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// part of NeoGS project (c) 2007-2008 NedoPC
//
// ports $00-$3f are in FPGA, $40-$ff are in CPLD
module ports(
input wire rst_n,
input wire cpu_clock, // Z80 CPU clock (clk_fpga on schematics)
input wire [ 7:0] din, // NGS z80 cpu DATA BUS inputs
output reg [ 7:0] dout, // NGS z80 cpu DATA BUS outputs
output reg busin, // direction of bus: =1 - input, =0 - output
input wire [15:0] a, // NSG z80 cpu ADDRESS BUS
input wire iorq_n,
input wire mreq_n,
input wire rd_n,
input wire wr_n, // NGS z80 cpu control signals
input wire [ 7:0] data_port_input, // data_port input from zxbus module (async)
output reg [ 7:0] data_port_output, // data_port output to zxbus module (async to zxbus, sync here)
input wire [ 7:0] command_port_input, // command_port input from zxbus (async)
input wire data_bit_input, // data_bit from zxbus module (sync)
input wire command_bit_input, // --//-- (sync)
output reg data_bit_output, // output to zxbus module
output reg command_bit_output,
output reg data_bit_wr, // strobes (positive) to zxbus module, synchronous
output reg command_bit_wr,
output reg mode_8chans, // mode outputs for sound_main module
output reg mode_pan4ch, //
output reg mode_inv7b, //
output reg mode_ramro, // mode outputs for memmap module
output reg mode_norom,
output reg [7:0] mode_pg0, // page registers for memmap module
output reg [7:0] mode_pg1,
output reg [7:0] mode_pg2,
output reg [7:0] mode_pg3,
output reg clksel0, // clock select (output from FPGA)
output reg clksel1,
output reg snd_wrtoggle, // toggle to write sound data to sound system memory
output reg snd_datnvol, // whether it's for volume (=0) or for samples (=1)
output reg [ 2:0] snd_addr, // address: which channel to be written (0-7)
output reg [ 7:0] snd_data, // actual 8-bit data to be written
output wire [ 7:0] md_din, // mp3 data interface
output wire md_start,
input wire md_dreq,
output reg md_halfspeed,
output reg mc_ncs, // mp3 control interface
output reg mc_xrst,
input wire [ 7:0] mc_dout,
output wire [ 7:0] mc_din,
output wire mc_start,
output reg [ 1:0] mc_speed,
input wire mc_rdy,
output reg sd_ncs, // SD card interface
input wire [ 7:0] sd_dout,
output wire [ 7:0] sd_din,
output wire sd_start,
input wire dma_sd_start,
input wire sd_det,
input wire sd_wp,
output reg led, // LED control
input wire led_toggle,
output reg [7:0] dma_din_modules, // DMA control
//
output reg dma_select_zx,
output reg dma_select_sd,
output reg dma_select_mp3,
//
input wire [7:0] dma_dout_zx,
input wire [7:0] dma_dout_sd,
input wire [7:0] dma_dout_mp3,
//
output reg dma_wrstb,
output reg [1:0] dma_regsel,
// timer freq selector
output reg [2:0] timer_rate,
// intena/intreq related
output wire intena_wr,
output wire intreq_wr,
input wire [7:0] intreq_rd
);
localparam MPAG = 6'h00;
localparam MPAGEX = 6'h10;
localparam ZXCMD = 6'h01;
localparam ZXDATRD = 6'h02;
localparam ZXDATWR = 6'h03;
localparam ZXSTAT = 6'h04;
localparam CLRCBIT = 6'h05;
localparam VOL1 = 6'h06;
localparam VOL2 = 6'h07;
localparam VOL3 = 6'h08;
localparam VOL4 = 6'h09;
localparam VOL5 = 6'h16;
localparam VOL6 = 6'h17;
localparam VOL7 = 6'h18;
localparam VOL8 = 6'h19;
localparam DAMNPORT1 = 6'h0a;
localparam DAMNPORT2 = 6'h0b;
localparam LEDCTR = 6'h01;
localparam GSCFG0 = 6'h0f;
localparam SCTRL = 6'h11;
localparam SSTAT = 6'h12;
localparam SD_SEND = 6'h13;
localparam SD_READ = 6'h13;
localparam SD_RSTR = 6'h14;
localparam MD_SEND = 6'h14; // same as SD_RSTR!!!
