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Added conditional jump support!

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(Tim) Efthimis Kritikos 2023-02-13 10:36:37 +00:00
parent 923bf07c72
commit 16e02e0788
3 changed files with 111 additions and 48 deletions
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2
cpu/Makefile
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@ -32,7 +32,7 @@ ${VVP} : ${SOURCES} ${INCLUDES}
.PHONY: disas
disas: brainfuck.bin
objdump -D -b binary -m i8086 $^
objdump -D -b binary -m i8086 $^ | less
.PHONY: clean
clean:

157
cpu/processor.v
View File

@ -27,7 +27,6 @@ reg unaligned_access;
reg [1:0]IN_MOD;
reg [2:0]IN_RM;
reg Wbit;
reg Suppress_ALU_Output;
reg [15:0]FLAGS;
/* . . . . O D I T S Z . A . P . C */
// C - Carry flag : carry out or borrow into the high order bit (8bit/16bit)
@ -55,7 +54,8 @@ reg [15:0]FLAGS;
// Execution units
reg [1:0] in1_sel;
reg [1:0] in2_sel;
reg [1:0] out_sel;
/* out_sel : { EXTRA_FUNCTIONS_BIT[0:0], MOD_OR_EXTRA_FUNCTION[1:0] } */
reg [2:0] out_sel;
/*** RESET LOGIC ***/
always @(negedge reset) begin
@ -90,7 +90,7 @@ register_file register_file(reg_write_addr,reg_write_data,reg_write_we,reg_read_
mux4 #(.WIDTH(16)) MUX16_1A(
PARAM1,
reg_read_data,
16'b0,
{ProgCount[14:0],unaligned_access}, /*THATS NOT ALL OF ADDR Bus, is that irrelevant with segmentation??*/
16'b0,
in1_sel,
ALU_1A);
@ -98,7 +98,7 @@ mux4 #(.WIDTH(16)) MUX16_1A(
mux4 #(.WIDTH(16)) MUX16_1B(
PARAM2,
reg_read_data,
16'b0,
{ProgCount[14:0],unaligned_access}, /*THATS NOT ALL OF ADDR Bus, is that irrelevant with segmentation??*/
16'b0,
in2_sel,
ALU_1B);
@ -134,19 +134,23 @@ always @(negedge clock) begin
state=`PROC_DE_STATE_ENTRY;
end
`PROC_EX_STATE_EXIT:begin
if(Suppress_ALU_Output==0)begin
case(out_sel)
2'b11:begin
reg_write_we=0;
state=`PROC_IF_STATE_ENTRY;
end
default:begin
`invalid_instruction
end
endcase
end else begin
state=`PROC_IF_STATE_ENTRY;
end
case(out_sel)
3'b011:begin
reg_write_we=0;
state=`PROC_IF_STATE_ENTRY;
end
3'b101:begin
ProgCount=ALU_1O[15:1];
unaligned_access=ALU_1O[0:0];
state=`PROC_IF_STATE_ENTRY;
end
3'b100:begin
state=`PROC_IF_STATE_ENTRY;
end
default:begin
`invalid_instruction
end
endcase
end
`PROC_DE_LOAD_16_EXTRA_FETCH_SET:begin
external_address_bus = ProgCount;
@ -165,7 +169,7 @@ always @(posedge clock) begin
end
`PROC_IF_STATE_ENTRY:begin
ERROR=0;
Suppress_ALU_Output=0;
$display("Fetched instruction at %04x",{ProgCount[18:0],unaligned_access});
external_address_bus <= ProgCount;
read <= 0;
write <= 1;
@ -197,7 +201,7 @@ always @(posedge clock) begin
IN_MOD=2'b11;
in1_sel=2'b00;
in2_sel=2'b01;
out_sel=2'b11;
out_sel=3'b011;
reg_read_addr={CIR[8:8],3'b000};
reg_write_addr={CIR[8:8],3'b000};
reg_read_oe=0;
@ -224,7 +228,7 @@ always @(posedge clock) begin
IN_MOD=2'b11;
in1_sel=2'b00;
in2_sel=2'b01;
out_sel=CIR[7:6];
out_sel={1'b0,CIR[7:6]};
reg_read_addr={CIR[8:8],CIR[2:0]};
reg_write_addr={CIR[8:8],CIR[2:0]};
reg_read_oe=0;
@ -254,7 +258,7 @@ always @(posedge clock) begin
IN_MOD=2'b11;
in1_sel=2'b00;
in2_sel=2'b00;
out_sel=2'b11;
out_sel=3'b011;
reg_write_addr={1'b0,CIR[10:8]};
PARAM1[7:0]=CIR[7:0];
PARAM2=0;
@ -273,7 +277,7 @@ always @(posedge clock) begin
IN_MOD=2'b11;
in1_sel=2'b00;
in2_sel=2'b00;
out_sel=2'b11;
out_sel=3'b011;
