not really regs
58 reg [15:0] alu_sum_out;
59 reg [15:0] alu_carry_out;
61 reg [2:0] alu_index [15:0];
66 for(idx = 0; idx < 16; idx=idx+1) begin
67 alu_index[idx] = (A[idx] << 2) + (B[idx] << 1) + F[idx];
68 alu_sum_out[idx] <= alu_sum[alu_index[idx]];
69 alu_carry_out[idx] <= alu_carry[alu_index[idx]];
73 reg [3:0] flags_addr_latch;
78 flags_addr <= flags_addr_latch;
93 wire [15:0] flags_out;
96 reg [15:0] latest_news;
98 RAM #(.ADDRESS_BITS(3)) flags (.clk(clk), .write(flags_write), .addr(flags_addr[2:0]), .in(flags_in), .out(flags_out));
100 reg [15:0] flag_or_news;
103 news newspaper (.news_in(latest_news), .direction(flags_addr[2:0]), .news_out(news_out));
105 assign flag_or_news = flags_addr[3] ? news_out : flags_out;
107 always @ (posedge clk) begin
110 if(flags_write) begin
112 flags_addr_latch <= 0;
131 Cond <= inv ? ~flag_or_news : flag_or_news;
138 for(idx = 0; idx < 16; idx++) begin
139 flags_in[idx] = Cond[idx] ? alu_carry_out[idx] : flags_out[idx];
140 latest_news[idx] <= flags_in[idx];
142 if(flags_addr) begin // we do not write to flag 0
144 flags_addr_latch <= flags_addr;
146 mem_in <= alu_sum_out;
160 alu_sum <= 8'b11110000; // out of A, B, F, select exactly A
169 led_out <= mem_out[3:0];
171 led_out <= mem_out[7:4];
173 led_out <= mem_out[11:8];
175 led_out <= mem_out[15:12];
180 if(!rw && ac && !news)
185 if(!rw && !ac && !news)
190 if(rw && ac && !news)
195 if(rw && !ac && !news)
200 if(rw && !ac && news)