localparam MC_SEND = 6'h15;
localparam MC_READ = 6'h15;
localparam DMA_MOD = 6'h1b; // read/write
localparam DMA_HAD = 6'h1c; // LSB bits 1:0 are 00 // read/write all
localparam DMA_MAD = 6'h1d; // 01
localparam DMA_LAD = 6'h1e; // 10
localparam DMA_CST = 6'h1f; // 11
localparam DMA_PORTS = 6'h1c; // mask for _HAD, _MAD, _LAD and _CST ports, two LSBs must be zero
localparam TIM_FREQ = 6'h0e;
localparam INTENA = 6'h0c;
localparam INTREQ = 6'h0d;
localparam PG0 = 6'h20;
localparam PG1 = 6'h21;
localparam PG2 = 6'h22;
localparam PG3 = 6'h23;
// FREE PORT ADDRESSES: $1A, $24-$3F
// internal regs & wires
reg mode_expag; // extended paging mode register
reg port09_bit5;
wire port_enabled; // =1 when port address is in enabled region ($00-$3f)
wire mem_enabled; // =1 when memory mapped sound regs are addressed ($6000-$7FFF)
reg volports_enabled; // when volume ports are addressed (6-9 and $16-$19)
reg iowrn_reg; // registered io write signal (all positive edge!)
reg iordn_reg; // --//--
reg merdn_reg; // --//--
reg port_wr; // synchronous positive write pulse (write from z80 to fpga regs)
reg port_rd; // synchronous positive read pulse (read done from fpga regs to z80)
reg memreg_rd; // when memory-mapped sound regs are read
wire port00_wr; // specific write and read strobes (1 clock cycle long positive)
wire p_ledctr_wr;
wire port02_rd;
wire port03_wr;
wire port05_wrrd;
wire port09_wr;
wire port0a_wrrd;
wire port0b_wrrd;
wire port0f_wr;
wire port10_wr;
// wire p_sstat_rd;
// wire p_sctrl_rd;
wire p_sctrl_wr;
wire p_sdsnd_wr;
// wire p_sdrd_rd;
wire p_sdrst_rd;
wire p_mdsnd_wr;
wire p_mcsnd_wr;
// wire p_mcrd_rd;
wire p_dmamod_wr;
wire p_dmaports_wr;
wire p_timfreq_wr;
wire pg0_wr;
wire pg1_wr;
wire pg2_wr;
wire pg3_wr;
reg [2:0] volnum; // volume register number from port address
reg [2:0] dma_module_select; // which dma module selected: zero - none selected
localparam DMA_NONE_SELECTED = 3'd0;
localparam DMA_MODULE_ZX = 3'd1;
localparam DMA_MODULE_SD = 3'd2;
localparam DMA_MODULE_MP3 = 3'd3;
// localparam DMA_MODULE_... = 3'd4;
reg [7:0] dma_dout_modules; // select in data from different modules
// actual code
//enabled ports
assign port_enabled = ~(a[7] | a[6]); // $00-$3F
//enabled mem
assign mem_enabled = (~a[15]) & a[14] & a[13]; // $6000-$7FFF
// volume ports enabled
always @*
begin
if( a[5:0]==VOL1 ||
a[5:0]==VOL2 ||
a[5:0]==VOL3 ||
a[5:0]==VOL4 ||
a[5:0]==VOL5 ||
a[5:0]==VOL6 ||
a[5:0]==VOL7 ||
a[5:0]==VOL8 )
volports_enabled <= 1'b1;
else
volports_enabled <= 1'b0;
end
//when data bus outputs
always @*
begin
if( port_enabled && (!iorq_n) && (!rd_n) )
busin <= 1'b0; // bus outputs
else
busin <= 1'b1; // bus inputs
end
// rd/wr/iorq syncing in and pulses - old gen
