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Added unconditional jumps and support for signed addition

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(Tim) Efthimis Kritikos 2023-02-14 14:48:35 +00:00
parent 037f6dd7da
commit f97f4625e6
3 changed files with 79 additions and 47 deletions
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3
cpu/alu.v
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@ -21,6 +21,8 @@
module ALU(input [15:0]A,input [15:0]B, input oe,output reg [15:0]OUT,input [`ALU_OP_BITS-1:0]op,output wire [7:0]FLAGS,input Wbit);
reg C_FLAG;
wire signed [15:0]SIGNED_B;
assign SIGNED_B=B;
assign FLAGS={(Wbit==1)?OUT[15:15]:OUT[7:7],(Wbit==1) ? (OUT[15:0]=='h0000) : (OUT[7:0]=='h00),5'b00000,C_FLAG};
@ -28,6 +30,7 @@ always @ ( * ) begin
if(Wbit==1)begin
case (op)
`ALU_OP_ADD: {C_FLAG,OUT}=A+B;
`ALU_OP_ADD_SIGNED_B: {C_FLAG,OUT}=A+SIGNED_B;
`ALU_OP_SUB: {C_FLAG,OUT}=A-B;
`ALU_OP_AND: OUT=A&B;
`ALU_OP_OR: OUT=A|B;

1
cpu/alu_header.v
View File

@ -23,3 +23,4 @@
`define ALU_OP_AND 3'b010
`define ALU_OP_OR 3'b011
`define ALU_OP_XOR 3'b100
`define ALU_OP_ADD_SIGNED_B 3'b101

44
cpu/processor.v
View File

@ -514,24 +514,21 @@ always @(posedge clock) begin
6'b011110,
6'b011111:begin
/* Conditional relative jumps */
/* Jump on Zero */
/* JE/JZ - Jump on Zero */
/* 0 1 1 1 0 1 0 0 | IP-INC8 |*/
/* Jump on Sign */
/* JS - Jump on Sign */
/* 0 1 1 1 1 0 0 0 | IP-INC8 |*/
/* Jump on not Sign */
/* JNS -Jump on not Sign */
/* 0 1 1 1 1 0 0 1 | IP-INC8 |*/
/* .... */
`start_aligning_instruction
Wbit=1;
in1_sel=2'b10;
in2_sel=2'b00;
PARAM2={8'b00000000,CIR[7:0]};
PARAM2={{8{CIR[7:7]}},CIR[7:0]};
ALU_1OE=0;
ALU_1OP=`ALU_OP_ADD;
ALU_1OP=`ALU_OP_ADD_SIGNED_B;
out_sel=3'b101;
if(CIR[7:7]==1) begin
`invalid_instruction; // We don't do singed add 8bit to unsigned 16bit
end else begin
case(CIR[11:9])
4'b000: begin
/* Jump on (not) Overflow */
@ -567,6 +564,37 @@ always @(posedge clock) begin
end
endcase
end
6'b111010:begin
/* JMP,CALL */
case(CIR[9:8])
2'b00: begin
/* CALL - Call direct within segment */
/* 1 1 1 0 1 0 0 0 | IP-INC-LO | IP-INC-HI |*/
`invalid_instruction
end
2'b01: begin
/* JMP - Uncoditional Jump direct within segment */
/* 1 1 1 0 1 0 0 1 | IP-INC-LO | IP-INC-HI |*/
`invalid_instruction
end
2'b10: begin
/* JMP - Unconditional jump direct intersegment */
/* 0 0 0 0 0 0 0 0 | IP-LO | IP-HI | CS-LO | CS-HI | */
`invalid_instruction
end
2'b11: begin
/* JMP - Unconditional jump direct within segment (short) */
/* | 1 1 1 0 1 0 0 1 | IP-INC-LO | */
Wbit=1;
in1_sel=2'b10;
in2_sel=2'b00;
PARAM2={{8{CIR[7:7]}},CIR[7:0]};
ALU_1OE=0;
ALU_1OP=`ALU_OP_ADD_SIGNED_B;
out_sel=3'b101;
state=`PROC_EX_STATE_ENTRY;
end
endcase
end
default:begin
`invalid_instruction