github.com/mist-devel.mist-board
1
0
Fork 0
mirror of https://github.com/mist-devel/mist-board.git synced 2026-02-06 16:14:42 +00:00
Code Issues Releases Wiki Activity

[C64] CIA: implement Timer B Bug

Browse Source 
Passes VICE test CIA-Timer-oldcias
This commit is contained in:
Gyorgy Szombathelyi
2019-04-14 01:08:20 +02:00
parent 67c76bdf8d
commit fee9441cbb
1 changed files with 13 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
cores/c64/rtl/mos6526.v
View File

@@ -2,7 +2,7 @@
// by Rayne
// Timers & Interrupts are rewritten by slingshot
// Passes all Lorenz CIA Timer tests
// Passes all "new" CIA tests from VICE, except dd0dtest
// Passes all CIA tests from VICE, except dd0dtest
module mos6526 (
input wire mode, // 0 - 6526 "old", 1 - 8521 "new"
@@ -55,6 +55,7 @@ reg [5:0] tod_hr;
reg [7:0] sdr;
reg [4:0] imr;
reg [4:0] icr;
reg timer_b_int; // for Timer B bug
reg [7:0] cra;
reg [7:0] crb;
@@ -249,10 +250,14 @@ always @(posedge clk) begin
timer_b <= 16'h0000;
timerBff <= 1'b0;
icr[1] <= 1'b0;
timer_b_int <= 0;
end
else begin
if (phi2_p) begin
if (int_reset) icr[1] <= 0;
if (int_reset) begin
icr[1] <= 0;
timer_b_int <= 0;
end
countB0 <= cnt_in && ~cnt_in_prev;
countB1 <= countB0;
countB2 <= timerBin & crb[0];
@@ -264,6 +269,7 @@ always @(posedge clk) begin
if (timerBoverflow) begin
timerBff <= ~timerBff;
icr[1] <= 1;
timer_b_int <= 1;
timer_b <= {tb_hi, tb_lo};
countB3 <= 0;
if (crb[3] | oneShotB0) begin
@@ -271,6 +277,8 @@ always @(posedge clk) begin
countB2 <= 0;
end
end
// Timer B bug - INT fired, but ICR not set
if (!mode & int_reset) icr[1] <= 0;
if (loadB1) begin
timer_b <= {tb_hi, tb_lo};
@@ -469,6 +477,8 @@ always @(posedge clk) begin
end
end
wire [4:0] icr_adj = {icr[4:2], timer_b_int, icr[0]};
// Interrupt Control
always @(posedge clk) begin
reg [7:0] imr_reg;
@@ -485,7 +495,7 @@ always @(posedge clk) begin
if (phi2_p | mode) begin
imr <= imr_reg[7] ? imr | imr_reg[4:0] : imr & ~imr_reg[4:0];
irq_n <= irq_n ? ~|(imr & icr) : irq_n;
irq_n <= irq_n ? ~|(imr & icr_adj) : irq_n;
end
if (phi2_p & int_reset) begin
irq_n <= 1;