always @(posedge cpu_clock)
begin
iowrn_reg <= iorq_n | wr_n;
iordn_reg <= iorq_n | rd_n;
if( port_enabled && (!iorq_n) && (!wr_n) && iowrn_reg )
port_wr <= 1'b1;
else
port_wr <= 1'b0;
if( port_enabled && (!iorq_n) && (!rd_n) && iordn_reg )
port_rd <= 1'b1;
else
port_rd <= 1'b0;
end
/*
// new gen of port_rd and port_wr
reg [2:0] rd_sync;
reg [2:0] wr_sync;
always @(posedge cpu_clock)
begin
rd_sync[2:0] <= { rd_sync[1:0], port_enabled&(~iorq_n)&(~rd_n) };
wr_sync[2:0] <= { wr_sync[1:0], port_enabled&(~iorq_n)&(~wr_n) };
port_wr <= (wr_sync[1:0]==2'b01);
port_rd <= (rd_sync[1:0]==2'b01);
end
*/
// mreq syncing and mem read pulse
always @(negedge cpu_clock)
begin
merdn_reg <= mreq_n | rd_n;
if( mem_enabled && (!mreq_n) && (!rd_n) && merdn_reg )
memreg_rd <= 1'b1;
else
memreg_rd <= 1'b0;
end
// specific ports strobes
assign port00_wr = ( a[5:0]==MPAG && port_wr );
assign port02_rd = ( a[5:0]==ZXDATRD && port_rd );
assign port03_wr = ( a[5:0]==ZXDATWR && port_wr );
assign port05_wrrd = ( a[5:0]==CLRCBIT && (port_wr||port_rd) );
assign port09_wr = ( a[5:0]==VOL4 && port_wr );
assign port0a_wrrd = ( a[5:0]==DAMNPORT1 && (port_wr||port_rd) );
assign port0b_wrrd = ( a[5:0]==DAMNPORT2 && (port_wr||port_rd) );
assign port0f_wr = ( a[5:0]==GSCFG0 && port_wr );
assign port10_wr = ( a[5:0]==MPAGEX && port_wr );
// assign p_sctrl_rd = ( a[5:0]==SCTRL && port_rd );
assign p_sctrl_wr = ( a[5:0]==SCTRL && port_wr );
// assign p_sstat_rd = ( a[5:0]==SSTAT && port_rd );
assign p_sdsnd_wr = ( a[5:0]==SD_SEND && port_wr );
// assign p_sdrd_rd = ( a[5:0]==SD_READ && port_rd );
assign p_sdrst_rd = ( a[5:0]==SD_RSTR && port_rd );
assign p_mdsnd_wr = ( a[5:0]==MD_SEND && port_wr );
assign p_mcsnd_wr = ( a[5:0]==MC_SEND && port_wr );
// assign p_mcrd_rd = ( a[5:0]==MC_READ && port_rd );
assign p_ledctr_wr = ( a[5:0]==LEDCTR && port_wr );
assign p_dmamod_wr = ( a[5:0]==DMA_MOD && port_wr );
assign p_dmaports_wr = ( {a[5:2],2'b00}==DMA_PORTS && port_wr );
assign p_timfreq_wr = ( a[5:0]==TIM_FREQ && port_wr );
assign intena_wr = ( a[5:0]==INTENA && port_wr );
assign intreq_wr = ( a[5:0]==INTREQ && port_wr );
assign pg0_wr = ( a[5:0]==PG0 && port_wr );
assign pg1_wr = ( a[5:0]==PG1 && port_wr );
assign pg2_wr = ( a[5:0]==PG2 && port_wr );
assign pg3_wr = ( a[5:0]==PG3 && port_wr );
// read from fpga to Z80
always @*
begin
case( a[5:0] )
ZXCMD: // command register
dout <= command_port_input;
ZXDATRD: // data register
dout <= data_port_input;
ZXSTAT: // status bits
dout <= { data_bit_input, 6'bXXXXXX, command_bit_input };
GSCFG0: // config register #0F
dout <= { mode_inv7b, mode_pan4ch, clksel1, clksel0, mode_expag, mode_8chans, mode_ramro, mode_norom };
SSTAT:
dout <= { 4'd0, mc_rdy, sd_wp, sd_det, md_dreq };
SCTRL:
dout <= { 2'd0, mc_speed[1], md_halfspeed, mc_speed[0], mc_xrst, mc_ncs, sd_ncs };
SD_READ:
dout <= sd_dout;
SD_RSTR:
dout <= sd_dout;
MC_READ:
dout <= mc_dout;
INTREQ:
dout <= intreq_rd;
DMA_MOD:
dout <= { 5'd0, dma_module_select };
DMA_HAD:
dout <= dma_dout_modules;
DMA_MAD:
dout <= dma_dout_modules;
DMA_LAD:
dout <= dma_dout_modules;
DMA_CST:
dout <= dma_dout_modules;
default:
dout <= 8'bXXXXXXXX;
endcase
end
// write to $00 and $10 ports -- old mem mapping control,
// also new mapping control (pg2 and pg3 ports)
always @(posedge cpu_clock)
if( port00_wr ) // port 00
begin
if( !mode_expag ) // normal paging
mode_pg2[7:0] <= { din[6:0], 1'b0 };
else // extended paging
mode_pg2[7:0] <= { din[6:0], din[7] };
end
else if( pg2_wr )
mode_pg2 <= din;
//
always @(posedge cpu_clock)
if( !mode_expag && port00_wr ) // port 10 (when in normal mode, part of port 00)
mode_pg3[7:0] <= { din[6:0], 1'b1 };
else if( mode_expag && port10_wr )
mode_pg3[7:0] <= { din[6:0], din[7] };
else if( pg3_wr )
mode_pg3 <= din;
// write to pg0 and pg1 ports
always @(posedge cpu_clock, negedge rst_n)
if( !rst_n )
mode_pg0 <= 8'b00000000;
else if( pg0_wr )
mode_pg0 <= din;
//
always @(posedge cpu_clock, negedge rst_n)
if( !rst_n )
mode_pg1 <= 8'b00000011;
else if( pg1_wr )
mode_pg1 <= din;
// port $03 write ++
always @(posedge cpu_clock)
begin
if( port03_wr==1'b1 )
data_port_output <= din;
end
// port $09 bit tracing
always @(posedge cpu_clock)
begin
if( port09_wr==1'b1 )
port09_bit5 <= din[5];
end
// write and reset of port $0F ++
always @(posedge cpu_clock,negedge rst_n)
begin
if( rst_n==1'b0 ) // reset!
{ mode_inv7b, mode_pan4ch, clksel1, clksel0, mode_expag, mode_8chans, mode_ramro, mode_norom } <= 8'b00110000;
else // write to port
begin
if( port0f_wr == 1'b1 )
begin
{ mode_inv7b, mode_pan4ch, clksel1, clksel0, mode_expag, mode_8chans, mode_ramro, mode_norom } <= din[7:0];
end
end
end
// data bit handling
always @*
case( {port02_rd,port03_wr,port0a_wrrd} )
3'b100:
begin
data_bit_output <= 1'b0;
data_bit_wr <= 1'b1;
end
3'b010:
begin
data_bit_output <= 1'b1; // ++
data_bit_wr <= 1'b1;
end
3'b001:
begin
data_bit_output <= ~mode_pg2[0];
data_bit_wr <= 1'b1;
end
default:
begin
data_bit_output <= 1'bX;
data_bit_wr <= 1'b0;
end
endcase
// command bit handling
always @*
case( {port05_wrrd,port0b_wrrd} )
2'b10:
begin
command_bit_output <= 1'b0;
command_bit_wr <= 1'b1;
end
2'b01:
begin
command_bit_output <= port09_bit5;
command_bit_wr <= 1'b1;
end
default:
begin
command_bit_output <= 1'bX;
command_bit_wr <= 1'b0;
end
endcase
// handle data going to sound module (volume and samples values)
always @*
begin
