src/wd279x.c

Sun, 05 Dec 2010 16:20:00 +0000

author
Philip Pemberton <philpem@philpem.me.uk>
date
Sun, 05 Dec 2010 16:20:00 +0000
changeset 52
a350dfa92895
parent 51
e5a92d7beecf
child 53
e1693c4b8a0c
permissions
-rw-r--r--

add preliminary WD279x emulation to core

philpem@48 1 #include <stdint.h>
philpem@48 2 #include <stdbool.h>
philpem@49 3 #include <malloc.h>
philpem@48 4 #include "wd279x.h"
philpem@48 5
philpem@48 6 /// WD2797 command constants
philpem@48 7 enum {
philpem@48 8 CMD_MASK = 0xF0, ///< Bit mask to detect command bits
philpem@48 9 CMD_RESTORE = 0x00, ///< Restore (recalibrate, seek to track 0)
philpem@48 10 CMD_SEEK = 0x10, ///< Seek to given track
philpem@48 11 CMD_STEP = 0x20, ///< Step
philpem@48 12 CMD_STEP_TU = 0x30, ///< Step and update track register
philpem@48 13 CMD_STEPIN = 0x40, ///< Step In
philpem@48 14 CMD_STEPIN_TU = 0x50, ///< Step In and update track register
philpem@48 15 CMD_STEPOUT = 0x60, ///< Step Out
philpem@48 16 CMD_STEPOUT_TU = 0x70, ///< Step Out and update track register
philpem@48 17 CMD_READ_SECTOR = 0x80, ///< Read Sector
philpem@48 18 CMD_READ_SECTOR_MULTI = 0x90, ///< Read Multiple Sectors
philpem@48 19 CMD_WRITE_SECTOR = 0xA0, ///< Write Sector
philpem@48 20 CMD_WRITE_SECTOR_MULTI = 0xB0, ///< Write Multiple Sectors
philpem@48 21 CMD_READ_ADDRESS = 0xC0, ///< Read Address (IDAM contents)
philpem@48 22 CMD_FORCE_INTERRUPT = 0xD0, ///< Force Interrupt
philpem@48 23 CMD_READ_TRACK = 0xE0, ///< Read Track
philpem@48 24 CMD_FORMAT_TRACK = 0xF0 ///< Format Track
philpem@48 25 };
philpem@48 26
philpem@48 27
philpem@49 28 void wd2797_init(WD2797_CTX *ctx)
philpem@48 29 {
philpem@48 30 // track, head and sector unknown
philpem@49 31 ctx->track = ctx->head = ctx->sector = 0;
philpem@48 32
philpem@49 33 // no IRQ pending
philpem@49 34 ctx->irql = ctx->irqe = false;
philpem@48 35
philpem@48 36 // no data available
philpem@49 37 ctx->data_pos = ctx->data_len = 0;
philpem@49 38 ctx->data = NULL;
philpem@49 39
philpem@49 40 // Status register clear, not busy
philpem@49 41 ctx->status = 0;
philpem@49 42
philpem@49 43 // Clear data register
philpem@49 44 ctx->data_reg = 0;
philpem@49 45
philpem@49 46 // Last step direction
philpem@49 47 ctx->last_step_dir = -1;
philpem@48 48
philpem@48 49 // No disc image loaded
philpem@48 50 ctx->disc_image = NULL;
philpem@49 51 ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = ctx->geom_tracks = 0;
philpem@48 52 }
philpem@48 53
philpem@48 54
philpem@49 55 void wd2797_reset(WD2797_CTX *ctx)
philpem@49 56 {
philpem@49 57 // track, head and sector unknown
philpem@49 58 ctx->track = ctx->head = ctx->sector = 0;
philpem@49 59
philpem@49 60 // no IRQ pending
philpem@49 61 ctx->irql = ctx->irqe = false;
philpem@49 62
philpem@49 63 // no data available
philpem@49 64 ctx->data_pos = ctx->data_len = 0;
philpem@49 65
philpem@49 66 // Status register clear, not busy
philpem@49 67 ctx->status = 0;
philpem@49 68
philpem@49 69 // Clear data register
philpem@49 70 ctx->data_reg = 0;
philpem@49 71
philpem@49 72 // Last step direction
philpem@49 73 ctx->last_step_dir = -1;
philpem@49 74 }
philpem@49 75
philpem@49 76
philpem@49 77 void wd2797_done(WD2797_CTX *ctx)
philpem@49 78 {
philpem@49 79 // Reset the WD2797
philpem@49 80 wd2797_reset(ctx);
philpem@49 81
philpem@49 82 // Free any allocated memory
philpem@49 83 if (ctx->data) {
philpem@49 84 free(ctx->data);
philpem@49 85 ctx->data = NULL;
philpem@49 86 }
philpem@49 87 }
philpem@49 88
philpem@49 89
philpem@49 90 bool wd2797_get_irq(WD2797_CTX *ctx)
