src/wd279x.c

Wed, 29 Dec 2010 09:06:17 +0000

author
Philip Pemberton <philpem@philpem.me.uk>
date
Wed, 29 Dec 2010 09:06:17 +0000
changeset 79
674226015c8a
parent 78
c149c13aff1c
parent 77
e7898cbae0c6
child 111
4c85846b09cd
permissions
-rw-r--r--

eliminate redundant head

philpem@48 1 #include <stdint.h>
philpem@48 2 #include <stdbool.h>
philpem@49 3 #include <malloc.h>
philpem@53 4 #include "musashi/m68k.h"
philpem@48 5 #include "wd279x.h"
philpem@48 6
philpem@73 7 #ifndef WD279X_DEBUG
philpem@71 8 #define NDEBUG
philpem@73 9 #endif
philpem@71 10 #include "utils.h"
philpem@71 11
philpem@48 12 /// WD2797 command constants
philpem@48 13 enum {
philpem@48 14 CMD_MASK = 0xF0, ///< Bit mask to detect command bits
philpem@48 15 CMD_RESTORE = 0x00, ///< Restore (recalibrate, seek to track 0)
philpem@48 16 CMD_SEEK = 0x10, ///< Seek to given track
philpem@48 17 CMD_STEP = 0x20, ///< Step
philpem@48 18 CMD_STEP_TU = 0x30, ///< Step and update track register
philpem@48 19 CMD_STEPIN = 0x40, ///< Step In
philpem@48 20 CMD_STEPIN_TU = 0x50, ///< Step In and update track register
philpem@48 21 CMD_STEPOUT = 0x60, ///< Step Out
philpem@48 22 CMD_STEPOUT_TU = 0x70, ///< Step Out and update track register
philpem@48 23 CMD_READ_SECTOR = 0x80, ///< Read Sector
philpem@48 24 CMD_READ_SECTOR_MULTI = 0x90, ///< Read Multiple Sectors
philpem@48 25 CMD_WRITE_SECTOR = 0xA0, ///< Write Sector
philpem@48 26 CMD_WRITE_SECTOR_MULTI = 0xB0, ///< Write Multiple Sectors
philpem@48 27 CMD_READ_ADDRESS = 0xC0, ///< Read Address (IDAM contents)
philpem@48 28 CMD_FORCE_INTERRUPT = 0xD0, ///< Force Interrupt
philpem@48 29 CMD_READ_TRACK = 0xE0, ///< Read Track
philpem@48 30 CMD_FORMAT_TRACK = 0xF0 ///< Format Track
philpem@48 31 };
philpem@48 32
philpem@48 33
philpem@49 34 void wd2797_init(WD2797_CTX *ctx)
philpem@48 35 {
philpem@48 36 // track, head and sector unknown
philpem@49 37 ctx->track = ctx->head = ctx->sector = 0;
philpem@48 38
philpem@49 39 // no IRQ pending
philpem@76 40 ctx->irq = false;
philpem@48 41
philpem@48 42 // no data available
philpem@49 43 ctx->data_pos = ctx->data_len = 0;
philpem@49 44 ctx->data = NULL;
philpem@49 45
philpem@76 46 // Status register clear, not busy; type1 command
philpem@49 47 ctx->status = 0;
philpem@76 48 ctx->cmd_has_drq = false;
philpem@49 49
philpem@49 50 // Clear data register
philpem@49 51 ctx->data_reg = 0;
philpem@49 52
philpem@76 53 // Last step direction = "towards zero"
philpem@49 54 ctx->last_step_dir = -1;
philpem@48 55
philpem@48 56 // No disc image loaded
philpem@48 57 ctx->disc_image = NULL;
philpem@49 58 ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = ctx->geom_tracks = 0;
philpem@48 59 }
philpem@48 60
philpem@48 61
philpem@49 62 void wd2797_reset(WD2797_CTX *ctx)
philpem@49 63 {
philpem@49 64 // track, head and sector unknown
philpem@49 65 ctx->track = ctx->head = ctx->sector = 0;
philpem@49 66
philpem@49 67 // no IRQ pending
philpem@76 68 ctx->irq = false;
philpem@49 69
philpem@49 70 // no data available
philpem@49 71 ctx->data_pos = ctx->data_len = 0;
philpem@49 72
philpem@49 73 // Status register clear, not busy
philpem@49 74 ctx->status = 0;
philpem@49 75
philpem@49 76 // Clear data register
philpem@49 77 ctx->data_reg = 0;
philpem@49 78
philpem@49 79 // Last step direction
philpem@49 80 ctx->last_step_dir = -1;
philpem@49 81 }
philpem@49 82
philpem@49 83
philpem@49 84 void wd2797_done(WD2797_CTX *ctx)
philpem@49 85 {
philpem@49 86 // Reset the WD2797
philpem@49 87 wd2797_reset(ctx);
philpem@49 88
philpem@49 89 // Free any allocated memory
philpem@49 90 if (ctx->data) {
philpem@49 91 free(ctx->data);
philpem@49 92 ctx->data = NULL;
philpem@49 93 }
philpem@49 94 }
philpem@49 95
philpem@49 96
philpem@49 97 bool wd2797_get_irq(WD2797_CTX *ctx)
philpem@48 98 {
philpem@76 99 return ctx->irq;
philpem@48 100 }
philpem@48 101
philpem@48 102
philpem@49 103 bool wd2797_get_drq(WD2797_CTX *ctx)
philpem@48 104 {
philpem@48 105 return (ctx->data_pos < ctx->data_len);
philpem@48 106 }
philpem@48 107
philpem@48 108
philpem@49 109 WD2797_ERR wd2797_load(WD2797_CTX *ctx, FILE *fp, int secsz, int spt, int heads)
philpem@49 110 {
philpem@49 111 size_t filesize;
philpem@49 112
philpem@49 113 // Start by finding out how big the image file is
philpem@49 114 fseek(fp, 0, SEEK_END);
philpem@49 115 filesize = ftell(fp);
philpem@49 116 fseek(fp, 0, SEEK_SET);
philpem@49 117
philpem@49 118 // Now figure out how many tracks it contains
philpem@49 119 int tracks = filesize / secsz / spt / heads;
philpem@49 120 // Confirm...
philpem@49 121 if (tracks < 1) {
philpem@49 122 return WD2797_ERR_BAD_GEOM;
philpem@49 123 }
philpem@49 124
philpem@49 125 // Allocate enough memory to store one disc track
philpem@49 126 if (ctx->data) {
philpem@49 127 free(ctx->data);
philpem@49 128 }
philpem@49 129 ctx->data = malloc(secsz * spt);
philpem@49 130 if (!ctx->data)
philpem@49 131 return WD2797_ERR_NO_MEMORY;
philpem@49 132
philpem@49 133 // Load the image and the geometry data
philpem@49 134 ctx->disc_image = fp;
philpem@49 135 ctx->geom_tracks = tracks;
philpem@49 136 ctx->geom_secsz = secsz;
philpem@49 137 ctx->geom_heads = heads;
philpem@49 138 ctx->geom_spt = spt;
philpem@49 139
philpem@49 140 return WD2797_ERR_OK;
philpem@49 141 }
philpem@49 142
philpem@49 143
philpem@49 144 void wd2797_unload(WD2797_CTX *ctx)
philpem@49 145 {
philpem@49 146 // Free memory buffer
philpem@49 147 if (ctx->data) {
philpem@49 148 free(ctx->data);
philpem@49 149 ctx->data = NULL;
philpem@49 150 }
philpem@49 151
philpem@49 152 // Clear file pointer
philpem@49 153 ctx->disc_image = NULL;
philpem@49 154
philpem@49 155 // Clear the disc geometry
philpem@49 156 ctx->geom_tracks = ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = 0;
philpem@49 157 }
philpem@49 158
philpem@49 159
philpem@49 160 uint8_t wd2797_read_reg(WD2797_CTX *ctx, uint8_t addr)
philpem@48 161 {
philpem@48 162 uint8_t temp = 0;
philpem@48 163
philpem@48 164 switch (addr & 0x03) {
philpem@49 165 case WD2797_REG_STATUS: // Status register
philpem@48 166 // Read from status register clears IRQ
philpem@76 167 ctx->irq = false;
philpem@48 168
philpem@48 169 // Get current status flags (set by last command)
philpem@48 170 // DRQ bit
philpem@53 171 if (ctx->cmd_has_drq) {
philpem@53 172 temp = ctx->status & ~0x03;
philpem@48 173 temp |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@71 174 LOG("\tWDFDC rd sr, has drq, pos=%lu len=%lu, sr=0x%02X", ctx->data_pos, ctx->data_len, temp);
philpem@53 175 } else {
philpem@53 176 temp = ctx->status & ~0x01;
philpem@53 177 }
philpem@48 178 // FDC is busy if there is still data in the buffer
philpem@48 179 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@49 180 // TODO: also if seek delay / read delay hasn't passed (but that's for later)
philpem@48 181 return temp;
philpem@48 182
philpem@49 183 case WD2797_REG_TRACK: // Track register
philpem@48 184 return ctx->track;
philpem@48 185
philpem@49 186 case WD2797_REG_SECTOR: // Sector register
philpem@48 187 return ctx->sector;
philpem@48 188
philpem@49 189 case WD2797_REG_DATA: // Data register
philpem@48 190 // If there's data in the buffer, return it. Otherwise return 0xFF.