case( a[5:0] ) // port addresses to volume register numbers
VOL1:
volnum <= 3'd0;
VOL2:
volnum <= 3'd1;
VOL3:
volnum <= 3'd2;
VOL4:
volnum <= 3'd3;
VOL5:
volnum <= 3'd4;
VOL6:
volnum <= 3'd5;
VOL7:
volnum <= 3'd6;
VOL8:
volnum <= 3'd7;
default:
volnum <= 3'bXXX;
endcase
end
// handling itself (sending data to sound module)
always @(posedge cpu_clock)
begin
if( memreg_rd ) // memory read - sample data write
begin
snd_wrtoggle <= ~snd_wrtoggle;
snd_datnvol <= 1'b1; // sample data
if( !mode_8chans ) // 4 channel mode
snd_addr <= { 1'b0, a[9:8] };
else // 8 channel mode
snd_addr <= a[10:8];
snd_data <= din;
end
else if( volports_enabled && port_wr )
begin
snd_wrtoggle <= ~snd_wrtoggle;
snd_datnvol <= 1'b0; // volume data
snd_addr <= volnum;
snd_data <= din;
end
end
//SPI (mp3, SD) interfaces
assign sd_din = (a[5:0]==SD_RSTR || dma_sd_start) ? 8'hFF : din;
assign mc_din = din;
assign md_din = din;
assign sd_start = p_sdsnd_wr | p_sdrst_rd;
assign mc_start = p_mcsnd_wr;
assign md_start = p_mdsnd_wr;
always @(posedge cpu_clock, negedge rst_n)
begin
if( !rst_n ) // async reset
begin
md_halfspeed <= 1'b0;
mc_speed <= 2'b01;
mc_xrst <= 1'b0;
mc_ncs <= 1'b1;
sd_ncs <= 1'b1;
end
else // clock
begin
if( p_sctrl_wr )
begin
if( din[0] )
sd_ncs <= din[7];
if( din[1] )
mc_ncs <= din[7];
if( din[2] )
mc_xrst <= din[7];
if( din[3] )
mc_speed[0] <= din[7];
if( din[4] )
md_halfspeed <= din[7];
if( din[5] )
mc_speed[1] <= din[7];
end
end
end
// LED control
always @(posedge cpu_clock, negedge rst_n)
begin
if( !rst_n )
led <= 1'b0;
else
begin
if( p_ledctr_wr )
led <= din[0];
else if( led_toggle )
led <= ~led;
end
end
// DMA control
//
always @(posedge cpu_clock, negedge rst_n) // selection of modules
if( !rst_n )
dma_module_select <= DMA_NONE_SELECTED;
else if( p_dmamod_wr )
dma_module_select <= din[2:0];
//
always @* dma_din_modules = din; // translate Z80 bus out to all DMA modules
//
always @* // select modules by individual signals
begin
dma_select_zx = ( dma_module_select==DMA_MODULE_ZX );
dma_select_sd = ( dma_module_select==DMA_MODULE_SD );
dma_select_mp3 = ( dma_module_select==DMA_MODULE_MP3 );
end
//
always @* dma_wrstb = p_dmaports_wr; // translate dma write strobe
//
always @* dma_regsel = a[1:0];
//
always @* // route data from modules to the common module bus
begin
case( dma_module_select )
DMA_MODULE_ZX:
dma_dout_modules <= dma_dout_zx;
DMA_MODULE_SD:
dma_dout_modules <= dma_dout_sd;
DMA_MODULE_MP3:
dma_dout_modules <= dma_dout_mp3;
//DMA_MODULE_...:
// dma_dout_modules <= dma_dout_...;
default:
dma_dout_modules <= 8'bxxxxxxxx;
endcase
end
// timer rate
//
always @(posedge cpu_clock,negedge rst_n)
if( !rst_n )
timer_rate <= 3'b000;
else if( p_timfreq_wr )
timer_rate <= din[2:0];
endmodule