philpem@48 91 {
philpem@48 92 // If an IRQ is pending, clear it and return true, otherwise return false
philpem@48 93 if (ctx->irqe) {
philpem@48 94 ctx->irqe = false;
philpem@48 95 return true;
philpem@48 96 } else {
philpem@48 97 return false;
philpem@48 98 }
philpem@48 99 }
philpem@48 100
philpem@48 101
philpem@49 102 bool wd2797_get_drq(WD2797_CTX *ctx)
philpem@48 103 {
philpem@48 104 return (ctx->data_pos < ctx->data_len);
philpem@48 105 }
philpem@48 106
philpem@48 107
philpem@49 108 WD2797_ERR wd2797_load(WD2797_CTX *ctx, FILE *fp, int secsz, int spt, int heads)
philpem@49 109 {
philpem@49 110 size_t filesize;
philpem@49 111
philpem@49 112 // Start by finding out how big the image file is
philpem@49 113 fseek(fp, 0, SEEK_END);
philpem@49 114 filesize = ftell(fp);
philpem@49 115 fseek(fp, 0, SEEK_SET);
philpem@49 116
philpem@49 117 // Now figure out how many tracks it contains
philpem@49 118 int tracks = filesize / secsz / spt / heads;
philpem@49 119 // Confirm...
philpem@49 120 if (tracks < 1) {
philpem@49 121 return WD2797_ERR_BAD_GEOM;
philpem@49 122 }
philpem@49 123
philpem@49 124 // Allocate enough memory to store one disc track
philpem@49 125 if (ctx->data) {
philpem@49 126 free(ctx->data);
philpem@49 127 }
philpem@49 128 ctx->data = malloc(secsz * spt);
philpem@49 129 if (!ctx->data)
philpem@49 130 return WD2797_ERR_NO_MEMORY;
philpem@49 131
philpem@49 132 // Load the image and the geometry data
philpem@49 133 ctx->disc_image = fp;
philpem@49 134 ctx->geom_tracks = tracks;
philpem@49 135 ctx->geom_secsz = secsz;
philpem@49 136 ctx->geom_heads = heads;
philpem@49 137 ctx->geom_spt = spt;
philpem@49 138
philpem@49 139 return WD2797_ERR_OK;
philpem@49 140 }
philpem@49 141
philpem@49 142
philpem@49 143 void wd2797_unload(WD2797_CTX *ctx)
philpem@49 144 {
philpem@49 145 // Free memory buffer
philpem@49 146 if (ctx->data) {
philpem@49 147 free(ctx->data);
philpem@49 148 ctx->data = NULL;
philpem@49 149 }
philpem@49 150
philpem@49 151 // Clear file pointer
philpem@49 152 ctx->disc_image = NULL;
philpem@49 153
philpem@49 154 // Clear the disc geometry
philpem@49 155 ctx->geom_tracks = ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = 0;
philpem@49 156 }
philpem@49 157
philpem@49 158
philpem@49 159 uint8_t wd2797_read_reg(WD2797_CTX *ctx, uint8_t addr)
philpem@48 160 {
philpem@48 161 uint8_t temp = 0;
philpem@48 162
philpem@48 163 switch (addr & 0x03) {
philpem@49 164 case WD2797_REG_STATUS: // Status register
philpem@48 165 // Read from status register clears IRQ
philpem@48 166 ctx->irql = false;
philpem@48 167
philpem@48 168 // Get current status flags (set by last command)
philpem@48 169 temp = ctx->status;
philpem@48 170 // DRQ bit
philpem@48 171 if (ctx->cmd_has_drq)
philpem@48 172 temp |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 173 // FDC is busy if there is still data in the buffer
philpem@48 174 temp |= (ctx->data_pos < ctx->data_len) ? 0x01 : 0x00; // if data in buffer, then DMA hasn't copied it yet, and we're still busy!
philpem@49 175 // TODO: also if seek delay / read delay hasn't passed (but that's for later)
philpem@48 176 return temp;
philpem@48 177
philpem@49 178 case WD2797_REG_TRACK: // Track register
philpem@48 179 return ctx->track;
philpem@48 180
philpem@49 181 case WD2797_REG_SECTOR: // Sector register
philpem@48 182 return ctx->sector;
philpem@48 183
philpem@49 184 case WD2797_REG_DATA: // Data register
philpem@48 185 // If there's data in the buffer, return it. Otherwise return 0xFF.
philpem@48 186 if (ctx->data_pos < ctx->data_len) {
philpem@48 187 // return data byte and increment pointer
philpem@48 188 return ctx->data[ctx->data_pos++];
philpem@48 189 } else {
philpem@48 190 return 0xff;
philpem@48 191 }
philpem@48 192
philpem@48 193 default:
philpem@48 194 // shut up annoying compilers which don't recognise unreachable code when they see it
philpem@48 195 // (here's looking at you, gcc!)
philpem@48 196 return 0xff;
philpem@48 197 }
philpem@48 198 }
philpem@48 199
philpem@48 200
philpem@49 201 void wd2797_write_reg(WD2797_CTX *ctx, uint8_t addr, uint8_t val)
philpem@48 202 {
philpem@48 203 uint8_t cmd = val & CMD_MASK;
philpem@48 204 size_t lba;
philpem@48 205 bool is_type1 = false;
philpem@49 206 int temp;
philpem@48 207
philpem@48 208 switch (addr) {
philpem@49 209 case WD2797_REG_COMMAND: // Command register
philpem@48 210 // write to command register clears interrupt request
philpem@48 211 ctx->irql = false;
philpem@48 212
philpem@48 213 // Is the drive ready?
philpem@48 214 if (ctx->disc_image == NULL) {
philpem@48 215 // No disc image, thus the drive is busy.
philpem@48 216 ctx->status = 0x80;
philpem@48 217 return;
philpem@48 218 }
philpem@48 219
philpem@48 220 // Handle Type 1 commands
philpem@48 221 switch (cmd) {
philpem@48 222 case CMD_RESTORE:
philpem@48 223 // Restore. Set track to 0 and throw an IRQ.
philpem@48 224 is_type1 = true;
philpem@48 225 ctx->track = 0;
philpem@48 226 break;
philpem@48 227
philpem@48 228 case CMD_SEEK:
philpem@48 229 // Seek. Seek to the track specced in the Data Register.
philpem@48 230 is_type1 = true;
philpem@48 231 if (ctx->data_reg < ctx->geom_tracks) {
philpem@48 232 ctx->track = ctx->data_reg;
philpem@48 233 } else {
philpem@48 234 // Seek error. :(
philpem@48 235 ctx->status = 0x10;
philpem@48 236 }
philpem@48 237
philpem@48 238 case CMD_STEP:
philpem@48 239 // TODO! deal with trk0!
philpem@48 240 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 241 is_type1 = true;
philpem@48 242 break;
philpem@48 243
philpem@48 244 case CMD_STEPIN:
philpem@48 245 case CMD_STEPOUT:
philpem@48 246 // TODO! deal with trk0!
philpem@48 247 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 248 if (cmd == CMD_STEPIN) {
philpem@48 249 ctx->last_step_dir = 1;
philpem@48 250 } else {
philpem@48 251 ctx->last_step_dir = -1;
philpem@48 252 }
philpem@48 253 is_type1 = true;
philpem@48 254 break;
philpem@48 255
philpem@48 256 case CMD_STEP_TU:
philpem@48 257 case CMD_STEPIN_TU:
philpem@48 258 case CMD_STEPOUT_TU:
philpem@48 259 // if this is a Step In or Step Out cmd, set the step-direction
philpem@48 260 if (cmd == CMD_STEPIN_TU) {
philpem@48 261 ctx->last_step_dir = 1;
philpem@48 262 } else if (cmd == CMD_STEPOUT_TU) {
philpem@48 263 ctx->last_step_dir = -1;
philpem@48 264 }
philpem@48 265
philpem@48 266 // Seek one step in the last direction used.
philpem@48 267 ctx->track += ctx->last_step_dir;
philpem@48 268 if (ctx->track < 0) ctx->track = 0;
philpem@48 269 if (ctx->track >= ctx->geom_tracks) {
philpem@48 270 // Seek past end of disc... that'll be a Seek Error then.
philpem@48 271 ctx->status = 0x10;
philpem@48 272 ctx->track = ctx->geom_tracks - 1;
philpem@48 273 }
philpem@48 274 is_type1 = true;
philpem@48 275 break;
philpem@48 276
philpem@48 277 default:
philpem@48 278 break;
philpem@48 279 }
philpem@48 280
philpem@48 281 if (is_type1) {
philpem@48 282 // Terminate any sector reads or writes
philpem@48 283 ctx->data_len = ctx->data_pos = 0;
philpem@48 284
philpem@48 285 // No DRQ bit for these commands.