philpem@48 191 if (ctx->data_pos < ctx->data_len) {
philpem@53 192 // set IRQ if this is the last data byte
philpem@53 193 if (ctx->data_pos == (ctx->data_len-1)) {
philpem@76 194 // Set IRQ
philpem@76 195 ctx->irq = true;
philpem@53 196 }
philpem@48 197 // return data byte and increment pointer
philpem@48 198 return ctx->data[ctx->data_pos++];
philpem@48 199 } else {
philpem@53 200 // command finished
philpem@48 201 return 0xff;
philpem@48 202 }
philpem@48 203
philpem@48 204 default:
philpem@48 205 // shut up annoying compilers which don't recognise unreachable code when they see it
philpem@48 206 // (here's looking at you, gcc!)
philpem@48 207 return 0xff;
philpem@48 208 }
philpem@48 209 }
philpem@48 210
philpem@48 211
philpem@49 212 void wd2797_write_reg(WD2797_CTX *ctx, uint8_t addr, uint8_t val)
philpem@48 213 {
philpem@48 214 uint8_t cmd = val & CMD_MASK;
philpem@48 215 size_t lba;
philpem@48 216 bool is_type1 = false;
philpem@49 217 int temp;
philpem@48 218
philpem@53 219 m68k_end_timeslice();
philpem@53 220
philpem@48 221 switch (addr) {
philpem@49 222 case WD2797_REG_COMMAND: // Command register
philpem@48 223 // write to command register clears interrupt request
philpem@76 224 ctx->irq = false;
philpem@48 225
philpem@48 226 // Is the drive ready?
philpem@48 227 if (ctx->disc_image == NULL) {
philpem@48 228 // No disc image, thus the drive is busy.
philpem@48 229 ctx->status = 0x80;
philpem@48 230 return;
philpem@48 231 }
philpem@48 232
philpem@48 233 // Handle Type 1 commands
philpem@48 234 switch (cmd) {
philpem@48 235 case CMD_RESTORE:
philpem@48 236 // Restore. Set track to 0 and throw an IRQ.
philpem@48 237 is_type1 = true;
philpem@48 238 ctx->track = 0;
philpem@48 239 break;
philpem@48 240
philpem@48 241 case CMD_SEEK:
philpem@48 242 // Seek. Seek to the track specced in the Data Register.
philpem@48 243 is_type1 = true;
philpem@48 244 if (ctx->data_reg < ctx->geom_tracks) {
philpem@48 245 ctx->track = ctx->data_reg;
philpem@48 246 } else {
philpem@48 247 // Seek error. :(
philpem@48 248 ctx->status = 0x10;
philpem@48 249 }
philpem@48 250
philpem@48 251 case CMD_STEP:
philpem@48 252 // TODO! deal with trk0!
philpem@48 253 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 254 is_type1 = true;
philpem@48 255 break;
philpem@48 256
philpem@48 257 case CMD_STEPIN:
philpem@48 258 case CMD_STEPOUT:
philpem@48 259 // TODO! deal with trk0!
philpem@48 260 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 261 if (cmd == CMD_STEPIN) {
philpem@48 262 ctx->last_step_dir = 1;
philpem@48 263 } else {
philpem@48 264 ctx->last_step_dir = -1;
philpem@48 265 }
philpem@48 266 is_type1 = true;
philpem@48 267 break;
philpem@48 268
philpem@48 269 case CMD_STEP_TU:
philpem@48 270 case CMD_STEPIN_TU:
philpem@48 271 case CMD_STEPOUT_TU:
philpem@48 272 // if this is a Step In or Step Out cmd, set the step-direction
philpem@48 273 if (cmd == CMD_STEPIN_TU) {
philpem@48 274 ctx->last_step_dir = 1;
philpem@48 275 } else if (cmd == CMD_STEPOUT_TU) {
philpem@48 276 ctx->last_step_dir = -1;
philpem@48 277 }
philpem@48 278
philpem@48 279 // Seek one step in the last direction used.
philpem@48 280 ctx->track += ctx->last_step_dir;
philpem@48 281 if (ctx->track < 0) ctx->track = 0;
philpem@48 282 if (ctx->track >= ctx->geom_tracks) {
philpem@48 283 // Seek past end of disc... that'll be a Seek Error then.
philpem@48 284 ctx->status = 0x10;
philpem@48 285 ctx->track = ctx->geom_tracks - 1;
philpem@48 286 }
philpem@48 287 is_type1 = true;
philpem@48 288 break;
philpem@48 289
philpem@48 290 default:
philpem@48 291 break;
philpem@48 292 }
philpem@48 293
philpem@48 294 if (is_type1) {
philpem@48 295 // Terminate any sector reads or writes
philpem@48 296 ctx->data_len = ctx->data_pos = 0;
philpem@48 297
philpem@48 298 // No DRQ bit for these commands.
philpem@48 299 ctx->cmd_has_drq = false;
philpem@48 300
philpem@48 301 // Type1 status byte...
philpem@48 302 ctx->status = 0;
philpem@48 303 // S7 = Not Ready. Command executed, therefore the drive was ready... :)
philpem@48 304 // S6 = Write Protect. TODO: add this
philpem@48 305 // S5 = Head Loaded. For certain emulation-related reasons, the heads are always loaded...
philpem@48 306 ctx->status |= 0x20;
philpem@48 307 // S4 = Seek Error. Not bloody likely if we got down here...!
philpem@48 308 // S3 = CRC Error. Not gonna happen on a disc image!
philpem@48 309 // S2 = Track 0
philpem@48 310 ctx->status |= (ctx->track == 0) ? 0x04 : 0x00;
philpem@48 311 // S1 = Index Pulse. TODO -- need periodics to emulate this
philpem@48 312 // S0 = Busy. We just exec'd the command, thus we're not busy.
philpem@48 313 // TODO: Set a timer for seeks, and ONLY clear BUSY when that timer expires. Need periodics for that.
philpem@48 314
philpem@76 315 // Set IRQ
philpem@76 316 ctx->irq = true;
philpem@48 317 return;
philpem@48 318 }
philpem@48 319
philpem@48 320 // That's the Type 1 (seek) commands sorted. Now for the others.
philpem@48 321
philpem@53 322 // All these commands return the DRQ bit...
philpem@53 323 ctx->cmd_has_drq = true;
philpem@53 324
philpem@48 325 // If drive isn't ready, then set status B7 and exit
philpem@48 326 if (ctx->disc_image == NULL) {
philpem@48 327 ctx->status = 0x80;
philpem@48 328 return;
philpem@48 329 }
philpem@48 330
philpem@48 331 // If this is a Write command, check write protect status too
philpem@48 332 // TODO!
philpem@48 333 if (false) {
philpem@48 334 // Write protected disc...
philpem@48 335 if ((cmd == CMD_WRITE_SECTOR) || (cmd == CMD_WRITE_SECTOR_MULTI) || (cmd == CMD_FORMAT_TRACK)) {
philpem@48 336 // Set Write Protect bit and bail.
philpem@48 337 ctx->status = 0x40;
philpem@48 338
philpem@76 339 // Set IRQ
philpem@76 340 ctx->irq = true;
philpem@48 341
philpem@48 342 return;
philpem@48 343 }
philpem@48 344 }
philpem@48 345
philpem@48 346 // Disc is ready to go. Parse the command word.
philpem@48 347 switch (cmd) {
philpem@48 348 case CMD_READ_ADDRESS:
philpem@48 349 // Read Address
philpem@54 350 ctx->head = (val & 0x02) ? 1 : 0;
philpem@48 351
philpem@48 352 // reset data pointers
philpem@48 353 ctx->data_pos = ctx->data_len = 0;
philpem@48 354
philpem@48 355 // load data buffer
philpem@48 356 ctx->data[ctx->data_len++] = ctx->track;
philpem@48 357 ctx->data[ctx->data_len++] = ctx->head;
philpem@48 358 ctx->data[ctx->data_len++] = ctx->sector;
philpem@48 359 switch (ctx->geom_secsz) {
philpem@48 360 case 128: ctx->data[ctx->data_len++] = 0; break;
philpem@48 361 case 256: ctx->data[ctx->data_len++] = 1; break;
philpem@48 362 case 512: ctx->data[ctx->data_len++] = 2; break;
philpem@48 363 case 1024: ctx->data[ctx->data_len++] = 3; break;
philpem@48 364 default: ctx->data[ctx->data_len++] = 0xFF; break; // TODO: deal with invalid values better
philpem@48 365 }
philpem@48 366 ctx->data[ctx->data_len++] = 0; // TODO: IDAM CRC!
philpem@48 367 ctx->data[ctx->data_len++] = 0;
philpem@48 368
philpem@53 369 ctx->status = 0;
philpem@48 370 // B6, B5 = 0
philpem@48 371 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 372 // B3 = CRC Error. Not possible.
philpem@48 373 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 374 // B1 = DRQ. Data request.
philpem@48 375 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 376 break;
philpem@48 377
philpem@48 378 case CMD_READ_SECTOR:
philpem@48 379 case CMD_READ_SECTOR_MULTI:
philpem@54 380 ctx->head = (val & 0x02) ? 1 : 0;
philpem@71 381 LOG("WD279X: READ SECTOR cmd=%02X chs=%d:%d:%d", cmd, ctx->track, ctx->head, ctx->sector);
philpem@48 382 // Read Sector or Read Sector Multiple
philpem@57 383
philpem@57 384 // Check to see if the cyl, hd and sec are valid
philpem@57 385 if ((ctx->track > (ctx->geom_tracks-1)) || (ctx->head > (ctx->geom_heads-1)) || (ctx->sector > ctx->geom_spt) || (ctx->sector == 0)) {
philpem@71 386 LOG("*** WD2797 ALERT: CHS parameter limit exceeded! CHS=%d:%d:%d, maxCHS=%d:%d:%d",
philpem@57 387 ctx->track, ctx->head, ctx->sector,
philpem@57 388 ctx->geom_tracks-1, ctx->geom_heads-1, ctx->geom_spt);
philpem@57 389 // CHS parameters exceed limits
philpem@57 390 ctx->status = 0x10; // Record Not Found
philpem@57 391 break;
philpem@78 392 // Set IRQ
philpem@78 393 ctx->irq = true;
philpem@57 394 }
philpem@57 395
philpem@48 396 // reset data pointers
philpem@48 397 ctx->data_pos = ctx->data_len = 0;
philpem@48 398
philpem@49 399 // Calculate number of sectors to read from disc
philpem@49 400 if (cmd == CMD_READ_SECTOR_MULTI)
philpem@49 401 temp = ctx->geom_spt;
philpem@49 402 else
philpem@49 403 temp = 1;
philpem@48 404
philpem@49 405 for (int i=0; i<temp; i++) {
philpem@49 406 // Calculate the LBA address of the required sector
philpem@57 407 // LBA = (C * nHeads * nSectors) + (H * nSectors) + S - 1
philpem@57 408 lba = (((ctx->track * ctx->geom_heads * ctx->geom_spt) + (ctx->head * ctx->geom_spt) + ctx->sector) + i) - 1;
philpem@57 409 // convert LBA to byte address
philpem@57 410 lba *= ctx->geom_secsz;
philpem@71 411 LOG("\tREAD lba = %lu", lba);
philpem@49 412
philpem@49 413 // Read the sector from the file
philpem@49 414 fseek(ctx->disc_image, lba, SEEK_SET);
philpem@71 415 // TODO: check fread return value! if < secsz, BAIL! (call it a crc error or secnotfound maybe? also log to stderr)
philpem@49 416 ctx->data_len += fread(&ctx->data[ctx->data_len], 1, ctx->geom_secsz, ctx->disc_image);
philpem@71 417 LOG("\tREAD len=%lu, pos=%lu, ssz=%d", ctx->data_len, ctx->data_pos, ctx->geom_secsz);
philpem@49 418 }
philpem@48 419
philpem@53 420 ctx->status = 0;
philpem@48 421 // B6 = 0
philpem@48 422 // B5 = Record Type -- 1 = deleted, 0 = normal. We can't emulate anything but normal data blocks.
philpem@57 423 // B4 = Record Not Found. Basically, the CHS parameters are bullcrap.
philpem@48 424 // B3 = CRC Error. Not possible.
philpem@48 425 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 426 // B1 = DRQ. Data request.
philpem@48 427 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 428 break;
philpem@48 429
philpem@48 430 case CMD_READ_TRACK:
philpem@48 431 // Read Track
philpem@49 432 // TODO! implement this
philpem@54 433 ctx->head = (val & 0x02) ? 1 : 0;
philpem@53 434 ctx->status = 0;
philpem@48 435 // B6, B5, B4, B3 = 0
philpem@48 436 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 437 // B1 = DRQ. Data request.
philpem@48 438 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 439 break;
philpem@48 440
philpem@48 441 case CMD_WRITE_SECTOR:
philpem@48 442 case CMD_WRITE_SECTOR_MULTI:
philpem@48 443 // Write Sector or Write Sector Multiple
philpem@48 444
philpem@54 445 ctx->head = (val & 0x02) ? 1 : 0;
philpem@48 446 // reset data pointers
philpem@48 447 ctx->data_pos = ctx->data_len = 0;
philpem@48 448
philpem@48 449 // TODO: set "write pending" flag, and write LBA, and go from there.
philpem@48 450
philpem@53 451 ctx->status = 0;
philpem@48 452 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 453 // B5 = 0
philpem@48 454 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 455 // B3 = CRC Error. Not possible.
philpem@48 456 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 457 // B1 = DRQ. Data request.
philpem@48 458 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 459 break;
philpem@48 460
philpem@48 461 case CMD_FORMAT_TRACK:
philpem@48 462 // Write Track (aka Format Track)
philpem@54 463 ctx->head = (val & 0x02) ? 1 : 0;
philpem@53 464 ctx->status = 0;
philpem@48 465 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 466 // B5, B4, B3 = 0
philpem@48 467 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 468 // B1 = DRQ. Data request.
philpem@48 469 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 470 break;
philpem@48 471
philpem@48 472 case CMD_FORCE_INTERRUPT:
philpem@48 473 // Force Interrupt...
philpem@49 474 // Terminates current operation and sends an interrupt
philpem@49 475 // TODO!
philpem@53 476 ctx->status = 0;
philpem@49 477 ctx->data_pos = ctx->data_len = 0;
philpem@76 478 // Set IRQ
philpem@76 479 ctx->irq = true;
philpem@48 480 break;
philpem@48 481 }
philpem@48 482 break;
philpem@48 483
philpem@49 484 case WD2797_REG_TRACK: // Track register
philpem@48 485 ctx->track = val;
philpem@48 486 break;
philpem@48 487
philpem@49 488 case WD2797_REG_SECTOR: // Sector register
philpem@48 489 ctx->sector = val;
philpem@48 490 break;
philpem@48 491
philpem@49 492 case WD2797_REG_DATA: // Data register
philpem@48 493 // Save the value written into the data register
philpem@48 494 ctx->data_reg = val;
philpem@48 495
philpem@48 496 // If we're processing a write command, and there's space in the
philpem@48 497 // buffer, allow the write.
philpem@48 498 if (ctx->data_pos < ctx->data_len) {
philpem@53 499 // set IRQ if this is the last data byte
philpem@53 500 if (ctx->data_pos == (ctx->data_len-1)) {
philpem@76 501 // Set IRQ
philpem@76 502 ctx->irq = true;
philpem@53 503 }
philpem@53 504
philpem@48 505 // store data byte and increment pointer
philpem@48 506 ctx->data[ctx->data_pos++] = val;
philpem@48 507 }
philpem@48 508 break;
philpem@48 509 }
philpem@48 510 }
philpem@48 511