uzix/zx-sizif-512
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correctly handle magic_map on magic button press when DivIDE addon is installed

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Eugene Lozovoy
2023-04-27 19:48:56 +03:00
parent 0d85510652
commit e306ef0a7d
1 changed files with 6 additions and 6 deletions
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12
cpld/rtl/magic.sv
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@ -47,7 +47,7 @@ localparam magic_on_start = 1'b1;
reg magic_unmap_next;
reg magic_map_next;
reg opcode_check_next;
reg [1:0] opcode_check_next;
reg opcode_match;
reg opcode_is_reading;
@ -58,7 +58,7 @@ always @(posedge clk28 or negedge rst_n) begin
magic_map <= magic_on_start;
magic_map_next <= 0;
magic_unmap_next <= 0;
opcode_check_next <= magic_on_start;
opcode_check_next <= {2{magic_on_start}};
opcode_match <= 0;
opcode_is_reading <= 0;
end
@ -69,8 +69,8 @@ always @(posedge clk28 or negedge rst_n) begin
magic_mode <= 1'b1;
end
if (opcode_check_next) begin
// Check first fetched opcode from magic rom is 0xEB
if (|opcode_check_next) begin
// Check two first fetched opcodes from magic rom is 0xEB
// Otherwise assume there is no magic rom
if (bus.mreq && bus.m1 && bus.rd) begin
opcode_is_reading <= 1'b1;
@ -78,7 +78,7 @@ always @(posedge clk28 or negedge rst_n) begin
end
else if (opcode_is_reading) begin
opcode_is_reading <= 1'b0;
opcode_check_next <= 1'b0;
opcode_check_next <= opcode_match? {1'b0, opcode_check_next[1]} : 2'b00;
magic_mode <= magic_mode && opcode_match;
magic_map <= magic_map && opcode_match;
end
@ -99,7 +99,7 @@ always @(posedge clk28 or negedge rst_n) begin
n_nmi <= 1'b1;
magic_map <= 1'b1;
magic_map_next <= 1'b0;
opcode_check_next <= bus.a == 16'h0066;
opcode_check_next[1] <= bus.a == 16'h0066;
end
end
end