philpem@48 286 ctx->cmd_has_drq = false;
philpem@48 287
philpem@48 288 // Type1 status byte...
philpem@48 289 ctx->status = 0;
philpem@48 290 // S7 = Not Ready. Command executed, therefore the drive was ready... :)
philpem@48 291 // S6 = Write Protect. TODO: add this
philpem@48 292 // S5 = Head Loaded. For certain emulation-related reasons, the heads are always loaded...
philpem@48 293 ctx->status |= 0x20;
philpem@48 294 // S4 = Seek Error. Not bloody likely if we got down here...!
philpem@48 295 // S3 = CRC Error. Not gonna happen on a disc image!
philpem@48 296 // S2 = Track 0
philpem@48 297 ctx->status |= (ctx->track == 0) ? 0x04 : 0x00;
philpem@48 298 // S1 = Index Pulse. TODO -- need periodics to emulate this
philpem@48 299 // S0 = Busy. We just exec'd the command, thus we're not busy.
philpem@48 300 // TODO: Set a timer for seeks, and ONLY clear BUSY when that timer expires. Need periodics for that.
philpem@48 301
philpem@48 302 // Set IRQ only if IRQL has been cleared (no pending IRQs)
philpem@48 303 ctx->irqe = !ctx->irql;
philpem@48 304 ctx->irql = true;
philpem@48 305 return;
philpem@48 306 }
philpem@48 307
philpem@48 308 // That's the Type 1 (seek) commands sorted. Now for the others.
philpem@48 309
philpem@48 310 // If drive isn't ready, then set status B7 and exit
philpem@48 311 if (ctx->disc_image == NULL) {
philpem@48 312 ctx->status = 0x80;
philpem@48 313 return;
philpem@48 314 }
philpem@48 315
philpem@48 316 // If this is a Write command, check write protect status too
philpem@48 317 // TODO!
philpem@48 318 if (false) {
philpem@48 319 // Write protected disc...
philpem@48 320 if ((cmd == CMD_WRITE_SECTOR) || (cmd == CMD_WRITE_SECTOR_MULTI) || (cmd == CMD_FORMAT_TRACK)) {
philpem@48 321 // Set Write Protect bit and bail.
philpem@48 322 ctx->status = 0x40;
philpem@48 323
philpem@48 324 // Set IRQ only if IRQL has been cleared (no pending IRQs)
philpem@48 325 ctx->irqe = !ctx->irql;
philpem@48 326 ctx->irql = true;
philpem@48 327
philpem@48 328 return;
philpem@48 329 }
philpem@48 330 }
philpem@48 331
philpem@48 332 // Disc is ready to go. Parse the command word.
philpem@48 333 switch (cmd) {
philpem@48 334 case CMD_READ_ADDRESS:
philpem@48 335 // Read Address
philpem@48 336
philpem@48 337 // reset data pointers
philpem@48 338 ctx->data_pos = ctx->data_len = 0;
philpem@48 339
philpem@48 340 // load data buffer
philpem@48 341 ctx->data[ctx->data_len++] = ctx->track;
philpem@48 342 ctx->data[ctx->data_len++] = ctx->head;
philpem@48 343 ctx->data[ctx->data_len++] = ctx->sector;
philpem@48 344 switch (ctx->geom_secsz) {
philpem@48 345 case 128: ctx->data[ctx->data_len++] = 0; break;
philpem@48 346 case 256: ctx->data[ctx->data_len++] = 1; break;
philpem@48 347 case 512: ctx->data[ctx->data_len++] = 2; break;
philpem@48 348 case 1024: ctx->data[ctx->data_len++] = 3; break;
philpem@48 349 default: ctx->data[ctx->data_len++] = 0xFF; break; // TODO: deal with invalid values better
philpem@48 350 }
philpem@48 351 ctx->data[ctx->data_len++] = 0; // TODO: IDAM CRC!
philpem@48 352 ctx->data[ctx->data_len++] = 0;
philpem@48 353
philpem@48 354 // B6, B5 = 0
philpem@48 355 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 356 // B3 = CRC Error. Not possible.
philpem@48 357 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 358 // B1 = DRQ. Data request.