reg_write_addr={1'b1,CIR[10:8]};
ALU_1OE=0;
ALU_1OP=`ALU_OP_ADD;
@ -298,7 +302,7 @@ always @(posedge clock) begin
in1_sel=2'b00;
end
in2_sel=2'b00;
out_sel=2'b11;
out_sel=3'b011;
reg_write_addr={CIR[8:8],CIR[5:3]};
end else begin
`invalid_instruction
@ -325,7 +329,7 @@ always @(posedge clock) begin
Wbit=1;
in1_sel=2'b01;
in2_sel=2'b00;
out_sel=2'b11;
out_sel=3'b011;
IN_MOD=2'b11;
PARAM2=1;
reg_read_addr={1'b1,CIR[10:8]};
@ -350,7 +354,7 @@ always @(posedge clock) begin
IN_MOD=CIR[7:6];
in1_sel=2'b00;/* number 1 */
in2_sel=(CIR[7:6]==2'b11)? 2'b01 : 2'b00;
out_sel=CIR[7:6];
out_sel={1'b0,CIR[7:6]};
PARAM1=1;
reg_read_addr={1'b0,CIR[2:0]};
reg_write_addr={1'b0,CIR[2:0]};
@ -399,12 +403,12 @@ always @(posedge clock) begin
`start_unaligning_instruction
else
`start_aligning_instruction
Suppress_ALU_Output=1;
IN_MOD=2'b11;
in1_sel=2'b00;
in2_sel=2'b01;
reg_read_addr={CIR[8:8],3'b000};
reg_read_oe=0;
out_sel=3'b100;
ALU_1OE=0;
ALU_1OP=`ALU_OP_SUB;
if(CIR[8:8]==1)
@ -417,6 +421,65 @@ always @(posedge clock) begin
`invalid_instruction
end
end
6'b011100,
6'b011101,
6'b011110,
6'b011111:begin
/* Conditional relative jumps */
/* Jump on Zero */
/* 0 1 1 1 0 1 0 0 | IP-INC8 |*/
/* Jump on Sign */
/* 0 1 1 1 1 0 0 0 | IP-INC8 |*/
/* 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]};
ALU_1OE=0;
ALU_1OP=`ALU_OP_ADD;
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 */
if(FLAGS[11:11]==CIR[8:8])
state=`PROC_IF_STATE_ENTRY;
else begin
state=`PROC_EX_STATE_ENTRY;
end
end
4'b010: begin
/* Jump on (not) Zero */
if(FLAGS[6:6]==CIR[8:8])
state=`PROC_IF_STATE_ENTRY;
else
state=`PROC_EX_STATE_ENTRY;
end
4'b100: begin
/* Jump on (not) Sign */
if(FLAGS[7:7]==CIR[8:8])
state=`PROC_IF_STATE_ENTRY;
else
state=`PROC_EX_STATE_ENTRY;
end
4'b101: begin
/* Jump on (not) Parity */
if(FLAGS[2:2]==CIR[8:8])
state=`PROC_IF_STATE_ENTRY;
else
state=`PROC_EX_STATE_ENTRY;
end
default:begin
`invalid_instruction; /*We don't support that condition*/
end
endcase
end
end
default:begin
`invalid_instruction
end
@ -483,28 +546,28 @@ always @(posedge clock) begin
if(IN_MOD!=2'b00)begin
/*Actually check if 01 and add the 8bits or if 10 add the 16bits ....*/
`invalid_instruction;
end
end
end
`PROC_MEMIO_GET_ALIGNED_DATA:begin
PARAM1=(Wbit==1)? external_data_bus : {8'b00000000,external_data_bus[15:8]} ;
state=`PROC_EX_STATE_ENTRY;
end
`PROC_MEMIO_GET_UNALIGNED_DATA:begin
if(Wbit==1) begin
`invalid_instruction //easy to implement, get the other byte from the next address
end else begin
PARAM1={8'b00000000,external_data_bus[7:0]};
state=`PROC_EX_STATE_ENTRY;
end
end
`PROC_EX_STATE_ENTRY:begin
reg_write_data=ALU_1O;
FLAGS[7:0] = ALU_FLAGS[7:0];
state=`PROC_EX_STATE_EXIT;
ERROR=0;
end
endcase
end
`PROC_MEMIO_GET_ALIGNED_DATA:begin
PARAM1=(Wbit==1)? external_data_bus : {8'b00000000,external_data_bus[15:8]} ;
state=`PROC_EX_STATE_ENTRY;
end
`PROC_MEMIO_GET_UNALIGNED_DATA:begin
if(Wbit==1) begin
`invalid_instruction //easy to implement, get the other byte from the next address
end else begin
PARAM1={8'b00000000,external_data_bus[7:0]};
state=`PROC_EX_STATE_ENTRY;
end
end
`PROC_EX_STATE_ENTRY:begin
reg_write_data=ALU_1O;
FLAGS[7:0] = ALU_FLAGS[7:0];
state=`PROC_EX_STATE_EXIT;
ERROR=0;
end
endcase
end

0
cpu/xt2
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