📄 3_09syst
字号:
always #1 if ((nRAMS1 == 1'b0) && (nSEL == 1'b0) && (TIMER_1 > 0)) s0298
TIMER_1 = TIMER_1 - 1; s0299
always #1 if ((nRAMS2 == 1'b0) && (nSEL == 1'b0) && (TIMER_2 > 0)) s0300
TIMER_2 = TIMER_2 - 1; s0301
always #1 if ((nRAMS3 == 1'b0) && (nSEL == 1'b0) && (TIMER_3 > 0)) s0302
TIMER_3 = TIMER_3 - 1; s0303
s0304
// s0305
// Set access wait time of a byte s0306
// group to RAM access time s0307
// s0308
always @(nRAMS0 or nSEL) s0309
if ((nRAMS0 == 1'b0) && (nSEL == 1'b0)) TIMER_0 = `RAMTIME; s0310
always @(nRAMS1 or nSEL) s0311
if ((nRAMS1 == 1'b0) && (nSEL == 1'b0)) TIMER_1 = `RAMTIME; s0312
always @(nRAMS2 or nSEL) s0313
if ((nRAMS2 == 1'b0) && (nSEL == 1'b0)) TIMER_2 = `RAMTIME; s0314
always @(nRAMS3 or nSEL) s0315
if ((nRAMS3 == 1'b0) && (nSEL == 1'b0)) TIMER_3 = `RAMTIME; s0316
s0317
// s0318
// Update state of data bus driver s0319
// (one byte group per 'always' statement) s0320
// s0321
always @(RAM_RnW or nRAMS0 or nSEL) s0322
if ((RAM_RnW == 1'b1) && (nRAMS0 == 1'b0) && (nSEL == 1'b0)) s0323
DATA_DRV[ 7: 0] = 8'bxxxxxxxx; s0324
else DATA_DRV[ 7: 0] = 8'bzzzzzzzz; s0325
always @(RAM_RnW or nRAMS1 or nSEL) s0326
if ((RAM_RnW == 1'b1) && (nRAMS1 == 1'b0) && (nSEL == 1'b0)) s0327
DATA_DRV[15: 8] = 8'bxxxxxxxx; s0328
else DATA_DRV[15: 8] = 8'bzzzzzzzz; s0329
always @(RAM_RnW or nRAMS2 or nSEL) s0330
if ((RAM_RnW == 1'b1) && (nRAMS2 == 1'b0) && (nSEL == 1'b0)) s0331
DATA_DRV[23:16] = 8'bxxxxxxxx; s0332
else DATA_DRV[23:16] = 8'bzzzzzzzz; s0333
always @(RAM_RnW or nRAMS3 or nSEL) s0334
if ((RAM_RnW == 1'b1) && (nRAMS3 == 1'b0) && (nSEL == 1'b0)) s0335
DATA_DRV[31:24] = 8'bxxxxxxxx; s0336
else DATA_DRV[31:24] = 8'bzzzzzzzz; s0337
s0338
// s0339
// When access address or access mode change, set access s0340
// wait time of all byte groups to memory access time s0341
// s0342
always @(RAM_ADDR or RAM_RnW) begin s0343
TIMER_0 = `RAMTIME; s0344
TIMER_1 = `RAMTIME; s0345
TIMER_2 = `RAMTIME; s0346
TIMER_3 = `RAMTIME; s0347
end s0348
s0349
endmodule // ram s0350
s0351
s0352
//---------------------------------------------------------------------------- s0353
// s0354
// ROM s0355
// s0356
// 4K 32-bit read-only memory with definable access time s0357
// s0358
//---------------------------------------------------------------------------- s0359
s0360
module rom (ROM_DATA, ROM_ADDR, nROM_SEL); s0361
s0362
parameter WC = 11; // word count = number of address lines s0363
// default 11 => 2^11 = 2K = 8KB s0364
s0365
output [31:0] ROM_DATA; // ROM data s0366
s0367
input [27:0] ROM_ADDR; // ROM address s0368
input nROM_SEL; // ROM selection s0369
s0370
reg [31:0] DATA_DRV; // data driver s0371
s0372
wire [31:0] ROM_DATA = DATA_DRV; // data bus s0373
wire [27:0] ROM_ADDR; // address bus s0374
wire nROM_SEL; // ROM selection s0375
s0376
reg [31:0] MEMORY[0:(1<<WC)-1]; // memory s0377
integer TIMER; // access time counter s0378
s0379
// s0380
// Load operating system s0381
// s0382
initial begin s0383
// s0384
// ROM size between s0385
// 1KB and 64MB s0386
// s0387
if (( WC < 8 ) || ( WC > 24) ) begin s0388
$display("FATAL ERROR:\n%m: wrong ROM size\n"); s0389
$finish(2); s0390
end s0391
// s0392
// Load program s0393
// s0394
if (`OS_FORMAT) $readmemh(`OS_ROM, MEMORY); s0395
else $readmemb(`OS_ROM, MEMORY); s0396
end s0397
s0398
s0399
// s0400
// After end of access wait time, s0401
// put data on data bus; s0402
// if address outside ROM, stop system s0403
// s0404
always @(TIMER) begin s0405
if ((nROM_SEL == 1'b0) && (TIMER == 0)) begin s0406
if ((`CHK_HGH_BITs == 1) && (ROM_ADDR[27:WC+1] != 0)) s0407
begin s0408
$display( s0409
"\nERROR: Addr invalid; Addr = --%b--\n", ROM_ADDR s0410
); s0411
$stop(2); s0412
end s0413
DATA_DRV = MEMORY[ROM_ADDR[WC-1:0]]; s0414
end s0415
end s0416
s0417
// s0418
// Count down access wait time s0419
// synchronously with simulation time s0420
// s0421
always #1 if ((nROM_SEL == 1'b0) && (TIMER > 0)) TIMER = TIMER - 1; s0422
s0423
// s0424
// When memory activation changes, update remaining s0425
// access wait time and state of data bus driver s0426
// s0427
always @(nROM_SEL) begin s0428
if (nROM_SEL == 1'b0) begin s0429
TIMER = `ROMTIME; s0430
DATA_DRV = {32{1'bx}}; s0431
end s0432
else DATA_DRV = {32{1'bz}}; s0433
end s0434
s0435
// s0436
// If change of address, set access s0437
// wait time to memory access time s0438
// s0439
always @(ROM_ADDR) TIMER = `ROMTIME; s0440
s0441
endmodule // rom s0442
s0443
s0444
//---------------------------------------------------------------------------- s0445
// s0446
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -