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

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