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separate block 8 as it's going to be rather large

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This commit is contained in:
Raphael Jacquot 2019-02-15 11:04:01 +01:00
parent 25385115e0
commit 343f1e2247
2 changed files with 88 additions and 86 deletions
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87
saturn_decoder.v
View file

@ -534,92 +534,7 @@ always @(posedge i_clk) begin
`endif
end
if (do_block_8x) begin
$display("block_8x %h | op %d", i_nibble, o_alu_op);
case (i_nibble)
4'h0: //
block_80x <= 1;
4'h2:
block_82x <= 1;
4'h4, 4'h5: // ST=[01] n
begin
o_alu_op <= i_nibble[0]?`ALU_OP_SET_BIT:`ALU_OP_RST_BIT;
block_sr_bit <= 1;
`ifdef SIM
o_unimplemented <= 0;
`endif
end
4'hC, 4'hD,
4'hE, 4'hF: // GOLONG, GOVLNG, GOSUBL, GOSBVL
begin
o_alu_no_stall <= 1;
o_alu_op <= i_nibble[0]?`ALU_OP_JMP_ABS5:`ALU_OP_JMP_REL4;
// is it a gosub ?
o_push <= i_nibble[1];
o_alu_debug <= i_nibble[1];
mem_load_max <= i_nibble[0]?4:3;
o_mem_pos <= 0;
block_jmp <= 1;
// debug for cases not tested
o_alu_debug <= !i_nibble[0];
`ifdef SIM
o_unimplemented <= 0;
`endif
end
default: begin
$display("block_8x %h error", i_nibble);
o_dec_error <= 1;
end
endcase
block_8x <= 0;
end
if (do_block_80x) begin
$display("block_80x %h | op %d", i_nibble, o_alu_op);
case (i_nibble)
4'h5: begin // CONFIG
next_nibble <= 0;
o_ins_decoded <= 1;
end
4'hA: begin // RESET
next_nibble <= 0;
o_ins_decoded <= 1;
end
4'hC: block_80Cx <= 1;
default: begin
$display("block_80x %h error", i_nibble);
o_dec_error <= 1;
end
endcase
block_80x <= 0;
end
if (do_block_80Cx) begin
o_ins_alu_op <= 1;
o_alu_op <= `ALU_OP_COPY;
next_nibble <= 0;
o_ins_decoded <= 1;
block_80Cx <= 0;
end
// 821 XM=0
// 822 SB=0
// 824 SR=0
// 828 MP=0
// 82F CLRHST
// 82x CLRHST x
if (do_block_82x) begin
o_ins_alu_op <= 1;
o_alu_op <= `ALU_OP_CLR_MASK;
o_imm_value <= i_nibble;
next_nibble <= 0;
o_ins_decoded <= 1;
`ifdef SIM
o_unimplemented <= 0;
`endif
block_82x <= 0;
end
`include "saturn_decoder_block_8.v"
if (do_block_Ax) begin
o_fields_table <= i_nibble[3]?`FT_TABLE_b:`FT_TABLE_a;

87
saturn_decoder_block_8.v Normal file
View file

@ -0,0 +1,87 @@
if (do_block_8x) begin
$display("block_8x %h | op %d", i_nibble, o_alu_op);
case (i_nibble)
4'h0: //
block_80x <= 1;
4'h2:
block_82x <= 1;
4'h4, 4'h5: // ST=[01] n
begin
o_alu_op <= i_nibble[0]?`ALU_OP_SET_BIT:`ALU_OP_RST_BIT;
block_sr_bit <= 1;
`ifdef SIM
o_unimplemented <= 0;
`endif
end
4'hC, 4'hD,
4'hE, 4'hF: // GOLONG, GOVLNG, GOSUBL, GOSBVL
begin
o_alu_no_stall <= 1;
o_alu_op <= i_nibble[0]?`ALU_OP_JMP_ABS5:`ALU_OP_JMP_REL4;
// is it a gosub ?
o_push <= i_nibble[1];
o_alu_debug <= i_nibble[1];
mem_load_max <= i_nibble[0]?4:3;
o_mem_pos <= 0;
block_jmp <= 1;
// debug for cases not tested
o_alu_debug <= !i_nibble[0];
`ifdef SIM
o_unimplemented <= 0;
`endif
end
default: begin
$display("block_8x %h error", i_nibble);
o_dec_error <= 1;
end
endcase
block_8x <= 0;
end
if (do_block_80x) begin
$display("block_80x %h | op %d", i_nibble, o_alu_op);
case (i_nibble)
4'h5: begin // CONFIG
next_nibble <= 0;
o_ins_decoded <= 1;
end
4'hA: begin // RESET
next_nibble <= 0;
o_ins_decoded <= 1;
end
4'hC: block_80Cx <= 1;
default: begin
$display("block_80x %h error", i_nibble);
o_dec_error <= 1;
end
endcase
block_80x <= 0;
end
if (do_block_80Cx) begin
o_ins_alu_op <= 1;
o_alu_op <= `ALU_OP_COPY;
next_nibble <= 0;
o_ins_decoded <= 1;
block_80Cx <= 0;
end
// 821 XM=0
// 822 SB=0
// 824 SR=0
// 828 MP=0
// 82F CLRHST
// 82x CLRHST x
if (do_block_82x) begin
o_ins_alu_op <= 1;
o_alu_op <= `ALU_OP_CLR_MASK;
o_imm_value <= i_nibble;
next_nibble <= 0;
o_ins_decoded <= 1;
`ifdef SIM
o_unimplemented <= 0;
`endif
block_82x <= 0;
end