philpem@48 359 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 360 break;
philpem@48 361
philpem@48 362 case CMD_READ_SECTOR:
philpem@48 363 case CMD_READ_SECTOR_MULTI:
philpem@48 364 // Read Sector or Read Sector Multiple
philpem@48 365 // reset data pointers
philpem@48 366 ctx->data_pos = ctx->data_len = 0;
philpem@48 367
philpem@49 368 // Calculate number of sectors to read from disc
philpem@49 369 if (cmd == CMD_READ_SECTOR_MULTI)
philpem@49 370 temp = ctx->geom_spt;
philpem@49 371 else
philpem@49 372 temp = 1;
philpem@48 373
philpem@49 374 for (int i=0; i<temp; i++) {
philpem@49 375 // Calculate the LBA address of the required sector
philpem@51 376 lba = ((((ctx->track * ctx->geom_heads) + ctx->head) * ctx->geom_spt) + ((ctx->sector + i - 1) % ctx->geom_spt)) * ctx->geom_secsz;
philpem@49 377
philpem@49 378 // Read the sector from the file
philpem@49 379 fseek(ctx->disc_image, lba, SEEK_SET);
philpem@49 380 ctx->data_len += fread(&ctx->data[ctx->data_len], 1, ctx->geom_secsz, ctx->disc_image);
philpem@49 381 // TODO: check fread return value! if < secsz, BAIL! (call it a crc error or secnotfound maybe? also log to stderr)
philpem@49 382 }
philpem@48 383
philpem@48 384 // B6 = 0
philpem@48 385 // B5 = Record Type -- 1 = deleted, 0 = normal. We can't emulate anything but normal data blocks.
philpem@48 386 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 387 // B3 = CRC Error. Not possible.
philpem@48 388 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 389 // B1 = DRQ. Data request.
philpem@48 390 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 391 break;
philpem@48 392
philpem@48 393 case CMD_READ_TRACK:
philpem@48 394 // Read Track
philpem@49 395 // TODO! implement this
philpem@48 396 // B6, B5, B4, B3 = 0
philpem@48 397 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 398 // B1 = DRQ. Data request.
philpem@48 399 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 400 break;
philpem@48 401
philpem@48 402 case CMD_WRITE_SECTOR:
philpem@48 403 case CMD_WRITE_SECTOR_MULTI:
philpem@48 404 // Write Sector or Write Sector Multiple
philpem@48 405
philpem@48 406 // reset data pointers
philpem@48 407 ctx->data_pos = ctx->data_len = 0;
philpem@48 408
philpem@48 409 // TODO: set "write pending" flag, and write LBA, and go from there.
philpem@48 410
philpem@48 411 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 412 // B5 = 0
philpem@48 413 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 414 // B3 = CRC Error. Not possible.
philpem@48 415 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 416 // B1 = DRQ. Data request.
philpem@48 417 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 418 break;
philpem@48 419
philpem@48 420 case CMD_FORMAT_TRACK:
philpem@48 421 // Write Track (aka Format Track)
philpem@48 422 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 423 // B5, B4, B3 = 0
philpem@48 424 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 425 // B1 = DRQ. Data request.
philpem@48 426 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 427 break;
philpem@48 428
philpem@48 429 case CMD_FORCE_INTERRUPT:
philpem@48 430 // Force Interrupt...
philpem@49 431 // Terminates current operation and sends an interrupt
philpem@49 432 // TODO!
philpem@49 433 ctx->data_pos = ctx->data_len = 0;
philpem@49 434 // Set IRQ only if IRQL has been cleared (no pending IRQs)
philpem@49 435 ctx->irqe = !ctx->irql;
philpem@49 436 ctx->irql = true;
philpem@48 437 break;
philpem@48 438 }
philpem@48 439 break;
philpem@48 440
philpem@49 441 case WD2797_REG_TRACK: // Track register
philpem@48 442 ctx->track = val;
philpem@48 443 break;
philpem@48 444
philpem@49 445 case WD2797_REG_SECTOR: // Sector register
philpem@48 446 ctx->sector = val;
philpem@48 447 break;
philpem@48 448
philpem@49 449 case WD2797_REG_DATA: // Data register
philpem@48 450 // Save the value written into the data register
philpem@48 451 ctx->data_reg = val;
philpem@48 452
philpem@48 453 // If we're processing a write command, and there's space in the
philpem@48 454 // buffer, allow the write.
philpem@48 455 if (ctx->data_pos < ctx->data_len) {
philpem@48 456 // store data byte and increment pointer
philpem@48 457 ctx->data[ctx->data_pos++] = val;
philpem@48 458 }
philpem@48 459 break;
philpem@48 460 }
philpem@48 461 }
philpem@48 462